research article dark energy from the gas of wormholes · 2017. 7. 17. · is called as the...
TRANSCRIPT
![Page 1: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/1.jpg)
Hindawi Publishing CorporationJournal of AstrophysicsVolume 2013 Article ID 543717 14 pageshttpdxdoiorg1011552013543717
Research ArticleDark Energy from the Gas of Wormholes
A A Kirillov and E P Savelova
Dubna International University of Nature Society and Man Universitetskaya Street 19 Dubna 141980 Russia
Correspondence should be addressed to A A Kirillov ka98mailru
Received 21 March 2013 Accepted 29 May 2013
Academic Editors C Ghag M Jamil and S Profumo
Copyright copy 2013 A A Kirillov and E P Savelova This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited
We assume the space-time foam picture in which the vacuum is filled with a gas of virtual wormholes It is shown that virtualwormholes form a finite (of the Planckian order) value of the energy density of zero-point fluctuations However such a hugevalue is compensated by the contribution of virtual wormholes to the mean curvature and the observed value of the cosmologicalconstant is close to zero A nonvanishing value appears due to the polarization of vacuum in external classical fields In the earlyUniverse some virtual wormholes may form actual ones We show that in the case of actual wormholes vacuum polarization effectsare negligible while their contribution to the mean curvature is apt to form the observed dark energy phenomenon Using thecontribution of wormholes to dark matter and dark energy we find estimates for characteristic parameters of the gas of wormholes
1 Introduction
As is well known modern astrophysics (and even moregenerally theoretical physics) faces two key problems Thoseare the nature of dark matter and dark energy Recall thatmore than 90 of matter of the Universe has a nonbaryonicdark (to say mysterious) form while lab experiments stillshow no evidence for the existence of such matter Bothdark components are intrinsically incorporated in the mostsuccessful ΛCDM (Lambda cold dark matter) model whichreproduces correctly properties of the Universe at very largescales (eg see [1] and references therein) We point out thatΛCDM predicts also the presence of cusps (120588DM sim 1119903)
in centers of galaxies [2] and a too large number of galaxysatellites Therefore other models are proposed for examplelike axions [3] which may avoid these To be successfulsuch models should involve a periodic self-interaction andtherefore require a fine tuning while in general the presenceof standard nonbaryonic particles cannot solve the problemof cusps Indeed if we admit the existence of a self-interactionin the dark matter component or some coupling to baryonicmatter (which should be sufficiently strong to remove cusps)then we completely change properties of the dark mattercomponent at the moment of recombination and destroy allsuccessful predictions at very large scales Recall that both
warm and self-interacting darkmatter candidates are rejectedby the observing Δ119879119879 spectrum [1] In other words the twokey observational phenomena (cores of darkmatter in centersof galaxies [4ndash6] andΔ119879119879 spectrum) give a very narrow gapfor dark matter particles which seems to require attractingsome exotic objects in addition to standard nonbaryonicparticles
As it was demonstrated recently [7] the problem of cuspscan be cured if some part of nonbaryon particles is replacedby wormholes Wormholes represent extremely heavy (incomparison to particles) objects which at very large scalesbehave exactly like nonbaryon cold particles while at smallerscales (in galaxies) they strongly interact with baryons andform the observed [4ndash6] cored (120588DM sim const) distributionWe note that stable wormholes violate necessarily the aver-aged null energy conditions which gives the basic argumentagainst the existence of such objects Without exotic matterstable wormholes may however exist in modified theoriesfor example see [8] and references therein In the casewhen the energy conditions hold a wormhole collapses intoa couple of conjugated (of equal masses) blackholes whichalmost impossible to distinguish from standard primordialblackholes However the topological nontriviality of suchobjects retains and gravitational effects of a gas of wormholesconsidered in [9] and some results of [7] still remain valid
2 Journal of Astrophysics
which means that nontraversable wormholes can be used tosmooth cusps in centers of galaxies Thus it worth expectingthatwormholesmay play an important role in the explanationof the dark matter phenomenon
Saving the dark matter component ΛCDM requiresthe presence (sim70) of dark energy (of the cosmologicalconstant) Moreover there is evidence for the start of anacceleration phase in the evolution of the Universe [10ndash14]In the present paper we use virtual wormholes to estimatethe contribution of zero-point fluctuations in the value of thecosmological constant The idea to relate virtual wormholes(or baby universes) and the cosmological constant is not newin somewhat different context it was used by Coleman in [15]and developed in [16] Our basic aim is to demonstrate thatvirtual wormholes form a finite value of the energy density ofzero-point fluctuations
It is necessary to point here out to the principle differ-ence between actual and virtual wormholes The principledifference is that a virtual wormhole exists only for a verysmall period of time and at very small scales and doesnot necessarily obey to the Einstein equations It representstunnelling event and therefore the averaged null energycondition (ANEC) cannot forbid the origin of such an objectFor the future we also note that a set of virtual wormholesmay work as an actual wormhole opening thus the way foran artificial construction of wormhole-type objects in labexperiments
In the present paper we describe a virtual wormholeas follows From the very beginning we use the Euclideanapproach (eg see [17] and the standard textbooks [18])Thenthe simplest virtual wormhole is described by themetric (120572 =
1 2 3 4)
1198891199042= ℎ
2(119903) 120575
120572120573119889119909
120572119889119909
120573 (1)
where
ℎ (119903) = 1 + 120579 (119886 minus 119903) (1198862
1199032minus 1) (2)
and 120579(119909) is the step function Such a wormhole has vanishingthroat length while the step function at the junction maycause a problem in Einsteinrsquos equation or when a topologicalEuler term is involved A more careful analysis needs to con-sider distributional curvature and so forth see [19] To avoidthese difficulties we may consider from the very beginninga wormhole of a finite throat length sim1120573 where the stepfunction is replaced with a smooth function (eg 120579(119909 120573) =
(exp (120573119909)+1)minus1)Thenwhere it is necessary onemay considerthe limit 120573 rarr infin only in final expressions This insuresthat the Bianchi identity holds and that the above metricremains inside of the domain of usual gravity (Unexpectedlyour approach (the use of step function) seems to irritate anessential part of physicists working with wormholes (egPRD reviewers moreover there is a claim that we studysome other exotic objects which are not wormholes [20])Therefore it is necessary to clarify our position here We arequite aware that at present state the physics of wormholes iscertainly on the most speculative side Therefore we do not
see the difference between specific forms of a smooth metricthat one may use For example the simplest choice ℎ = (1 +
1198862119903
2) gives the well-known metric which in 3-dimensions
is called as the Bronnikov-Ellis metric or the metric ℎ =
(1 + (119887119903) + (1198862119903
2)) which includes an additional parameter
(an arbitrary length of the handle) which is not called by anyname but is not less trivial In the case of actual wormholesthe exact and correct form of metric may be establishedonly upon understanding the nature and properties of exoticmatter which may support such a metric as a stable solutionto the Einstein equations For this time has not come yet Inthe case of virtual wormholes even this is not important for inthe complete theory one has to sum over all possible metricswhich formally may be included in 120593 in (5) Our basic aimis to present sufficiently clear and simple model (let it be farfrom realistic) which retains basic qualitative features relatedto a nontrivial topology)
In the region 119903 gt 119886 ℎ = 1 and the metric (2) is flatwhile the region 119903 lt 119886 with the obvious transformation119910120572= (119886
2119903
2)119909
120572 is also flat for 119910 gt 119886 Therefore the regions119903 gt 119886 and 119903 lt 119886 represent two Euclidean spaces glued at thesurface of a sphere 1198783 with the centre at the origin 119903 = 0 andradius 119903 = 119886 Such a space can be described with the ordinarydouble-valued flat metric in the region 119903
plusmngt 119886 by
1198891199042= 120575
120572120573119889119909
120572
plusmn119889119909
120573
plusmn (3)
where the coordinates 119909120572
plusmndescribe two different sheets of
space Now identifying the inner and outer regions of thesphere 1198783 allows the construction of a wormhole which con-nects regions in the same space (instead of two independentspaces) This is achieved by gluing the two spaces in (3) bymotions of the Euclidean space (the Poincare motions) If 119877
plusmn
is the position of the sphere in coordinates 119909120583
plusmn then the gluing
is the rule
119909120583
+= 119877
120583
++ Λ
120583
] (119909]minusminus 119877
]minus) (4)
where Λ120583
] isin 119874 (4) which represents the composition of atranslation and a rotation of the Euclidean space (Lorentztransformation) In terms of common coordinates such awormhole represents the standard flat space in which the twospheres 1198783
plusmn(with centers at positions 119877
plusmn) are glued by the rule
(4)We point out that the physical region is the outer region ofthe two spheres Thus in general the wormhole is describedby a set of parameters the throat radius 119886 positions of throats119877plusmn and rotation matrix Λ120583
] isin 119874 (4)In the present paper we assume the space-time foam
picture in which the vacuum is filled with a gas of virtualwormholes We show that virtual wormholes form a finite (ofthe Planckian order) value of the energy density of zero-pointfluctuations However such a huge value is compensated bythe contribution of virtual wormholes to the mean curvatureand the observed value of the cosmological constant shouldbe close to zero
To achieve our aimwe in Section 2 present the construc-tion of the generating functional in quantum field theoryThe main idea is that the partition function includes thesum over field configurations and the sum over topologies
Journal of Astrophysics 3
Where the sum over topologies is the sum over virtualwormholes described above Such an approach gives a rathergood leading approximation for calculation of the partitionfunction and corresponds to the standard methods (egRitza method etc) In Section 3 we investigate properties ofthe two-point Green function We show that the presenceof the gas of virtual wormholes can be described by thetopological bias exactly as it happens in the presence of actualwormholes [7 9] For limiting topologies when the densityof virtual wormholes becomes infinite the Green functionshows a good ultraviolet behavior which means that thereexists a class of such systems when quantum field theoriesare free of divergencies We demonstrate how the sum overtopologies defines themean value for the bias which takes thesense of a cutoff function in the space of modes In Section 4we explicitly demonstrate that for a particular set of virtualwormholes the bias defines not more than the projectionoperator on the subspace of functions obeying to the properboundary conditions at wormhole throats The projectivenature of the bias means that wormholes merely cut someportion of degrees of freedom (modes) Phenomenologicallyit means that wormholes can be described by the presence ofghost fields which compensate the extra (cut by wormholes)modes In Section 5 we show how the cutoff expresses viasome dynamic parameters of wormholesThe exact definitionof such parameters we leave it for the future investigationIn Section 6 we consider the origin of the cosmologicalconstant We demonstrate that the cosmological constantis determined by the contribution of the energy density ofzero-point fluctuations and by the contribution of virtualwormholes to the mean curvature We estimate contributionof virtual wormholes to the mean curvature and show alsothat wormholes lead to a finite (of the planckian order)value of ⟨119879
120583]⟩ which requires considering the contributionfrom the smaller and smaller wormholes with divergentdensity 119899 rarr infin We also present arguments of why inthe absence of external classical fields the total value ofthe cosmological constant is exactly zero while it acquiresa nonvanishing value due to vacuum polarization effects(ie due to an additional distribution of virtual wormholes)in external fields We also speculate the possibility of theformation of actual wormholes and in Section 7 we estimatetheir contribution to the dark energy Finally in Section 8 werepeat basic results an discuss some perspectives
2 Generating Function
The basic aim of this section is to construct the generatingfunctional which can be used to get all possible correlationfunctions Consider the partition functionwhich includes thesum over topologies and the sum over field configurations
119885total = sum
120591
sum
120593
119890minus119878 (5)
For the sake of simplicity we use from the very beginning theEuclidean approach The action has the form
119878 = minus1
2(120593119860120593) + (119869120593) (6)
and we use the notions (119869120593) = int 119869(119909)120593(119909)1198894119909 If we fix
the topology of space by placing a set of wormholes withparameters 120585
119894 then the sum over field configurations 120593 gives
the well-known result
119885lowast(119869) = 119885
0(119860) 119890
minus(12)(119869119860minus1
119869) (7)
where 1198850(119860) = int[119863120593]119890
(12)(120593119860120593) is the standard expressionand 119860
minus1= 119860
minus1(120585) is the Green function for a fixed topology
that is for a fixed set of wormholes 1205851 120585
119873
Consider now the sum over topologies 120591 To this end werestrict the sum over the number of wormholes and integralsover parameters of wormholes
sum
120591
997888rarr sum
119873
int
119873
prod
119894=1
119889120585119894= int [119863119865] (8)
where
119865 (120585119873) =1
119873
119873
sum
119894=1
120575 (120585 minus 120585119894) (9)
and 119873119865 is the density of wormholes in the configurationspace 120585 We also point out that in general the integration overparameters is not free (eg it obeys the obvious restriction|
+
119894minus
minus
119894| ge 2119886
119894) This defines the generating function as
119885total (119869) = int [119863119865]1198850(119860) 119890
minus(12)(119869119860minus1
119869) (10)
The sum over topologies assumes an additional averaging outfor all mean values with the measure 119889120583
119873= 120588(120585119873)119889
119873120585
where
120588 (120585119873) =
1198850(119860 (120585119873))
119885total (0) (11)
which obey the obvious normalization conditionsum119873int119889120583
119873=
sum119873120588119873
= 1 The averaging out over topologies assumes thetwo stages First we fix the total number of wormholes 119873and average over the parameters of wormholes 120585 (ie overparameters of a static gas of wormholes in 119877
4) Then we sumover the number of wormholes119873 (the so-called big canonicalensemble)
The basic difficulty of the standard field theory is thatthe perturbation scheme based on (7) leads to divergentexpressions This remains true for every particular topologyof space (ie for any particular finite set of wormholes) sincethere always exists a scale below which the space looks likethe ordinary Euclidean spaceWhat we expect is that the sumover all possible topologies will remove such a difficulty
And indeed the above measure (11) has the structure
1198850(119860 (120585119873)) = exp(minusintΛ (120585119873) 119889
4119909) (12)
where Λ(120585119873) is the cosmological constant related to theenergy density of zero-point fluctuations calculated for aparticular distribution of wormholes (We recall that the total
4 Journal of Astrophysics
cosmological constant should include also the contributionfrom the mean curvature (55)) Any finite distribution ofwormholes leads to the divergent expression Λ(120585119873) rarr
infin and is suppressed (ie 120588 (120585119873) rarr 0) However thesum over all possible topologies assumes also the limitingtopologies 119899 rarr infin where 119899 = 119873119881 is the density ofwormholes In this limit wormhole throats degenerate intopoints and the minimal scale below which the space lookslike the Euclidean space is merely absent We point out thatfrom the rigorous mathematical standpoint such limitingtopologies cannot be described in terms of smoothmanifoldssince they are not locally Euclidean and does not possess afinite set of maps In mathematics similar objects are wellknown for example fractal sets However if a fractal set isobtained by cutting (by means of a specific rule or iterations)portions of space our limiting topologies are obtained bygluing (identifying) some portions (or in the limit couplesof points) of the Euclidean space The basic feature of suchtopologies is that QFT becomes finite on such a set Indeedas we shall see a particular infinite distribution of wormholescan always be chosen in such a way that the energy of zero-point fluctuations becomes a finite 0 le Λ
infin(120585) lt infin (eg
see the next section or the second term in (67)) In the sumover topologies only such limiting topologies do survive (ie120588infin(120585) = 0)
3 The Two-Point Green Function
From (7) we see that the very basic role in QFT plays the twopoint Green function Such a Green function can be foundfrom the equation
119860119866(119909 1199091015840) = minus120575 (119909 minus 119909
1015840) (13)
with proper boundary conditions at wormholes which gives119866 = 119860
minus1 Now let us introduce the bias function119873(119909 1199091015840) as
119866 (119909 119910) = int1198660(119909 119909
1015840)119873 (119909
1015840 119910) 119889119909
1015840 (14)
where 1198660(119909 119909
1015840) is the ballistic (or the standard Euclidean
Green function) and the bias can be presented as
119873(119909 1199091015840) = 120575 (119909 minus 119909
1015840) +sum
119894
119887119894120575 (119909 minus 119909
119894) (15)
where 119887119894are fictitious sources at positions 119909
119894which should
be added to obey the proper boundary conditions We pointout that the bias can be explicitly expressed via parametersof wormholes that is 119873(119909 119909
1015840) = 119873(119909 119909
1015840 120585
1 120585
119873) For the
sake of illustration we consider first a particular example
31 The Bias for a Particular Distribution of Wormholes(Rarefied Gas Approximation) Consider now the bias for aparticular set of wormholes For the sake of simplicity weconsider the case when119898 = 0 The Green function obeys theLaplace equation
minusΔ119866 (119909 1199091015840) = 120575 (119909 minus 119909
1015840) (16)
with proper boundary conditions at throats (we require119866 and120597119866120597119899 to be continual at throats)The Green function for theEuclidean space is merely 119866
0(119909 119909
1015840) = 14120587
2(119909 minus 119909
1015840)2 (and
1198660(119896) = 1119896
2 for the Fourier transform) In the presence ofa single wormhole which connects two Euclidean spaces thisequation admits the exact solution For outer region of thethroat 1198783 the source 120575(119909 minus 119909
1015840) generates a set of multipoles
placed in the center of sphere which gives the corrections tothe Green function 119866
0in the form (we suppose the center of
the sphere at the origin)
120575119866 = minus1
412058721199092
infin
sum
119899=1
1
119899 + 1(119886
1199091015840)
2119899
(1199091015840
119909)
119899minus1
119876119899 (17)
where 119876119899= (4120587
22119899)sum
119899minus1
119897=0sum
119897
119898=minus119897119876
lowast1015840
119899119897119898119876
119899119897119898and 119876
119899119897119898(Ω) are
four-dimensional spherical harmonics for example see [21]In the present section we shall consider a dilute gas approx-imation and therefore it is sufficient to retain the lowest(monopole) term only A single wormhole which connectstwo regions in the same space is a couple of conjugatedspheres 1198783
plusmnof the radius 119886with a distance =
+minus
minusbetween
centers of spheres So the parameters of the wormhole are(The additional parameter (rotation matrix Λ) is importantonly for multipoles of higher orders) 120585 = (119886 119877
+ 119877
minus) The
interior of the spheres is removed and surfaces are gluedtogether Then the proper boundary conditions (the actualtopology) can be accounted for by adding the bias of thesource
120575 (119909 minus 1199091015840) 997888rarr 120575 (119909 minus 119909
1015840) + 119887 (119909 119909
1015840) (18)
In the approximation 119886119883 ≪ 1 (eg see for details [9]) thebias for a single wormhole takes the form
1198871(119909 119909
1015840 120585) =
1198862
2(
1
(119877minusminus 1199091015840)
2minus
1
(119877+minus 1199091015840)
2)
times [120575 ( minus +) minus 120575 ( minus
minus)]
(19)
This form for the bias is convenient when constructing thetrue Green function and considering the long-wave limithowever it is not acceptable in considering the short-wavebehavior and vacuum polarization effects Indeed the posi-tions of additional sources are in the physically nonadmissibleregion of space (the interior of spheres 1198783
plusmn) To account for
the finite value of the throat size we should replace in (19)the point-like source with the surface density (induced on thethroat) that is
120575 ( minus plusmn) 997888rarr
1
212058721198863120575 (
10038161003816100381610038161003816 minus
plusmn
10038161003816100381610038161003816minus 119886) (20)
Such a replacement does not change the value of the trueGreen function however now all extra sources are in thephysically admissible region of space
In the rarefied gas approximation the total bias is additivethat is
119887total (119909 1199091015840) = sum119887
1(119909 119909
1015840 120585
119894) = 119873int119887
1(119909 119909
1015840 120585) 119865 (120585) 119889120585
(21)
Journal of Astrophysics 5
where 119873119865 is given by (9) For a homogeneous and isotropicdistribution 119865(120585) = 119865(119886119883) and then for the bias we find
119887total (119909 minus 1199091015840)
= int1
21205872119886(
1
1198772
minus
minus1
1198772
+
)120575 (10038161003816100381610038161003816 minus
1015840minus
+
10038161003816100381610038161003816minus 119886)119873119865 (120585) 119889120585
(22)
Consider the Fourier transform 119865(119886119883) = int119865(119886 119896)119890minus119894119896119883
sdot
(1198894119896(2120587)
4) and using the integral 11199092
= int(41205872119896
2)119890
minus119894119896119909sdot
(1198894119896(2120587)
4) we find for 119887(119896) = int 119887(119909)119890
1198941198961199091198894119909 the expression
119887total (119896) = 119873int1198862 4120587
2
1198962(119865 (119886 119896) minus 119865 (119886 0))
1198691(119896119886)
1198961198862119889119886 (23)
(1) Example of a Finite Density of Wormholes Consider nowa particular (of a finite density) distribution of wormholes119865(119886119883) for example
119873119865 (119886119883) =119899
212058721199033
0
120575 (119886 minus 1198860) 120575 (119883 minus 119903
0) (24)
where 119899 = 119873119881 is the density of wormholes In the case119873 = 1 this function corresponds to a single wormhole withthe throat size 119886
0and the distance between throats 119903
0=
|119877+minus119877
minus|We recall that the action (6) remains invariant under
translations and rotations which straightforwardly leads tothe above function Then 119873119865(119886 119896) = int119873119865(119886119883)119890
1198941198961199091198894119909 re-
duces to 119873119865(119886 119896) = 119899(1198691(119896119903
0)(119896119903
02))120575(119886 minus 119886
0) Thus from
(23) we find
119887 (119896) = minus1198991198862 4120587
2
1198962(1 minus
1198691(119896119903
0)
11989611990302
)1198691(119896119886
0)
11989611988602
(25)
And for the true Green function we get
119866true = 1198660(119896)119873 (119896) = 119866
0(119896) (1 + 119887 (119896)) (26)
In the short-wave limit (119896119886 1198961199030≫ 1) 119887(119896) rarr 0 and
therefore 119873(119896) rarr 1 This means that at very small scalesthe space filled with a finite density of wormholes looks likethe ordinary Euclidean space In the long-wave limit 119896 rarr 0
we get 1198691(119896119903
0)(119896119903
02) asymp 1 minus (12) (119896119903
02)
2+ sdot sdot sdot which gives
119887(119896) asymp minus1205872119899119886
21199032
02 while in a more general case we find
119887(119896) asymp minus int(12058722)119886
21199032
0119899(119886 119903
0)119889119886 119889119903
0 where 119899(119886 119903
0) is the den-
sity of wormholes with a particular values of 119886 and 1199030 and for
the bias function (15) we get
119873(119896) 997888rarr 1 minus1205872
2int 119886
4119899 (119886 119903
0)1199032
0
1198862119889119886 119889119903
0le 1 (27)
In other words in the long-wave limit (119896119886 1198961199030≪ 1) the
presence of a particular set of virtual wormholes diminishesmerely the value of the charge values
(2) Limiting Topologies or Infinite Densities of WormholesConsider now the limiting distribution when the density of
wormholes 119899 rarr infin Since every throat cuts the finite portionof the volume (120587
22)119886
4 this case requires considering thelimit 119886 rarr 0 We assume that in this limit 1198862119873119865(119886119883) rarr
120575(119886)](119883) where ](119883) is a finite specific distribution Then(23) reduces to 119887total(119896) = (4120587
2119896
2) (](119896) minus ](0)) where ](119896) =
int ](119883)119890119894119896119883
1198894119883 and the bias (15) (18)119873(119896) becomes
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (28)
It is important that this limit still agrees with the rarefiedgas approximation for the basic gas parameter (ie theportion of volume cut by wormholes) tends to 120585 =
int(12058722)119886
4119865(119886119883)119889
4119883119889119886 rarr 0 The above expression is ob-
tained in the linear approximation only Taking into accountnext orders (eg see [22] where the case of a dense gas is alsoconsidered) we find 119873(119896) = 1 + 119887total(119896) + 119887
2
total(119896) + sdot sdot sdot andthe true Green function in a gas of wormholes becomes
119866true = 1198660(119896)119873 (119896) =
1
1198962 + 41205872(] (0) minus ] (119896))
(29)
In the long-wave limit 119896 rarr 0 the function ](119896) can beexpanded as ](119896) asymp ](0) + (12)]10158401015840(0)1198962 which also definesa renormalization of charge values119873(119896) rarr 1(1minus2120587
2]10158401015840(0))which coincides with (27) However in this limiting case wehave some freedom in the choice of ](119896) which we can useto assign 119873(119896) an arbitrary function of 119896 In other wordswe may get here a class of limiting topologies where Greenfunctions119866true = 119866
0(119896)119873(119896) have a good ultraviolet behavior
and quantumfield theories in such spaces turn out to be finiteIn particular this will certainly be the case when
119866true (119909 minus 1199091015840= 0) = int
1
1198962 + 41205872(] (0) minus ] (119896))
1198894119896
(2120587)4lt infin
(30)
This possibility however requires the further and more deepinvestigation
32 Green Function General Consideration The action (6)remains invariant under translations
1015840= + 119888 with an
arbitrary 119888 which means that the measure (11) does notactually depend on the position of the center of mass of thegas of wormholes and therefore we may restrict ourself withhomogeneous distributions 119865(120585) of wormholes in space onlyIndeed we may define 119889119873
120585 = 11988911987312058510158401198894119888 while the integration
over 1198894119888 gives the volume of1198774 that is int1198894
119888 = 1198714= 119881which
disappears from (11) due to the denominator (Technically wemay first restrict a portion of1198774 in (6) to a finite volume119881 andthen in final expressions consider the limit 119881 rarr infin (whichrepresents the standard tool in thermodynamics and QFT))In what follows we shall omit the prime from 120585
1015840Let us consider the Fourier representation119873(119909 119909
1015840 120585) rarr
119873(119896 1198961015840 120585) which in the case of a homogeneous distribution
of wormholes gives119873(119896 1198961015840) = 119873(119896 120585) 120575(119896 minus 119896
1015840) then we find
119866 (119896) = 1198660(119896)119873 (119896 120585) (31)
6 Journal of Astrophysics
and the Green function can be taken as
119866 =119873 (119896 120585)
1198962 + 1198982 (32)
Then for the total partition function we find
119885total (119869)
= int [119863119873 (119896)] 119890minus119868(119873)
119890minus(12)(119871
4
(2120587)4
) int((119873(119896)(1198962
+1198982
))|119869119896
|2
)119889119896
(33)
where [119863119873] = prod119896119889119873
119896and 120590(119873) comes from the integration
measure (ie from the Jacobian of transformation from 119865(120585)
to119873(119896))
119890minus119868(119873)
= int [119863119865]1198850(119873 (119896 120585)) 120575 (119873 (119896) minus 119873 (119896 120585)) (34)
We point out that 119868(119873) can be changed by means of addingto the action (6) of an arbitrary ldquonondynamicalrdquo constantterm which depends only on topology 119878 rarr 119878 + Δ119878 (119873(119896))
(eg a topological Euler term) The multiplier 1198850(119873) defines
the simplest measure for topologies Now by means of usingthe expression (32) and (33) we find the two-point Greenfunction in the form
119866 (119896) =119873 (119896)
1198962 + 1198982 (35)
where 119873(119896) is the cutoff function (the mean bias) whichis given by (We recall that in this integral contribute onlylimiting topologies in which density of wormholes diverges(119899 rarr infin))
119873(119896) =1
119885total (0)int [119863119873] 119890
minus119868(119873)119873(119896) (36)
At the present stage we still cannot evaluate the exactform for the cutoff function 119873(119896) in virtue of the ambiguityof Δ119878(119873(119896)) pointed out Such a term may include twoparts First part Δ
1119878 describes the proper dynamics of
wormholes and should be considered separately Indeedin general wormholes are dynamical self-gravitating objectswhich require considering the gravitational contribution tothe action Some part of such a contribution (mean curvatureinduced by wormholes) is discussed in Section 6 Howeversince a wormhole represents an extended nonlocal objectit possesses a rather complex dynamics and this problemrequires the further investigation The second part Δ
2119878 may
describe ldquoexternal conditionsrdquo (eg an external classicalfield in (33)) for the mean topology Actually the last termcan be used to prescribe an arbitrary particular value forthe cutoff function 119873(119896) = 119891(119896) Indeed the ldquoexternalconditionsrdquo can be accounted for by adding the term Δ
2119878 =
(120582119873) = int 120582(119896)119873(119896)1198894119896 where 120582(119896) plays the role of a
specific chemical potential which implicitly depends on 119891(119896)
through the equation
119891 (119896) =1
119885total (120582 0)int [119863119873] 119890
(120582119873)minus119868(119873)119873(119896) (37)
From (33) we see that the role of such a chemical potentialmay play the external current 120582(119896) = minus(12)(119871
4(2120587)
4)sdot
1198660(119896)|119869
ext119896|2 or equivalently an external classical field 120593
ext=
1198660(119896)119869
ext119896 In quantum field theory such a term leads merely
to a renormalization of the cosmological constant By otherwords the mean topology (ie the cutoff function or meandistribution of wormholes) is driven by the cosmologicalconstant Λ and vice versa
4 Topological Bias as a Projection Operator
By the construction the topological bias 119873(119909 1199091015840) plays the
role of a projection operator onto the space of functions (asubspace of functions on 119877
4) which obey the proper bound-ary conditions at throats of wormholes This means thatfor any particular topology (for a set of wormholes) thereexists the basis 119891
119894(119909) in which it takes the diagonal form
119873(119909 1199091015840) = sum119873
119894119891119894(119909)119891
lowast
119894(119909
1015840) with eigenvalues 119873
119894= 0 1
(since 1198732
119894= 119873
119894) In this section we illustrate this simple fact
(which is probably not obvious for readers) by the explicitconstruction of the reference system for a single wormholewhen physical functions become (due to the boundaryconditions) periodic functions of one of coordinates
Indeed consider a single wormhole with parameters 120585(ie 120585 = (119886 119877
+ 119877
minus) where 119886 is the throat radius and 119877
plusmn
are positions of throats in space (In general there existsan additional parameter Λ120572
120573which defines a rotation of one
of throats before gluing However it does not change thesubsequent constructionThere always exists a diffeomorphicmap of coordinates 1199091015840
= ℎ(119909) which sets such a matrix tounity)) Consider now a particular solution120601
0to the equation
Δ1206010= 0 (harmonic function) for 1198774 in the presence of the
wormhole which corresponds to the situation when throatspossess a unit chargemass but those have the opposite signsNow define the family of lines of force 119909(119904 119909
0) which obey
the equation 119889119909119889119904 = minusnabla1206010(119909) with initial conditions 119909(0) =
1199090 Physically such lines correspond to lines of force for a
two charged particles in positions 119877plusmn with charges plusmn1 Wenote that all points which lay on the trajectory 119909(119904 119909
0) may
be taken as initial conditions and they define the same lineof force with the obvious redefinition 119904 rarr 119904 minus 119904
0 By
other words we may take as a new coordinates the parameter119904 and portion of the coordinates orthogonal to the familyof lines 119909
perp
0 Coordinates 119909
perp
0can be taken as laying in the
hyperplane 1198773 which is orthogonal to the vector 119889 = minusminus
+
and goes through the point 0
= (minus+
+)2 (Instead
of the construction used here one may use also anothermethod Indeed consider two point charges and then thefunction 120601
0= 1(119909 minus 119909
+)2minus 1(119909 minus 119909
minus)2 can be taken as a
new coordinate Wormhole appears when we identify (glue)surfaces 120601
0= plusmn120596 We point out that such surfaces are not
spheres though they reduce to spheres in the limit |119909+minus
119909minus| rarr infin or 120596 rarr infin)Let 119904plusmn(119909perp
0) be the values of the parameter 119904 at which
the line intersects the throats 119877plusmn Then instead of 119904 we mayconsider a new parameter 120579 as 119904(120579) = 119904
minus+ (119904
+minus 119904
minus)1205792120587
so that when 120579 = 0 2120587 the parameter 119904 takes the values
Journal of Astrophysics 7
119904 = 119904minus 119904+ respectivelyThe gluing procedure at throatsmeans
merely that we identify points at 120579 = 0 and 120579 = 2120587 and allphysical functions in the space 119877
4 with a single wormhole120585 become periodic functions of 120579 Thus the coordinatetransformation 119909 = 119909(120579 119909
perp
0) gives the map of the above space
onto the cylinder with a specific metric 1198891198972 = (119889(120579 119909perp
0))
2
=
119892120572120573119889119910
120572119889119910
120573 (where 119910 = (120579 119909perp
0)) whose components are also
periodic in terms of 120579 Now we can continue the coordinatesto thewhole space1198774 (to construct a cover of the fundamentalregion 120579 isin [0 2120587]) simply admitting all valuesminusinfin lt 120579 lt +infin
this however requires to introduce the bias
1
radic119892120575 (120579 minus 120579
1015840) 997888rarr 119873(120579 minus 120579
1015840) =
+infin
sum
119899=minusinfin
1
radic119892120575 (120579 minus 120579
1015840+ 2120587119899)
(38)
since every point and every source in the fundamental regionacquires a countable set of images in the nonphysical region(inside of wormhole throats) Considering now the Fouriertransforms for 120579 we find
119873(119896 1198961015840) =
+infin
sum
119899=minusinfin
120575 (119896 minus 119899) 120575 (119896 minus 1198961015840) (39)
We point out that the above bias gives the unit operator in thespace of periodic functions of 120579 From the standpoint of allpossible functions on 1198774 it represents the projection operator
2= (120585) (taking an arbitrary function 119891 we find that upon
the projection 119891119873= 119891 119891
119873becomes a periodic function of
120579 that is only periodic functions survive)The above construction can be easily generalized to the
presence of a set of wormholes In the approximation of adilute gas of wormholes we may neglect the influence ofwormholes on each other (at least there always exists a suf-ficiently smooth map which transforms the family of linesof force for ldquoindependentrdquo wormholes onto the actual lines)Then the total bias (projection) may be considered as theproduct
119873total (119909 1199091015840) = int(prod
119894
radic1198921198941198894119910119894)119873(120585
1 119909 119910
1)
times 119873 (1205852 119910
1 119910
2) sdot sdot sdot 119873 (120585
119873 119910
119873minus1 119909
1015840)
(40)
where 119873(120585119894 119909 119909
1015840) is the bias for a single wormhole with
parameters 120585119894 Every such a particular bias119873(120585
119894 119909 119909
1015840) realizes
projection on a subspace of functions which are periodic withrespect to a particular coordinate 120579
119894(119909) while the total bias
gives the projection onto the intersection of such particularsubspaces (functions which are periodic with respect to everyparameter 120579
119894)
5 Cutoff
The projective nature of the bias operator 119873(119909 1199091015840) allows us
to express the cutoff function 119873(119896) via dynamic parametersof wormholes Indeed consider a box 1198714 in 119877
4 and periodic
boundary conditions which gives 119896 = 2120587119899119871 (in final expres-sions we consider the limit 119871 rarr infin which gives sum
119896rarr
(1198714(2120587)
4) int 119889
4119896) And let us consider the decomposition for
the integration measure in (33) as
119868 = 1198680+sum120582
1(119896)119873 (119896) +
1
2sum120582
2(119896 119896
1015840)119873 (119896)119873 (119896
1015840) + sdot sdot sdot
(41)
where 1205821(119896) includes also the contribution from 119885
0(119896) We
point out that this measure plays the role of the action for thebias119873(119896) Indeed the variation of the above expression givesthe equation of motions for the bias in the form
sum
1198961015840
1205822(119896 119896
1015840)119873 (119896
1015840) = minus120582
1(119896) (42)
which can be found by considering the proper dynamics ofwormholes We however do not consider the problem of thedynamic description of wormholes here and leave this forthe future research Moreover we may expect that in the firstapproximation one may retain the linear term only Indeedthis takes place when119873(119896) is not a dynamic variable or if wetake into account that 119873(119896) is a collective variable Then theprojective nature of the bias 119873(119896) = 0 1 means that it canbe phenomenologically expressed via some Fermionic ghostfield Ψ(119896) (eg 119873(119896 119896
1015840) = Ψ(119896)Ψ
+(119896
1015840)) where the negative
and positive frequency parts of the operator Ψ(119896) obey theanticommutation relationsΨ+
(119896)Ψ(1198961015840)+Ψ(119896
1015840) Ψ
+(119896) = 120575(119896minus
1198961015840) In the absence of ghost particles Ψ(119896)|0⟩ = 0 we get
119873(119896 1198961015840) = 120575(119896 minus 119896
1015840) that is 119873(119896) = 1 and wormholes
are absent In the term of the ghost field the action becomes119868(119873) = 119868
0+ (Ψ
1Ψ) + sdot sdot sdot Therefore in the leading approx-
imation equations of motion take the linear form 1Ψ = 0
Thus taken into account that 119873(119896) = 0 1 (1198732= 119873) we
find
119873(119896) =1
119885total (119896)sum
119873=01
119890minus1205821
(119896)119873(119896)119873(119896) =
119890minus1205821
(119896)
1 + 119890minus1205821(119896) (43)
The simplest choice gives merely 1205821(119896) = minussum ln119885
0(119896)
where the sum is taken over the number of fields and 1198850(119896)
is given by 1198850(119896) = radic120587(1198962 + 1198982) In the case of a set
of massless fields we find 119873(119896) = 119885(119896)(1 + 119885(119896)) where119885(119896) = (radic120587119896)
120572 and 120572 is the effective number of degreesof freedom (the number of boson minus fermion fields) Toensure the absence of divergencies one has to consider thenumber of fields 120572 gt 4 [23] However such a choice givesthe simplest estimate which in general cannot be correctIndeed while its behavior at very small scales (ie whenexceeding the Planckian scales 119885(119896) ≲ 1 and 119873(119896) = 119885(119896))may be physically accepted since it produces some kind of acutoff on the mass-shell 1198962 + 119898
2rarr 0 it gives the behavior
119873(119896) rarr 1 which is merely incorrect (eg from (27) we seethat the true behavior should be119873(119896) rarr const lt 1)
One may expect that the true cutoff function has a muchmore complex behavior Indeed some theoretical models inparticle physics (eg string theory) have the property tobe lower-dimensional at very small scales The mean cutoff
8 Journal of Astrophysics
119873(119896) gives the natural tool to describe a scale-dependantdimensional reduction [24 25] In fact this function definesthe spectral number of modes in the interval between 119896 and119896 + 119889119896 as
int119873 (119896)1198894119896
(2120587)4= int
119873 (119896) 1198964
(2120587)2
119889119896
119896 (44)
Hence we can define the effective spectral dimension 119863 ofspace as follows
1198964119873(119896) sim 119896
119863 (45)
From the empirical standpoint the dimension 119863 = 4 isverified at laboratory scales only while the rigorous tool todefine the spectral density of states (or the mean cutoff) cangive the lattice quantum gravity for example see [26 27]and references therein And indeed the spectral dimensionfor nonperturbative quantum gravity defined via Euclideandynamical triangulations was calculated recently in [28] Itturns out that it runs from a value of119863 = 32 at short distanceto 119863 = 4 at large distance scales We also point out that allobserved dark matter phenomena can be explained by thefractal dimension119863 asymp 2 starting from scales 119871 ≳ (1 divide 5)Kpcfor example [29ndash33]
6 Cosmological Constant
Let us consider the total Euclidean action [17]
119868119864= minus
1
16120587119866int (119877 minus 2Λ
0)radic119892119889
4119909 minus int119871
119898radic1198921198894119909 (46)
The variation of the above action leads to the Einstein equa-tions
119877119886119887minus1
2119892119886119887119877 + 119892
119886119887Λ
0= 8120587119866119879
119886119887 (47)
where 119879119886119887= (12)(119892)
minus12(120575119871
119898120575119892
119886119887) is the stress energy ten-
sor and Λ0is a naked cosmological constant In cosmology
such equations are considered from the classical standpointwhich means that they involve characteristic scales ℓ ≫ ℓplHowever the presence of virtual wormholes at Planckianscales defines some additional contribution in both parts ofthese equations which can be adsorbed into the cosmologicalconstant Therefore the total cosmological constant can bedefined as
Λ tot = Λ0+ Λ
119898+ Λ
119877= Λ
0+ 2120587119866 ⟨119879⟩ +
1
4⟨119877⟩119908 (48)
where ⟨119879⟩ is the energy of zero-point fluctuations (It includesalso the contribution of zero-point fluctuations of gravitons)That is themean vacuum value (we recall that in the standardQFTΛ
119898is infinite while wormholes form a finite value) and
⟨119877⟩119908
= Λ119877is a contribution of wormholes into the mean
curvature due to gluing (1)
61 Contribution of Virtual Wormholes into Mean CurvatureConsider a single wormhole whose metric is given by (1)
1198891199042= ℎ
2(119903)120575
120572120573119889119909
120572119889119909
120573 then the components of the Riccitensor are (We are much obliged to the Referee who pointedout to the subtleties when working with a step function in themetric)
119877120572120573
= 7 minus (ℎ1015840
ℎ)
1015840
(120575120572120573
+ (119873 minus 2) 119899120572119899120573)
minus1
119903
ℎ1015840
ℎ((119873 minus 2) Δ
120572120573+ 120575
120572120573(119873 minus 1))
minus (ℎ1015840
ℎ)
2
(119873 minus 2) Δ120572120573
(49)
where 119899]= 119909
]119886 is the unite normal vector to the throat
surface Δ120572120573
= 120575120572120573
minus 119899120572119899120573 ℎ1015840 = 120597ℎ120597119903 and119873 is the number
of dimensions The curvature scalar is
119877 = minus(119873 minus 1)
ℎ2[2
ℎ10158401015840
ℎ+ 2
1
119903
ℎ1015840
ℎ(119873 minus 1) + (
ℎ1015840
ℎ)
2
(119873 minus 4)]
(50)
Then substituting ℎ = 1 + (1198862119903
2minus 1)120579 in the above equation
we find
minusℎ4
119873 minus 1119877 = 4ℎ
1198862
1199033120575 +
2ℎ
119903119873minus1(119903
119873minus1120582)
1015840
+ (119873 minus 4)(1205822minus 4120579
1198862
1199033120582)
+ 4 (119873 minus 4)1198862
1199034120579 (120579 minus 1)
(51)
where 120579 is a smooth function which only in a limit becomesa step function 120582 = (1 minus 119886
2119903
2)120575 and 120575 = minus120579
1015840 In the limit120579 rarr 120579(119886 minus 119903) we find 120575 rarr 120575(119903 minus 119886) and the last two terms in(51) are negligible as compared to the first two terms while infour dimensions the last two terms vanishThen the curvatureis concentrated on the throat of the wormhole where 120579 differsfrom the step function In the limit of a vanishing throat sizewe have ℎ rarr 1 at the throat and we get
minus119877 =4 (119873 minus 1)
119886120575 (119903 minus 119886) +
2 (119873 minus 1)
119903119873minus1(119903
119873minus3(119903
2minus 119886
2) 120575)
1015840
(52)
In general all the terms together in (51) and analogous termsin the Ricci tensor provide that the Bianchi identity holdsand the energy is conserved [19] Therefore none of themcan be dropped out However it is easy to see the leadingcontribution to the integral over space comes from the firstterm only and in the limit of a vanishing throat size we findfor a single wormhole
1
4int119877radic119892119889
4119909 = minus6120587
21198862 (53)
Journal of Astrophysics 9
In the case of a set of wormholes (24) we find
1
4int119877radic119892119889
4119909 = minus6120587
2sum
119895
1198862
119895
= minus121205872int119899 (119886) 119886
2119889119886 119889
4119909 = intΛ
1198771198894119909
(54)
where 2119899(119886) = int 119899(119886 1199030)119889119903
0is the density of wormhole
throats with a fixed value of the throat size 119886 This definesthe contribution to the cosmological constant from the meancurvature as
Λ119877= minus12120587
2int119899 (119886) 119886
2119889119886 lt 0 (55)
We see that this quantity is always negative
62 Stress Energy Tensor In this section we consider thecontribution from matter fields In the case of a scalar fieldthe stress energy tensor has the form
minus119879120572120573
(119909) = 120597120572120593120597
120573120593 minus
1
2119892120572120573
(120597120583120593120597
120583120593 + 119898
21205932) (56)
Then the mean vacuum value of the stress energy tensor canbe obtained directly from the two-point green function (32)(35) as
minus ⟨119879120572120573
(119909)⟩
= lim1199091015840
rarr119909
(1205971205721205971015840
120573minus1
2119892120572120573
(1205971205831205971015840
120583+ 119898
2)) ⟨119866 (119909 119909
1015840 120585)⟩
(57)
By means of using the Fourier transform 119866(119909 1199091015840 120585) =
int 119890minus119894119896(119909minus119909
1015840
)119866(119896 120585) (119889
4119896(2120587)
4) and the expressions (32) (35)
we arrive at
⟨119879120572120573
(119909)⟩ =1
4119892120572120573
int(1 +119898
2
1198962 + 1198982)119873 (119896)
1198894119896
(2120587)4 (58)
where the property int 119896120572119896120573119891(119896
2)119889
4119896 = (14)119892
120572120573int 119896
2119891(119896
2)119889
4119896
has been used and 119873(119896) = ⟨119873(119896 120585)⟩ is the cutoff function(36)
For the sake of simplicity we consider the massless caseThen by the use of the cutoff 119873(119896) = 120587
1205722(120587
1205722+ 119896
120572) from
the previous section we get the finite estimate (120572 gt 4 is theeffective number of the field helicity states)
Λ119898=2120587119866sumint
1205871205722
1205871205722+119896120572
1198894119896
(2120587)4=120587119866
4Γ (
120572 minus 4
120572) Γ (
4
120572) sim 1
(59)
where the sum is taken over the number of fields Since theleading contribution comes here from very small scales wemay hope that this value will not essentially change if thetrue cutoff function changes the behavior on the mass-shellas 119896 rarr 0 (eg if we take 120582
1(119896) = minussum ln119885
0(119896) + 120575120582(119896) with
120575120582(119896) ≪ ln1198850(119896) as 119896 ≫ 1)
To understand how wormholes remove divergencies itwill be convenient to split the bias function into two parts119873(119896 120585) = 1 + 119887(119896 120585) where 1 corresponds to the standardEuclidean contribution while 119887(119896 120585) is the contribution ofwormholes The first part gives the well-known divergentcontribution of vacuumfield fluctuations 8120587119866⟨1198790
120572120573⟩ = Λ
lowast119892120572120573
with Λlowast
rarr +infin while the second part remains finite forany finite number of wormholes and due to the projectivenature of the bias described in the previous section itpartially compensates (reduces) the value of the cosmologicalconstant that is 8120587119866⟨Δ119879
120572120573⟩ = 120575Λ119892
120572120573 where 120575Λ =
sum119873120588119873120575Λ(119873) and 120575Λ(119873) is a negative finite contribution of
a finite set of wormholesConsider now the particular distribution of virtual
wormholes (24) and evaluate their contribution tothe cosmological constant which is given by 120575Λ(119873) =
2120587119866int 119887(119896) (1198894119896(2120587)
4) = 2120587119866119887total(0) Then from the ex-
pressions (22) and (24) we get
119887total (0) = minus119899
4120587411988631199033
0
int(1 minus1198862
1198772
minus
)120575 (119877+minus 119886)
times 120575 (1003816100381610038161003816119877+
minus 119877minus
1003816100381610038161003816 minus 1199030) 119889
4119877minus1198894119877+
(60)
which gives
119887total (0) = minus119899(1 minus 119891(119886
1199030
)) (61)
where
119891(119886
1199030
) =2
120587int
120587
0
1198862sin2
120579119889120579
1198862 + 21198861199030cos 120579 + 119903
2
0
(62)
For 1198861199030≪ 1 (we recall that by the construction 119886119903
0le 12)
this function has the value 119891(1198861199030) asymp 119886
2119903
2
0 Thus for the
contribution of wormholes we find
120575Λ119898= minus2120587119866int119899 (119886 119903
0) (1 minus 119891(
119886
1199030
))119889119886 1198891199030
= minus2120587119866119899 (1 minus ⟨119891⟩)
(63)
63 Vacuum Value of the Cosmological Constant From theabove expression we see that to get the finite value of thecosmological constant Λ
119898= Λ
lowast+ 120575Λ
119898lt infin one should
consider the limit 119899 rarr infin (infinite density of virtualwormholes) which requires considering the smaller andsmaller wormholes From the other handwe have the obviousrestriction int 2119899(119886 119903
0)(120587
22)119886
4119889119886 119889119903
0lt 1 where (120587
22)119886
4
is the volume of one throat (wormholes cannot cut morethan the total volume of space) (We also point out that inremoving divergencies the leading role plays the zero-pointenergy Indeed 120575Λ
119898sim minus2120587119866119899 while the mean curvature has
the order Λ119877sim minus119886
2119899 and for 119886 ≪ ℓpl we have 120575Λ119898
≫ Λ119877
Moreover in the limit 119899 rarr infin one gets 119886 rarr 0 and thereforeΛ
119877120575Λ
119898rarr 0)Therefore in the leading order it seems to be
sufficient to retain point-like wormholes only (ie consider
10 Journal of Astrophysics
the limit 119886 rarr 0) Then instead of (24) we may assume thevacuum distribution of virtual wormholes in the form
119873119865 (119886119883) =1
1198862120575 (119886) ] (119883) (64)
where ](119883) = int 1198862119873119865(119886119883)119889119886 and int(1119886
2)](119883)119889
4119883 =
119899 rarr infin has the meaning of the infinite density of point-like wormholes while ] sim 119886
2119899 remains a finite In this case
the volume cut by wormholes vanishes int 2119899(12058722)119886
4119889119886 119889119903
0=
1198862int ](119883)119889
4119883 rarr 0 and the rarefied gas approximationworks
wellThis defines the bias and themean cutoff (here we definethe Fourier transform ](119896) = int ](119883)119890
1198941198961198831198894119883) as
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (65)
The contribution to themean curvature (55) can be expressedvia the same function ](119896) as
Λ119877= minus12120587
2int119899 (119886 119903
0) 119886
2119889119886 119889119903
0
= minus121205872int ] (119883) 119889
4119883 = minus12120587
2] (0)
(66)
Thus for the total cosmological constant we get the expres-sion
Λ tot = Λ0
+ 2120587119866int(1minus4120587
2
1198962(] (0)minus] (119896)))
1198894119896
(2120587)4minus12120587
2] (0)
(67)
We stress that all these terms should be finite Indeed all dis-tributions of virtual wormholes ](119896) which lead to an infinitevalue of Λ tot are suppressed in (5) by the factor sim119890minusintΛ tot119889
4
119909while the minimal value is reached when wormholes cut allof the volume of space and the action is merely 119878 = 0(Frankly speaking this statement is not rigorous At first lookthe two last terms in (67) are independent and one may tryto take ](0) an arbitrary big If this were the case then theaction would not possess the minimum at all However ](0)cannot be arbitrary big since it will violate the rarefied gasapproximation and the linear expression (67) brakes downMoreover fermions give here a contribution of the oppositesign The rigorous investigation of this problem requires thefurther studying and we present it elsewhere) We also pointout that here we considered the real scalar field as the mattersource while in the general case the stress energy tensorshould include all existing Bose and Fermi fields (Fermi fieldsgive a negative contribution to Λ
119898)
The value of Λ0looks like a free parameter which in
quantum gravity runs with scales [27] However at largescales its asymptotic value may be uniquely fixed by thesimple arguments as follows Indeed in quantum field theoryproperties of the ground state (vacuum) change when weimply an external classical fields The same is true for thedistribution of virtualwormholes ](119896 119869) for example see (33)and (37) and therefore Λ tot = Λ tot(119869) which we describe
in the next subsection We recall that in gravity the role ofthe external current plays the stress energy tensor of matterfields 119869 = 119879
119886119887 However one believes that in the absence
of all classical fields the vacuum state should represent themost symmetric (Lorentz invariant) state which in our casecorresponds to the Euclidean space In order to be consistentwith the Einstein equations this requires Λ tot(119869 = 0) = 0
which uniquely fixes the value of Λ0in (67) We point out
that from somewhat different considerations such a choicewas advocated earlier in [15 34 35]
64 Vacuum Polarization in an External Field Consider nowtopology fluctuations in the presence of an external currentIn the presence of an external current 119869ext the distribution ofvirtual wormholes changes ](119896 119869) = ](119896) + 120575](119896 119869) Indeedin (33) for the case of a weak external field the contributionof the external current into the action can be expanded asexp(minus119881(119869)) ≃ 1 minus 119881 where
119881 = minus1
2int 119869 (119909) 119866 (119909 119910) 119869 (119910) 119889
4119909 119889
4119910
= minus1
2
1198714
(2120587)4int119866
0(119896)119873 (119896)
10038161003816100381610038161198691198961003816100381610038161003816
2
1198894119896
(68)
Then using (36) we find119873(119896 119869) = 119873(119896 0) + 120575119873(119896 119869) where
120575119873 (119896 119869) = 120575119887 (119869) ≃ minus1
2
1198714
(2120587)4int120590
2(119896 119901) 119866
0(119901)
10038161003816100381610038161003816119869119901
10038161003816100381610038161003816
2
1198894119901
(69)
is the bias related to an additional distribution of virtualwormholes and 120590
2(119896 119901) = Δ119873lowast(119896)Δ119873(119901)
1205902(119896 119901) =
1
119885total (0)int [119863119873] 119890
minus119868(119873)Δ119873
lowast(119896) Δ119873 (119901) (70)
defines the dispersion of vacuum topology fluctuations (hereΔ119873 = 119873 minus 119873) The exact definition of 1205902
(119896 119901) requires thefurther development of a fundamental theory In particular itcan be numerically calculated in lattice quantum gravity [28]However it can be shown that at scales 119896 119901 ≫ 119896pl it reducesto 1205902
(119896 119901) rarr 1205902
119896120575(119896 minus 119901) and therefore
120575119887 (119869) = minus1205902
119896
41205872
21198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(71)
Now comparing this function with (23) we relate the addi-tional distribution of virtual wormholes and the externalclassical field as
41205872
1198962(120575] (0 119869) minus 120575] (119896 119869)) =
1
21205902
119896
41205872
1198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(72)
where 120575](119896 119869) = int 1198862120575119873119865(119886 119896)119889119886 We point out that the
above expression does not define the value 120575](0 119869) whichrequires an additional considerationMoreover in general theexternal field 119869 does not possess a symmetry and therefore thecorrection ⟨120575119879
120572120573(119909)⟩ does not reduce to a single cosmological
Journal of Astrophysics 11
constant However such corrections always violate the aver-aged null energy condition [36 37] and may be considered assome kind of dark energy or by other words it represents anexotic matter Some portion of dark energy still has the formof the cosmological constant which defines a nonvanishingpresent day value (we recall that fermions give a contributionof the opposite sign)
120575Λ tot = minus2120587119866int4120587
2
1198962⟨120575] (0 119869) minus 120575] (119896 119869)⟩
1198894119896
(2120587)4
minus 121205872120575] (0 119869)
(73)
where ⟨120575](119896 119869)⟩ denotes an averaging over rotationsThe only unknown parameter in (72) is the dispersion
1205902
119896which defines the intensity of topology fluctuations in
the vacuum It has also the sense of the efficiency coefficientwhich defines the portion of the energy of the external fieldspent on the formation of additional wormholes Thoughthe evaluation of 1205902
119896requires the further development of a
fundamental theory one may expect that 1205902
119896= 119873(119896)(1 minus
119873(119896)) where 119873(119896) is the mean cutoff It is expected that119873(119896) rarr 0 as 119896 ≫ 119896pl and119873(119896) rarr 119873
0le 1 This means that
120590 rarr 0 as 119896 ≫ 119896pl and 120590 rarr 1205900≪ 1 as 119896 ≪ 119896pl while it takes
the maximum value 120590max sim 1 at Planckian scales 119896 sim 119896pl Byotherwords themost efficient transmission of the energy intowormholes takes place for wormholes of the Planckian sizeIn the case when external classical fields have characteristicscales 120582 = 2120587119896 ≫ ℓpl in (72) the efficiency coefficient 1205902
119896and
the cutoff 119873(119896) become constant 120590 ≃ 1205900 119873(119896) ≃ 119873
0 while
their ratiomay be estimated as 1205721205902
0119873
0= ΩDEΩ119887
where 120572 isthe effective number of fundamental fields which contributeto 120575Λ tot and ΩDE Ω119887
are dark energy and baryon energydensities respectively According to the modern picture thisratio gives ΩDEΩ119887
asymp 075005 = 15 while 1205902
0119873
0sim 1
(as 1198730≪ 1) and therefore this defines the estimate for the
effective number of fundamental fields (helicity states) as 120572 sim
15
65 Speculations on the Formation of Actual WormholesAs we already pointed out the additional distribution ofvirtual wormholes (72) reflects the symmetry of externalclassical fields and therefore it forms a homogeneous andisotropic background and perturbations We recall that vir-tual wormholes represent an exotic form of matter In theearly Universe such perturbations start to develop and mayform actual wormholes The rigorous description of sucha process represents an extremely complex and interestingproblemwhich requires the further study Some aspects of thebehavior of the exotic density perturbations were consideredin [7] while the simplest example of the formation of awormhole-type object was discussed recently by us in [38]Therefore we may expect that some portion of such a form ofdark energy is reserved now in actual wormholes which weconsider in the next section
7 Dark Energy from Actual Wormholes
Consider now the contribution to the dark energy fromthe gas of actual wormholes Unlike the virtual wormholesactual wormholes do exist at all times and therefore a singlewormhole can be viewed as a couple of conjugated cylinders1198793
plusmn= 119878
2
plusmntimes 119877
1 So that the number of parameters of an actualwormhole is less 120578 = (119886 119903
+ 119903
minus) where 119886 is the radius of 1198782
plusmn
and 119903plusmnisin 119877
3 is a spatial part of 119877plusmn
Actual wormholes also produce two kinds of contributionto the dark energy One comes from their contribution tothe mean curvature which corresponds to an exotic stressenergy momentum tensor Such a stress energy momentumtensor reflects the dark energy reserved by additional virtualwormholes discussed in the previous section Such energyis necessary to support actual wormholes as a solution tothe Einstein equations The second part comes from vacuumpolarization effects by actual wormholes The considerationin the previous section shows that for macroscopic worm-holes the second part has the order ⟨Δ119879
120572120573⟩ sim 8120587119866119899 and
is negligible as compared to the curvature 119877 sim 1198862119899 (since
macroscopic wormholes have throats 119886 ≫ ℓpl) Howeverfor the sake of completeness and for methodological aims wedescribe it as well
For rigorous evaluation of dark energy of the secondtype we first have to find the bias 119887
1(119909 119909
1015840 120578) analogous to
(19) for the topology 1198774(119879
3
+cup 119879
3
minus) There are many papers
treating different wormholes in this respect (eg see [36 37]and references therein) However in the present paper for anestimation we shall use a more simple trick
71 Beads of Virtual Wormholes (Quantum Wormhole)Indeed instead of the cylinders 1198793
plusmnwe consider a couple of
chains (beads of virtual wormholes 1198793
plusmnrarr cup
1198991198783
plusmn119899) Such an
idea was first suggested in [39] and one may call such anobject as quantum wormhole Then the bias can be writtenstraightforwardly
1198871(119909 119909
1015840 120578) =
+infin
sum
119899=minusinfin
1
41205872119886(
1
(119877minus119899
minus 1199091015840)2minus
1
(119877+119899
minus 1199091015840)2)
times [120575 (10038161003816100381610038161003816 minus
+119899
10038161003816100381610038161003816minus 119886) minus 120575 (
10038161003816100381610038161003816 minus
minus119899
10038161003816100381610038161003816minus 119886)]
(74)
where 119877plusmn119899
= (119905119899 119903
plusmn) with 119905
119899= 119905
0+ 2ℓ119899 and ℓ ge 119886 is the
step We may expect that upon averaging over the position1199050isin [minusℓ ℓ] the bias for the beads will reproduce the bias for
cylinders1198793
plusmn(at least it looks like a very good approximation)
We point out that the averaging out (12ℓ) intℓ
minusℓ119889119905
0and the
sum sum+infin
119899=minusinfinreduces to a single integral (12ℓ) intinfin
minusinfin119889119905 of the
zero term in (74) And moreover the resulting total biascorresponds merely to a specific choice of the distributionfunction 119865(120585) in (21) Namely we may take
119873119865 (120585) =1
2ℓ120575 (119905
+minus 119905
minus) 119891 (
1003816100381610038161003816119903+ minus 119903minus
1003816100381610038161003816 119886) (75)
12 Journal of Astrophysics
where119877plusmn= (119905
plusmn 119903
plusmn) and119891(119904 119886) is the distribution of cylinders
which can be taken as (119899 is 3-dimensional density)
119891 (120578) =119899 (119886)
41205871199032
0
120575 (119904 minus 1199030) (76)
Using the normalization condition int119873119865(120585)119889120585 = 119873 we findthe relation 119873 = (12ℓ)119899119881 = 119899119881 where 119899 is a 4-dimensional density of wormholes and 1(2ℓ) is the effectivenumber of wormholes on the unit length of the cylinder (iethe frequency with which the virtual wormhole appears atthe positions 119903
plusmn) This frequency is uniquely fixed by the
requirement that the volume which cuts the bead is equal tothat which cuts the cylinder (43)1205871198863 = (120587
22)119886
4(12ℓ) (ie
2ℓ = (31205878)119886 and 119899 = (83120587119886)119899) Thus we can use directlyexpression (23) and find (compare to (25))
119887 (119896) = minusint 119899 (119886) 1198862 4120587
2
1198962(1 minus
sin |k| 1199030|k| 1199030
)1198691(119896119886)
1198961198862119889119886 (77)
where 119896 = (1198960 k) Here the first term merely coincides with
that in (25) and therefore it gives the contribution to thecosmological constant 120575Λ(8120587119866) = minus1198994 = minus2119899(3120587119886)while the second term describes a correction which does notreduce to the cosmological constant and requires a separateconsideration
72 Stress Energy Tensor From (57) we find that the stressenergy tensor
minus⟨Δ119879120572120573
(119909)⟩ = int
119896120573119896120572minus (12) 119892
1205721205731198962
1198962119887 (119896 120585)
1198894119896
(2120587)4
(78)
reduces to the two functions
11987900
= 120576 = 1205821minus1
2120583
119879119894119895= 119901120575
119894119895 119901 =
1
31205822minus1
2120583
(79)
where 120576 + 3119901 = minus120583 and 1205821+ 120582
2= 120583 and these functions are
1205821= minusint
1198962
0
11989621198871198894119896
(2120587)4 120582
2= minusint
|k|2
11989621198871198894119896
(2120587)4 (80)
By means of the use of the spherical coordinates 11989620119896
2=
cos2120579 |k|21198962 = sin2120579 and 119889
4119896 = 4120587sin2
1205791198963119889119896119889120579 we get
120582119894=119899 (119886 119903
0)
4120573119894
(1 minus 2120573119894(119886
1199030
)
2
119891119894(119886
1199030
)) (81)
where 1205731= 1 120573
2= 13 and 119891
119894is given by
119891(1
2)(119910)
=2
120587int
1
minus1
int
infin
0
sin (119909 sin 120579)1198691(119910119909)
1199101199092(cos2120579sin2
120579) 119889119909 119889cos 120579
(82)
For 1198861199030≪ 1 we find
11989112
(119886
1199030
) asymp (1 + 11990012
(119886
1199030
)) (83)
Thus finally we find
120576 ≃ minus119899
4= minus
2119899
3120587119886 119901 ≃ 120576(1 minus
4
3(119886
1199030
)
2
) (84)
which upon the continuation to the Minkowsky space givesthe equation of state in the form (An arbitrary gas ofwormholes splits in fractions with a fixed 119886 and 119903
0)
119901 = minus(1 minus4
3(119886
1199030
)
2
) 120576 (85)
which in the case when 1198861199030≪ 1 behaves like a cosmological
constant However when 119886 ≫ ℓpl such a constant is extremelysmall and can be neglected while the leading contributioncomes from the mean curvature
73 Mean Curvature In this subsection we consider theMinkowsky spaceThen the simplest actual wormhole can bedescribed by the metric analogous to (1) for example see [7]
1198891199042= 119888
2119889119905
2minus ℎ
2(119903) 120575
120572120573119889119909
120572119889119909
120573 (86)
where ℎ(119903) = 1 + 120579(119886 minus 119903)(1198862119903
2minus 1) To avoid problems
with the Bianchi identity and the conservation of energy thestep function should be also smoothed as in (1) The stressenergy tensor which produces such a wormhole can be foundfrom the Einstein equation 8120587119866119879
120573
120572= 119877
120573
120572minus (12)120575
120573
120572119877 Both
regions 119903 gt 119886 and 119903 lt 119886 represent portions of the ordinaryflat Minkowsky space and therefore the curvature is 119877119896
119894equiv 0
However on the boundary 119903 = 119886 it has the singularity Sincethe metric (86) does not depend on time we find
1198770
0= 119877
0
120572= 0 119877
120573
120572=2
119886120575 (119886 minus 119903) 119899
120572119899120573+ 120575
120573
120572 + 120582
120573
120572 (87)
where 119899120572 = 119899120572= 119909
120572119903 is the outer normal to the throat 1198782
and 120582120573
120572are additional terms (eg see (49) and (51)) which
in the leading order are negligible upon averaging over someportion of space Δ119881 ≳ 119886
3 In the case of a set of wormholesthis gives in the leading order
1198770
0= 119877
0
120572= 0 119877
120573
120572= sum
2
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119903
119894
1003816100381610038161003816) 119899119894120572119899120573
119894+ 120575
120573
120572
(88)
where 119886119894is the radius of a throat and 119903
119894is the position of the
center of the throat in space and 119899120572
119894= (119909
120572minus 119903
120572
119894)|119903 minus 119903
119894|
In the case of a homogeneous and isotropic distribution ofsuch throats we find 119877
120573
120572= (13)119877120575
120573
120572(averaging over spatial
directions gives ⟨119899120572119899120573⟩ = (13)120575
120573
120572) where
119877 = minus8120587119866119879 = sum8
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119877
119894
1003816100381610038161003816) = 32120587int 119886119899 (119886) 119889119886
(89)
Journal of Astrophysics 13
where 119879 stands for the trace of the stress energy momentumtensor which one has to add to the Einstein equations tosupport such awormhole It is clear that such a source violatesthe weak energy condition and therefore it reproduces theformof dark energy (ie119879 = 120576+3119901 lt 0) If the density of suchsources (and resp the density of wormholes) is sufficientlyhigh then this results in the observed [10ndash14] accelerationof the scale factor for the Friedmann space as sim 119905
120572 with120572 = 21205763(120576 + 119901) = 2120576(2120576 + (120576 + 3119901)) gt 1 for examplesee also [40ndash42] In terms of the 4-dimensional density ofwormholes 119899 = (83120587119886)119899 we get 119877 sim 119886
2119899 ≫ 8120587119866119899 as 119886 ≫ ℓpl
and therefore the leading contribution indeed comes fromthe mean curvature
8 Estimates and Concluding Remarks
Now consider the simplest estimates Actual wormholes seemto be responsible for the dark matter [7 9] Therefore to getthe estimate to the number density of wormholes is ratherstraightforward First wormholes appear at scales when darkmatter effects start to display themselves that is at scales ofthe order 119871 sim (1 divide 5)Kpc which gives in that range thenumber density
119899 sim1
1198713sim (3 divide 0024) times 10
minus65cmminus3 (90)
The characteristic size of throats can be estimated from (89)120576DE sim (119866)
minus1119899119886 Since the density of dark energy is 120576DE1205760 =
ΩDE sim 075 where 1205760is the critical density then we find the
estimate
119886 sim2
3(1 divide 125) times 10
minus3119877⊙ΩDEℎ
2
75 (91)
where119877⊙is the Solar radius ℎ
75= 119867(75 km(secMpc)) and
119867 is the Hubble constant We also recall that the backgrounddensity of baryons 120576
119887generates a nonvanishingwormhole rest
mass119872119908= (43)120587119886
31198773120576119887(where119877(119905) is the scale factor of the
Universe and therefore 119872119908remains constant) for example
see [7] It produces the dark matter density related to thewormholes as 120576DM ≃ 119872
119908119899 The typical mass of a wormhole
119872119908is estimated as
119872119908sim 1 7 times (1 divide 125) times 10
2119872
⊙ΩDMℎ
2
75 (92)
where 119872⊙is the Solar mass We point out that this mass
has not the direct relation to the parameters of the gas ofwormholes However it defines the moment when wormholethroats separated from the cosmological expansion Theabove estimate shows that if wormholes form due to thedevelopment of perturbations in the exotic matter then thisprocess should start much earlier than the formation ofgalaxies
Thus we see that virtual wormholes should indeed leadto the regularization of all divergencies in QFT which agreeswith recent results [28] Therefore they form the local finitevalue of the cosmological constant In the absence of externalclassical fields such a value should be exactly zero at macro-scopic scales A some nonvanishing value for the cosmolog-ical constant appears as the result of vacuum polarization
effects in external fields Indeed external fields form anadditional distribution of virtual wormholes which possessan exotic stress energy tensor (some kind of dark energy)Only some part of it forms the cosmological constant whilethe rest reflects the symmetry of external fields and possessesinhomogeneitiesWe assume that during the evolution of ourUniverse inhomogeneities in the exotic matter develop andmay form actual wormholes Although this problem requiresthe further and more deep investigation we refer to [38]where the formation of a simplest wormhole-like object hasbeen considered In other words such polarization energyis reserved now in a gas of actual wormholes We estimatedparameters of such a gas and believe that such a gas mayindeed be responsible for both dark matter and dark energyphenomena
References
[1] J R Primack ldquoThe nature ofdark matterrdquo httparxivorgabsastro-ph0112255
[2] J Diemand M Zemp B Moore J Stadel and M CarolloldquoCusps in cold dark matter haloesrdquoMonthly Notices of the RoyalAstronomical Society vol 364 no 2 pp 665ndash673 2005
[3] E W Mielke and J A V Velez Perez ldquoAxion condensate as amodel for dark matter halosrdquo Physics Letters B vol 671 no 1pp 174ndash178 2009
[4] G Gentile P Salucci U Klein D Vergani and P Kalberla ldquoThecored distribution of dark matter in spiral galaxiesrdquo MonthlyNotices of the Royal Astronomical Society vol 351 no 3 pp 903ndash922 2004
[5] D T F Weldrake W J G de Blok and F Walter ldquoA high-resolution rotation curve of NGC 6822 a test-case for cold darkmatterrdquo Monthly Notices of the Royal Astronomical Society vol340 no 1 pp 12ndash28 2003
[6] W J G de Blok andA Bosma ldquoHigh-resolution rotation curvesof low surface brightness galaxiesrdquoAstronomy and Astrophysicsvol 385 pp 816ndash846 2002
[7] A Kirillov and E P Savelova ldquoDensity perturbations in a gas ofwormholesrdquoMonthly Notices of the Royal Astronomical Societyvol 412 no 3 pp 1710ndash1720 2011
[8] P Kanti B Kleihaus and J Kunz ldquoStable Lorentzianwormholesin dilatonic Einstein-Gauss-Bonnet theoryrdquo Physical Review Dvol 85 no 4 Article ID 044007 2012
[9] A A Kirillov and E P Savelova ldquoDark matter from a gas ofwormholesrdquo Physics Letters B vol 660 no 3 pp 93ndash99 2008
[10] A G Riess A V Filippenko P Challis et al ldquoObservationalevidence from supernovae for an accelerating universe and acosmological constantrdquo The Astronomical Journal vol 116 no3 p 1009 1998
[11] S Perlmutter G Aldering G Goldhaber et al ldquoMeasurementsofΩ andΛ from42high-redshift supernovaerdquoTheAstrophysicalJournal vol 517 no 2 p 565 1999
[12] J L Tonry B P Schmidt B Barris et al ldquoCosmological resultsfromhigh-z supernovaerdquoTheAstrophysical Journal vol 594 no1 p 594 2003
[13] N W Halverson E M Leitch C Pryke et al ldquoDegreeangular scale interferometer first results a measurement of thecosmic microwave background angular power spectrumrdquo TheAstrophysical Journal vol 568 no 1 p 38 2002
14 Journal of Astrophysics
[14] C B Netterfield P A R Ade J J Bock et al ldquoA measurementby BOOMERANGofmultiple peaks in the angular power spec-trum of the cosmic microwave backgroundrdquo The AstrophysicalJournal vol 571 no 2 p 604 2002
[15] S Coleman ldquoWhy there is nothing rather than something atheory of the cosmological constantrdquoNuclear Physics B vol 310no 3-4 pp 643ndash668 1988
[16] I Klebanov L Susskind and T Banks ldquoWormholes and thecosmological constantrdquo Nuclear Physics B vol 317 no 3 pp665ndash692 1989
[17] S W Hawking ldquoSpacetime foamrdquoNuclear Physics B vol 114 p349 1978
[18] T P Cheng and L F Li Gauge Theory of Elementary ParticlesClarendon Press Oxford UK 1984
[19] A H Taub ldquoSpace-times with distribution valued curvaturetensorsrdquo Journal ofMathematical Physics vol 21 no 6 pp 1423ndash1431 1980
[20] A Shatsky privite communications[21] V A Fock ldquoZur Theorie des Wasserstoffatomsrdquo Zeitschrift fur
Physik vol 98 no 3-4 pp 145ndash154 1935[22] E P Savelova ldquoGas of wormholes in Euclidean quantum field
theoryrdquo httparxivorgabs12115106[23] A A Kirillov and E P Savelova ldquoOn the behavior of
bosonic systems in the presence of topology fluctuationsrdquohttparxivorgabs08082478
[24] A A Kirillov ldquoViolation of the Pauli principle and dimensionof the Universe at very large distancesrdquo Physics Letters B vol555 no 1-2 pp 13ndash21 2003
[25] A A Kirillov ldquoDark matter dark charge and the fractalstructure of the Universerdquo Physics Letters B vol 535 no 1ndash4pp 22ndash24 2002
[26] J Ambjorn J Jurkiewicz and R Loll ldquoThe spectral dimensionof the universe is scale dependentrdquo Physical Review Letters vol95 no 17 Article ID 171301 4 pages 2005
[27] E Manrique S Rechenberger and F Saueressig ldquoAsymptoti-cally safe Lorentzian gravityrdquo Physical Review Letters vol 106no 25 Article ID 251302 4 pages 2011
[28] J Laiho and D Coumbe ldquoEvidence for asymptotic safety fromlattice quantum gravityrdquo Physical Review Letters vol 107 no 16Article ID 161301 2011
[29] A A Kirillov and D Turaev ldquoOn modification of the Newtonrsquoslaw of gravity at very large distancesrdquo Physics Letters B vol 532no 3-4 pp 185ndash192 2002
[30] A A Kirillov and D Turaev ldquoThe universal rotation curveof spiral galaxiesrdquo Monthly Notices of the Royal AstronomicalSociety vol 371 no 1 pp L31ndashL35 2006
[31] A A Kirillov and D Turaev ldquoFoam-like structure of theuniverserdquo Physics Letters B vol 656 pp 1ndash8 2007
[32] A A Kirillov ldquoThe nature of dark matterrdquo Physics Letters B vol632 no 4 pp 453ndash462 2006
[33] A A Kirillov and E P Savelova ldquoAstrophysical effects of space-time foamrdquo Gravitation and Cosmology vol 14 no 3 pp 256ndash261 2008
[34] S W Hawking and N Turok ldquoOpen inflation without falsevacuardquo Physics Letters B vol 425 no 1-2 pp 25ndash32 1998
[35] Z C Wu ldquoThe cosmological constant is probably zero and aproof is possibly rightrdquo Physics Letters B vol 659 no 5 pp 891ndash893 2008
[36] R Garattini ldquoEntropy and the cosmological constant aspacetime-foam approachrdquo Nuclear Physics B vol 88 no 1ndash3Article ID 991003 pp 297ndash300 2000
[37] MVisserLorentzianWormholes SpringerNewYorkNYUSA1996
[38] A A Kirillov and E P Savelova ldquoArtificial wormholerdquohttparxivorgabs12040351
[39] E W Mielke ldquoKnot wormholes in geometrodynamicsrdquo Gen-eral Relativity and Gravitation vol 8 no 3 pp 175ndash196 1977
[40] E B Gliner ldquoAlgebraic properties of the energy-momentumtensor and vacuum-like states of matterrdquo Journal of Experimen-tal and Theoretical Physics vol 22 p 378 1966
[41] A H Guth ldquoInflationary universe a possible solution to thehorizon and flatness problemsrdquo Physical Review D vol 23 no2 pp 347ndash356 1981
[42] A A Linde ldquoA new inflationary universe scenario a possiblesolution of the horizon flatness homogeneity isotropy andprimordial monopole problemsrdquo Physics Letters B vol 108 no6 pp 389ndash393 1982
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
![Page 2: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/2.jpg)
2 Journal of Astrophysics
which means that nontraversable wormholes can be used tosmooth cusps in centers of galaxies Thus it worth expectingthatwormholesmay play an important role in the explanationof the dark matter phenomenon
Saving the dark matter component ΛCDM requiresthe presence (sim70) of dark energy (of the cosmologicalconstant) Moreover there is evidence for the start of anacceleration phase in the evolution of the Universe [10ndash14]In the present paper we use virtual wormholes to estimatethe contribution of zero-point fluctuations in the value of thecosmological constant The idea to relate virtual wormholes(or baby universes) and the cosmological constant is not newin somewhat different context it was used by Coleman in [15]and developed in [16] Our basic aim is to demonstrate thatvirtual wormholes form a finite value of the energy density ofzero-point fluctuations
It is necessary to point here out to the principle differ-ence between actual and virtual wormholes The principledifference is that a virtual wormhole exists only for a verysmall period of time and at very small scales and doesnot necessarily obey to the Einstein equations It representstunnelling event and therefore the averaged null energycondition (ANEC) cannot forbid the origin of such an objectFor the future we also note that a set of virtual wormholesmay work as an actual wormhole opening thus the way foran artificial construction of wormhole-type objects in labexperiments
In the present paper we describe a virtual wormholeas follows From the very beginning we use the Euclideanapproach (eg see [17] and the standard textbooks [18])Thenthe simplest virtual wormhole is described by themetric (120572 =
1 2 3 4)
1198891199042= ℎ
2(119903) 120575
120572120573119889119909
120572119889119909
120573 (1)
where
ℎ (119903) = 1 + 120579 (119886 minus 119903) (1198862
1199032minus 1) (2)
and 120579(119909) is the step function Such a wormhole has vanishingthroat length while the step function at the junction maycause a problem in Einsteinrsquos equation or when a topologicalEuler term is involved A more careful analysis needs to con-sider distributional curvature and so forth see [19] To avoidthese difficulties we may consider from the very beginninga wormhole of a finite throat length sim1120573 where the stepfunction is replaced with a smooth function (eg 120579(119909 120573) =
(exp (120573119909)+1)minus1)Thenwhere it is necessary onemay considerthe limit 120573 rarr infin only in final expressions This insuresthat the Bianchi identity holds and that the above metricremains inside of the domain of usual gravity (Unexpectedlyour approach (the use of step function) seems to irritate anessential part of physicists working with wormholes (egPRD reviewers moreover there is a claim that we studysome other exotic objects which are not wormholes [20])Therefore it is necessary to clarify our position here We arequite aware that at present state the physics of wormholes iscertainly on the most speculative side Therefore we do not
see the difference between specific forms of a smooth metricthat one may use For example the simplest choice ℎ = (1 +
1198862119903
2) gives the well-known metric which in 3-dimensions
is called as the Bronnikov-Ellis metric or the metric ℎ =
(1 + (119887119903) + (1198862119903
2)) which includes an additional parameter
(an arbitrary length of the handle) which is not called by anyname but is not less trivial In the case of actual wormholesthe exact and correct form of metric may be establishedonly upon understanding the nature and properties of exoticmatter which may support such a metric as a stable solutionto the Einstein equations For this time has not come yet Inthe case of virtual wormholes even this is not important for inthe complete theory one has to sum over all possible metricswhich formally may be included in 120593 in (5) Our basic aimis to present sufficiently clear and simple model (let it be farfrom realistic) which retains basic qualitative features relatedto a nontrivial topology)
In the region 119903 gt 119886 ℎ = 1 and the metric (2) is flatwhile the region 119903 lt 119886 with the obvious transformation119910120572= (119886
2119903
2)119909
120572 is also flat for 119910 gt 119886 Therefore the regions119903 gt 119886 and 119903 lt 119886 represent two Euclidean spaces glued at thesurface of a sphere 1198783 with the centre at the origin 119903 = 0 andradius 119903 = 119886 Such a space can be described with the ordinarydouble-valued flat metric in the region 119903
plusmngt 119886 by
1198891199042= 120575
120572120573119889119909
120572
plusmn119889119909
120573
plusmn (3)
where the coordinates 119909120572
plusmndescribe two different sheets of
space Now identifying the inner and outer regions of thesphere 1198783 allows the construction of a wormhole which con-nects regions in the same space (instead of two independentspaces) This is achieved by gluing the two spaces in (3) bymotions of the Euclidean space (the Poincare motions) If 119877
plusmn
is the position of the sphere in coordinates 119909120583
plusmn then the gluing
is the rule
119909120583
+= 119877
120583
++ Λ
120583
] (119909]minusminus 119877
]minus) (4)
where Λ120583
] isin 119874 (4) which represents the composition of atranslation and a rotation of the Euclidean space (Lorentztransformation) In terms of common coordinates such awormhole represents the standard flat space in which the twospheres 1198783
plusmn(with centers at positions 119877
plusmn) are glued by the rule
(4)We point out that the physical region is the outer region ofthe two spheres Thus in general the wormhole is describedby a set of parameters the throat radius 119886 positions of throats119877plusmn and rotation matrix Λ120583
] isin 119874 (4)In the present paper we assume the space-time foam
picture in which the vacuum is filled with a gas of virtualwormholes We show that virtual wormholes form a finite (ofthe Planckian order) value of the energy density of zero-pointfluctuations However such a huge value is compensated bythe contribution of virtual wormholes to the mean curvatureand the observed value of the cosmological constant shouldbe close to zero
To achieve our aimwe in Section 2 present the construc-tion of the generating functional in quantum field theoryThe main idea is that the partition function includes thesum over field configurations and the sum over topologies
Journal of Astrophysics 3
Where the sum over topologies is the sum over virtualwormholes described above Such an approach gives a rathergood leading approximation for calculation of the partitionfunction and corresponds to the standard methods (egRitza method etc) In Section 3 we investigate properties ofthe two-point Green function We show that the presenceof the gas of virtual wormholes can be described by thetopological bias exactly as it happens in the presence of actualwormholes [7 9] For limiting topologies when the densityof virtual wormholes becomes infinite the Green functionshows a good ultraviolet behavior which means that thereexists a class of such systems when quantum field theoriesare free of divergencies We demonstrate how the sum overtopologies defines themean value for the bias which takes thesense of a cutoff function in the space of modes In Section 4we explicitly demonstrate that for a particular set of virtualwormholes the bias defines not more than the projectionoperator on the subspace of functions obeying to the properboundary conditions at wormhole throats The projectivenature of the bias means that wormholes merely cut someportion of degrees of freedom (modes) Phenomenologicallyit means that wormholes can be described by the presence ofghost fields which compensate the extra (cut by wormholes)modes In Section 5 we show how the cutoff expresses viasome dynamic parameters of wormholesThe exact definitionof such parameters we leave it for the future investigationIn Section 6 we consider the origin of the cosmologicalconstant We demonstrate that the cosmological constantis determined by the contribution of the energy density ofzero-point fluctuations and by the contribution of virtualwormholes to the mean curvature We estimate contributionof virtual wormholes to the mean curvature and show alsothat wormholes lead to a finite (of the planckian order)value of ⟨119879
120583]⟩ which requires considering the contributionfrom the smaller and smaller wormholes with divergentdensity 119899 rarr infin We also present arguments of why inthe absence of external classical fields the total value ofthe cosmological constant is exactly zero while it acquiresa nonvanishing value due to vacuum polarization effects(ie due to an additional distribution of virtual wormholes)in external fields We also speculate the possibility of theformation of actual wormholes and in Section 7 we estimatetheir contribution to the dark energy Finally in Section 8 werepeat basic results an discuss some perspectives
2 Generating Function
The basic aim of this section is to construct the generatingfunctional which can be used to get all possible correlationfunctions Consider the partition functionwhich includes thesum over topologies and the sum over field configurations
119885total = sum
120591
sum
120593
119890minus119878 (5)
For the sake of simplicity we use from the very beginning theEuclidean approach The action has the form
119878 = minus1
2(120593119860120593) + (119869120593) (6)
and we use the notions (119869120593) = int 119869(119909)120593(119909)1198894119909 If we fix
the topology of space by placing a set of wormholes withparameters 120585
119894 then the sum over field configurations 120593 gives
the well-known result
119885lowast(119869) = 119885
0(119860) 119890
minus(12)(119869119860minus1
119869) (7)
where 1198850(119860) = int[119863120593]119890
(12)(120593119860120593) is the standard expressionand 119860
minus1= 119860
minus1(120585) is the Green function for a fixed topology
that is for a fixed set of wormholes 1205851 120585
119873
Consider now the sum over topologies 120591 To this end werestrict the sum over the number of wormholes and integralsover parameters of wormholes
sum
120591
997888rarr sum
119873
int
119873
prod
119894=1
119889120585119894= int [119863119865] (8)
where
119865 (120585119873) =1
119873
119873
sum
119894=1
120575 (120585 minus 120585119894) (9)
and 119873119865 is the density of wormholes in the configurationspace 120585 We also point out that in general the integration overparameters is not free (eg it obeys the obvious restriction|
+
119894minus
minus
119894| ge 2119886
119894) This defines the generating function as
119885total (119869) = int [119863119865]1198850(119860) 119890
minus(12)(119869119860minus1
119869) (10)
The sum over topologies assumes an additional averaging outfor all mean values with the measure 119889120583
119873= 120588(120585119873)119889
119873120585
where
120588 (120585119873) =
1198850(119860 (120585119873))
119885total (0) (11)
which obey the obvious normalization conditionsum119873int119889120583
119873=
sum119873120588119873
= 1 The averaging out over topologies assumes thetwo stages First we fix the total number of wormholes 119873and average over the parameters of wormholes 120585 (ie overparameters of a static gas of wormholes in 119877
4) Then we sumover the number of wormholes119873 (the so-called big canonicalensemble)
The basic difficulty of the standard field theory is thatthe perturbation scheme based on (7) leads to divergentexpressions This remains true for every particular topologyof space (ie for any particular finite set of wormholes) sincethere always exists a scale below which the space looks likethe ordinary Euclidean spaceWhat we expect is that the sumover all possible topologies will remove such a difficulty
And indeed the above measure (11) has the structure
1198850(119860 (120585119873)) = exp(minusintΛ (120585119873) 119889
4119909) (12)
where Λ(120585119873) is the cosmological constant related to theenergy density of zero-point fluctuations calculated for aparticular distribution of wormholes (We recall that the total
4 Journal of Astrophysics
cosmological constant should include also the contributionfrom the mean curvature (55)) Any finite distribution ofwormholes leads to the divergent expression Λ(120585119873) rarr
infin and is suppressed (ie 120588 (120585119873) rarr 0) However thesum over all possible topologies assumes also the limitingtopologies 119899 rarr infin where 119899 = 119873119881 is the density ofwormholes In this limit wormhole throats degenerate intopoints and the minimal scale below which the space lookslike the Euclidean space is merely absent We point out thatfrom the rigorous mathematical standpoint such limitingtopologies cannot be described in terms of smoothmanifoldssince they are not locally Euclidean and does not possess afinite set of maps In mathematics similar objects are wellknown for example fractal sets However if a fractal set isobtained by cutting (by means of a specific rule or iterations)portions of space our limiting topologies are obtained bygluing (identifying) some portions (or in the limit couplesof points) of the Euclidean space The basic feature of suchtopologies is that QFT becomes finite on such a set Indeedas we shall see a particular infinite distribution of wormholescan always be chosen in such a way that the energy of zero-point fluctuations becomes a finite 0 le Λ
infin(120585) lt infin (eg
see the next section or the second term in (67)) In the sumover topologies only such limiting topologies do survive (ie120588infin(120585) = 0)
3 The Two-Point Green Function
From (7) we see that the very basic role in QFT plays the twopoint Green function Such a Green function can be foundfrom the equation
119860119866(119909 1199091015840) = minus120575 (119909 minus 119909
1015840) (13)
with proper boundary conditions at wormholes which gives119866 = 119860
minus1 Now let us introduce the bias function119873(119909 1199091015840) as
119866 (119909 119910) = int1198660(119909 119909
1015840)119873 (119909
1015840 119910) 119889119909
1015840 (14)
where 1198660(119909 119909
1015840) is the ballistic (or the standard Euclidean
Green function) and the bias can be presented as
119873(119909 1199091015840) = 120575 (119909 minus 119909
1015840) +sum
119894
119887119894120575 (119909 minus 119909
119894) (15)
where 119887119894are fictitious sources at positions 119909
119894which should
be added to obey the proper boundary conditions We pointout that the bias can be explicitly expressed via parametersof wormholes that is 119873(119909 119909
1015840) = 119873(119909 119909
1015840 120585
1 120585
119873) For the
sake of illustration we consider first a particular example
31 The Bias for a Particular Distribution of Wormholes(Rarefied Gas Approximation) Consider now the bias for aparticular set of wormholes For the sake of simplicity weconsider the case when119898 = 0 The Green function obeys theLaplace equation
minusΔ119866 (119909 1199091015840) = 120575 (119909 minus 119909
1015840) (16)
with proper boundary conditions at throats (we require119866 and120597119866120597119899 to be continual at throats)The Green function for theEuclidean space is merely 119866
0(119909 119909
1015840) = 14120587
2(119909 minus 119909
1015840)2 (and
1198660(119896) = 1119896
2 for the Fourier transform) In the presence ofa single wormhole which connects two Euclidean spaces thisequation admits the exact solution For outer region of thethroat 1198783 the source 120575(119909 minus 119909
1015840) generates a set of multipoles
placed in the center of sphere which gives the corrections tothe Green function 119866
0in the form (we suppose the center of
the sphere at the origin)
120575119866 = minus1
412058721199092
infin
sum
119899=1
1
119899 + 1(119886
1199091015840)
2119899
(1199091015840
119909)
119899minus1
119876119899 (17)
where 119876119899= (4120587
22119899)sum
119899minus1
119897=0sum
119897
119898=minus119897119876
lowast1015840
119899119897119898119876
119899119897119898and 119876
119899119897119898(Ω) are
four-dimensional spherical harmonics for example see [21]In the present section we shall consider a dilute gas approx-imation and therefore it is sufficient to retain the lowest(monopole) term only A single wormhole which connectstwo regions in the same space is a couple of conjugatedspheres 1198783
plusmnof the radius 119886with a distance =
+minus
minusbetween
centers of spheres So the parameters of the wormhole are(The additional parameter (rotation matrix Λ) is importantonly for multipoles of higher orders) 120585 = (119886 119877
+ 119877
minus) The
interior of the spheres is removed and surfaces are gluedtogether Then the proper boundary conditions (the actualtopology) can be accounted for by adding the bias of thesource
120575 (119909 minus 1199091015840) 997888rarr 120575 (119909 minus 119909
1015840) + 119887 (119909 119909
1015840) (18)
In the approximation 119886119883 ≪ 1 (eg see for details [9]) thebias for a single wormhole takes the form
1198871(119909 119909
1015840 120585) =
1198862
2(
1
(119877minusminus 1199091015840)
2minus
1
(119877+minus 1199091015840)
2)
times [120575 ( minus +) minus 120575 ( minus
minus)]
(19)
This form for the bias is convenient when constructing thetrue Green function and considering the long-wave limithowever it is not acceptable in considering the short-wavebehavior and vacuum polarization effects Indeed the posi-tions of additional sources are in the physically nonadmissibleregion of space (the interior of spheres 1198783
plusmn) To account for
the finite value of the throat size we should replace in (19)the point-like source with the surface density (induced on thethroat) that is
120575 ( minus plusmn) 997888rarr
1
212058721198863120575 (
10038161003816100381610038161003816 minus
plusmn
10038161003816100381610038161003816minus 119886) (20)
Such a replacement does not change the value of the trueGreen function however now all extra sources are in thephysically admissible region of space
In the rarefied gas approximation the total bias is additivethat is
119887total (119909 1199091015840) = sum119887
1(119909 119909
1015840 120585
119894) = 119873int119887
1(119909 119909
1015840 120585) 119865 (120585) 119889120585
(21)
Journal of Astrophysics 5
where 119873119865 is given by (9) For a homogeneous and isotropicdistribution 119865(120585) = 119865(119886119883) and then for the bias we find
119887total (119909 minus 1199091015840)
= int1
21205872119886(
1
1198772
minus
minus1
1198772
+
)120575 (10038161003816100381610038161003816 minus
1015840minus
+
10038161003816100381610038161003816minus 119886)119873119865 (120585) 119889120585
(22)
Consider the Fourier transform 119865(119886119883) = int119865(119886 119896)119890minus119894119896119883
sdot
(1198894119896(2120587)
4) and using the integral 11199092
= int(41205872119896
2)119890
minus119894119896119909sdot
(1198894119896(2120587)
4) we find for 119887(119896) = int 119887(119909)119890
1198941198961199091198894119909 the expression
119887total (119896) = 119873int1198862 4120587
2
1198962(119865 (119886 119896) minus 119865 (119886 0))
1198691(119896119886)
1198961198862119889119886 (23)
(1) Example of a Finite Density of Wormholes Consider nowa particular (of a finite density) distribution of wormholes119865(119886119883) for example
119873119865 (119886119883) =119899
212058721199033
0
120575 (119886 minus 1198860) 120575 (119883 minus 119903
0) (24)
where 119899 = 119873119881 is the density of wormholes In the case119873 = 1 this function corresponds to a single wormhole withthe throat size 119886
0and the distance between throats 119903
0=
|119877+minus119877
minus|We recall that the action (6) remains invariant under
translations and rotations which straightforwardly leads tothe above function Then 119873119865(119886 119896) = int119873119865(119886119883)119890
1198941198961199091198894119909 re-
duces to 119873119865(119886 119896) = 119899(1198691(119896119903
0)(119896119903
02))120575(119886 minus 119886
0) Thus from
(23) we find
119887 (119896) = minus1198991198862 4120587
2
1198962(1 minus
1198691(119896119903
0)
11989611990302
)1198691(119896119886
0)
11989611988602
(25)
And for the true Green function we get
119866true = 1198660(119896)119873 (119896) = 119866
0(119896) (1 + 119887 (119896)) (26)
In the short-wave limit (119896119886 1198961199030≫ 1) 119887(119896) rarr 0 and
therefore 119873(119896) rarr 1 This means that at very small scalesthe space filled with a finite density of wormholes looks likethe ordinary Euclidean space In the long-wave limit 119896 rarr 0
we get 1198691(119896119903
0)(119896119903
02) asymp 1 minus (12) (119896119903
02)
2+ sdot sdot sdot which gives
119887(119896) asymp minus1205872119899119886
21199032
02 while in a more general case we find
119887(119896) asymp minus int(12058722)119886
21199032
0119899(119886 119903
0)119889119886 119889119903
0 where 119899(119886 119903
0) is the den-
sity of wormholes with a particular values of 119886 and 1199030 and for
the bias function (15) we get
119873(119896) 997888rarr 1 minus1205872
2int 119886
4119899 (119886 119903
0)1199032
0
1198862119889119886 119889119903
0le 1 (27)
In other words in the long-wave limit (119896119886 1198961199030≪ 1) the
presence of a particular set of virtual wormholes diminishesmerely the value of the charge values
(2) Limiting Topologies or Infinite Densities of WormholesConsider now the limiting distribution when the density of
wormholes 119899 rarr infin Since every throat cuts the finite portionof the volume (120587
22)119886
4 this case requires considering thelimit 119886 rarr 0 We assume that in this limit 1198862119873119865(119886119883) rarr
120575(119886)](119883) where ](119883) is a finite specific distribution Then(23) reduces to 119887total(119896) = (4120587
2119896
2) (](119896) minus ](0)) where ](119896) =
int ](119883)119890119894119896119883
1198894119883 and the bias (15) (18)119873(119896) becomes
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (28)
It is important that this limit still agrees with the rarefiedgas approximation for the basic gas parameter (ie theportion of volume cut by wormholes) tends to 120585 =
int(12058722)119886
4119865(119886119883)119889
4119883119889119886 rarr 0 The above expression is ob-
tained in the linear approximation only Taking into accountnext orders (eg see [22] where the case of a dense gas is alsoconsidered) we find 119873(119896) = 1 + 119887total(119896) + 119887
2
total(119896) + sdot sdot sdot andthe true Green function in a gas of wormholes becomes
119866true = 1198660(119896)119873 (119896) =
1
1198962 + 41205872(] (0) minus ] (119896))
(29)
In the long-wave limit 119896 rarr 0 the function ](119896) can beexpanded as ](119896) asymp ](0) + (12)]10158401015840(0)1198962 which also definesa renormalization of charge values119873(119896) rarr 1(1minus2120587
2]10158401015840(0))which coincides with (27) However in this limiting case wehave some freedom in the choice of ](119896) which we can useto assign 119873(119896) an arbitrary function of 119896 In other wordswe may get here a class of limiting topologies where Greenfunctions119866true = 119866
0(119896)119873(119896) have a good ultraviolet behavior
and quantumfield theories in such spaces turn out to be finiteIn particular this will certainly be the case when
119866true (119909 minus 1199091015840= 0) = int
1
1198962 + 41205872(] (0) minus ] (119896))
1198894119896
(2120587)4lt infin
(30)
This possibility however requires the further and more deepinvestigation
32 Green Function General Consideration The action (6)remains invariant under translations
1015840= + 119888 with an
arbitrary 119888 which means that the measure (11) does notactually depend on the position of the center of mass of thegas of wormholes and therefore we may restrict ourself withhomogeneous distributions 119865(120585) of wormholes in space onlyIndeed we may define 119889119873
120585 = 11988911987312058510158401198894119888 while the integration
over 1198894119888 gives the volume of1198774 that is int1198894
119888 = 1198714= 119881which
disappears from (11) due to the denominator (Technically wemay first restrict a portion of1198774 in (6) to a finite volume119881 andthen in final expressions consider the limit 119881 rarr infin (whichrepresents the standard tool in thermodynamics and QFT))In what follows we shall omit the prime from 120585
1015840Let us consider the Fourier representation119873(119909 119909
1015840 120585) rarr
119873(119896 1198961015840 120585) which in the case of a homogeneous distribution
of wormholes gives119873(119896 1198961015840) = 119873(119896 120585) 120575(119896 minus 119896
1015840) then we find
119866 (119896) = 1198660(119896)119873 (119896 120585) (31)
6 Journal of Astrophysics
and the Green function can be taken as
119866 =119873 (119896 120585)
1198962 + 1198982 (32)
Then for the total partition function we find
119885total (119869)
= int [119863119873 (119896)] 119890minus119868(119873)
119890minus(12)(119871
4
(2120587)4
) int((119873(119896)(1198962
+1198982
))|119869119896
|2
)119889119896
(33)
where [119863119873] = prod119896119889119873
119896and 120590(119873) comes from the integration
measure (ie from the Jacobian of transformation from 119865(120585)
to119873(119896))
119890minus119868(119873)
= int [119863119865]1198850(119873 (119896 120585)) 120575 (119873 (119896) minus 119873 (119896 120585)) (34)
We point out that 119868(119873) can be changed by means of addingto the action (6) of an arbitrary ldquonondynamicalrdquo constantterm which depends only on topology 119878 rarr 119878 + Δ119878 (119873(119896))
(eg a topological Euler term) The multiplier 1198850(119873) defines
the simplest measure for topologies Now by means of usingthe expression (32) and (33) we find the two-point Greenfunction in the form
119866 (119896) =119873 (119896)
1198962 + 1198982 (35)
where 119873(119896) is the cutoff function (the mean bias) whichis given by (We recall that in this integral contribute onlylimiting topologies in which density of wormholes diverges(119899 rarr infin))
119873(119896) =1
119885total (0)int [119863119873] 119890
minus119868(119873)119873(119896) (36)
At the present stage we still cannot evaluate the exactform for the cutoff function 119873(119896) in virtue of the ambiguityof Δ119878(119873(119896)) pointed out Such a term may include twoparts First part Δ
1119878 describes the proper dynamics of
wormholes and should be considered separately Indeedin general wormholes are dynamical self-gravitating objectswhich require considering the gravitational contribution tothe action Some part of such a contribution (mean curvatureinduced by wormholes) is discussed in Section 6 Howeversince a wormhole represents an extended nonlocal objectit possesses a rather complex dynamics and this problemrequires the further investigation The second part Δ
2119878 may
describe ldquoexternal conditionsrdquo (eg an external classicalfield in (33)) for the mean topology Actually the last termcan be used to prescribe an arbitrary particular value forthe cutoff function 119873(119896) = 119891(119896) Indeed the ldquoexternalconditionsrdquo can be accounted for by adding the term Δ
2119878 =
(120582119873) = int 120582(119896)119873(119896)1198894119896 where 120582(119896) plays the role of a
specific chemical potential which implicitly depends on 119891(119896)
through the equation
119891 (119896) =1
119885total (120582 0)int [119863119873] 119890
(120582119873)minus119868(119873)119873(119896) (37)
From (33) we see that the role of such a chemical potentialmay play the external current 120582(119896) = minus(12)(119871
4(2120587)
4)sdot
1198660(119896)|119869
ext119896|2 or equivalently an external classical field 120593
ext=
1198660(119896)119869
ext119896 In quantum field theory such a term leads merely
to a renormalization of the cosmological constant By otherwords the mean topology (ie the cutoff function or meandistribution of wormholes) is driven by the cosmologicalconstant Λ and vice versa
4 Topological Bias as a Projection Operator
By the construction the topological bias 119873(119909 1199091015840) plays the
role of a projection operator onto the space of functions (asubspace of functions on 119877
4) which obey the proper bound-ary conditions at throats of wormholes This means thatfor any particular topology (for a set of wormholes) thereexists the basis 119891
119894(119909) in which it takes the diagonal form
119873(119909 1199091015840) = sum119873
119894119891119894(119909)119891
lowast
119894(119909
1015840) with eigenvalues 119873
119894= 0 1
(since 1198732
119894= 119873
119894) In this section we illustrate this simple fact
(which is probably not obvious for readers) by the explicitconstruction of the reference system for a single wormholewhen physical functions become (due to the boundaryconditions) periodic functions of one of coordinates
Indeed consider a single wormhole with parameters 120585(ie 120585 = (119886 119877
+ 119877
minus) where 119886 is the throat radius and 119877
plusmn
are positions of throats in space (In general there existsan additional parameter Λ120572
120573which defines a rotation of one
of throats before gluing However it does not change thesubsequent constructionThere always exists a diffeomorphicmap of coordinates 1199091015840
= ℎ(119909) which sets such a matrix tounity)) Consider now a particular solution120601
0to the equation
Δ1206010= 0 (harmonic function) for 1198774 in the presence of the
wormhole which corresponds to the situation when throatspossess a unit chargemass but those have the opposite signsNow define the family of lines of force 119909(119904 119909
0) which obey
the equation 119889119909119889119904 = minusnabla1206010(119909) with initial conditions 119909(0) =
1199090 Physically such lines correspond to lines of force for a
two charged particles in positions 119877plusmn with charges plusmn1 Wenote that all points which lay on the trajectory 119909(119904 119909
0) may
be taken as initial conditions and they define the same lineof force with the obvious redefinition 119904 rarr 119904 minus 119904
0 By
other words we may take as a new coordinates the parameter119904 and portion of the coordinates orthogonal to the familyof lines 119909
perp
0 Coordinates 119909
perp
0can be taken as laying in the
hyperplane 1198773 which is orthogonal to the vector 119889 = minusminus
+
and goes through the point 0
= (minus+
+)2 (Instead
of the construction used here one may use also anothermethod Indeed consider two point charges and then thefunction 120601
0= 1(119909 minus 119909
+)2minus 1(119909 minus 119909
minus)2 can be taken as a
new coordinate Wormhole appears when we identify (glue)surfaces 120601
0= plusmn120596 We point out that such surfaces are not
spheres though they reduce to spheres in the limit |119909+minus
119909minus| rarr infin or 120596 rarr infin)Let 119904plusmn(119909perp
0) be the values of the parameter 119904 at which
the line intersects the throats 119877plusmn Then instead of 119904 we mayconsider a new parameter 120579 as 119904(120579) = 119904
minus+ (119904
+minus 119904
minus)1205792120587
so that when 120579 = 0 2120587 the parameter 119904 takes the values
Journal of Astrophysics 7
119904 = 119904minus 119904+ respectivelyThe gluing procedure at throatsmeans
merely that we identify points at 120579 = 0 and 120579 = 2120587 and allphysical functions in the space 119877
4 with a single wormhole120585 become periodic functions of 120579 Thus the coordinatetransformation 119909 = 119909(120579 119909
perp
0) gives the map of the above space
onto the cylinder with a specific metric 1198891198972 = (119889(120579 119909perp
0))
2
=
119892120572120573119889119910
120572119889119910
120573 (where 119910 = (120579 119909perp
0)) whose components are also
periodic in terms of 120579 Now we can continue the coordinatesto thewhole space1198774 (to construct a cover of the fundamentalregion 120579 isin [0 2120587]) simply admitting all valuesminusinfin lt 120579 lt +infin
this however requires to introduce the bias
1
radic119892120575 (120579 minus 120579
1015840) 997888rarr 119873(120579 minus 120579
1015840) =
+infin
sum
119899=minusinfin
1
radic119892120575 (120579 minus 120579
1015840+ 2120587119899)
(38)
since every point and every source in the fundamental regionacquires a countable set of images in the nonphysical region(inside of wormhole throats) Considering now the Fouriertransforms for 120579 we find
119873(119896 1198961015840) =
+infin
sum
119899=minusinfin
120575 (119896 minus 119899) 120575 (119896 minus 1198961015840) (39)
We point out that the above bias gives the unit operator in thespace of periodic functions of 120579 From the standpoint of allpossible functions on 1198774 it represents the projection operator
2= (120585) (taking an arbitrary function 119891 we find that upon
the projection 119891119873= 119891 119891
119873becomes a periodic function of
120579 that is only periodic functions survive)The above construction can be easily generalized to the
presence of a set of wormholes In the approximation of adilute gas of wormholes we may neglect the influence ofwormholes on each other (at least there always exists a suf-ficiently smooth map which transforms the family of linesof force for ldquoindependentrdquo wormholes onto the actual lines)Then the total bias (projection) may be considered as theproduct
119873total (119909 1199091015840) = int(prod
119894
radic1198921198941198894119910119894)119873(120585
1 119909 119910
1)
times 119873 (1205852 119910
1 119910
2) sdot sdot sdot 119873 (120585
119873 119910
119873minus1 119909
1015840)
(40)
where 119873(120585119894 119909 119909
1015840) is the bias for a single wormhole with
parameters 120585119894 Every such a particular bias119873(120585
119894 119909 119909
1015840) realizes
projection on a subspace of functions which are periodic withrespect to a particular coordinate 120579
119894(119909) while the total bias
gives the projection onto the intersection of such particularsubspaces (functions which are periodic with respect to everyparameter 120579
119894)
5 Cutoff
The projective nature of the bias operator 119873(119909 1199091015840) allows us
to express the cutoff function 119873(119896) via dynamic parametersof wormholes Indeed consider a box 1198714 in 119877
4 and periodic
boundary conditions which gives 119896 = 2120587119899119871 (in final expres-sions we consider the limit 119871 rarr infin which gives sum
119896rarr
(1198714(2120587)
4) int 119889
4119896) And let us consider the decomposition for
the integration measure in (33) as
119868 = 1198680+sum120582
1(119896)119873 (119896) +
1
2sum120582
2(119896 119896
1015840)119873 (119896)119873 (119896
1015840) + sdot sdot sdot
(41)
where 1205821(119896) includes also the contribution from 119885
0(119896) We
point out that this measure plays the role of the action for thebias119873(119896) Indeed the variation of the above expression givesthe equation of motions for the bias in the form
sum
1198961015840
1205822(119896 119896
1015840)119873 (119896
1015840) = minus120582
1(119896) (42)
which can be found by considering the proper dynamics ofwormholes We however do not consider the problem of thedynamic description of wormholes here and leave this forthe future research Moreover we may expect that in the firstapproximation one may retain the linear term only Indeedthis takes place when119873(119896) is not a dynamic variable or if wetake into account that 119873(119896) is a collective variable Then theprojective nature of the bias 119873(119896) = 0 1 means that it canbe phenomenologically expressed via some Fermionic ghostfield Ψ(119896) (eg 119873(119896 119896
1015840) = Ψ(119896)Ψ
+(119896
1015840)) where the negative
and positive frequency parts of the operator Ψ(119896) obey theanticommutation relationsΨ+
(119896)Ψ(1198961015840)+Ψ(119896
1015840) Ψ
+(119896) = 120575(119896minus
1198961015840) In the absence of ghost particles Ψ(119896)|0⟩ = 0 we get
119873(119896 1198961015840) = 120575(119896 minus 119896
1015840) that is 119873(119896) = 1 and wormholes
are absent In the term of the ghost field the action becomes119868(119873) = 119868
0+ (Ψ
1Ψ) + sdot sdot sdot Therefore in the leading approx-
imation equations of motion take the linear form 1Ψ = 0
Thus taken into account that 119873(119896) = 0 1 (1198732= 119873) we
find
119873(119896) =1
119885total (119896)sum
119873=01
119890minus1205821
(119896)119873(119896)119873(119896) =
119890minus1205821
(119896)
1 + 119890minus1205821(119896) (43)
The simplest choice gives merely 1205821(119896) = minussum ln119885
0(119896)
where the sum is taken over the number of fields and 1198850(119896)
is given by 1198850(119896) = radic120587(1198962 + 1198982) In the case of a set
of massless fields we find 119873(119896) = 119885(119896)(1 + 119885(119896)) where119885(119896) = (radic120587119896)
120572 and 120572 is the effective number of degreesof freedom (the number of boson minus fermion fields) Toensure the absence of divergencies one has to consider thenumber of fields 120572 gt 4 [23] However such a choice givesthe simplest estimate which in general cannot be correctIndeed while its behavior at very small scales (ie whenexceeding the Planckian scales 119885(119896) ≲ 1 and 119873(119896) = 119885(119896))may be physically accepted since it produces some kind of acutoff on the mass-shell 1198962 + 119898
2rarr 0 it gives the behavior
119873(119896) rarr 1 which is merely incorrect (eg from (27) we seethat the true behavior should be119873(119896) rarr const lt 1)
One may expect that the true cutoff function has a muchmore complex behavior Indeed some theoretical models inparticle physics (eg string theory) have the property tobe lower-dimensional at very small scales The mean cutoff
8 Journal of Astrophysics
119873(119896) gives the natural tool to describe a scale-dependantdimensional reduction [24 25] In fact this function definesthe spectral number of modes in the interval between 119896 and119896 + 119889119896 as
int119873 (119896)1198894119896
(2120587)4= int
119873 (119896) 1198964
(2120587)2
119889119896
119896 (44)
Hence we can define the effective spectral dimension 119863 ofspace as follows
1198964119873(119896) sim 119896
119863 (45)
From the empirical standpoint the dimension 119863 = 4 isverified at laboratory scales only while the rigorous tool todefine the spectral density of states (or the mean cutoff) cangive the lattice quantum gravity for example see [26 27]and references therein And indeed the spectral dimensionfor nonperturbative quantum gravity defined via Euclideandynamical triangulations was calculated recently in [28] Itturns out that it runs from a value of119863 = 32 at short distanceto 119863 = 4 at large distance scales We also point out that allobserved dark matter phenomena can be explained by thefractal dimension119863 asymp 2 starting from scales 119871 ≳ (1 divide 5)Kpcfor example [29ndash33]
6 Cosmological Constant
Let us consider the total Euclidean action [17]
119868119864= minus
1
16120587119866int (119877 minus 2Λ
0)radic119892119889
4119909 minus int119871
119898radic1198921198894119909 (46)
The variation of the above action leads to the Einstein equa-tions
119877119886119887minus1
2119892119886119887119877 + 119892
119886119887Λ
0= 8120587119866119879
119886119887 (47)
where 119879119886119887= (12)(119892)
minus12(120575119871
119898120575119892
119886119887) is the stress energy ten-
sor and Λ0is a naked cosmological constant In cosmology
such equations are considered from the classical standpointwhich means that they involve characteristic scales ℓ ≫ ℓplHowever the presence of virtual wormholes at Planckianscales defines some additional contribution in both parts ofthese equations which can be adsorbed into the cosmologicalconstant Therefore the total cosmological constant can bedefined as
Λ tot = Λ0+ Λ
119898+ Λ
119877= Λ
0+ 2120587119866 ⟨119879⟩ +
1
4⟨119877⟩119908 (48)
where ⟨119879⟩ is the energy of zero-point fluctuations (It includesalso the contribution of zero-point fluctuations of gravitons)That is themean vacuum value (we recall that in the standardQFTΛ
119898is infinite while wormholes form a finite value) and
⟨119877⟩119908
= Λ119877is a contribution of wormholes into the mean
curvature due to gluing (1)
61 Contribution of Virtual Wormholes into Mean CurvatureConsider a single wormhole whose metric is given by (1)
1198891199042= ℎ
2(119903)120575
120572120573119889119909
120572119889119909
120573 then the components of the Riccitensor are (We are much obliged to the Referee who pointedout to the subtleties when working with a step function in themetric)
119877120572120573
= 7 minus (ℎ1015840
ℎ)
1015840
(120575120572120573
+ (119873 minus 2) 119899120572119899120573)
minus1
119903
ℎ1015840
ℎ((119873 minus 2) Δ
120572120573+ 120575
120572120573(119873 minus 1))
minus (ℎ1015840
ℎ)
2
(119873 minus 2) Δ120572120573
(49)
where 119899]= 119909
]119886 is the unite normal vector to the throat
surface Δ120572120573
= 120575120572120573
minus 119899120572119899120573 ℎ1015840 = 120597ℎ120597119903 and119873 is the number
of dimensions The curvature scalar is
119877 = minus(119873 minus 1)
ℎ2[2
ℎ10158401015840
ℎ+ 2
1
119903
ℎ1015840
ℎ(119873 minus 1) + (
ℎ1015840
ℎ)
2
(119873 minus 4)]
(50)
Then substituting ℎ = 1 + (1198862119903
2minus 1)120579 in the above equation
we find
minusℎ4
119873 minus 1119877 = 4ℎ
1198862
1199033120575 +
2ℎ
119903119873minus1(119903
119873minus1120582)
1015840
+ (119873 minus 4)(1205822minus 4120579
1198862
1199033120582)
+ 4 (119873 minus 4)1198862
1199034120579 (120579 minus 1)
(51)
where 120579 is a smooth function which only in a limit becomesa step function 120582 = (1 minus 119886
2119903
2)120575 and 120575 = minus120579
1015840 In the limit120579 rarr 120579(119886 minus 119903) we find 120575 rarr 120575(119903 minus 119886) and the last two terms in(51) are negligible as compared to the first two terms while infour dimensions the last two terms vanishThen the curvatureis concentrated on the throat of the wormhole where 120579 differsfrom the step function In the limit of a vanishing throat sizewe have ℎ rarr 1 at the throat and we get
minus119877 =4 (119873 minus 1)
119886120575 (119903 minus 119886) +
2 (119873 minus 1)
119903119873minus1(119903
119873minus3(119903
2minus 119886
2) 120575)
1015840
(52)
In general all the terms together in (51) and analogous termsin the Ricci tensor provide that the Bianchi identity holdsand the energy is conserved [19] Therefore none of themcan be dropped out However it is easy to see the leadingcontribution to the integral over space comes from the firstterm only and in the limit of a vanishing throat size we findfor a single wormhole
1
4int119877radic119892119889
4119909 = minus6120587
21198862 (53)
Journal of Astrophysics 9
In the case of a set of wormholes (24) we find
1
4int119877radic119892119889
4119909 = minus6120587
2sum
119895
1198862
119895
= minus121205872int119899 (119886) 119886
2119889119886 119889
4119909 = intΛ
1198771198894119909
(54)
where 2119899(119886) = int 119899(119886 1199030)119889119903
0is the density of wormhole
throats with a fixed value of the throat size 119886 This definesthe contribution to the cosmological constant from the meancurvature as
Λ119877= minus12120587
2int119899 (119886) 119886
2119889119886 lt 0 (55)
We see that this quantity is always negative
62 Stress Energy Tensor In this section we consider thecontribution from matter fields In the case of a scalar fieldthe stress energy tensor has the form
minus119879120572120573
(119909) = 120597120572120593120597
120573120593 minus
1
2119892120572120573
(120597120583120593120597
120583120593 + 119898
21205932) (56)
Then the mean vacuum value of the stress energy tensor canbe obtained directly from the two-point green function (32)(35) as
minus ⟨119879120572120573
(119909)⟩
= lim1199091015840
rarr119909
(1205971205721205971015840
120573minus1
2119892120572120573
(1205971205831205971015840
120583+ 119898
2)) ⟨119866 (119909 119909
1015840 120585)⟩
(57)
By means of using the Fourier transform 119866(119909 1199091015840 120585) =
int 119890minus119894119896(119909minus119909
1015840
)119866(119896 120585) (119889
4119896(2120587)
4) and the expressions (32) (35)
we arrive at
⟨119879120572120573
(119909)⟩ =1
4119892120572120573
int(1 +119898
2
1198962 + 1198982)119873 (119896)
1198894119896
(2120587)4 (58)
where the property int 119896120572119896120573119891(119896
2)119889
4119896 = (14)119892
120572120573int 119896
2119891(119896
2)119889
4119896
has been used and 119873(119896) = ⟨119873(119896 120585)⟩ is the cutoff function(36)
For the sake of simplicity we consider the massless caseThen by the use of the cutoff 119873(119896) = 120587
1205722(120587
1205722+ 119896
120572) from
the previous section we get the finite estimate (120572 gt 4 is theeffective number of the field helicity states)
Λ119898=2120587119866sumint
1205871205722
1205871205722+119896120572
1198894119896
(2120587)4=120587119866
4Γ (
120572 minus 4
120572) Γ (
4
120572) sim 1
(59)
where the sum is taken over the number of fields Since theleading contribution comes here from very small scales wemay hope that this value will not essentially change if thetrue cutoff function changes the behavior on the mass-shellas 119896 rarr 0 (eg if we take 120582
1(119896) = minussum ln119885
0(119896) + 120575120582(119896) with
120575120582(119896) ≪ ln1198850(119896) as 119896 ≫ 1)
To understand how wormholes remove divergencies itwill be convenient to split the bias function into two parts119873(119896 120585) = 1 + 119887(119896 120585) where 1 corresponds to the standardEuclidean contribution while 119887(119896 120585) is the contribution ofwormholes The first part gives the well-known divergentcontribution of vacuumfield fluctuations 8120587119866⟨1198790
120572120573⟩ = Λ
lowast119892120572120573
with Λlowast
rarr +infin while the second part remains finite forany finite number of wormholes and due to the projectivenature of the bias described in the previous section itpartially compensates (reduces) the value of the cosmologicalconstant that is 8120587119866⟨Δ119879
120572120573⟩ = 120575Λ119892
120572120573 where 120575Λ =
sum119873120588119873120575Λ(119873) and 120575Λ(119873) is a negative finite contribution of
a finite set of wormholesConsider now the particular distribution of virtual
wormholes (24) and evaluate their contribution tothe cosmological constant which is given by 120575Λ(119873) =
2120587119866int 119887(119896) (1198894119896(2120587)
4) = 2120587119866119887total(0) Then from the ex-
pressions (22) and (24) we get
119887total (0) = minus119899
4120587411988631199033
0
int(1 minus1198862
1198772
minus
)120575 (119877+minus 119886)
times 120575 (1003816100381610038161003816119877+
minus 119877minus
1003816100381610038161003816 minus 1199030) 119889
4119877minus1198894119877+
(60)
which gives
119887total (0) = minus119899(1 minus 119891(119886
1199030
)) (61)
where
119891(119886
1199030
) =2
120587int
120587
0
1198862sin2
120579119889120579
1198862 + 21198861199030cos 120579 + 119903
2
0
(62)
For 1198861199030≪ 1 (we recall that by the construction 119886119903
0le 12)
this function has the value 119891(1198861199030) asymp 119886
2119903
2
0 Thus for the
contribution of wormholes we find
120575Λ119898= minus2120587119866int119899 (119886 119903
0) (1 minus 119891(
119886
1199030
))119889119886 1198891199030
= minus2120587119866119899 (1 minus ⟨119891⟩)
(63)
63 Vacuum Value of the Cosmological Constant From theabove expression we see that to get the finite value of thecosmological constant Λ
119898= Λ
lowast+ 120575Λ
119898lt infin one should
consider the limit 119899 rarr infin (infinite density of virtualwormholes) which requires considering the smaller andsmaller wormholes From the other handwe have the obviousrestriction int 2119899(119886 119903
0)(120587
22)119886
4119889119886 119889119903
0lt 1 where (120587
22)119886
4
is the volume of one throat (wormholes cannot cut morethan the total volume of space) (We also point out that inremoving divergencies the leading role plays the zero-pointenergy Indeed 120575Λ
119898sim minus2120587119866119899 while the mean curvature has
the order Λ119877sim minus119886
2119899 and for 119886 ≪ ℓpl we have 120575Λ119898
≫ Λ119877
Moreover in the limit 119899 rarr infin one gets 119886 rarr 0 and thereforeΛ
119877120575Λ
119898rarr 0)Therefore in the leading order it seems to be
sufficient to retain point-like wormholes only (ie consider
10 Journal of Astrophysics
the limit 119886 rarr 0) Then instead of (24) we may assume thevacuum distribution of virtual wormholes in the form
119873119865 (119886119883) =1
1198862120575 (119886) ] (119883) (64)
where ](119883) = int 1198862119873119865(119886119883)119889119886 and int(1119886
2)](119883)119889
4119883 =
119899 rarr infin has the meaning of the infinite density of point-like wormholes while ] sim 119886
2119899 remains a finite In this case
the volume cut by wormholes vanishes int 2119899(12058722)119886
4119889119886 119889119903
0=
1198862int ](119883)119889
4119883 rarr 0 and the rarefied gas approximationworks
wellThis defines the bias and themean cutoff (here we definethe Fourier transform ](119896) = int ](119883)119890
1198941198961198831198894119883) as
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (65)
The contribution to themean curvature (55) can be expressedvia the same function ](119896) as
Λ119877= minus12120587
2int119899 (119886 119903
0) 119886
2119889119886 119889119903
0
= minus121205872int ] (119883) 119889
4119883 = minus12120587
2] (0)
(66)
Thus for the total cosmological constant we get the expres-sion
Λ tot = Λ0
+ 2120587119866int(1minus4120587
2
1198962(] (0)minus] (119896)))
1198894119896
(2120587)4minus12120587
2] (0)
(67)
We stress that all these terms should be finite Indeed all dis-tributions of virtual wormholes ](119896) which lead to an infinitevalue of Λ tot are suppressed in (5) by the factor sim119890minusintΛ tot119889
4
119909while the minimal value is reached when wormholes cut allof the volume of space and the action is merely 119878 = 0(Frankly speaking this statement is not rigorous At first lookthe two last terms in (67) are independent and one may tryto take ](0) an arbitrary big If this were the case then theaction would not possess the minimum at all However ](0)cannot be arbitrary big since it will violate the rarefied gasapproximation and the linear expression (67) brakes downMoreover fermions give here a contribution of the oppositesign The rigorous investigation of this problem requires thefurther studying and we present it elsewhere) We also pointout that here we considered the real scalar field as the mattersource while in the general case the stress energy tensorshould include all existing Bose and Fermi fields (Fermi fieldsgive a negative contribution to Λ
119898)
The value of Λ0looks like a free parameter which in
quantum gravity runs with scales [27] However at largescales its asymptotic value may be uniquely fixed by thesimple arguments as follows Indeed in quantum field theoryproperties of the ground state (vacuum) change when weimply an external classical fields The same is true for thedistribution of virtualwormholes ](119896 119869) for example see (33)and (37) and therefore Λ tot = Λ tot(119869) which we describe
in the next subsection We recall that in gravity the role ofthe external current plays the stress energy tensor of matterfields 119869 = 119879
119886119887 However one believes that in the absence
of all classical fields the vacuum state should represent themost symmetric (Lorentz invariant) state which in our casecorresponds to the Euclidean space In order to be consistentwith the Einstein equations this requires Λ tot(119869 = 0) = 0
which uniquely fixes the value of Λ0in (67) We point out
that from somewhat different considerations such a choicewas advocated earlier in [15 34 35]
64 Vacuum Polarization in an External Field Consider nowtopology fluctuations in the presence of an external currentIn the presence of an external current 119869ext the distribution ofvirtual wormholes changes ](119896 119869) = ](119896) + 120575](119896 119869) Indeedin (33) for the case of a weak external field the contributionof the external current into the action can be expanded asexp(minus119881(119869)) ≃ 1 minus 119881 where
119881 = minus1
2int 119869 (119909) 119866 (119909 119910) 119869 (119910) 119889
4119909 119889
4119910
= minus1
2
1198714
(2120587)4int119866
0(119896)119873 (119896)
10038161003816100381610038161198691198961003816100381610038161003816
2
1198894119896
(68)
Then using (36) we find119873(119896 119869) = 119873(119896 0) + 120575119873(119896 119869) where
120575119873 (119896 119869) = 120575119887 (119869) ≃ minus1
2
1198714
(2120587)4int120590
2(119896 119901) 119866
0(119901)
10038161003816100381610038161003816119869119901
10038161003816100381610038161003816
2
1198894119901
(69)
is the bias related to an additional distribution of virtualwormholes and 120590
2(119896 119901) = Δ119873lowast(119896)Δ119873(119901)
1205902(119896 119901) =
1
119885total (0)int [119863119873] 119890
minus119868(119873)Δ119873
lowast(119896) Δ119873 (119901) (70)
defines the dispersion of vacuum topology fluctuations (hereΔ119873 = 119873 minus 119873) The exact definition of 1205902
(119896 119901) requires thefurther development of a fundamental theory In particular itcan be numerically calculated in lattice quantum gravity [28]However it can be shown that at scales 119896 119901 ≫ 119896pl it reducesto 1205902
(119896 119901) rarr 1205902
119896120575(119896 minus 119901) and therefore
120575119887 (119869) = minus1205902
119896
41205872
21198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(71)
Now comparing this function with (23) we relate the addi-tional distribution of virtual wormholes and the externalclassical field as
41205872
1198962(120575] (0 119869) minus 120575] (119896 119869)) =
1
21205902
119896
41205872
1198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(72)
where 120575](119896 119869) = int 1198862120575119873119865(119886 119896)119889119886 We point out that the
above expression does not define the value 120575](0 119869) whichrequires an additional considerationMoreover in general theexternal field 119869 does not possess a symmetry and therefore thecorrection ⟨120575119879
120572120573(119909)⟩ does not reduce to a single cosmological
Journal of Astrophysics 11
constant However such corrections always violate the aver-aged null energy condition [36 37] and may be considered assome kind of dark energy or by other words it represents anexotic matter Some portion of dark energy still has the formof the cosmological constant which defines a nonvanishingpresent day value (we recall that fermions give a contributionof the opposite sign)
120575Λ tot = minus2120587119866int4120587
2
1198962⟨120575] (0 119869) minus 120575] (119896 119869)⟩
1198894119896
(2120587)4
minus 121205872120575] (0 119869)
(73)
where ⟨120575](119896 119869)⟩ denotes an averaging over rotationsThe only unknown parameter in (72) is the dispersion
1205902
119896which defines the intensity of topology fluctuations in
the vacuum It has also the sense of the efficiency coefficientwhich defines the portion of the energy of the external fieldspent on the formation of additional wormholes Thoughthe evaluation of 1205902
119896requires the further development of a
fundamental theory one may expect that 1205902
119896= 119873(119896)(1 minus
119873(119896)) where 119873(119896) is the mean cutoff It is expected that119873(119896) rarr 0 as 119896 ≫ 119896pl and119873(119896) rarr 119873
0le 1 This means that
120590 rarr 0 as 119896 ≫ 119896pl and 120590 rarr 1205900≪ 1 as 119896 ≪ 119896pl while it takes
the maximum value 120590max sim 1 at Planckian scales 119896 sim 119896pl Byotherwords themost efficient transmission of the energy intowormholes takes place for wormholes of the Planckian sizeIn the case when external classical fields have characteristicscales 120582 = 2120587119896 ≫ ℓpl in (72) the efficiency coefficient 1205902
119896and
the cutoff 119873(119896) become constant 120590 ≃ 1205900 119873(119896) ≃ 119873
0 while
their ratiomay be estimated as 1205721205902
0119873
0= ΩDEΩ119887
where 120572 isthe effective number of fundamental fields which contributeto 120575Λ tot and ΩDE Ω119887
are dark energy and baryon energydensities respectively According to the modern picture thisratio gives ΩDEΩ119887
asymp 075005 = 15 while 1205902
0119873
0sim 1
(as 1198730≪ 1) and therefore this defines the estimate for the
effective number of fundamental fields (helicity states) as 120572 sim
15
65 Speculations on the Formation of Actual WormholesAs we already pointed out the additional distribution ofvirtual wormholes (72) reflects the symmetry of externalclassical fields and therefore it forms a homogeneous andisotropic background and perturbations We recall that vir-tual wormholes represent an exotic form of matter In theearly Universe such perturbations start to develop and mayform actual wormholes The rigorous description of sucha process represents an extremely complex and interestingproblemwhich requires the further study Some aspects of thebehavior of the exotic density perturbations were consideredin [7] while the simplest example of the formation of awormhole-type object was discussed recently by us in [38]Therefore we may expect that some portion of such a form ofdark energy is reserved now in actual wormholes which weconsider in the next section
7 Dark Energy from Actual Wormholes
Consider now the contribution to the dark energy fromthe gas of actual wormholes Unlike the virtual wormholesactual wormholes do exist at all times and therefore a singlewormhole can be viewed as a couple of conjugated cylinders1198793
plusmn= 119878
2
plusmntimes 119877
1 So that the number of parameters of an actualwormhole is less 120578 = (119886 119903
+ 119903
minus) where 119886 is the radius of 1198782
plusmn
and 119903plusmnisin 119877
3 is a spatial part of 119877plusmn
Actual wormholes also produce two kinds of contributionto the dark energy One comes from their contribution tothe mean curvature which corresponds to an exotic stressenergy momentum tensor Such a stress energy momentumtensor reflects the dark energy reserved by additional virtualwormholes discussed in the previous section Such energyis necessary to support actual wormholes as a solution tothe Einstein equations The second part comes from vacuumpolarization effects by actual wormholes The considerationin the previous section shows that for macroscopic worm-holes the second part has the order ⟨Δ119879
120572120573⟩ sim 8120587119866119899 and
is negligible as compared to the curvature 119877 sim 1198862119899 (since
macroscopic wormholes have throats 119886 ≫ ℓpl) Howeverfor the sake of completeness and for methodological aims wedescribe it as well
For rigorous evaluation of dark energy of the secondtype we first have to find the bias 119887
1(119909 119909
1015840 120578) analogous to
(19) for the topology 1198774(119879
3
+cup 119879
3
minus) There are many papers
treating different wormholes in this respect (eg see [36 37]and references therein) However in the present paper for anestimation we shall use a more simple trick
71 Beads of Virtual Wormholes (Quantum Wormhole)Indeed instead of the cylinders 1198793
plusmnwe consider a couple of
chains (beads of virtual wormholes 1198793
plusmnrarr cup
1198991198783
plusmn119899) Such an
idea was first suggested in [39] and one may call such anobject as quantum wormhole Then the bias can be writtenstraightforwardly
1198871(119909 119909
1015840 120578) =
+infin
sum
119899=minusinfin
1
41205872119886(
1
(119877minus119899
minus 1199091015840)2minus
1
(119877+119899
minus 1199091015840)2)
times [120575 (10038161003816100381610038161003816 minus
+119899
10038161003816100381610038161003816minus 119886) minus 120575 (
10038161003816100381610038161003816 minus
minus119899
10038161003816100381610038161003816minus 119886)]
(74)
where 119877plusmn119899
= (119905119899 119903
plusmn) with 119905
119899= 119905
0+ 2ℓ119899 and ℓ ge 119886 is the
step We may expect that upon averaging over the position1199050isin [minusℓ ℓ] the bias for the beads will reproduce the bias for
cylinders1198793
plusmn(at least it looks like a very good approximation)
We point out that the averaging out (12ℓ) intℓ
minusℓ119889119905
0and the
sum sum+infin
119899=minusinfinreduces to a single integral (12ℓ) intinfin
minusinfin119889119905 of the
zero term in (74) And moreover the resulting total biascorresponds merely to a specific choice of the distributionfunction 119865(120585) in (21) Namely we may take
119873119865 (120585) =1
2ℓ120575 (119905
+minus 119905
minus) 119891 (
1003816100381610038161003816119903+ minus 119903minus
1003816100381610038161003816 119886) (75)
12 Journal of Astrophysics
where119877plusmn= (119905
plusmn 119903
plusmn) and119891(119904 119886) is the distribution of cylinders
which can be taken as (119899 is 3-dimensional density)
119891 (120578) =119899 (119886)
41205871199032
0
120575 (119904 minus 1199030) (76)
Using the normalization condition int119873119865(120585)119889120585 = 119873 we findthe relation 119873 = (12ℓ)119899119881 = 119899119881 where 119899 is a 4-dimensional density of wormholes and 1(2ℓ) is the effectivenumber of wormholes on the unit length of the cylinder (iethe frequency with which the virtual wormhole appears atthe positions 119903
plusmn) This frequency is uniquely fixed by the
requirement that the volume which cuts the bead is equal tothat which cuts the cylinder (43)1205871198863 = (120587
22)119886
4(12ℓ) (ie
2ℓ = (31205878)119886 and 119899 = (83120587119886)119899) Thus we can use directlyexpression (23) and find (compare to (25))
119887 (119896) = minusint 119899 (119886) 1198862 4120587
2
1198962(1 minus
sin |k| 1199030|k| 1199030
)1198691(119896119886)
1198961198862119889119886 (77)
where 119896 = (1198960 k) Here the first term merely coincides with
that in (25) and therefore it gives the contribution to thecosmological constant 120575Λ(8120587119866) = minus1198994 = minus2119899(3120587119886)while the second term describes a correction which does notreduce to the cosmological constant and requires a separateconsideration
72 Stress Energy Tensor From (57) we find that the stressenergy tensor
minus⟨Δ119879120572120573
(119909)⟩ = int
119896120573119896120572minus (12) 119892
1205721205731198962
1198962119887 (119896 120585)
1198894119896
(2120587)4
(78)
reduces to the two functions
11987900
= 120576 = 1205821minus1
2120583
119879119894119895= 119901120575
119894119895 119901 =
1
31205822minus1
2120583
(79)
where 120576 + 3119901 = minus120583 and 1205821+ 120582
2= 120583 and these functions are
1205821= minusint
1198962
0
11989621198871198894119896
(2120587)4 120582
2= minusint
|k|2
11989621198871198894119896
(2120587)4 (80)
By means of the use of the spherical coordinates 11989620119896
2=
cos2120579 |k|21198962 = sin2120579 and 119889
4119896 = 4120587sin2
1205791198963119889119896119889120579 we get
120582119894=119899 (119886 119903
0)
4120573119894
(1 minus 2120573119894(119886
1199030
)
2
119891119894(119886
1199030
)) (81)
where 1205731= 1 120573
2= 13 and 119891
119894is given by
119891(1
2)(119910)
=2
120587int
1
minus1
int
infin
0
sin (119909 sin 120579)1198691(119910119909)
1199101199092(cos2120579sin2
120579) 119889119909 119889cos 120579
(82)
For 1198861199030≪ 1 we find
11989112
(119886
1199030
) asymp (1 + 11990012
(119886
1199030
)) (83)
Thus finally we find
120576 ≃ minus119899
4= minus
2119899
3120587119886 119901 ≃ 120576(1 minus
4
3(119886
1199030
)
2
) (84)
which upon the continuation to the Minkowsky space givesthe equation of state in the form (An arbitrary gas ofwormholes splits in fractions with a fixed 119886 and 119903
0)
119901 = minus(1 minus4
3(119886
1199030
)
2
) 120576 (85)
which in the case when 1198861199030≪ 1 behaves like a cosmological
constant However when 119886 ≫ ℓpl such a constant is extremelysmall and can be neglected while the leading contributioncomes from the mean curvature
73 Mean Curvature In this subsection we consider theMinkowsky spaceThen the simplest actual wormhole can bedescribed by the metric analogous to (1) for example see [7]
1198891199042= 119888
2119889119905
2minus ℎ
2(119903) 120575
120572120573119889119909
120572119889119909
120573 (86)
where ℎ(119903) = 1 + 120579(119886 minus 119903)(1198862119903
2minus 1) To avoid problems
with the Bianchi identity and the conservation of energy thestep function should be also smoothed as in (1) The stressenergy tensor which produces such a wormhole can be foundfrom the Einstein equation 8120587119866119879
120573
120572= 119877
120573
120572minus (12)120575
120573
120572119877 Both
regions 119903 gt 119886 and 119903 lt 119886 represent portions of the ordinaryflat Minkowsky space and therefore the curvature is 119877119896
119894equiv 0
However on the boundary 119903 = 119886 it has the singularity Sincethe metric (86) does not depend on time we find
1198770
0= 119877
0
120572= 0 119877
120573
120572=2
119886120575 (119886 minus 119903) 119899
120572119899120573+ 120575
120573
120572 + 120582
120573
120572 (87)
where 119899120572 = 119899120572= 119909
120572119903 is the outer normal to the throat 1198782
and 120582120573
120572are additional terms (eg see (49) and (51)) which
in the leading order are negligible upon averaging over someportion of space Δ119881 ≳ 119886
3 In the case of a set of wormholesthis gives in the leading order
1198770
0= 119877
0
120572= 0 119877
120573
120572= sum
2
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119903
119894
1003816100381610038161003816) 119899119894120572119899120573
119894+ 120575
120573
120572
(88)
where 119886119894is the radius of a throat and 119903
119894is the position of the
center of the throat in space and 119899120572
119894= (119909
120572minus 119903
120572
119894)|119903 minus 119903
119894|
In the case of a homogeneous and isotropic distribution ofsuch throats we find 119877
120573
120572= (13)119877120575
120573
120572(averaging over spatial
directions gives ⟨119899120572119899120573⟩ = (13)120575
120573
120572) where
119877 = minus8120587119866119879 = sum8
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119877
119894
1003816100381610038161003816) = 32120587int 119886119899 (119886) 119889119886
(89)
Journal of Astrophysics 13
where 119879 stands for the trace of the stress energy momentumtensor which one has to add to the Einstein equations tosupport such awormhole It is clear that such a source violatesthe weak energy condition and therefore it reproduces theformof dark energy (ie119879 = 120576+3119901 lt 0) If the density of suchsources (and resp the density of wormholes) is sufficientlyhigh then this results in the observed [10ndash14] accelerationof the scale factor for the Friedmann space as sim 119905
120572 with120572 = 21205763(120576 + 119901) = 2120576(2120576 + (120576 + 3119901)) gt 1 for examplesee also [40ndash42] In terms of the 4-dimensional density ofwormholes 119899 = (83120587119886)119899 we get 119877 sim 119886
2119899 ≫ 8120587119866119899 as 119886 ≫ ℓpl
and therefore the leading contribution indeed comes fromthe mean curvature
8 Estimates and Concluding Remarks
Now consider the simplest estimates Actual wormholes seemto be responsible for the dark matter [7 9] Therefore to getthe estimate to the number density of wormholes is ratherstraightforward First wormholes appear at scales when darkmatter effects start to display themselves that is at scales ofthe order 119871 sim (1 divide 5)Kpc which gives in that range thenumber density
119899 sim1
1198713sim (3 divide 0024) times 10
minus65cmminus3 (90)
The characteristic size of throats can be estimated from (89)120576DE sim (119866)
minus1119899119886 Since the density of dark energy is 120576DE1205760 =
ΩDE sim 075 where 1205760is the critical density then we find the
estimate
119886 sim2
3(1 divide 125) times 10
minus3119877⊙ΩDEℎ
2
75 (91)
where119877⊙is the Solar radius ℎ
75= 119867(75 km(secMpc)) and
119867 is the Hubble constant We also recall that the backgrounddensity of baryons 120576
119887generates a nonvanishingwormhole rest
mass119872119908= (43)120587119886
31198773120576119887(where119877(119905) is the scale factor of the
Universe and therefore 119872119908remains constant) for example
see [7] It produces the dark matter density related to thewormholes as 120576DM ≃ 119872
119908119899 The typical mass of a wormhole
119872119908is estimated as
119872119908sim 1 7 times (1 divide 125) times 10
2119872
⊙ΩDMℎ
2
75 (92)
where 119872⊙is the Solar mass We point out that this mass
has not the direct relation to the parameters of the gas ofwormholes However it defines the moment when wormholethroats separated from the cosmological expansion Theabove estimate shows that if wormholes form due to thedevelopment of perturbations in the exotic matter then thisprocess should start much earlier than the formation ofgalaxies
Thus we see that virtual wormholes should indeed leadto the regularization of all divergencies in QFT which agreeswith recent results [28] Therefore they form the local finitevalue of the cosmological constant In the absence of externalclassical fields such a value should be exactly zero at macro-scopic scales A some nonvanishing value for the cosmolog-ical constant appears as the result of vacuum polarization
effects in external fields Indeed external fields form anadditional distribution of virtual wormholes which possessan exotic stress energy tensor (some kind of dark energy)Only some part of it forms the cosmological constant whilethe rest reflects the symmetry of external fields and possessesinhomogeneitiesWe assume that during the evolution of ourUniverse inhomogeneities in the exotic matter develop andmay form actual wormholes Although this problem requiresthe further and more deep investigation we refer to [38]where the formation of a simplest wormhole-like object hasbeen considered In other words such polarization energyis reserved now in a gas of actual wormholes We estimatedparameters of such a gas and believe that such a gas mayindeed be responsible for both dark matter and dark energyphenomena
References
[1] J R Primack ldquoThe nature ofdark matterrdquo httparxivorgabsastro-ph0112255
[2] J Diemand M Zemp B Moore J Stadel and M CarolloldquoCusps in cold dark matter haloesrdquoMonthly Notices of the RoyalAstronomical Society vol 364 no 2 pp 665ndash673 2005
[3] E W Mielke and J A V Velez Perez ldquoAxion condensate as amodel for dark matter halosrdquo Physics Letters B vol 671 no 1pp 174ndash178 2009
[4] G Gentile P Salucci U Klein D Vergani and P Kalberla ldquoThecored distribution of dark matter in spiral galaxiesrdquo MonthlyNotices of the Royal Astronomical Society vol 351 no 3 pp 903ndash922 2004
[5] D T F Weldrake W J G de Blok and F Walter ldquoA high-resolution rotation curve of NGC 6822 a test-case for cold darkmatterrdquo Monthly Notices of the Royal Astronomical Society vol340 no 1 pp 12ndash28 2003
[6] W J G de Blok andA Bosma ldquoHigh-resolution rotation curvesof low surface brightness galaxiesrdquoAstronomy and Astrophysicsvol 385 pp 816ndash846 2002
[7] A Kirillov and E P Savelova ldquoDensity perturbations in a gas ofwormholesrdquoMonthly Notices of the Royal Astronomical Societyvol 412 no 3 pp 1710ndash1720 2011
[8] P Kanti B Kleihaus and J Kunz ldquoStable Lorentzianwormholesin dilatonic Einstein-Gauss-Bonnet theoryrdquo Physical Review Dvol 85 no 4 Article ID 044007 2012
[9] A A Kirillov and E P Savelova ldquoDark matter from a gas ofwormholesrdquo Physics Letters B vol 660 no 3 pp 93ndash99 2008
[10] A G Riess A V Filippenko P Challis et al ldquoObservationalevidence from supernovae for an accelerating universe and acosmological constantrdquo The Astronomical Journal vol 116 no3 p 1009 1998
[11] S Perlmutter G Aldering G Goldhaber et al ldquoMeasurementsofΩ andΛ from42high-redshift supernovaerdquoTheAstrophysicalJournal vol 517 no 2 p 565 1999
[12] J L Tonry B P Schmidt B Barris et al ldquoCosmological resultsfromhigh-z supernovaerdquoTheAstrophysical Journal vol 594 no1 p 594 2003
[13] N W Halverson E M Leitch C Pryke et al ldquoDegreeangular scale interferometer first results a measurement of thecosmic microwave background angular power spectrumrdquo TheAstrophysical Journal vol 568 no 1 p 38 2002
14 Journal of Astrophysics
[14] C B Netterfield P A R Ade J J Bock et al ldquoA measurementby BOOMERANGofmultiple peaks in the angular power spec-trum of the cosmic microwave backgroundrdquo The AstrophysicalJournal vol 571 no 2 p 604 2002
[15] S Coleman ldquoWhy there is nothing rather than something atheory of the cosmological constantrdquoNuclear Physics B vol 310no 3-4 pp 643ndash668 1988
[16] I Klebanov L Susskind and T Banks ldquoWormholes and thecosmological constantrdquo Nuclear Physics B vol 317 no 3 pp665ndash692 1989
[17] S W Hawking ldquoSpacetime foamrdquoNuclear Physics B vol 114 p349 1978
[18] T P Cheng and L F Li Gauge Theory of Elementary ParticlesClarendon Press Oxford UK 1984
[19] A H Taub ldquoSpace-times with distribution valued curvaturetensorsrdquo Journal ofMathematical Physics vol 21 no 6 pp 1423ndash1431 1980
[20] A Shatsky privite communications[21] V A Fock ldquoZur Theorie des Wasserstoffatomsrdquo Zeitschrift fur
Physik vol 98 no 3-4 pp 145ndash154 1935[22] E P Savelova ldquoGas of wormholes in Euclidean quantum field
theoryrdquo httparxivorgabs12115106[23] A A Kirillov and E P Savelova ldquoOn the behavior of
bosonic systems in the presence of topology fluctuationsrdquohttparxivorgabs08082478
[24] A A Kirillov ldquoViolation of the Pauli principle and dimensionof the Universe at very large distancesrdquo Physics Letters B vol555 no 1-2 pp 13ndash21 2003
[25] A A Kirillov ldquoDark matter dark charge and the fractalstructure of the Universerdquo Physics Letters B vol 535 no 1ndash4pp 22ndash24 2002
[26] J Ambjorn J Jurkiewicz and R Loll ldquoThe spectral dimensionof the universe is scale dependentrdquo Physical Review Letters vol95 no 17 Article ID 171301 4 pages 2005
[27] E Manrique S Rechenberger and F Saueressig ldquoAsymptoti-cally safe Lorentzian gravityrdquo Physical Review Letters vol 106no 25 Article ID 251302 4 pages 2011
[28] J Laiho and D Coumbe ldquoEvidence for asymptotic safety fromlattice quantum gravityrdquo Physical Review Letters vol 107 no 16Article ID 161301 2011
[29] A A Kirillov and D Turaev ldquoOn modification of the Newtonrsquoslaw of gravity at very large distancesrdquo Physics Letters B vol 532no 3-4 pp 185ndash192 2002
[30] A A Kirillov and D Turaev ldquoThe universal rotation curveof spiral galaxiesrdquo Monthly Notices of the Royal AstronomicalSociety vol 371 no 1 pp L31ndashL35 2006
[31] A A Kirillov and D Turaev ldquoFoam-like structure of theuniverserdquo Physics Letters B vol 656 pp 1ndash8 2007
[32] A A Kirillov ldquoThe nature of dark matterrdquo Physics Letters B vol632 no 4 pp 453ndash462 2006
[33] A A Kirillov and E P Savelova ldquoAstrophysical effects of space-time foamrdquo Gravitation and Cosmology vol 14 no 3 pp 256ndash261 2008
[34] S W Hawking and N Turok ldquoOpen inflation without falsevacuardquo Physics Letters B vol 425 no 1-2 pp 25ndash32 1998
[35] Z C Wu ldquoThe cosmological constant is probably zero and aproof is possibly rightrdquo Physics Letters B vol 659 no 5 pp 891ndash893 2008
[36] R Garattini ldquoEntropy and the cosmological constant aspacetime-foam approachrdquo Nuclear Physics B vol 88 no 1ndash3Article ID 991003 pp 297ndash300 2000
[37] MVisserLorentzianWormholes SpringerNewYorkNYUSA1996
[38] A A Kirillov and E P Savelova ldquoArtificial wormholerdquohttparxivorgabs12040351
[39] E W Mielke ldquoKnot wormholes in geometrodynamicsrdquo Gen-eral Relativity and Gravitation vol 8 no 3 pp 175ndash196 1977
[40] E B Gliner ldquoAlgebraic properties of the energy-momentumtensor and vacuum-like states of matterrdquo Journal of Experimen-tal and Theoretical Physics vol 22 p 378 1966
[41] A H Guth ldquoInflationary universe a possible solution to thehorizon and flatness problemsrdquo Physical Review D vol 23 no2 pp 347ndash356 1981
[42] A A Linde ldquoA new inflationary universe scenario a possiblesolution of the horizon flatness homogeneity isotropy andprimordial monopole problemsrdquo Physics Letters B vol 108 no6 pp 389ndash393 1982
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
![Page 3: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/3.jpg)
Journal of Astrophysics 3
Where the sum over topologies is the sum over virtualwormholes described above Such an approach gives a rathergood leading approximation for calculation of the partitionfunction and corresponds to the standard methods (egRitza method etc) In Section 3 we investigate properties ofthe two-point Green function We show that the presenceof the gas of virtual wormholes can be described by thetopological bias exactly as it happens in the presence of actualwormholes [7 9] For limiting topologies when the densityof virtual wormholes becomes infinite the Green functionshows a good ultraviolet behavior which means that thereexists a class of such systems when quantum field theoriesare free of divergencies We demonstrate how the sum overtopologies defines themean value for the bias which takes thesense of a cutoff function in the space of modes In Section 4we explicitly demonstrate that for a particular set of virtualwormholes the bias defines not more than the projectionoperator on the subspace of functions obeying to the properboundary conditions at wormhole throats The projectivenature of the bias means that wormholes merely cut someportion of degrees of freedom (modes) Phenomenologicallyit means that wormholes can be described by the presence ofghost fields which compensate the extra (cut by wormholes)modes In Section 5 we show how the cutoff expresses viasome dynamic parameters of wormholesThe exact definitionof such parameters we leave it for the future investigationIn Section 6 we consider the origin of the cosmologicalconstant We demonstrate that the cosmological constantis determined by the contribution of the energy density ofzero-point fluctuations and by the contribution of virtualwormholes to the mean curvature We estimate contributionof virtual wormholes to the mean curvature and show alsothat wormholes lead to a finite (of the planckian order)value of ⟨119879
120583]⟩ which requires considering the contributionfrom the smaller and smaller wormholes with divergentdensity 119899 rarr infin We also present arguments of why inthe absence of external classical fields the total value ofthe cosmological constant is exactly zero while it acquiresa nonvanishing value due to vacuum polarization effects(ie due to an additional distribution of virtual wormholes)in external fields We also speculate the possibility of theformation of actual wormholes and in Section 7 we estimatetheir contribution to the dark energy Finally in Section 8 werepeat basic results an discuss some perspectives
2 Generating Function
The basic aim of this section is to construct the generatingfunctional which can be used to get all possible correlationfunctions Consider the partition functionwhich includes thesum over topologies and the sum over field configurations
119885total = sum
120591
sum
120593
119890minus119878 (5)
For the sake of simplicity we use from the very beginning theEuclidean approach The action has the form
119878 = minus1
2(120593119860120593) + (119869120593) (6)
and we use the notions (119869120593) = int 119869(119909)120593(119909)1198894119909 If we fix
the topology of space by placing a set of wormholes withparameters 120585
119894 then the sum over field configurations 120593 gives
the well-known result
119885lowast(119869) = 119885
0(119860) 119890
minus(12)(119869119860minus1
119869) (7)
where 1198850(119860) = int[119863120593]119890
(12)(120593119860120593) is the standard expressionand 119860
minus1= 119860
minus1(120585) is the Green function for a fixed topology
that is for a fixed set of wormholes 1205851 120585
119873
Consider now the sum over topologies 120591 To this end werestrict the sum over the number of wormholes and integralsover parameters of wormholes
sum
120591
997888rarr sum
119873
int
119873
prod
119894=1
119889120585119894= int [119863119865] (8)
where
119865 (120585119873) =1
119873
119873
sum
119894=1
120575 (120585 minus 120585119894) (9)
and 119873119865 is the density of wormholes in the configurationspace 120585 We also point out that in general the integration overparameters is not free (eg it obeys the obvious restriction|
+
119894minus
minus
119894| ge 2119886
119894) This defines the generating function as
119885total (119869) = int [119863119865]1198850(119860) 119890
minus(12)(119869119860minus1
119869) (10)
The sum over topologies assumes an additional averaging outfor all mean values with the measure 119889120583
119873= 120588(120585119873)119889
119873120585
where
120588 (120585119873) =
1198850(119860 (120585119873))
119885total (0) (11)
which obey the obvious normalization conditionsum119873int119889120583
119873=
sum119873120588119873
= 1 The averaging out over topologies assumes thetwo stages First we fix the total number of wormholes 119873and average over the parameters of wormholes 120585 (ie overparameters of a static gas of wormholes in 119877
4) Then we sumover the number of wormholes119873 (the so-called big canonicalensemble)
The basic difficulty of the standard field theory is thatthe perturbation scheme based on (7) leads to divergentexpressions This remains true for every particular topologyof space (ie for any particular finite set of wormholes) sincethere always exists a scale below which the space looks likethe ordinary Euclidean spaceWhat we expect is that the sumover all possible topologies will remove such a difficulty
And indeed the above measure (11) has the structure
1198850(119860 (120585119873)) = exp(minusintΛ (120585119873) 119889
4119909) (12)
where Λ(120585119873) is the cosmological constant related to theenergy density of zero-point fluctuations calculated for aparticular distribution of wormholes (We recall that the total
4 Journal of Astrophysics
cosmological constant should include also the contributionfrom the mean curvature (55)) Any finite distribution ofwormholes leads to the divergent expression Λ(120585119873) rarr
infin and is suppressed (ie 120588 (120585119873) rarr 0) However thesum over all possible topologies assumes also the limitingtopologies 119899 rarr infin where 119899 = 119873119881 is the density ofwormholes In this limit wormhole throats degenerate intopoints and the minimal scale below which the space lookslike the Euclidean space is merely absent We point out thatfrom the rigorous mathematical standpoint such limitingtopologies cannot be described in terms of smoothmanifoldssince they are not locally Euclidean and does not possess afinite set of maps In mathematics similar objects are wellknown for example fractal sets However if a fractal set isobtained by cutting (by means of a specific rule or iterations)portions of space our limiting topologies are obtained bygluing (identifying) some portions (or in the limit couplesof points) of the Euclidean space The basic feature of suchtopologies is that QFT becomes finite on such a set Indeedas we shall see a particular infinite distribution of wormholescan always be chosen in such a way that the energy of zero-point fluctuations becomes a finite 0 le Λ
infin(120585) lt infin (eg
see the next section or the second term in (67)) In the sumover topologies only such limiting topologies do survive (ie120588infin(120585) = 0)
3 The Two-Point Green Function
From (7) we see that the very basic role in QFT plays the twopoint Green function Such a Green function can be foundfrom the equation
119860119866(119909 1199091015840) = minus120575 (119909 minus 119909
1015840) (13)
with proper boundary conditions at wormholes which gives119866 = 119860
minus1 Now let us introduce the bias function119873(119909 1199091015840) as
119866 (119909 119910) = int1198660(119909 119909
1015840)119873 (119909
1015840 119910) 119889119909
1015840 (14)
where 1198660(119909 119909
1015840) is the ballistic (or the standard Euclidean
Green function) and the bias can be presented as
119873(119909 1199091015840) = 120575 (119909 minus 119909
1015840) +sum
119894
119887119894120575 (119909 minus 119909
119894) (15)
where 119887119894are fictitious sources at positions 119909
119894which should
be added to obey the proper boundary conditions We pointout that the bias can be explicitly expressed via parametersof wormholes that is 119873(119909 119909
1015840) = 119873(119909 119909
1015840 120585
1 120585
119873) For the
sake of illustration we consider first a particular example
31 The Bias for a Particular Distribution of Wormholes(Rarefied Gas Approximation) Consider now the bias for aparticular set of wormholes For the sake of simplicity weconsider the case when119898 = 0 The Green function obeys theLaplace equation
minusΔ119866 (119909 1199091015840) = 120575 (119909 minus 119909
1015840) (16)
with proper boundary conditions at throats (we require119866 and120597119866120597119899 to be continual at throats)The Green function for theEuclidean space is merely 119866
0(119909 119909
1015840) = 14120587
2(119909 minus 119909
1015840)2 (and
1198660(119896) = 1119896
2 for the Fourier transform) In the presence ofa single wormhole which connects two Euclidean spaces thisequation admits the exact solution For outer region of thethroat 1198783 the source 120575(119909 minus 119909
1015840) generates a set of multipoles
placed in the center of sphere which gives the corrections tothe Green function 119866
0in the form (we suppose the center of
the sphere at the origin)
120575119866 = minus1
412058721199092
infin
sum
119899=1
1
119899 + 1(119886
1199091015840)
2119899
(1199091015840
119909)
119899minus1
119876119899 (17)
where 119876119899= (4120587
22119899)sum
119899minus1
119897=0sum
119897
119898=minus119897119876
lowast1015840
119899119897119898119876
119899119897119898and 119876
119899119897119898(Ω) are
four-dimensional spherical harmonics for example see [21]In the present section we shall consider a dilute gas approx-imation and therefore it is sufficient to retain the lowest(monopole) term only A single wormhole which connectstwo regions in the same space is a couple of conjugatedspheres 1198783
plusmnof the radius 119886with a distance =
+minus
minusbetween
centers of spheres So the parameters of the wormhole are(The additional parameter (rotation matrix Λ) is importantonly for multipoles of higher orders) 120585 = (119886 119877
+ 119877
minus) The
interior of the spheres is removed and surfaces are gluedtogether Then the proper boundary conditions (the actualtopology) can be accounted for by adding the bias of thesource
120575 (119909 minus 1199091015840) 997888rarr 120575 (119909 minus 119909
1015840) + 119887 (119909 119909
1015840) (18)
In the approximation 119886119883 ≪ 1 (eg see for details [9]) thebias for a single wormhole takes the form
1198871(119909 119909
1015840 120585) =
1198862
2(
1
(119877minusminus 1199091015840)
2minus
1
(119877+minus 1199091015840)
2)
times [120575 ( minus +) minus 120575 ( minus
minus)]
(19)
This form for the bias is convenient when constructing thetrue Green function and considering the long-wave limithowever it is not acceptable in considering the short-wavebehavior and vacuum polarization effects Indeed the posi-tions of additional sources are in the physically nonadmissibleregion of space (the interior of spheres 1198783
plusmn) To account for
the finite value of the throat size we should replace in (19)the point-like source with the surface density (induced on thethroat) that is
120575 ( minus plusmn) 997888rarr
1
212058721198863120575 (
10038161003816100381610038161003816 minus
plusmn
10038161003816100381610038161003816minus 119886) (20)
Such a replacement does not change the value of the trueGreen function however now all extra sources are in thephysically admissible region of space
In the rarefied gas approximation the total bias is additivethat is
119887total (119909 1199091015840) = sum119887
1(119909 119909
1015840 120585
119894) = 119873int119887
1(119909 119909
1015840 120585) 119865 (120585) 119889120585
(21)
Journal of Astrophysics 5
where 119873119865 is given by (9) For a homogeneous and isotropicdistribution 119865(120585) = 119865(119886119883) and then for the bias we find
119887total (119909 minus 1199091015840)
= int1
21205872119886(
1
1198772
minus
minus1
1198772
+
)120575 (10038161003816100381610038161003816 minus
1015840minus
+
10038161003816100381610038161003816minus 119886)119873119865 (120585) 119889120585
(22)
Consider the Fourier transform 119865(119886119883) = int119865(119886 119896)119890minus119894119896119883
sdot
(1198894119896(2120587)
4) and using the integral 11199092
= int(41205872119896
2)119890
minus119894119896119909sdot
(1198894119896(2120587)
4) we find for 119887(119896) = int 119887(119909)119890
1198941198961199091198894119909 the expression
119887total (119896) = 119873int1198862 4120587
2
1198962(119865 (119886 119896) minus 119865 (119886 0))
1198691(119896119886)
1198961198862119889119886 (23)
(1) Example of a Finite Density of Wormholes Consider nowa particular (of a finite density) distribution of wormholes119865(119886119883) for example
119873119865 (119886119883) =119899
212058721199033
0
120575 (119886 minus 1198860) 120575 (119883 minus 119903
0) (24)
where 119899 = 119873119881 is the density of wormholes In the case119873 = 1 this function corresponds to a single wormhole withthe throat size 119886
0and the distance between throats 119903
0=
|119877+minus119877
minus|We recall that the action (6) remains invariant under
translations and rotations which straightforwardly leads tothe above function Then 119873119865(119886 119896) = int119873119865(119886119883)119890
1198941198961199091198894119909 re-
duces to 119873119865(119886 119896) = 119899(1198691(119896119903
0)(119896119903
02))120575(119886 minus 119886
0) Thus from
(23) we find
119887 (119896) = minus1198991198862 4120587
2
1198962(1 minus
1198691(119896119903
0)
11989611990302
)1198691(119896119886
0)
11989611988602
(25)
And for the true Green function we get
119866true = 1198660(119896)119873 (119896) = 119866
0(119896) (1 + 119887 (119896)) (26)
In the short-wave limit (119896119886 1198961199030≫ 1) 119887(119896) rarr 0 and
therefore 119873(119896) rarr 1 This means that at very small scalesthe space filled with a finite density of wormholes looks likethe ordinary Euclidean space In the long-wave limit 119896 rarr 0
we get 1198691(119896119903
0)(119896119903
02) asymp 1 minus (12) (119896119903
02)
2+ sdot sdot sdot which gives
119887(119896) asymp minus1205872119899119886
21199032
02 while in a more general case we find
119887(119896) asymp minus int(12058722)119886
21199032
0119899(119886 119903
0)119889119886 119889119903
0 where 119899(119886 119903
0) is the den-
sity of wormholes with a particular values of 119886 and 1199030 and for
the bias function (15) we get
119873(119896) 997888rarr 1 minus1205872
2int 119886
4119899 (119886 119903
0)1199032
0
1198862119889119886 119889119903
0le 1 (27)
In other words in the long-wave limit (119896119886 1198961199030≪ 1) the
presence of a particular set of virtual wormholes diminishesmerely the value of the charge values
(2) Limiting Topologies or Infinite Densities of WormholesConsider now the limiting distribution when the density of
wormholes 119899 rarr infin Since every throat cuts the finite portionof the volume (120587
22)119886
4 this case requires considering thelimit 119886 rarr 0 We assume that in this limit 1198862119873119865(119886119883) rarr
120575(119886)](119883) where ](119883) is a finite specific distribution Then(23) reduces to 119887total(119896) = (4120587
2119896
2) (](119896) minus ](0)) where ](119896) =
int ](119883)119890119894119896119883
1198894119883 and the bias (15) (18)119873(119896) becomes
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (28)
It is important that this limit still agrees with the rarefiedgas approximation for the basic gas parameter (ie theportion of volume cut by wormholes) tends to 120585 =
int(12058722)119886
4119865(119886119883)119889
4119883119889119886 rarr 0 The above expression is ob-
tained in the linear approximation only Taking into accountnext orders (eg see [22] where the case of a dense gas is alsoconsidered) we find 119873(119896) = 1 + 119887total(119896) + 119887
2
total(119896) + sdot sdot sdot andthe true Green function in a gas of wormholes becomes
119866true = 1198660(119896)119873 (119896) =
1
1198962 + 41205872(] (0) minus ] (119896))
(29)
In the long-wave limit 119896 rarr 0 the function ](119896) can beexpanded as ](119896) asymp ](0) + (12)]10158401015840(0)1198962 which also definesa renormalization of charge values119873(119896) rarr 1(1minus2120587
2]10158401015840(0))which coincides with (27) However in this limiting case wehave some freedom in the choice of ](119896) which we can useto assign 119873(119896) an arbitrary function of 119896 In other wordswe may get here a class of limiting topologies where Greenfunctions119866true = 119866
0(119896)119873(119896) have a good ultraviolet behavior
and quantumfield theories in such spaces turn out to be finiteIn particular this will certainly be the case when
119866true (119909 minus 1199091015840= 0) = int
1
1198962 + 41205872(] (0) minus ] (119896))
1198894119896
(2120587)4lt infin
(30)
This possibility however requires the further and more deepinvestigation
32 Green Function General Consideration The action (6)remains invariant under translations
1015840= + 119888 with an
arbitrary 119888 which means that the measure (11) does notactually depend on the position of the center of mass of thegas of wormholes and therefore we may restrict ourself withhomogeneous distributions 119865(120585) of wormholes in space onlyIndeed we may define 119889119873
120585 = 11988911987312058510158401198894119888 while the integration
over 1198894119888 gives the volume of1198774 that is int1198894
119888 = 1198714= 119881which
disappears from (11) due to the denominator (Technically wemay first restrict a portion of1198774 in (6) to a finite volume119881 andthen in final expressions consider the limit 119881 rarr infin (whichrepresents the standard tool in thermodynamics and QFT))In what follows we shall omit the prime from 120585
1015840Let us consider the Fourier representation119873(119909 119909
1015840 120585) rarr
119873(119896 1198961015840 120585) which in the case of a homogeneous distribution
of wormholes gives119873(119896 1198961015840) = 119873(119896 120585) 120575(119896 minus 119896
1015840) then we find
119866 (119896) = 1198660(119896)119873 (119896 120585) (31)
6 Journal of Astrophysics
and the Green function can be taken as
119866 =119873 (119896 120585)
1198962 + 1198982 (32)
Then for the total partition function we find
119885total (119869)
= int [119863119873 (119896)] 119890minus119868(119873)
119890minus(12)(119871
4
(2120587)4
) int((119873(119896)(1198962
+1198982
))|119869119896
|2
)119889119896
(33)
where [119863119873] = prod119896119889119873
119896and 120590(119873) comes from the integration
measure (ie from the Jacobian of transformation from 119865(120585)
to119873(119896))
119890minus119868(119873)
= int [119863119865]1198850(119873 (119896 120585)) 120575 (119873 (119896) minus 119873 (119896 120585)) (34)
We point out that 119868(119873) can be changed by means of addingto the action (6) of an arbitrary ldquonondynamicalrdquo constantterm which depends only on topology 119878 rarr 119878 + Δ119878 (119873(119896))
(eg a topological Euler term) The multiplier 1198850(119873) defines
the simplest measure for topologies Now by means of usingthe expression (32) and (33) we find the two-point Greenfunction in the form
119866 (119896) =119873 (119896)
1198962 + 1198982 (35)
where 119873(119896) is the cutoff function (the mean bias) whichis given by (We recall that in this integral contribute onlylimiting topologies in which density of wormholes diverges(119899 rarr infin))
119873(119896) =1
119885total (0)int [119863119873] 119890
minus119868(119873)119873(119896) (36)
At the present stage we still cannot evaluate the exactform for the cutoff function 119873(119896) in virtue of the ambiguityof Δ119878(119873(119896)) pointed out Such a term may include twoparts First part Δ
1119878 describes the proper dynamics of
wormholes and should be considered separately Indeedin general wormholes are dynamical self-gravitating objectswhich require considering the gravitational contribution tothe action Some part of such a contribution (mean curvatureinduced by wormholes) is discussed in Section 6 Howeversince a wormhole represents an extended nonlocal objectit possesses a rather complex dynamics and this problemrequires the further investigation The second part Δ
2119878 may
describe ldquoexternal conditionsrdquo (eg an external classicalfield in (33)) for the mean topology Actually the last termcan be used to prescribe an arbitrary particular value forthe cutoff function 119873(119896) = 119891(119896) Indeed the ldquoexternalconditionsrdquo can be accounted for by adding the term Δ
2119878 =
(120582119873) = int 120582(119896)119873(119896)1198894119896 where 120582(119896) plays the role of a
specific chemical potential which implicitly depends on 119891(119896)
through the equation
119891 (119896) =1
119885total (120582 0)int [119863119873] 119890
(120582119873)minus119868(119873)119873(119896) (37)
From (33) we see that the role of such a chemical potentialmay play the external current 120582(119896) = minus(12)(119871
4(2120587)
4)sdot
1198660(119896)|119869
ext119896|2 or equivalently an external classical field 120593
ext=
1198660(119896)119869
ext119896 In quantum field theory such a term leads merely
to a renormalization of the cosmological constant By otherwords the mean topology (ie the cutoff function or meandistribution of wormholes) is driven by the cosmologicalconstant Λ and vice versa
4 Topological Bias as a Projection Operator
By the construction the topological bias 119873(119909 1199091015840) plays the
role of a projection operator onto the space of functions (asubspace of functions on 119877
4) which obey the proper bound-ary conditions at throats of wormholes This means thatfor any particular topology (for a set of wormholes) thereexists the basis 119891
119894(119909) in which it takes the diagonal form
119873(119909 1199091015840) = sum119873
119894119891119894(119909)119891
lowast
119894(119909
1015840) with eigenvalues 119873
119894= 0 1
(since 1198732
119894= 119873
119894) In this section we illustrate this simple fact
(which is probably not obvious for readers) by the explicitconstruction of the reference system for a single wormholewhen physical functions become (due to the boundaryconditions) periodic functions of one of coordinates
Indeed consider a single wormhole with parameters 120585(ie 120585 = (119886 119877
+ 119877
minus) where 119886 is the throat radius and 119877
plusmn
are positions of throats in space (In general there existsan additional parameter Λ120572
120573which defines a rotation of one
of throats before gluing However it does not change thesubsequent constructionThere always exists a diffeomorphicmap of coordinates 1199091015840
= ℎ(119909) which sets such a matrix tounity)) Consider now a particular solution120601
0to the equation
Δ1206010= 0 (harmonic function) for 1198774 in the presence of the
wormhole which corresponds to the situation when throatspossess a unit chargemass but those have the opposite signsNow define the family of lines of force 119909(119904 119909
0) which obey
the equation 119889119909119889119904 = minusnabla1206010(119909) with initial conditions 119909(0) =
1199090 Physically such lines correspond to lines of force for a
two charged particles in positions 119877plusmn with charges plusmn1 Wenote that all points which lay on the trajectory 119909(119904 119909
0) may
be taken as initial conditions and they define the same lineof force with the obvious redefinition 119904 rarr 119904 minus 119904
0 By
other words we may take as a new coordinates the parameter119904 and portion of the coordinates orthogonal to the familyof lines 119909
perp
0 Coordinates 119909
perp
0can be taken as laying in the
hyperplane 1198773 which is orthogonal to the vector 119889 = minusminus
+
and goes through the point 0
= (minus+
+)2 (Instead
of the construction used here one may use also anothermethod Indeed consider two point charges and then thefunction 120601
0= 1(119909 minus 119909
+)2minus 1(119909 minus 119909
minus)2 can be taken as a
new coordinate Wormhole appears when we identify (glue)surfaces 120601
0= plusmn120596 We point out that such surfaces are not
spheres though they reduce to spheres in the limit |119909+minus
119909minus| rarr infin or 120596 rarr infin)Let 119904plusmn(119909perp
0) be the values of the parameter 119904 at which
the line intersects the throats 119877plusmn Then instead of 119904 we mayconsider a new parameter 120579 as 119904(120579) = 119904
minus+ (119904
+minus 119904
minus)1205792120587
so that when 120579 = 0 2120587 the parameter 119904 takes the values
Journal of Astrophysics 7
119904 = 119904minus 119904+ respectivelyThe gluing procedure at throatsmeans
merely that we identify points at 120579 = 0 and 120579 = 2120587 and allphysical functions in the space 119877
4 with a single wormhole120585 become periodic functions of 120579 Thus the coordinatetransformation 119909 = 119909(120579 119909
perp
0) gives the map of the above space
onto the cylinder with a specific metric 1198891198972 = (119889(120579 119909perp
0))
2
=
119892120572120573119889119910
120572119889119910
120573 (where 119910 = (120579 119909perp
0)) whose components are also
periodic in terms of 120579 Now we can continue the coordinatesto thewhole space1198774 (to construct a cover of the fundamentalregion 120579 isin [0 2120587]) simply admitting all valuesminusinfin lt 120579 lt +infin
this however requires to introduce the bias
1
radic119892120575 (120579 minus 120579
1015840) 997888rarr 119873(120579 minus 120579
1015840) =
+infin
sum
119899=minusinfin
1
radic119892120575 (120579 minus 120579
1015840+ 2120587119899)
(38)
since every point and every source in the fundamental regionacquires a countable set of images in the nonphysical region(inside of wormhole throats) Considering now the Fouriertransforms for 120579 we find
119873(119896 1198961015840) =
+infin
sum
119899=minusinfin
120575 (119896 minus 119899) 120575 (119896 minus 1198961015840) (39)
We point out that the above bias gives the unit operator in thespace of periodic functions of 120579 From the standpoint of allpossible functions on 1198774 it represents the projection operator
2= (120585) (taking an arbitrary function 119891 we find that upon
the projection 119891119873= 119891 119891
119873becomes a periodic function of
120579 that is only periodic functions survive)The above construction can be easily generalized to the
presence of a set of wormholes In the approximation of adilute gas of wormholes we may neglect the influence ofwormholes on each other (at least there always exists a suf-ficiently smooth map which transforms the family of linesof force for ldquoindependentrdquo wormholes onto the actual lines)Then the total bias (projection) may be considered as theproduct
119873total (119909 1199091015840) = int(prod
119894
radic1198921198941198894119910119894)119873(120585
1 119909 119910
1)
times 119873 (1205852 119910
1 119910
2) sdot sdot sdot 119873 (120585
119873 119910
119873minus1 119909
1015840)
(40)
where 119873(120585119894 119909 119909
1015840) is the bias for a single wormhole with
parameters 120585119894 Every such a particular bias119873(120585
119894 119909 119909
1015840) realizes
projection on a subspace of functions which are periodic withrespect to a particular coordinate 120579
119894(119909) while the total bias
gives the projection onto the intersection of such particularsubspaces (functions which are periodic with respect to everyparameter 120579
119894)
5 Cutoff
The projective nature of the bias operator 119873(119909 1199091015840) allows us
to express the cutoff function 119873(119896) via dynamic parametersof wormholes Indeed consider a box 1198714 in 119877
4 and periodic
boundary conditions which gives 119896 = 2120587119899119871 (in final expres-sions we consider the limit 119871 rarr infin which gives sum
119896rarr
(1198714(2120587)
4) int 119889
4119896) And let us consider the decomposition for
the integration measure in (33) as
119868 = 1198680+sum120582
1(119896)119873 (119896) +
1
2sum120582
2(119896 119896
1015840)119873 (119896)119873 (119896
1015840) + sdot sdot sdot
(41)
where 1205821(119896) includes also the contribution from 119885
0(119896) We
point out that this measure plays the role of the action for thebias119873(119896) Indeed the variation of the above expression givesthe equation of motions for the bias in the form
sum
1198961015840
1205822(119896 119896
1015840)119873 (119896
1015840) = minus120582
1(119896) (42)
which can be found by considering the proper dynamics ofwormholes We however do not consider the problem of thedynamic description of wormholes here and leave this forthe future research Moreover we may expect that in the firstapproximation one may retain the linear term only Indeedthis takes place when119873(119896) is not a dynamic variable or if wetake into account that 119873(119896) is a collective variable Then theprojective nature of the bias 119873(119896) = 0 1 means that it canbe phenomenologically expressed via some Fermionic ghostfield Ψ(119896) (eg 119873(119896 119896
1015840) = Ψ(119896)Ψ
+(119896
1015840)) where the negative
and positive frequency parts of the operator Ψ(119896) obey theanticommutation relationsΨ+
(119896)Ψ(1198961015840)+Ψ(119896
1015840) Ψ
+(119896) = 120575(119896minus
1198961015840) In the absence of ghost particles Ψ(119896)|0⟩ = 0 we get
119873(119896 1198961015840) = 120575(119896 minus 119896
1015840) that is 119873(119896) = 1 and wormholes
are absent In the term of the ghost field the action becomes119868(119873) = 119868
0+ (Ψ
1Ψ) + sdot sdot sdot Therefore in the leading approx-
imation equations of motion take the linear form 1Ψ = 0
Thus taken into account that 119873(119896) = 0 1 (1198732= 119873) we
find
119873(119896) =1
119885total (119896)sum
119873=01
119890minus1205821
(119896)119873(119896)119873(119896) =
119890minus1205821
(119896)
1 + 119890minus1205821(119896) (43)
The simplest choice gives merely 1205821(119896) = minussum ln119885
0(119896)
where the sum is taken over the number of fields and 1198850(119896)
is given by 1198850(119896) = radic120587(1198962 + 1198982) In the case of a set
of massless fields we find 119873(119896) = 119885(119896)(1 + 119885(119896)) where119885(119896) = (radic120587119896)
120572 and 120572 is the effective number of degreesof freedom (the number of boson minus fermion fields) Toensure the absence of divergencies one has to consider thenumber of fields 120572 gt 4 [23] However such a choice givesthe simplest estimate which in general cannot be correctIndeed while its behavior at very small scales (ie whenexceeding the Planckian scales 119885(119896) ≲ 1 and 119873(119896) = 119885(119896))may be physically accepted since it produces some kind of acutoff on the mass-shell 1198962 + 119898
2rarr 0 it gives the behavior
119873(119896) rarr 1 which is merely incorrect (eg from (27) we seethat the true behavior should be119873(119896) rarr const lt 1)
One may expect that the true cutoff function has a muchmore complex behavior Indeed some theoretical models inparticle physics (eg string theory) have the property tobe lower-dimensional at very small scales The mean cutoff
8 Journal of Astrophysics
119873(119896) gives the natural tool to describe a scale-dependantdimensional reduction [24 25] In fact this function definesthe spectral number of modes in the interval between 119896 and119896 + 119889119896 as
int119873 (119896)1198894119896
(2120587)4= int
119873 (119896) 1198964
(2120587)2
119889119896
119896 (44)
Hence we can define the effective spectral dimension 119863 ofspace as follows
1198964119873(119896) sim 119896
119863 (45)
From the empirical standpoint the dimension 119863 = 4 isverified at laboratory scales only while the rigorous tool todefine the spectral density of states (or the mean cutoff) cangive the lattice quantum gravity for example see [26 27]and references therein And indeed the spectral dimensionfor nonperturbative quantum gravity defined via Euclideandynamical triangulations was calculated recently in [28] Itturns out that it runs from a value of119863 = 32 at short distanceto 119863 = 4 at large distance scales We also point out that allobserved dark matter phenomena can be explained by thefractal dimension119863 asymp 2 starting from scales 119871 ≳ (1 divide 5)Kpcfor example [29ndash33]
6 Cosmological Constant
Let us consider the total Euclidean action [17]
119868119864= minus
1
16120587119866int (119877 minus 2Λ
0)radic119892119889
4119909 minus int119871
119898radic1198921198894119909 (46)
The variation of the above action leads to the Einstein equa-tions
119877119886119887minus1
2119892119886119887119877 + 119892
119886119887Λ
0= 8120587119866119879
119886119887 (47)
where 119879119886119887= (12)(119892)
minus12(120575119871
119898120575119892
119886119887) is the stress energy ten-
sor and Λ0is a naked cosmological constant In cosmology
such equations are considered from the classical standpointwhich means that they involve characteristic scales ℓ ≫ ℓplHowever the presence of virtual wormholes at Planckianscales defines some additional contribution in both parts ofthese equations which can be adsorbed into the cosmologicalconstant Therefore the total cosmological constant can bedefined as
Λ tot = Λ0+ Λ
119898+ Λ
119877= Λ
0+ 2120587119866 ⟨119879⟩ +
1
4⟨119877⟩119908 (48)
where ⟨119879⟩ is the energy of zero-point fluctuations (It includesalso the contribution of zero-point fluctuations of gravitons)That is themean vacuum value (we recall that in the standardQFTΛ
119898is infinite while wormholes form a finite value) and
⟨119877⟩119908
= Λ119877is a contribution of wormholes into the mean
curvature due to gluing (1)
61 Contribution of Virtual Wormholes into Mean CurvatureConsider a single wormhole whose metric is given by (1)
1198891199042= ℎ
2(119903)120575
120572120573119889119909
120572119889119909
120573 then the components of the Riccitensor are (We are much obliged to the Referee who pointedout to the subtleties when working with a step function in themetric)
119877120572120573
= 7 minus (ℎ1015840
ℎ)
1015840
(120575120572120573
+ (119873 minus 2) 119899120572119899120573)
minus1
119903
ℎ1015840
ℎ((119873 minus 2) Δ
120572120573+ 120575
120572120573(119873 minus 1))
minus (ℎ1015840
ℎ)
2
(119873 minus 2) Δ120572120573
(49)
where 119899]= 119909
]119886 is the unite normal vector to the throat
surface Δ120572120573
= 120575120572120573
minus 119899120572119899120573 ℎ1015840 = 120597ℎ120597119903 and119873 is the number
of dimensions The curvature scalar is
119877 = minus(119873 minus 1)
ℎ2[2
ℎ10158401015840
ℎ+ 2
1
119903
ℎ1015840
ℎ(119873 minus 1) + (
ℎ1015840
ℎ)
2
(119873 minus 4)]
(50)
Then substituting ℎ = 1 + (1198862119903
2minus 1)120579 in the above equation
we find
minusℎ4
119873 minus 1119877 = 4ℎ
1198862
1199033120575 +
2ℎ
119903119873minus1(119903
119873minus1120582)
1015840
+ (119873 minus 4)(1205822minus 4120579
1198862
1199033120582)
+ 4 (119873 minus 4)1198862
1199034120579 (120579 minus 1)
(51)
where 120579 is a smooth function which only in a limit becomesa step function 120582 = (1 minus 119886
2119903
2)120575 and 120575 = minus120579
1015840 In the limit120579 rarr 120579(119886 minus 119903) we find 120575 rarr 120575(119903 minus 119886) and the last two terms in(51) are negligible as compared to the first two terms while infour dimensions the last two terms vanishThen the curvatureis concentrated on the throat of the wormhole where 120579 differsfrom the step function In the limit of a vanishing throat sizewe have ℎ rarr 1 at the throat and we get
minus119877 =4 (119873 minus 1)
119886120575 (119903 minus 119886) +
2 (119873 minus 1)
119903119873minus1(119903
119873minus3(119903
2minus 119886
2) 120575)
1015840
(52)
In general all the terms together in (51) and analogous termsin the Ricci tensor provide that the Bianchi identity holdsand the energy is conserved [19] Therefore none of themcan be dropped out However it is easy to see the leadingcontribution to the integral over space comes from the firstterm only and in the limit of a vanishing throat size we findfor a single wormhole
1
4int119877radic119892119889
4119909 = minus6120587
21198862 (53)
Journal of Astrophysics 9
In the case of a set of wormholes (24) we find
1
4int119877radic119892119889
4119909 = minus6120587
2sum
119895
1198862
119895
= minus121205872int119899 (119886) 119886
2119889119886 119889
4119909 = intΛ
1198771198894119909
(54)
where 2119899(119886) = int 119899(119886 1199030)119889119903
0is the density of wormhole
throats with a fixed value of the throat size 119886 This definesthe contribution to the cosmological constant from the meancurvature as
Λ119877= minus12120587
2int119899 (119886) 119886
2119889119886 lt 0 (55)
We see that this quantity is always negative
62 Stress Energy Tensor In this section we consider thecontribution from matter fields In the case of a scalar fieldthe stress energy tensor has the form
minus119879120572120573
(119909) = 120597120572120593120597
120573120593 minus
1
2119892120572120573
(120597120583120593120597
120583120593 + 119898
21205932) (56)
Then the mean vacuum value of the stress energy tensor canbe obtained directly from the two-point green function (32)(35) as
minus ⟨119879120572120573
(119909)⟩
= lim1199091015840
rarr119909
(1205971205721205971015840
120573minus1
2119892120572120573
(1205971205831205971015840
120583+ 119898
2)) ⟨119866 (119909 119909
1015840 120585)⟩
(57)
By means of using the Fourier transform 119866(119909 1199091015840 120585) =
int 119890minus119894119896(119909minus119909
1015840
)119866(119896 120585) (119889
4119896(2120587)
4) and the expressions (32) (35)
we arrive at
⟨119879120572120573
(119909)⟩ =1
4119892120572120573
int(1 +119898
2
1198962 + 1198982)119873 (119896)
1198894119896
(2120587)4 (58)
where the property int 119896120572119896120573119891(119896
2)119889
4119896 = (14)119892
120572120573int 119896
2119891(119896
2)119889
4119896
has been used and 119873(119896) = ⟨119873(119896 120585)⟩ is the cutoff function(36)
For the sake of simplicity we consider the massless caseThen by the use of the cutoff 119873(119896) = 120587
1205722(120587
1205722+ 119896
120572) from
the previous section we get the finite estimate (120572 gt 4 is theeffective number of the field helicity states)
Λ119898=2120587119866sumint
1205871205722
1205871205722+119896120572
1198894119896
(2120587)4=120587119866
4Γ (
120572 minus 4
120572) Γ (
4
120572) sim 1
(59)
where the sum is taken over the number of fields Since theleading contribution comes here from very small scales wemay hope that this value will not essentially change if thetrue cutoff function changes the behavior on the mass-shellas 119896 rarr 0 (eg if we take 120582
1(119896) = minussum ln119885
0(119896) + 120575120582(119896) with
120575120582(119896) ≪ ln1198850(119896) as 119896 ≫ 1)
To understand how wormholes remove divergencies itwill be convenient to split the bias function into two parts119873(119896 120585) = 1 + 119887(119896 120585) where 1 corresponds to the standardEuclidean contribution while 119887(119896 120585) is the contribution ofwormholes The first part gives the well-known divergentcontribution of vacuumfield fluctuations 8120587119866⟨1198790
120572120573⟩ = Λ
lowast119892120572120573
with Λlowast
rarr +infin while the second part remains finite forany finite number of wormholes and due to the projectivenature of the bias described in the previous section itpartially compensates (reduces) the value of the cosmologicalconstant that is 8120587119866⟨Δ119879
120572120573⟩ = 120575Λ119892
120572120573 where 120575Λ =
sum119873120588119873120575Λ(119873) and 120575Λ(119873) is a negative finite contribution of
a finite set of wormholesConsider now the particular distribution of virtual
wormholes (24) and evaluate their contribution tothe cosmological constant which is given by 120575Λ(119873) =
2120587119866int 119887(119896) (1198894119896(2120587)
4) = 2120587119866119887total(0) Then from the ex-
pressions (22) and (24) we get
119887total (0) = minus119899
4120587411988631199033
0
int(1 minus1198862
1198772
minus
)120575 (119877+minus 119886)
times 120575 (1003816100381610038161003816119877+
minus 119877minus
1003816100381610038161003816 minus 1199030) 119889
4119877minus1198894119877+
(60)
which gives
119887total (0) = minus119899(1 minus 119891(119886
1199030
)) (61)
where
119891(119886
1199030
) =2
120587int
120587
0
1198862sin2
120579119889120579
1198862 + 21198861199030cos 120579 + 119903
2
0
(62)
For 1198861199030≪ 1 (we recall that by the construction 119886119903
0le 12)
this function has the value 119891(1198861199030) asymp 119886
2119903
2
0 Thus for the
contribution of wormholes we find
120575Λ119898= minus2120587119866int119899 (119886 119903
0) (1 minus 119891(
119886
1199030
))119889119886 1198891199030
= minus2120587119866119899 (1 minus ⟨119891⟩)
(63)
63 Vacuum Value of the Cosmological Constant From theabove expression we see that to get the finite value of thecosmological constant Λ
119898= Λ
lowast+ 120575Λ
119898lt infin one should
consider the limit 119899 rarr infin (infinite density of virtualwormholes) which requires considering the smaller andsmaller wormholes From the other handwe have the obviousrestriction int 2119899(119886 119903
0)(120587
22)119886
4119889119886 119889119903
0lt 1 where (120587
22)119886
4
is the volume of one throat (wormholes cannot cut morethan the total volume of space) (We also point out that inremoving divergencies the leading role plays the zero-pointenergy Indeed 120575Λ
119898sim minus2120587119866119899 while the mean curvature has
the order Λ119877sim minus119886
2119899 and for 119886 ≪ ℓpl we have 120575Λ119898
≫ Λ119877
Moreover in the limit 119899 rarr infin one gets 119886 rarr 0 and thereforeΛ
119877120575Λ
119898rarr 0)Therefore in the leading order it seems to be
sufficient to retain point-like wormholes only (ie consider
10 Journal of Astrophysics
the limit 119886 rarr 0) Then instead of (24) we may assume thevacuum distribution of virtual wormholes in the form
119873119865 (119886119883) =1
1198862120575 (119886) ] (119883) (64)
where ](119883) = int 1198862119873119865(119886119883)119889119886 and int(1119886
2)](119883)119889
4119883 =
119899 rarr infin has the meaning of the infinite density of point-like wormholes while ] sim 119886
2119899 remains a finite In this case
the volume cut by wormholes vanishes int 2119899(12058722)119886
4119889119886 119889119903
0=
1198862int ](119883)119889
4119883 rarr 0 and the rarefied gas approximationworks
wellThis defines the bias and themean cutoff (here we definethe Fourier transform ](119896) = int ](119883)119890
1198941198961198831198894119883) as
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (65)
The contribution to themean curvature (55) can be expressedvia the same function ](119896) as
Λ119877= minus12120587
2int119899 (119886 119903
0) 119886
2119889119886 119889119903
0
= minus121205872int ] (119883) 119889
4119883 = minus12120587
2] (0)
(66)
Thus for the total cosmological constant we get the expres-sion
Λ tot = Λ0
+ 2120587119866int(1minus4120587
2
1198962(] (0)minus] (119896)))
1198894119896
(2120587)4minus12120587
2] (0)
(67)
We stress that all these terms should be finite Indeed all dis-tributions of virtual wormholes ](119896) which lead to an infinitevalue of Λ tot are suppressed in (5) by the factor sim119890minusintΛ tot119889
4
119909while the minimal value is reached when wormholes cut allof the volume of space and the action is merely 119878 = 0(Frankly speaking this statement is not rigorous At first lookthe two last terms in (67) are independent and one may tryto take ](0) an arbitrary big If this were the case then theaction would not possess the minimum at all However ](0)cannot be arbitrary big since it will violate the rarefied gasapproximation and the linear expression (67) brakes downMoreover fermions give here a contribution of the oppositesign The rigorous investigation of this problem requires thefurther studying and we present it elsewhere) We also pointout that here we considered the real scalar field as the mattersource while in the general case the stress energy tensorshould include all existing Bose and Fermi fields (Fermi fieldsgive a negative contribution to Λ
119898)
The value of Λ0looks like a free parameter which in
quantum gravity runs with scales [27] However at largescales its asymptotic value may be uniquely fixed by thesimple arguments as follows Indeed in quantum field theoryproperties of the ground state (vacuum) change when weimply an external classical fields The same is true for thedistribution of virtualwormholes ](119896 119869) for example see (33)and (37) and therefore Λ tot = Λ tot(119869) which we describe
in the next subsection We recall that in gravity the role ofthe external current plays the stress energy tensor of matterfields 119869 = 119879
119886119887 However one believes that in the absence
of all classical fields the vacuum state should represent themost symmetric (Lorentz invariant) state which in our casecorresponds to the Euclidean space In order to be consistentwith the Einstein equations this requires Λ tot(119869 = 0) = 0
which uniquely fixes the value of Λ0in (67) We point out
that from somewhat different considerations such a choicewas advocated earlier in [15 34 35]
64 Vacuum Polarization in an External Field Consider nowtopology fluctuations in the presence of an external currentIn the presence of an external current 119869ext the distribution ofvirtual wormholes changes ](119896 119869) = ](119896) + 120575](119896 119869) Indeedin (33) for the case of a weak external field the contributionof the external current into the action can be expanded asexp(minus119881(119869)) ≃ 1 minus 119881 where
119881 = minus1
2int 119869 (119909) 119866 (119909 119910) 119869 (119910) 119889
4119909 119889
4119910
= minus1
2
1198714
(2120587)4int119866
0(119896)119873 (119896)
10038161003816100381610038161198691198961003816100381610038161003816
2
1198894119896
(68)
Then using (36) we find119873(119896 119869) = 119873(119896 0) + 120575119873(119896 119869) where
120575119873 (119896 119869) = 120575119887 (119869) ≃ minus1
2
1198714
(2120587)4int120590
2(119896 119901) 119866
0(119901)
10038161003816100381610038161003816119869119901
10038161003816100381610038161003816
2
1198894119901
(69)
is the bias related to an additional distribution of virtualwormholes and 120590
2(119896 119901) = Δ119873lowast(119896)Δ119873(119901)
1205902(119896 119901) =
1
119885total (0)int [119863119873] 119890
minus119868(119873)Δ119873
lowast(119896) Δ119873 (119901) (70)
defines the dispersion of vacuum topology fluctuations (hereΔ119873 = 119873 minus 119873) The exact definition of 1205902
(119896 119901) requires thefurther development of a fundamental theory In particular itcan be numerically calculated in lattice quantum gravity [28]However it can be shown that at scales 119896 119901 ≫ 119896pl it reducesto 1205902
(119896 119901) rarr 1205902
119896120575(119896 minus 119901) and therefore
120575119887 (119869) = minus1205902
119896
41205872
21198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(71)
Now comparing this function with (23) we relate the addi-tional distribution of virtual wormholes and the externalclassical field as
41205872
1198962(120575] (0 119869) minus 120575] (119896 119869)) =
1
21205902
119896
41205872
1198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(72)
where 120575](119896 119869) = int 1198862120575119873119865(119886 119896)119889119886 We point out that the
above expression does not define the value 120575](0 119869) whichrequires an additional considerationMoreover in general theexternal field 119869 does not possess a symmetry and therefore thecorrection ⟨120575119879
120572120573(119909)⟩ does not reduce to a single cosmological
Journal of Astrophysics 11
constant However such corrections always violate the aver-aged null energy condition [36 37] and may be considered assome kind of dark energy or by other words it represents anexotic matter Some portion of dark energy still has the formof the cosmological constant which defines a nonvanishingpresent day value (we recall that fermions give a contributionof the opposite sign)
120575Λ tot = minus2120587119866int4120587
2
1198962⟨120575] (0 119869) minus 120575] (119896 119869)⟩
1198894119896
(2120587)4
minus 121205872120575] (0 119869)
(73)
where ⟨120575](119896 119869)⟩ denotes an averaging over rotationsThe only unknown parameter in (72) is the dispersion
1205902
119896which defines the intensity of topology fluctuations in
the vacuum It has also the sense of the efficiency coefficientwhich defines the portion of the energy of the external fieldspent on the formation of additional wormholes Thoughthe evaluation of 1205902
119896requires the further development of a
fundamental theory one may expect that 1205902
119896= 119873(119896)(1 minus
119873(119896)) where 119873(119896) is the mean cutoff It is expected that119873(119896) rarr 0 as 119896 ≫ 119896pl and119873(119896) rarr 119873
0le 1 This means that
120590 rarr 0 as 119896 ≫ 119896pl and 120590 rarr 1205900≪ 1 as 119896 ≪ 119896pl while it takes
the maximum value 120590max sim 1 at Planckian scales 119896 sim 119896pl Byotherwords themost efficient transmission of the energy intowormholes takes place for wormholes of the Planckian sizeIn the case when external classical fields have characteristicscales 120582 = 2120587119896 ≫ ℓpl in (72) the efficiency coefficient 1205902
119896and
the cutoff 119873(119896) become constant 120590 ≃ 1205900 119873(119896) ≃ 119873
0 while
their ratiomay be estimated as 1205721205902
0119873
0= ΩDEΩ119887
where 120572 isthe effective number of fundamental fields which contributeto 120575Λ tot and ΩDE Ω119887
are dark energy and baryon energydensities respectively According to the modern picture thisratio gives ΩDEΩ119887
asymp 075005 = 15 while 1205902
0119873
0sim 1
(as 1198730≪ 1) and therefore this defines the estimate for the
effective number of fundamental fields (helicity states) as 120572 sim
15
65 Speculations on the Formation of Actual WormholesAs we already pointed out the additional distribution ofvirtual wormholes (72) reflects the symmetry of externalclassical fields and therefore it forms a homogeneous andisotropic background and perturbations We recall that vir-tual wormholes represent an exotic form of matter In theearly Universe such perturbations start to develop and mayform actual wormholes The rigorous description of sucha process represents an extremely complex and interestingproblemwhich requires the further study Some aspects of thebehavior of the exotic density perturbations were consideredin [7] while the simplest example of the formation of awormhole-type object was discussed recently by us in [38]Therefore we may expect that some portion of such a form ofdark energy is reserved now in actual wormholes which weconsider in the next section
7 Dark Energy from Actual Wormholes
Consider now the contribution to the dark energy fromthe gas of actual wormholes Unlike the virtual wormholesactual wormholes do exist at all times and therefore a singlewormhole can be viewed as a couple of conjugated cylinders1198793
plusmn= 119878
2
plusmntimes 119877
1 So that the number of parameters of an actualwormhole is less 120578 = (119886 119903
+ 119903
minus) where 119886 is the radius of 1198782
plusmn
and 119903plusmnisin 119877
3 is a spatial part of 119877plusmn
Actual wormholes also produce two kinds of contributionto the dark energy One comes from their contribution tothe mean curvature which corresponds to an exotic stressenergy momentum tensor Such a stress energy momentumtensor reflects the dark energy reserved by additional virtualwormholes discussed in the previous section Such energyis necessary to support actual wormholes as a solution tothe Einstein equations The second part comes from vacuumpolarization effects by actual wormholes The considerationin the previous section shows that for macroscopic worm-holes the second part has the order ⟨Δ119879
120572120573⟩ sim 8120587119866119899 and
is negligible as compared to the curvature 119877 sim 1198862119899 (since
macroscopic wormholes have throats 119886 ≫ ℓpl) Howeverfor the sake of completeness and for methodological aims wedescribe it as well
For rigorous evaluation of dark energy of the secondtype we first have to find the bias 119887
1(119909 119909
1015840 120578) analogous to
(19) for the topology 1198774(119879
3
+cup 119879
3
minus) There are many papers
treating different wormholes in this respect (eg see [36 37]and references therein) However in the present paper for anestimation we shall use a more simple trick
71 Beads of Virtual Wormholes (Quantum Wormhole)Indeed instead of the cylinders 1198793
plusmnwe consider a couple of
chains (beads of virtual wormholes 1198793
plusmnrarr cup
1198991198783
plusmn119899) Such an
idea was first suggested in [39] and one may call such anobject as quantum wormhole Then the bias can be writtenstraightforwardly
1198871(119909 119909
1015840 120578) =
+infin
sum
119899=minusinfin
1
41205872119886(
1
(119877minus119899
minus 1199091015840)2minus
1
(119877+119899
minus 1199091015840)2)
times [120575 (10038161003816100381610038161003816 minus
+119899
10038161003816100381610038161003816minus 119886) minus 120575 (
10038161003816100381610038161003816 minus
minus119899
10038161003816100381610038161003816minus 119886)]
(74)
where 119877plusmn119899
= (119905119899 119903
plusmn) with 119905
119899= 119905
0+ 2ℓ119899 and ℓ ge 119886 is the
step We may expect that upon averaging over the position1199050isin [minusℓ ℓ] the bias for the beads will reproduce the bias for
cylinders1198793
plusmn(at least it looks like a very good approximation)
We point out that the averaging out (12ℓ) intℓ
minusℓ119889119905
0and the
sum sum+infin
119899=minusinfinreduces to a single integral (12ℓ) intinfin
minusinfin119889119905 of the
zero term in (74) And moreover the resulting total biascorresponds merely to a specific choice of the distributionfunction 119865(120585) in (21) Namely we may take
119873119865 (120585) =1
2ℓ120575 (119905
+minus 119905
minus) 119891 (
1003816100381610038161003816119903+ minus 119903minus
1003816100381610038161003816 119886) (75)
12 Journal of Astrophysics
where119877plusmn= (119905
plusmn 119903
plusmn) and119891(119904 119886) is the distribution of cylinders
which can be taken as (119899 is 3-dimensional density)
119891 (120578) =119899 (119886)
41205871199032
0
120575 (119904 minus 1199030) (76)
Using the normalization condition int119873119865(120585)119889120585 = 119873 we findthe relation 119873 = (12ℓ)119899119881 = 119899119881 where 119899 is a 4-dimensional density of wormholes and 1(2ℓ) is the effectivenumber of wormholes on the unit length of the cylinder (iethe frequency with which the virtual wormhole appears atthe positions 119903
plusmn) This frequency is uniquely fixed by the
requirement that the volume which cuts the bead is equal tothat which cuts the cylinder (43)1205871198863 = (120587
22)119886
4(12ℓ) (ie
2ℓ = (31205878)119886 and 119899 = (83120587119886)119899) Thus we can use directlyexpression (23) and find (compare to (25))
119887 (119896) = minusint 119899 (119886) 1198862 4120587
2
1198962(1 minus
sin |k| 1199030|k| 1199030
)1198691(119896119886)
1198961198862119889119886 (77)
where 119896 = (1198960 k) Here the first term merely coincides with
that in (25) and therefore it gives the contribution to thecosmological constant 120575Λ(8120587119866) = minus1198994 = minus2119899(3120587119886)while the second term describes a correction which does notreduce to the cosmological constant and requires a separateconsideration
72 Stress Energy Tensor From (57) we find that the stressenergy tensor
minus⟨Δ119879120572120573
(119909)⟩ = int
119896120573119896120572minus (12) 119892
1205721205731198962
1198962119887 (119896 120585)
1198894119896
(2120587)4
(78)
reduces to the two functions
11987900
= 120576 = 1205821minus1
2120583
119879119894119895= 119901120575
119894119895 119901 =
1
31205822minus1
2120583
(79)
where 120576 + 3119901 = minus120583 and 1205821+ 120582
2= 120583 and these functions are
1205821= minusint
1198962
0
11989621198871198894119896
(2120587)4 120582
2= minusint
|k|2
11989621198871198894119896
(2120587)4 (80)
By means of the use of the spherical coordinates 11989620119896
2=
cos2120579 |k|21198962 = sin2120579 and 119889
4119896 = 4120587sin2
1205791198963119889119896119889120579 we get
120582119894=119899 (119886 119903
0)
4120573119894
(1 minus 2120573119894(119886
1199030
)
2
119891119894(119886
1199030
)) (81)
where 1205731= 1 120573
2= 13 and 119891
119894is given by
119891(1
2)(119910)
=2
120587int
1
minus1
int
infin
0
sin (119909 sin 120579)1198691(119910119909)
1199101199092(cos2120579sin2
120579) 119889119909 119889cos 120579
(82)
For 1198861199030≪ 1 we find
11989112
(119886
1199030
) asymp (1 + 11990012
(119886
1199030
)) (83)
Thus finally we find
120576 ≃ minus119899
4= minus
2119899
3120587119886 119901 ≃ 120576(1 minus
4
3(119886
1199030
)
2
) (84)
which upon the continuation to the Minkowsky space givesthe equation of state in the form (An arbitrary gas ofwormholes splits in fractions with a fixed 119886 and 119903
0)
119901 = minus(1 minus4
3(119886
1199030
)
2
) 120576 (85)
which in the case when 1198861199030≪ 1 behaves like a cosmological
constant However when 119886 ≫ ℓpl such a constant is extremelysmall and can be neglected while the leading contributioncomes from the mean curvature
73 Mean Curvature In this subsection we consider theMinkowsky spaceThen the simplest actual wormhole can bedescribed by the metric analogous to (1) for example see [7]
1198891199042= 119888
2119889119905
2minus ℎ
2(119903) 120575
120572120573119889119909
120572119889119909
120573 (86)
where ℎ(119903) = 1 + 120579(119886 minus 119903)(1198862119903
2minus 1) To avoid problems
with the Bianchi identity and the conservation of energy thestep function should be also smoothed as in (1) The stressenergy tensor which produces such a wormhole can be foundfrom the Einstein equation 8120587119866119879
120573
120572= 119877
120573
120572minus (12)120575
120573
120572119877 Both
regions 119903 gt 119886 and 119903 lt 119886 represent portions of the ordinaryflat Minkowsky space and therefore the curvature is 119877119896
119894equiv 0
However on the boundary 119903 = 119886 it has the singularity Sincethe metric (86) does not depend on time we find
1198770
0= 119877
0
120572= 0 119877
120573
120572=2
119886120575 (119886 minus 119903) 119899
120572119899120573+ 120575
120573
120572 + 120582
120573
120572 (87)
where 119899120572 = 119899120572= 119909
120572119903 is the outer normal to the throat 1198782
and 120582120573
120572are additional terms (eg see (49) and (51)) which
in the leading order are negligible upon averaging over someportion of space Δ119881 ≳ 119886
3 In the case of a set of wormholesthis gives in the leading order
1198770
0= 119877
0
120572= 0 119877
120573
120572= sum
2
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119903
119894
1003816100381610038161003816) 119899119894120572119899120573
119894+ 120575
120573
120572
(88)
where 119886119894is the radius of a throat and 119903
119894is the position of the
center of the throat in space and 119899120572
119894= (119909
120572minus 119903
120572
119894)|119903 minus 119903
119894|
In the case of a homogeneous and isotropic distribution ofsuch throats we find 119877
120573
120572= (13)119877120575
120573
120572(averaging over spatial
directions gives ⟨119899120572119899120573⟩ = (13)120575
120573
120572) where
119877 = minus8120587119866119879 = sum8
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119877
119894
1003816100381610038161003816) = 32120587int 119886119899 (119886) 119889119886
(89)
Journal of Astrophysics 13
where 119879 stands for the trace of the stress energy momentumtensor which one has to add to the Einstein equations tosupport such awormhole It is clear that such a source violatesthe weak energy condition and therefore it reproduces theformof dark energy (ie119879 = 120576+3119901 lt 0) If the density of suchsources (and resp the density of wormholes) is sufficientlyhigh then this results in the observed [10ndash14] accelerationof the scale factor for the Friedmann space as sim 119905
120572 with120572 = 21205763(120576 + 119901) = 2120576(2120576 + (120576 + 3119901)) gt 1 for examplesee also [40ndash42] In terms of the 4-dimensional density ofwormholes 119899 = (83120587119886)119899 we get 119877 sim 119886
2119899 ≫ 8120587119866119899 as 119886 ≫ ℓpl
and therefore the leading contribution indeed comes fromthe mean curvature
8 Estimates and Concluding Remarks
Now consider the simplest estimates Actual wormholes seemto be responsible for the dark matter [7 9] Therefore to getthe estimate to the number density of wormholes is ratherstraightforward First wormholes appear at scales when darkmatter effects start to display themselves that is at scales ofthe order 119871 sim (1 divide 5)Kpc which gives in that range thenumber density
119899 sim1
1198713sim (3 divide 0024) times 10
minus65cmminus3 (90)
The characteristic size of throats can be estimated from (89)120576DE sim (119866)
minus1119899119886 Since the density of dark energy is 120576DE1205760 =
ΩDE sim 075 where 1205760is the critical density then we find the
estimate
119886 sim2
3(1 divide 125) times 10
minus3119877⊙ΩDEℎ
2
75 (91)
where119877⊙is the Solar radius ℎ
75= 119867(75 km(secMpc)) and
119867 is the Hubble constant We also recall that the backgrounddensity of baryons 120576
119887generates a nonvanishingwormhole rest
mass119872119908= (43)120587119886
31198773120576119887(where119877(119905) is the scale factor of the
Universe and therefore 119872119908remains constant) for example
see [7] It produces the dark matter density related to thewormholes as 120576DM ≃ 119872
119908119899 The typical mass of a wormhole
119872119908is estimated as
119872119908sim 1 7 times (1 divide 125) times 10
2119872
⊙ΩDMℎ
2
75 (92)
where 119872⊙is the Solar mass We point out that this mass
has not the direct relation to the parameters of the gas ofwormholes However it defines the moment when wormholethroats separated from the cosmological expansion Theabove estimate shows that if wormholes form due to thedevelopment of perturbations in the exotic matter then thisprocess should start much earlier than the formation ofgalaxies
Thus we see that virtual wormholes should indeed leadto the regularization of all divergencies in QFT which agreeswith recent results [28] Therefore they form the local finitevalue of the cosmological constant In the absence of externalclassical fields such a value should be exactly zero at macro-scopic scales A some nonvanishing value for the cosmolog-ical constant appears as the result of vacuum polarization
effects in external fields Indeed external fields form anadditional distribution of virtual wormholes which possessan exotic stress energy tensor (some kind of dark energy)Only some part of it forms the cosmological constant whilethe rest reflects the symmetry of external fields and possessesinhomogeneitiesWe assume that during the evolution of ourUniverse inhomogeneities in the exotic matter develop andmay form actual wormholes Although this problem requiresthe further and more deep investigation we refer to [38]where the formation of a simplest wormhole-like object hasbeen considered In other words such polarization energyis reserved now in a gas of actual wormholes We estimatedparameters of such a gas and believe that such a gas mayindeed be responsible for both dark matter and dark energyphenomena
References
[1] J R Primack ldquoThe nature ofdark matterrdquo httparxivorgabsastro-ph0112255
[2] J Diemand M Zemp B Moore J Stadel and M CarolloldquoCusps in cold dark matter haloesrdquoMonthly Notices of the RoyalAstronomical Society vol 364 no 2 pp 665ndash673 2005
[3] E W Mielke and J A V Velez Perez ldquoAxion condensate as amodel for dark matter halosrdquo Physics Letters B vol 671 no 1pp 174ndash178 2009
[4] G Gentile P Salucci U Klein D Vergani and P Kalberla ldquoThecored distribution of dark matter in spiral galaxiesrdquo MonthlyNotices of the Royal Astronomical Society vol 351 no 3 pp 903ndash922 2004
[5] D T F Weldrake W J G de Blok and F Walter ldquoA high-resolution rotation curve of NGC 6822 a test-case for cold darkmatterrdquo Monthly Notices of the Royal Astronomical Society vol340 no 1 pp 12ndash28 2003
[6] W J G de Blok andA Bosma ldquoHigh-resolution rotation curvesof low surface brightness galaxiesrdquoAstronomy and Astrophysicsvol 385 pp 816ndash846 2002
[7] A Kirillov and E P Savelova ldquoDensity perturbations in a gas ofwormholesrdquoMonthly Notices of the Royal Astronomical Societyvol 412 no 3 pp 1710ndash1720 2011
[8] P Kanti B Kleihaus and J Kunz ldquoStable Lorentzianwormholesin dilatonic Einstein-Gauss-Bonnet theoryrdquo Physical Review Dvol 85 no 4 Article ID 044007 2012
[9] A A Kirillov and E P Savelova ldquoDark matter from a gas ofwormholesrdquo Physics Letters B vol 660 no 3 pp 93ndash99 2008
[10] A G Riess A V Filippenko P Challis et al ldquoObservationalevidence from supernovae for an accelerating universe and acosmological constantrdquo The Astronomical Journal vol 116 no3 p 1009 1998
[11] S Perlmutter G Aldering G Goldhaber et al ldquoMeasurementsofΩ andΛ from42high-redshift supernovaerdquoTheAstrophysicalJournal vol 517 no 2 p 565 1999
[12] J L Tonry B P Schmidt B Barris et al ldquoCosmological resultsfromhigh-z supernovaerdquoTheAstrophysical Journal vol 594 no1 p 594 2003
[13] N W Halverson E M Leitch C Pryke et al ldquoDegreeangular scale interferometer first results a measurement of thecosmic microwave background angular power spectrumrdquo TheAstrophysical Journal vol 568 no 1 p 38 2002
14 Journal of Astrophysics
[14] C B Netterfield P A R Ade J J Bock et al ldquoA measurementby BOOMERANGofmultiple peaks in the angular power spec-trum of the cosmic microwave backgroundrdquo The AstrophysicalJournal vol 571 no 2 p 604 2002
[15] S Coleman ldquoWhy there is nothing rather than something atheory of the cosmological constantrdquoNuclear Physics B vol 310no 3-4 pp 643ndash668 1988
[16] I Klebanov L Susskind and T Banks ldquoWormholes and thecosmological constantrdquo Nuclear Physics B vol 317 no 3 pp665ndash692 1989
[17] S W Hawking ldquoSpacetime foamrdquoNuclear Physics B vol 114 p349 1978
[18] T P Cheng and L F Li Gauge Theory of Elementary ParticlesClarendon Press Oxford UK 1984
[19] A H Taub ldquoSpace-times with distribution valued curvaturetensorsrdquo Journal ofMathematical Physics vol 21 no 6 pp 1423ndash1431 1980
[20] A Shatsky privite communications[21] V A Fock ldquoZur Theorie des Wasserstoffatomsrdquo Zeitschrift fur
Physik vol 98 no 3-4 pp 145ndash154 1935[22] E P Savelova ldquoGas of wormholes in Euclidean quantum field
theoryrdquo httparxivorgabs12115106[23] A A Kirillov and E P Savelova ldquoOn the behavior of
bosonic systems in the presence of topology fluctuationsrdquohttparxivorgabs08082478
[24] A A Kirillov ldquoViolation of the Pauli principle and dimensionof the Universe at very large distancesrdquo Physics Letters B vol555 no 1-2 pp 13ndash21 2003
[25] A A Kirillov ldquoDark matter dark charge and the fractalstructure of the Universerdquo Physics Letters B vol 535 no 1ndash4pp 22ndash24 2002
[26] J Ambjorn J Jurkiewicz and R Loll ldquoThe spectral dimensionof the universe is scale dependentrdquo Physical Review Letters vol95 no 17 Article ID 171301 4 pages 2005
[27] E Manrique S Rechenberger and F Saueressig ldquoAsymptoti-cally safe Lorentzian gravityrdquo Physical Review Letters vol 106no 25 Article ID 251302 4 pages 2011
[28] J Laiho and D Coumbe ldquoEvidence for asymptotic safety fromlattice quantum gravityrdquo Physical Review Letters vol 107 no 16Article ID 161301 2011
[29] A A Kirillov and D Turaev ldquoOn modification of the Newtonrsquoslaw of gravity at very large distancesrdquo Physics Letters B vol 532no 3-4 pp 185ndash192 2002
[30] A A Kirillov and D Turaev ldquoThe universal rotation curveof spiral galaxiesrdquo Monthly Notices of the Royal AstronomicalSociety vol 371 no 1 pp L31ndashL35 2006
[31] A A Kirillov and D Turaev ldquoFoam-like structure of theuniverserdquo Physics Letters B vol 656 pp 1ndash8 2007
[32] A A Kirillov ldquoThe nature of dark matterrdquo Physics Letters B vol632 no 4 pp 453ndash462 2006
[33] A A Kirillov and E P Savelova ldquoAstrophysical effects of space-time foamrdquo Gravitation and Cosmology vol 14 no 3 pp 256ndash261 2008
[34] S W Hawking and N Turok ldquoOpen inflation without falsevacuardquo Physics Letters B vol 425 no 1-2 pp 25ndash32 1998
[35] Z C Wu ldquoThe cosmological constant is probably zero and aproof is possibly rightrdquo Physics Letters B vol 659 no 5 pp 891ndash893 2008
[36] R Garattini ldquoEntropy and the cosmological constant aspacetime-foam approachrdquo Nuclear Physics B vol 88 no 1ndash3Article ID 991003 pp 297ndash300 2000
[37] MVisserLorentzianWormholes SpringerNewYorkNYUSA1996
[38] A A Kirillov and E P Savelova ldquoArtificial wormholerdquohttparxivorgabs12040351
[39] E W Mielke ldquoKnot wormholes in geometrodynamicsrdquo Gen-eral Relativity and Gravitation vol 8 no 3 pp 175ndash196 1977
[40] E B Gliner ldquoAlgebraic properties of the energy-momentumtensor and vacuum-like states of matterrdquo Journal of Experimen-tal and Theoretical Physics vol 22 p 378 1966
[41] A H Guth ldquoInflationary universe a possible solution to thehorizon and flatness problemsrdquo Physical Review D vol 23 no2 pp 347ndash356 1981
[42] A A Linde ldquoA new inflationary universe scenario a possiblesolution of the horizon flatness homogeneity isotropy andprimordial monopole problemsrdquo Physics Letters B vol 108 no6 pp 389ndash393 1982
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
![Page 4: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/4.jpg)
4 Journal of Astrophysics
cosmological constant should include also the contributionfrom the mean curvature (55)) Any finite distribution ofwormholes leads to the divergent expression Λ(120585119873) rarr
infin and is suppressed (ie 120588 (120585119873) rarr 0) However thesum over all possible topologies assumes also the limitingtopologies 119899 rarr infin where 119899 = 119873119881 is the density ofwormholes In this limit wormhole throats degenerate intopoints and the minimal scale below which the space lookslike the Euclidean space is merely absent We point out thatfrom the rigorous mathematical standpoint such limitingtopologies cannot be described in terms of smoothmanifoldssince they are not locally Euclidean and does not possess afinite set of maps In mathematics similar objects are wellknown for example fractal sets However if a fractal set isobtained by cutting (by means of a specific rule or iterations)portions of space our limiting topologies are obtained bygluing (identifying) some portions (or in the limit couplesof points) of the Euclidean space The basic feature of suchtopologies is that QFT becomes finite on such a set Indeedas we shall see a particular infinite distribution of wormholescan always be chosen in such a way that the energy of zero-point fluctuations becomes a finite 0 le Λ
infin(120585) lt infin (eg
see the next section or the second term in (67)) In the sumover topologies only such limiting topologies do survive (ie120588infin(120585) = 0)
3 The Two-Point Green Function
From (7) we see that the very basic role in QFT plays the twopoint Green function Such a Green function can be foundfrom the equation
119860119866(119909 1199091015840) = minus120575 (119909 minus 119909
1015840) (13)
with proper boundary conditions at wormholes which gives119866 = 119860
minus1 Now let us introduce the bias function119873(119909 1199091015840) as
119866 (119909 119910) = int1198660(119909 119909
1015840)119873 (119909
1015840 119910) 119889119909
1015840 (14)
where 1198660(119909 119909
1015840) is the ballistic (or the standard Euclidean
Green function) and the bias can be presented as
119873(119909 1199091015840) = 120575 (119909 minus 119909
1015840) +sum
119894
119887119894120575 (119909 minus 119909
119894) (15)
where 119887119894are fictitious sources at positions 119909
119894which should
be added to obey the proper boundary conditions We pointout that the bias can be explicitly expressed via parametersof wormholes that is 119873(119909 119909
1015840) = 119873(119909 119909
1015840 120585
1 120585
119873) For the
sake of illustration we consider first a particular example
31 The Bias for a Particular Distribution of Wormholes(Rarefied Gas Approximation) Consider now the bias for aparticular set of wormholes For the sake of simplicity weconsider the case when119898 = 0 The Green function obeys theLaplace equation
minusΔ119866 (119909 1199091015840) = 120575 (119909 minus 119909
1015840) (16)
with proper boundary conditions at throats (we require119866 and120597119866120597119899 to be continual at throats)The Green function for theEuclidean space is merely 119866
0(119909 119909
1015840) = 14120587
2(119909 minus 119909
1015840)2 (and
1198660(119896) = 1119896
2 for the Fourier transform) In the presence ofa single wormhole which connects two Euclidean spaces thisequation admits the exact solution For outer region of thethroat 1198783 the source 120575(119909 minus 119909
1015840) generates a set of multipoles
placed in the center of sphere which gives the corrections tothe Green function 119866
0in the form (we suppose the center of
the sphere at the origin)
120575119866 = minus1
412058721199092
infin
sum
119899=1
1
119899 + 1(119886
1199091015840)
2119899
(1199091015840
119909)
119899minus1
119876119899 (17)
where 119876119899= (4120587
22119899)sum
119899minus1
119897=0sum
119897
119898=minus119897119876
lowast1015840
119899119897119898119876
119899119897119898and 119876
119899119897119898(Ω) are
four-dimensional spherical harmonics for example see [21]In the present section we shall consider a dilute gas approx-imation and therefore it is sufficient to retain the lowest(monopole) term only A single wormhole which connectstwo regions in the same space is a couple of conjugatedspheres 1198783
plusmnof the radius 119886with a distance =
+minus
minusbetween
centers of spheres So the parameters of the wormhole are(The additional parameter (rotation matrix Λ) is importantonly for multipoles of higher orders) 120585 = (119886 119877
+ 119877
minus) The
interior of the spheres is removed and surfaces are gluedtogether Then the proper boundary conditions (the actualtopology) can be accounted for by adding the bias of thesource
120575 (119909 minus 1199091015840) 997888rarr 120575 (119909 minus 119909
1015840) + 119887 (119909 119909
1015840) (18)
In the approximation 119886119883 ≪ 1 (eg see for details [9]) thebias for a single wormhole takes the form
1198871(119909 119909
1015840 120585) =
1198862
2(
1
(119877minusminus 1199091015840)
2minus
1
(119877+minus 1199091015840)
2)
times [120575 ( minus +) minus 120575 ( minus
minus)]
(19)
This form for the bias is convenient when constructing thetrue Green function and considering the long-wave limithowever it is not acceptable in considering the short-wavebehavior and vacuum polarization effects Indeed the posi-tions of additional sources are in the physically nonadmissibleregion of space (the interior of spheres 1198783
plusmn) To account for
the finite value of the throat size we should replace in (19)the point-like source with the surface density (induced on thethroat) that is
120575 ( minus plusmn) 997888rarr
1
212058721198863120575 (
10038161003816100381610038161003816 minus
plusmn
10038161003816100381610038161003816minus 119886) (20)
Such a replacement does not change the value of the trueGreen function however now all extra sources are in thephysically admissible region of space
In the rarefied gas approximation the total bias is additivethat is
119887total (119909 1199091015840) = sum119887
1(119909 119909
1015840 120585
119894) = 119873int119887
1(119909 119909
1015840 120585) 119865 (120585) 119889120585
(21)
Journal of Astrophysics 5
where 119873119865 is given by (9) For a homogeneous and isotropicdistribution 119865(120585) = 119865(119886119883) and then for the bias we find
119887total (119909 minus 1199091015840)
= int1
21205872119886(
1
1198772
minus
minus1
1198772
+
)120575 (10038161003816100381610038161003816 minus
1015840minus
+
10038161003816100381610038161003816minus 119886)119873119865 (120585) 119889120585
(22)
Consider the Fourier transform 119865(119886119883) = int119865(119886 119896)119890minus119894119896119883
sdot
(1198894119896(2120587)
4) and using the integral 11199092
= int(41205872119896
2)119890
minus119894119896119909sdot
(1198894119896(2120587)
4) we find for 119887(119896) = int 119887(119909)119890
1198941198961199091198894119909 the expression
119887total (119896) = 119873int1198862 4120587
2
1198962(119865 (119886 119896) minus 119865 (119886 0))
1198691(119896119886)
1198961198862119889119886 (23)
(1) Example of a Finite Density of Wormholes Consider nowa particular (of a finite density) distribution of wormholes119865(119886119883) for example
119873119865 (119886119883) =119899
212058721199033
0
120575 (119886 minus 1198860) 120575 (119883 minus 119903
0) (24)
where 119899 = 119873119881 is the density of wormholes In the case119873 = 1 this function corresponds to a single wormhole withthe throat size 119886
0and the distance between throats 119903
0=
|119877+minus119877
minus|We recall that the action (6) remains invariant under
translations and rotations which straightforwardly leads tothe above function Then 119873119865(119886 119896) = int119873119865(119886119883)119890
1198941198961199091198894119909 re-
duces to 119873119865(119886 119896) = 119899(1198691(119896119903
0)(119896119903
02))120575(119886 minus 119886
0) Thus from
(23) we find
119887 (119896) = minus1198991198862 4120587
2
1198962(1 minus
1198691(119896119903
0)
11989611990302
)1198691(119896119886
0)
11989611988602
(25)
And for the true Green function we get
119866true = 1198660(119896)119873 (119896) = 119866
0(119896) (1 + 119887 (119896)) (26)
In the short-wave limit (119896119886 1198961199030≫ 1) 119887(119896) rarr 0 and
therefore 119873(119896) rarr 1 This means that at very small scalesthe space filled with a finite density of wormholes looks likethe ordinary Euclidean space In the long-wave limit 119896 rarr 0
we get 1198691(119896119903
0)(119896119903
02) asymp 1 minus (12) (119896119903
02)
2+ sdot sdot sdot which gives
119887(119896) asymp minus1205872119899119886
21199032
02 while in a more general case we find
119887(119896) asymp minus int(12058722)119886
21199032
0119899(119886 119903
0)119889119886 119889119903
0 where 119899(119886 119903
0) is the den-
sity of wormholes with a particular values of 119886 and 1199030 and for
the bias function (15) we get
119873(119896) 997888rarr 1 minus1205872
2int 119886
4119899 (119886 119903
0)1199032
0
1198862119889119886 119889119903
0le 1 (27)
In other words in the long-wave limit (119896119886 1198961199030≪ 1) the
presence of a particular set of virtual wormholes diminishesmerely the value of the charge values
(2) Limiting Topologies or Infinite Densities of WormholesConsider now the limiting distribution when the density of
wormholes 119899 rarr infin Since every throat cuts the finite portionof the volume (120587
22)119886
4 this case requires considering thelimit 119886 rarr 0 We assume that in this limit 1198862119873119865(119886119883) rarr
120575(119886)](119883) where ](119883) is a finite specific distribution Then(23) reduces to 119887total(119896) = (4120587
2119896
2) (](119896) minus ](0)) where ](119896) =
int ](119883)119890119894119896119883
1198894119883 and the bias (15) (18)119873(119896) becomes
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (28)
It is important that this limit still agrees with the rarefiedgas approximation for the basic gas parameter (ie theportion of volume cut by wormholes) tends to 120585 =
int(12058722)119886
4119865(119886119883)119889
4119883119889119886 rarr 0 The above expression is ob-
tained in the linear approximation only Taking into accountnext orders (eg see [22] where the case of a dense gas is alsoconsidered) we find 119873(119896) = 1 + 119887total(119896) + 119887
2
total(119896) + sdot sdot sdot andthe true Green function in a gas of wormholes becomes
119866true = 1198660(119896)119873 (119896) =
1
1198962 + 41205872(] (0) minus ] (119896))
(29)
In the long-wave limit 119896 rarr 0 the function ](119896) can beexpanded as ](119896) asymp ](0) + (12)]10158401015840(0)1198962 which also definesa renormalization of charge values119873(119896) rarr 1(1minus2120587
2]10158401015840(0))which coincides with (27) However in this limiting case wehave some freedom in the choice of ](119896) which we can useto assign 119873(119896) an arbitrary function of 119896 In other wordswe may get here a class of limiting topologies where Greenfunctions119866true = 119866
0(119896)119873(119896) have a good ultraviolet behavior
and quantumfield theories in such spaces turn out to be finiteIn particular this will certainly be the case when
119866true (119909 minus 1199091015840= 0) = int
1
1198962 + 41205872(] (0) minus ] (119896))
1198894119896
(2120587)4lt infin
(30)
This possibility however requires the further and more deepinvestigation
32 Green Function General Consideration The action (6)remains invariant under translations
1015840= + 119888 with an
arbitrary 119888 which means that the measure (11) does notactually depend on the position of the center of mass of thegas of wormholes and therefore we may restrict ourself withhomogeneous distributions 119865(120585) of wormholes in space onlyIndeed we may define 119889119873
120585 = 11988911987312058510158401198894119888 while the integration
over 1198894119888 gives the volume of1198774 that is int1198894
119888 = 1198714= 119881which
disappears from (11) due to the denominator (Technically wemay first restrict a portion of1198774 in (6) to a finite volume119881 andthen in final expressions consider the limit 119881 rarr infin (whichrepresents the standard tool in thermodynamics and QFT))In what follows we shall omit the prime from 120585
1015840Let us consider the Fourier representation119873(119909 119909
1015840 120585) rarr
119873(119896 1198961015840 120585) which in the case of a homogeneous distribution
of wormholes gives119873(119896 1198961015840) = 119873(119896 120585) 120575(119896 minus 119896
1015840) then we find
119866 (119896) = 1198660(119896)119873 (119896 120585) (31)
6 Journal of Astrophysics
and the Green function can be taken as
119866 =119873 (119896 120585)
1198962 + 1198982 (32)
Then for the total partition function we find
119885total (119869)
= int [119863119873 (119896)] 119890minus119868(119873)
119890minus(12)(119871
4
(2120587)4
) int((119873(119896)(1198962
+1198982
))|119869119896
|2
)119889119896
(33)
where [119863119873] = prod119896119889119873
119896and 120590(119873) comes from the integration
measure (ie from the Jacobian of transformation from 119865(120585)
to119873(119896))
119890minus119868(119873)
= int [119863119865]1198850(119873 (119896 120585)) 120575 (119873 (119896) minus 119873 (119896 120585)) (34)
We point out that 119868(119873) can be changed by means of addingto the action (6) of an arbitrary ldquonondynamicalrdquo constantterm which depends only on topology 119878 rarr 119878 + Δ119878 (119873(119896))
(eg a topological Euler term) The multiplier 1198850(119873) defines
the simplest measure for topologies Now by means of usingthe expression (32) and (33) we find the two-point Greenfunction in the form
119866 (119896) =119873 (119896)
1198962 + 1198982 (35)
where 119873(119896) is the cutoff function (the mean bias) whichis given by (We recall that in this integral contribute onlylimiting topologies in which density of wormholes diverges(119899 rarr infin))
119873(119896) =1
119885total (0)int [119863119873] 119890
minus119868(119873)119873(119896) (36)
At the present stage we still cannot evaluate the exactform for the cutoff function 119873(119896) in virtue of the ambiguityof Δ119878(119873(119896)) pointed out Such a term may include twoparts First part Δ
1119878 describes the proper dynamics of
wormholes and should be considered separately Indeedin general wormholes are dynamical self-gravitating objectswhich require considering the gravitational contribution tothe action Some part of such a contribution (mean curvatureinduced by wormholes) is discussed in Section 6 Howeversince a wormhole represents an extended nonlocal objectit possesses a rather complex dynamics and this problemrequires the further investigation The second part Δ
2119878 may
describe ldquoexternal conditionsrdquo (eg an external classicalfield in (33)) for the mean topology Actually the last termcan be used to prescribe an arbitrary particular value forthe cutoff function 119873(119896) = 119891(119896) Indeed the ldquoexternalconditionsrdquo can be accounted for by adding the term Δ
2119878 =
(120582119873) = int 120582(119896)119873(119896)1198894119896 where 120582(119896) plays the role of a
specific chemical potential which implicitly depends on 119891(119896)
through the equation
119891 (119896) =1
119885total (120582 0)int [119863119873] 119890
(120582119873)minus119868(119873)119873(119896) (37)
From (33) we see that the role of such a chemical potentialmay play the external current 120582(119896) = minus(12)(119871
4(2120587)
4)sdot
1198660(119896)|119869
ext119896|2 or equivalently an external classical field 120593
ext=
1198660(119896)119869
ext119896 In quantum field theory such a term leads merely
to a renormalization of the cosmological constant By otherwords the mean topology (ie the cutoff function or meandistribution of wormholes) is driven by the cosmologicalconstant Λ and vice versa
4 Topological Bias as a Projection Operator
By the construction the topological bias 119873(119909 1199091015840) plays the
role of a projection operator onto the space of functions (asubspace of functions on 119877
4) which obey the proper bound-ary conditions at throats of wormholes This means thatfor any particular topology (for a set of wormholes) thereexists the basis 119891
119894(119909) in which it takes the diagonal form
119873(119909 1199091015840) = sum119873
119894119891119894(119909)119891
lowast
119894(119909
1015840) with eigenvalues 119873
119894= 0 1
(since 1198732
119894= 119873
119894) In this section we illustrate this simple fact
(which is probably not obvious for readers) by the explicitconstruction of the reference system for a single wormholewhen physical functions become (due to the boundaryconditions) periodic functions of one of coordinates
Indeed consider a single wormhole with parameters 120585(ie 120585 = (119886 119877
+ 119877
minus) where 119886 is the throat radius and 119877
plusmn
are positions of throats in space (In general there existsan additional parameter Λ120572
120573which defines a rotation of one
of throats before gluing However it does not change thesubsequent constructionThere always exists a diffeomorphicmap of coordinates 1199091015840
= ℎ(119909) which sets such a matrix tounity)) Consider now a particular solution120601
0to the equation
Δ1206010= 0 (harmonic function) for 1198774 in the presence of the
wormhole which corresponds to the situation when throatspossess a unit chargemass but those have the opposite signsNow define the family of lines of force 119909(119904 119909
0) which obey
the equation 119889119909119889119904 = minusnabla1206010(119909) with initial conditions 119909(0) =
1199090 Physically such lines correspond to lines of force for a
two charged particles in positions 119877plusmn with charges plusmn1 Wenote that all points which lay on the trajectory 119909(119904 119909
0) may
be taken as initial conditions and they define the same lineof force with the obvious redefinition 119904 rarr 119904 minus 119904
0 By
other words we may take as a new coordinates the parameter119904 and portion of the coordinates orthogonal to the familyof lines 119909
perp
0 Coordinates 119909
perp
0can be taken as laying in the
hyperplane 1198773 which is orthogonal to the vector 119889 = minusminus
+
and goes through the point 0
= (minus+
+)2 (Instead
of the construction used here one may use also anothermethod Indeed consider two point charges and then thefunction 120601
0= 1(119909 minus 119909
+)2minus 1(119909 minus 119909
minus)2 can be taken as a
new coordinate Wormhole appears when we identify (glue)surfaces 120601
0= plusmn120596 We point out that such surfaces are not
spheres though they reduce to spheres in the limit |119909+minus
119909minus| rarr infin or 120596 rarr infin)Let 119904plusmn(119909perp
0) be the values of the parameter 119904 at which
the line intersects the throats 119877plusmn Then instead of 119904 we mayconsider a new parameter 120579 as 119904(120579) = 119904
minus+ (119904
+minus 119904
minus)1205792120587
so that when 120579 = 0 2120587 the parameter 119904 takes the values
Journal of Astrophysics 7
119904 = 119904minus 119904+ respectivelyThe gluing procedure at throatsmeans
merely that we identify points at 120579 = 0 and 120579 = 2120587 and allphysical functions in the space 119877
4 with a single wormhole120585 become periodic functions of 120579 Thus the coordinatetransformation 119909 = 119909(120579 119909
perp
0) gives the map of the above space
onto the cylinder with a specific metric 1198891198972 = (119889(120579 119909perp
0))
2
=
119892120572120573119889119910
120572119889119910
120573 (where 119910 = (120579 119909perp
0)) whose components are also
periodic in terms of 120579 Now we can continue the coordinatesto thewhole space1198774 (to construct a cover of the fundamentalregion 120579 isin [0 2120587]) simply admitting all valuesminusinfin lt 120579 lt +infin
this however requires to introduce the bias
1
radic119892120575 (120579 minus 120579
1015840) 997888rarr 119873(120579 minus 120579
1015840) =
+infin
sum
119899=minusinfin
1
radic119892120575 (120579 minus 120579
1015840+ 2120587119899)
(38)
since every point and every source in the fundamental regionacquires a countable set of images in the nonphysical region(inside of wormhole throats) Considering now the Fouriertransforms for 120579 we find
119873(119896 1198961015840) =
+infin
sum
119899=minusinfin
120575 (119896 minus 119899) 120575 (119896 minus 1198961015840) (39)
We point out that the above bias gives the unit operator in thespace of periodic functions of 120579 From the standpoint of allpossible functions on 1198774 it represents the projection operator
2= (120585) (taking an arbitrary function 119891 we find that upon
the projection 119891119873= 119891 119891
119873becomes a periodic function of
120579 that is only periodic functions survive)The above construction can be easily generalized to the
presence of a set of wormholes In the approximation of adilute gas of wormholes we may neglect the influence ofwormholes on each other (at least there always exists a suf-ficiently smooth map which transforms the family of linesof force for ldquoindependentrdquo wormholes onto the actual lines)Then the total bias (projection) may be considered as theproduct
119873total (119909 1199091015840) = int(prod
119894
radic1198921198941198894119910119894)119873(120585
1 119909 119910
1)
times 119873 (1205852 119910
1 119910
2) sdot sdot sdot 119873 (120585
119873 119910
119873minus1 119909
1015840)
(40)
where 119873(120585119894 119909 119909
1015840) is the bias for a single wormhole with
parameters 120585119894 Every such a particular bias119873(120585
119894 119909 119909
1015840) realizes
projection on a subspace of functions which are periodic withrespect to a particular coordinate 120579
119894(119909) while the total bias
gives the projection onto the intersection of such particularsubspaces (functions which are periodic with respect to everyparameter 120579
119894)
5 Cutoff
The projective nature of the bias operator 119873(119909 1199091015840) allows us
to express the cutoff function 119873(119896) via dynamic parametersof wormholes Indeed consider a box 1198714 in 119877
4 and periodic
boundary conditions which gives 119896 = 2120587119899119871 (in final expres-sions we consider the limit 119871 rarr infin which gives sum
119896rarr
(1198714(2120587)
4) int 119889
4119896) And let us consider the decomposition for
the integration measure in (33) as
119868 = 1198680+sum120582
1(119896)119873 (119896) +
1
2sum120582
2(119896 119896
1015840)119873 (119896)119873 (119896
1015840) + sdot sdot sdot
(41)
where 1205821(119896) includes also the contribution from 119885
0(119896) We
point out that this measure plays the role of the action for thebias119873(119896) Indeed the variation of the above expression givesthe equation of motions for the bias in the form
sum
1198961015840
1205822(119896 119896
1015840)119873 (119896
1015840) = minus120582
1(119896) (42)
which can be found by considering the proper dynamics ofwormholes We however do not consider the problem of thedynamic description of wormholes here and leave this forthe future research Moreover we may expect that in the firstapproximation one may retain the linear term only Indeedthis takes place when119873(119896) is not a dynamic variable or if wetake into account that 119873(119896) is a collective variable Then theprojective nature of the bias 119873(119896) = 0 1 means that it canbe phenomenologically expressed via some Fermionic ghostfield Ψ(119896) (eg 119873(119896 119896
1015840) = Ψ(119896)Ψ
+(119896
1015840)) where the negative
and positive frequency parts of the operator Ψ(119896) obey theanticommutation relationsΨ+
(119896)Ψ(1198961015840)+Ψ(119896
1015840) Ψ
+(119896) = 120575(119896minus
1198961015840) In the absence of ghost particles Ψ(119896)|0⟩ = 0 we get
119873(119896 1198961015840) = 120575(119896 minus 119896
1015840) that is 119873(119896) = 1 and wormholes
are absent In the term of the ghost field the action becomes119868(119873) = 119868
0+ (Ψ
1Ψ) + sdot sdot sdot Therefore in the leading approx-
imation equations of motion take the linear form 1Ψ = 0
Thus taken into account that 119873(119896) = 0 1 (1198732= 119873) we
find
119873(119896) =1
119885total (119896)sum
119873=01
119890minus1205821
(119896)119873(119896)119873(119896) =
119890minus1205821
(119896)
1 + 119890minus1205821(119896) (43)
The simplest choice gives merely 1205821(119896) = minussum ln119885
0(119896)
where the sum is taken over the number of fields and 1198850(119896)
is given by 1198850(119896) = radic120587(1198962 + 1198982) In the case of a set
of massless fields we find 119873(119896) = 119885(119896)(1 + 119885(119896)) where119885(119896) = (radic120587119896)
120572 and 120572 is the effective number of degreesof freedom (the number of boson minus fermion fields) Toensure the absence of divergencies one has to consider thenumber of fields 120572 gt 4 [23] However such a choice givesthe simplest estimate which in general cannot be correctIndeed while its behavior at very small scales (ie whenexceeding the Planckian scales 119885(119896) ≲ 1 and 119873(119896) = 119885(119896))may be physically accepted since it produces some kind of acutoff on the mass-shell 1198962 + 119898
2rarr 0 it gives the behavior
119873(119896) rarr 1 which is merely incorrect (eg from (27) we seethat the true behavior should be119873(119896) rarr const lt 1)
One may expect that the true cutoff function has a muchmore complex behavior Indeed some theoretical models inparticle physics (eg string theory) have the property tobe lower-dimensional at very small scales The mean cutoff
8 Journal of Astrophysics
119873(119896) gives the natural tool to describe a scale-dependantdimensional reduction [24 25] In fact this function definesthe spectral number of modes in the interval between 119896 and119896 + 119889119896 as
int119873 (119896)1198894119896
(2120587)4= int
119873 (119896) 1198964
(2120587)2
119889119896
119896 (44)
Hence we can define the effective spectral dimension 119863 ofspace as follows
1198964119873(119896) sim 119896
119863 (45)
From the empirical standpoint the dimension 119863 = 4 isverified at laboratory scales only while the rigorous tool todefine the spectral density of states (or the mean cutoff) cangive the lattice quantum gravity for example see [26 27]and references therein And indeed the spectral dimensionfor nonperturbative quantum gravity defined via Euclideandynamical triangulations was calculated recently in [28] Itturns out that it runs from a value of119863 = 32 at short distanceto 119863 = 4 at large distance scales We also point out that allobserved dark matter phenomena can be explained by thefractal dimension119863 asymp 2 starting from scales 119871 ≳ (1 divide 5)Kpcfor example [29ndash33]
6 Cosmological Constant
Let us consider the total Euclidean action [17]
119868119864= minus
1
16120587119866int (119877 minus 2Λ
0)radic119892119889
4119909 minus int119871
119898radic1198921198894119909 (46)
The variation of the above action leads to the Einstein equa-tions
119877119886119887minus1
2119892119886119887119877 + 119892
119886119887Λ
0= 8120587119866119879
119886119887 (47)
where 119879119886119887= (12)(119892)
minus12(120575119871
119898120575119892
119886119887) is the stress energy ten-
sor and Λ0is a naked cosmological constant In cosmology
such equations are considered from the classical standpointwhich means that they involve characteristic scales ℓ ≫ ℓplHowever the presence of virtual wormholes at Planckianscales defines some additional contribution in both parts ofthese equations which can be adsorbed into the cosmologicalconstant Therefore the total cosmological constant can bedefined as
Λ tot = Λ0+ Λ
119898+ Λ
119877= Λ
0+ 2120587119866 ⟨119879⟩ +
1
4⟨119877⟩119908 (48)
where ⟨119879⟩ is the energy of zero-point fluctuations (It includesalso the contribution of zero-point fluctuations of gravitons)That is themean vacuum value (we recall that in the standardQFTΛ
119898is infinite while wormholes form a finite value) and
⟨119877⟩119908
= Λ119877is a contribution of wormholes into the mean
curvature due to gluing (1)
61 Contribution of Virtual Wormholes into Mean CurvatureConsider a single wormhole whose metric is given by (1)
1198891199042= ℎ
2(119903)120575
120572120573119889119909
120572119889119909
120573 then the components of the Riccitensor are (We are much obliged to the Referee who pointedout to the subtleties when working with a step function in themetric)
119877120572120573
= 7 minus (ℎ1015840
ℎ)
1015840
(120575120572120573
+ (119873 minus 2) 119899120572119899120573)
minus1
119903
ℎ1015840
ℎ((119873 minus 2) Δ
120572120573+ 120575
120572120573(119873 minus 1))
minus (ℎ1015840
ℎ)
2
(119873 minus 2) Δ120572120573
(49)
where 119899]= 119909
]119886 is the unite normal vector to the throat
surface Δ120572120573
= 120575120572120573
minus 119899120572119899120573 ℎ1015840 = 120597ℎ120597119903 and119873 is the number
of dimensions The curvature scalar is
119877 = minus(119873 minus 1)
ℎ2[2
ℎ10158401015840
ℎ+ 2
1
119903
ℎ1015840
ℎ(119873 minus 1) + (
ℎ1015840
ℎ)
2
(119873 minus 4)]
(50)
Then substituting ℎ = 1 + (1198862119903
2minus 1)120579 in the above equation
we find
minusℎ4
119873 minus 1119877 = 4ℎ
1198862
1199033120575 +
2ℎ
119903119873minus1(119903
119873minus1120582)
1015840
+ (119873 minus 4)(1205822minus 4120579
1198862
1199033120582)
+ 4 (119873 minus 4)1198862
1199034120579 (120579 minus 1)
(51)
where 120579 is a smooth function which only in a limit becomesa step function 120582 = (1 minus 119886
2119903
2)120575 and 120575 = minus120579
1015840 In the limit120579 rarr 120579(119886 minus 119903) we find 120575 rarr 120575(119903 minus 119886) and the last two terms in(51) are negligible as compared to the first two terms while infour dimensions the last two terms vanishThen the curvatureis concentrated on the throat of the wormhole where 120579 differsfrom the step function In the limit of a vanishing throat sizewe have ℎ rarr 1 at the throat and we get
minus119877 =4 (119873 minus 1)
119886120575 (119903 minus 119886) +
2 (119873 minus 1)
119903119873minus1(119903
119873minus3(119903
2minus 119886
2) 120575)
1015840
(52)
In general all the terms together in (51) and analogous termsin the Ricci tensor provide that the Bianchi identity holdsand the energy is conserved [19] Therefore none of themcan be dropped out However it is easy to see the leadingcontribution to the integral over space comes from the firstterm only and in the limit of a vanishing throat size we findfor a single wormhole
1
4int119877radic119892119889
4119909 = minus6120587
21198862 (53)
Journal of Astrophysics 9
In the case of a set of wormholes (24) we find
1
4int119877radic119892119889
4119909 = minus6120587
2sum
119895
1198862
119895
= minus121205872int119899 (119886) 119886
2119889119886 119889
4119909 = intΛ
1198771198894119909
(54)
where 2119899(119886) = int 119899(119886 1199030)119889119903
0is the density of wormhole
throats with a fixed value of the throat size 119886 This definesthe contribution to the cosmological constant from the meancurvature as
Λ119877= minus12120587
2int119899 (119886) 119886
2119889119886 lt 0 (55)
We see that this quantity is always negative
62 Stress Energy Tensor In this section we consider thecontribution from matter fields In the case of a scalar fieldthe stress energy tensor has the form
minus119879120572120573
(119909) = 120597120572120593120597
120573120593 minus
1
2119892120572120573
(120597120583120593120597
120583120593 + 119898
21205932) (56)
Then the mean vacuum value of the stress energy tensor canbe obtained directly from the two-point green function (32)(35) as
minus ⟨119879120572120573
(119909)⟩
= lim1199091015840
rarr119909
(1205971205721205971015840
120573minus1
2119892120572120573
(1205971205831205971015840
120583+ 119898
2)) ⟨119866 (119909 119909
1015840 120585)⟩
(57)
By means of using the Fourier transform 119866(119909 1199091015840 120585) =
int 119890minus119894119896(119909minus119909
1015840
)119866(119896 120585) (119889
4119896(2120587)
4) and the expressions (32) (35)
we arrive at
⟨119879120572120573
(119909)⟩ =1
4119892120572120573
int(1 +119898
2
1198962 + 1198982)119873 (119896)
1198894119896
(2120587)4 (58)
where the property int 119896120572119896120573119891(119896
2)119889
4119896 = (14)119892
120572120573int 119896
2119891(119896
2)119889
4119896
has been used and 119873(119896) = ⟨119873(119896 120585)⟩ is the cutoff function(36)
For the sake of simplicity we consider the massless caseThen by the use of the cutoff 119873(119896) = 120587
1205722(120587
1205722+ 119896
120572) from
the previous section we get the finite estimate (120572 gt 4 is theeffective number of the field helicity states)
Λ119898=2120587119866sumint
1205871205722
1205871205722+119896120572
1198894119896
(2120587)4=120587119866
4Γ (
120572 minus 4
120572) Γ (
4
120572) sim 1
(59)
where the sum is taken over the number of fields Since theleading contribution comes here from very small scales wemay hope that this value will not essentially change if thetrue cutoff function changes the behavior on the mass-shellas 119896 rarr 0 (eg if we take 120582
1(119896) = minussum ln119885
0(119896) + 120575120582(119896) with
120575120582(119896) ≪ ln1198850(119896) as 119896 ≫ 1)
To understand how wormholes remove divergencies itwill be convenient to split the bias function into two parts119873(119896 120585) = 1 + 119887(119896 120585) where 1 corresponds to the standardEuclidean contribution while 119887(119896 120585) is the contribution ofwormholes The first part gives the well-known divergentcontribution of vacuumfield fluctuations 8120587119866⟨1198790
120572120573⟩ = Λ
lowast119892120572120573
with Λlowast
rarr +infin while the second part remains finite forany finite number of wormholes and due to the projectivenature of the bias described in the previous section itpartially compensates (reduces) the value of the cosmologicalconstant that is 8120587119866⟨Δ119879
120572120573⟩ = 120575Λ119892
120572120573 where 120575Λ =
sum119873120588119873120575Λ(119873) and 120575Λ(119873) is a negative finite contribution of
a finite set of wormholesConsider now the particular distribution of virtual
wormholes (24) and evaluate their contribution tothe cosmological constant which is given by 120575Λ(119873) =
2120587119866int 119887(119896) (1198894119896(2120587)
4) = 2120587119866119887total(0) Then from the ex-
pressions (22) and (24) we get
119887total (0) = minus119899
4120587411988631199033
0
int(1 minus1198862
1198772
minus
)120575 (119877+minus 119886)
times 120575 (1003816100381610038161003816119877+
minus 119877minus
1003816100381610038161003816 minus 1199030) 119889
4119877minus1198894119877+
(60)
which gives
119887total (0) = minus119899(1 minus 119891(119886
1199030
)) (61)
where
119891(119886
1199030
) =2
120587int
120587
0
1198862sin2
120579119889120579
1198862 + 21198861199030cos 120579 + 119903
2
0
(62)
For 1198861199030≪ 1 (we recall that by the construction 119886119903
0le 12)
this function has the value 119891(1198861199030) asymp 119886
2119903
2
0 Thus for the
contribution of wormholes we find
120575Λ119898= minus2120587119866int119899 (119886 119903
0) (1 minus 119891(
119886
1199030
))119889119886 1198891199030
= minus2120587119866119899 (1 minus ⟨119891⟩)
(63)
63 Vacuum Value of the Cosmological Constant From theabove expression we see that to get the finite value of thecosmological constant Λ
119898= Λ
lowast+ 120575Λ
119898lt infin one should
consider the limit 119899 rarr infin (infinite density of virtualwormholes) which requires considering the smaller andsmaller wormholes From the other handwe have the obviousrestriction int 2119899(119886 119903
0)(120587
22)119886
4119889119886 119889119903
0lt 1 where (120587
22)119886
4
is the volume of one throat (wormholes cannot cut morethan the total volume of space) (We also point out that inremoving divergencies the leading role plays the zero-pointenergy Indeed 120575Λ
119898sim minus2120587119866119899 while the mean curvature has
the order Λ119877sim minus119886
2119899 and for 119886 ≪ ℓpl we have 120575Λ119898
≫ Λ119877
Moreover in the limit 119899 rarr infin one gets 119886 rarr 0 and thereforeΛ
119877120575Λ
119898rarr 0)Therefore in the leading order it seems to be
sufficient to retain point-like wormholes only (ie consider
10 Journal of Astrophysics
the limit 119886 rarr 0) Then instead of (24) we may assume thevacuum distribution of virtual wormholes in the form
119873119865 (119886119883) =1
1198862120575 (119886) ] (119883) (64)
where ](119883) = int 1198862119873119865(119886119883)119889119886 and int(1119886
2)](119883)119889
4119883 =
119899 rarr infin has the meaning of the infinite density of point-like wormholes while ] sim 119886
2119899 remains a finite In this case
the volume cut by wormholes vanishes int 2119899(12058722)119886
4119889119886 119889119903
0=
1198862int ](119883)119889
4119883 rarr 0 and the rarefied gas approximationworks
wellThis defines the bias and themean cutoff (here we definethe Fourier transform ](119896) = int ](119883)119890
1198941198961198831198894119883) as
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (65)
The contribution to themean curvature (55) can be expressedvia the same function ](119896) as
Λ119877= minus12120587
2int119899 (119886 119903
0) 119886
2119889119886 119889119903
0
= minus121205872int ] (119883) 119889
4119883 = minus12120587
2] (0)
(66)
Thus for the total cosmological constant we get the expres-sion
Λ tot = Λ0
+ 2120587119866int(1minus4120587
2
1198962(] (0)minus] (119896)))
1198894119896
(2120587)4minus12120587
2] (0)
(67)
We stress that all these terms should be finite Indeed all dis-tributions of virtual wormholes ](119896) which lead to an infinitevalue of Λ tot are suppressed in (5) by the factor sim119890minusintΛ tot119889
4
119909while the minimal value is reached when wormholes cut allof the volume of space and the action is merely 119878 = 0(Frankly speaking this statement is not rigorous At first lookthe two last terms in (67) are independent and one may tryto take ](0) an arbitrary big If this were the case then theaction would not possess the minimum at all However ](0)cannot be arbitrary big since it will violate the rarefied gasapproximation and the linear expression (67) brakes downMoreover fermions give here a contribution of the oppositesign The rigorous investigation of this problem requires thefurther studying and we present it elsewhere) We also pointout that here we considered the real scalar field as the mattersource while in the general case the stress energy tensorshould include all existing Bose and Fermi fields (Fermi fieldsgive a negative contribution to Λ
119898)
The value of Λ0looks like a free parameter which in
quantum gravity runs with scales [27] However at largescales its asymptotic value may be uniquely fixed by thesimple arguments as follows Indeed in quantum field theoryproperties of the ground state (vacuum) change when weimply an external classical fields The same is true for thedistribution of virtualwormholes ](119896 119869) for example see (33)and (37) and therefore Λ tot = Λ tot(119869) which we describe
in the next subsection We recall that in gravity the role ofthe external current plays the stress energy tensor of matterfields 119869 = 119879
119886119887 However one believes that in the absence
of all classical fields the vacuum state should represent themost symmetric (Lorentz invariant) state which in our casecorresponds to the Euclidean space In order to be consistentwith the Einstein equations this requires Λ tot(119869 = 0) = 0
which uniquely fixes the value of Λ0in (67) We point out
that from somewhat different considerations such a choicewas advocated earlier in [15 34 35]
64 Vacuum Polarization in an External Field Consider nowtopology fluctuations in the presence of an external currentIn the presence of an external current 119869ext the distribution ofvirtual wormholes changes ](119896 119869) = ](119896) + 120575](119896 119869) Indeedin (33) for the case of a weak external field the contributionof the external current into the action can be expanded asexp(minus119881(119869)) ≃ 1 minus 119881 where
119881 = minus1
2int 119869 (119909) 119866 (119909 119910) 119869 (119910) 119889
4119909 119889
4119910
= minus1
2
1198714
(2120587)4int119866
0(119896)119873 (119896)
10038161003816100381610038161198691198961003816100381610038161003816
2
1198894119896
(68)
Then using (36) we find119873(119896 119869) = 119873(119896 0) + 120575119873(119896 119869) where
120575119873 (119896 119869) = 120575119887 (119869) ≃ minus1
2
1198714
(2120587)4int120590
2(119896 119901) 119866
0(119901)
10038161003816100381610038161003816119869119901
10038161003816100381610038161003816
2
1198894119901
(69)
is the bias related to an additional distribution of virtualwormholes and 120590
2(119896 119901) = Δ119873lowast(119896)Δ119873(119901)
1205902(119896 119901) =
1
119885total (0)int [119863119873] 119890
minus119868(119873)Δ119873
lowast(119896) Δ119873 (119901) (70)
defines the dispersion of vacuum topology fluctuations (hereΔ119873 = 119873 minus 119873) The exact definition of 1205902
(119896 119901) requires thefurther development of a fundamental theory In particular itcan be numerically calculated in lattice quantum gravity [28]However it can be shown that at scales 119896 119901 ≫ 119896pl it reducesto 1205902
(119896 119901) rarr 1205902
119896120575(119896 minus 119901) and therefore
120575119887 (119869) = minus1205902
119896
41205872
21198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(71)
Now comparing this function with (23) we relate the addi-tional distribution of virtual wormholes and the externalclassical field as
41205872
1198962(120575] (0 119869) minus 120575] (119896 119869)) =
1
21205902
119896
41205872
1198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(72)
where 120575](119896 119869) = int 1198862120575119873119865(119886 119896)119889119886 We point out that the
above expression does not define the value 120575](0 119869) whichrequires an additional considerationMoreover in general theexternal field 119869 does not possess a symmetry and therefore thecorrection ⟨120575119879
120572120573(119909)⟩ does not reduce to a single cosmological
Journal of Astrophysics 11
constant However such corrections always violate the aver-aged null energy condition [36 37] and may be considered assome kind of dark energy or by other words it represents anexotic matter Some portion of dark energy still has the formof the cosmological constant which defines a nonvanishingpresent day value (we recall that fermions give a contributionof the opposite sign)
120575Λ tot = minus2120587119866int4120587
2
1198962⟨120575] (0 119869) minus 120575] (119896 119869)⟩
1198894119896
(2120587)4
minus 121205872120575] (0 119869)
(73)
where ⟨120575](119896 119869)⟩ denotes an averaging over rotationsThe only unknown parameter in (72) is the dispersion
1205902
119896which defines the intensity of topology fluctuations in
the vacuum It has also the sense of the efficiency coefficientwhich defines the portion of the energy of the external fieldspent on the formation of additional wormholes Thoughthe evaluation of 1205902
119896requires the further development of a
fundamental theory one may expect that 1205902
119896= 119873(119896)(1 minus
119873(119896)) where 119873(119896) is the mean cutoff It is expected that119873(119896) rarr 0 as 119896 ≫ 119896pl and119873(119896) rarr 119873
0le 1 This means that
120590 rarr 0 as 119896 ≫ 119896pl and 120590 rarr 1205900≪ 1 as 119896 ≪ 119896pl while it takes
the maximum value 120590max sim 1 at Planckian scales 119896 sim 119896pl Byotherwords themost efficient transmission of the energy intowormholes takes place for wormholes of the Planckian sizeIn the case when external classical fields have characteristicscales 120582 = 2120587119896 ≫ ℓpl in (72) the efficiency coefficient 1205902
119896and
the cutoff 119873(119896) become constant 120590 ≃ 1205900 119873(119896) ≃ 119873
0 while
their ratiomay be estimated as 1205721205902
0119873
0= ΩDEΩ119887
where 120572 isthe effective number of fundamental fields which contributeto 120575Λ tot and ΩDE Ω119887
are dark energy and baryon energydensities respectively According to the modern picture thisratio gives ΩDEΩ119887
asymp 075005 = 15 while 1205902
0119873
0sim 1
(as 1198730≪ 1) and therefore this defines the estimate for the
effective number of fundamental fields (helicity states) as 120572 sim
15
65 Speculations on the Formation of Actual WormholesAs we already pointed out the additional distribution ofvirtual wormholes (72) reflects the symmetry of externalclassical fields and therefore it forms a homogeneous andisotropic background and perturbations We recall that vir-tual wormholes represent an exotic form of matter In theearly Universe such perturbations start to develop and mayform actual wormholes The rigorous description of sucha process represents an extremely complex and interestingproblemwhich requires the further study Some aspects of thebehavior of the exotic density perturbations were consideredin [7] while the simplest example of the formation of awormhole-type object was discussed recently by us in [38]Therefore we may expect that some portion of such a form ofdark energy is reserved now in actual wormholes which weconsider in the next section
7 Dark Energy from Actual Wormholes
Consider now the contribution to the dark energy fromthe gas of actual wormholes Unlike the virtual wormholesactual wormholes do exist at all times and therefore a singlewormhole can be viewed as a couple of conjugated cylinders1198793
plusmn= 119878
2
plusmntimes 119877
1 So that the number of parameters of an actualwormhole is less 120578 = (119886 119903
+ 119903
minus) where 119886 is the radius of 1198782
plusmn
and 119903plusmnisin 119877
3 is a spatial part of 119877plusmn
Actual wormholes also produce two kinds of contributionto the dark energy One comes from their contribution tothe mean curvature which corresponds to an exotic stressenergy momentum tensor Such a stress energy momentumtensor reflects the dark energy reserved by additional virtualwormholes discussed in the previous section Such energyis necessary to support actual wormholes as a solution tothe Einstein equations The second part comes from vacuumpolarization effects by actual wormholes The considerationin the previous section shows that for macroscopic worm-holes the second part has the order ⟨Δ119879
120572120573⟩ sim 8120587119866119899 and
is negligible as compared to the curvature 119877 sim 1198862119899 (since
macroscopic wormholes have throats 119886 ≫ ℓpl) Howeverfor the sake of completeness and for methodological aims wedescribe it as well
For rigorous evaluation of dark energy of the secondtype we first have to find the bias 119887
1(119909 119909
1015840 120578) analogous to
(19) for the topology 1198774(119879
3
+cup 119879
3
minus) There are many papers
treating different wormholes in this respect (eg see [36 37]and references therein) However in the present paper for anestimation we shall use a more simple trick
71 Beads of Virtual Wormholes (Quantum Wormhole)Indeed instead of the cylinders 1198793
plusmnwe consider a couple of
chains (beads of virtual wormholes 1198793
plusmnrarr cup
1198991198783
plusmn119899) Such an
idea was first suggested in [39] and one may call such anobject as quantum wormhole Then the bias can be writtenstraightforwardly
1198871(119909 119909
1015840 120578) =
+infin
sum
119899=minusinfin
1
41205872119886(
1
(119877minus119899
minus 1199091015840)2minus
1
(119877+119899
minus 1199091015840)2)
times [120575 (10038161003816100381610038161003816 minus
+119899
10038161003816100381610038161003816minus 119886) minus 120575 (
10038161003816100381610038161003816 minus
minus119899
10038161003816100381610038161003816minus 119886)]
(74)
where 119877plusmn119899
= (119905119899 119903
plusmn) with 119905
119899= 119905
0+ 2ℓ119899 and ℓ ge 119886 is the
step We may expect that upon averaging over the position1199050isin [minusℓ ℓ] the bias for the beads will reproduce the bias for
cylinders1198793
plusmn(at least it looks like a very good approximation)
We point out that the averaging out (12ℓ) intℓ
minusℓ119889119905
0and the
sum sum+infin
119899=minusinfinreduces to a single integral (12ℓ) intinfin
minusinfin119889119905 of the
zero term in (74) And moreover the resulting total biascorresponds merely to a specific choice of the distributionfunction 119865(120585) in (21) Namely we may take
119873119865 (120585) =1
2ℓ120575 (119905
+minus 119905
minus) 119891 (
1003816100381610038161003816119903+ minus 119903minus
1003816100381610038161003816 119886) (75)
12 Journal of Astrophysics
where119877plusmn= (119905
plusmn 119903
plusmn) and119891(119904 119886) is the distribution of cylinders
which can be taken as (119899 is 3-dimensional density)
119891 (120578) =119899 (119886)
41205871199032
0
120575 (119904 minus 1199030) (76)
Using the normalization condition int119873119865(120585)119889120585 = 119873 we findthe relation 119873 = (12ℓ)119899119881 = 119899119881 where 119899 is a 4-dimensional density of wormholes and 1(2ℓ) is the effectivenumber of wormholes on the unit length of the cylinder (iethe frequency with which the virtual wormhole appears atthe positions 119903
plusmn) This frequency is uniquely fixed by the
requirement that the volume which cuts the bead is equal tothat which cuts the cylinder (43)1205871198863 = (120587
22)119886
4(12ℓ) (ie
2ℓ = (31205878)119886 and 119899 = (83120587119886)119899) Thus we can use directlyexpression (23) and find (compare to (25))
119887 (119896) = minusint 119899 (119886) 1198862 4120587
2
1198962(1 minus
sin |k| 1199030|k| 1199030
)1198691(119896119886)
1198961198862119889119886 (77)
where 119896 = (1198960 k) Here the first term merely coincides with
that in (25) and therefore it gives the contribution to thecosmological constant 120575Λ(8120587119866) = minus1198994 = minus2119899(3120587119886)while the second term describes a correction which does notreduce to the cosmological constant and requires a separateconsideration
72 Stress Energy Tensor From (57) we find that the stressenergy tensor
minus⟨Δ119879120572120573
(119909)⟩ = int
119896120573119896120572minus (12) 119892
1205721205731198962
1198962119887 (119896 120585)
1198894119896
(2120587)4
(78)
reduces to the two functions
11987900
= 120576 = 1205821minus1
2120583
119879119894119895= 119901120575
119894119895 119901 =
1
31205822minus1
2120583
(79)
where 120576 + 3119901 = minus120583 and 1205821+ 120582
2= 120583 and these functions are
1205821= minusint
1198962
0
11989621198871198894119896
(2120587)4 120582
2= minusint
|k|2
11989621198871198894119896
(2120587)4 (80)
By means of the use of the spherical coordinates 11989620119896
2=
cos2120579 |k|21198962 = sin2120579 and 119889
4119896 = 4120587sin2
1205791198963119889119896119889120579 we get
120582119894=119899 (119886 119903
0)
4120573119894
(1 minus 2120573119894(119886
1199030
)
2
119891119894(119886
1199030
)) (81)
where 1205731= 1 120573
2= 13 and 119891
119894is given by
119891(1
2)(119910)
=2
120587int
1
minus1
int
infin
0
sin (119909 sin 120579)1198691(119910119909)
1199101199092(cos2120579sin2
120579) 119889119909 119889cos 120579
(82)
For 1198861199030≪ 1 we find
11989112
(119886
1199030
) asymp (1 + 11990012
(119886
1199030
)) (83)
Thus finally we find
120576 ≃ minus119899
4= minus
2119899
3120587119886 119901 ≃ 120576(1 minus
4
3(119886
1199030
)
2
) (84)
which upon the continuation to the Minkowsky space givesthe equation of state in the form (An arbitrary gas ofwormholes splits in fractions with a fixed 119886 and 119903
0)
119901 = minus(1 minus4
3(119886
1199030
)
2
) 120576 (85)
which in the case when 1198861199030≪ 1 behaves like a cosmological
constant However when 119886 ≫ ℓpl such a constant is extremelysmall and can be neglected while the leading contributioncomes from the mean curvature
73 Mean Curvature In this subsection we consider theMinkowsky spaceThen the simplest actual wormhole can bedescribed by the metric analogous to (1) for example see [7]
1198891199042= 119888
2119889119905
2minus ℎ
2(119903) 120575
120572120573119889119909
120572119889119909
120573 (86)
where ℎ(119903) = 1 + 120579(119886 minus 119903)(1198862119903
2minus 1) To avoid problems
with the Bianchi identity and the conservation of energy thestep function should be also smoothed as in (1) The stressenergy tensor which produces such a wormhole can be foundfrom the Einstein equation 8120587119866119879
120573
120572= 119877
120573
120572minus (12)120575
120573
120572119877 Both
regions 119903 gt 119886 and 119903 lt 119886 represent portions of the ordinaryflat Minkowsky space and therefore the curvature is 119877119896
119894equiv 0
However on the boundary 119903 = 119886 it has the singularity Sincethe metric (86) does not depend on time we find
1198770
0= 119877
0
120572= 0 119877
120573
120572=2
119886120575 (119886 minus 119903) 119899
120572119899120573+ 120575
120573
120572 + 120582
120573
120572 (87)
where 119899120572 = 119899120572= 119909
120572119903 is the outer normal to the throat 1198782
and 120582120573
120572are additional terms (eg see (49) and (51)) which
in the leading order are negligible upon averaging over someportion of space Δ119881 ≳ 119886
3 In the case of a set of wormholesthis gives in the leading order
1198770
0= 119877
0
120572= 0 119877
120573
120572= sum
2
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119903
119894
1003816100381610038161003816) 119899119894120572119899120573
119894+ 120575
120573
120572
(88)
where 119886119894is the radius of a throat and 119903
119894is the position of the
center of the throat in space and 119899120572
119894= (119909
120572minus 119903
120572
119894)|119903 minus 119903
119894|
In the case of a homogeneous and isotropic distribution ofsuch throats we find 119877
120573
120572= (13)119877120575
120573
120572(averaging over spatial
directions gives ⟨119899120572119899120573⟩ = (13)120575
120573
120572) where
119877 = minus8120587119866119879 = sum8
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119877
119894
1003816100381610038161003816) = 32120587int 119886119899 (119886) 119889119886
(89)
Journal of Astrophysics 13
where 119879 stands for the trace of the stress energy momentumtensor which one has to add to the Einstein equations tosupport such awormhole It is clear that such a source violatesthe weak energy condition and therefore it reproduces theformof dark energy (ie119879 = 120576+3119901 lt 0) If the density of suchsources (and resp the density of wormholes) is sufficientlyhigh then this results in the observed [10ndash14] accelerationof the scale factor for the Friedmann space as sim 119905
120572 with120572 = 21205763(120576 + 119901) = 2120576(2120576 + (120576 + 3119901)) gt 1 for examplesee also [40ndash42] In terms of the 4-dimensional density ofwormholes 119899 = (83120587119886)119899 we get 119877 sim 119886
2119899 ≫ 8120587119866119899 as 119886 ≫ ℓpl
and therefore the leading contribution indeed comes fromthe mean curvature
8 Estimates and Concluding Remarks
Now consider the simplest estimates Actual wormholes seemto be responsible for the dark matter [7 9] Therefore to getthe estimate to the number density of wormholes is ratherstraightforward First wormholes appear at scales when darkmatter effects start to display themselves that is at scales ofthe order 119871 sim (1 divide 5)Kpc which gives in that range thenumber density
119899 sim1
1198713sim (3 divide 0024) times 10
minus65cmminus3 (90)
The characteristic size of throats can be estimated from (89)120576DE sim (119866)
minus1119899119886 Since the density of dark energy is 120576DE1205760 =
ΩDE sim 075 where 1205760is the critical density then we find the
estimate
119886 sim2
3(1 divide 125) times 10
minus3119877⊙ΩDEℎ
2
75 (91)
where119877⊙is the Solar radius ℎ
75= 119867(75 km(secMpc)) and
119867 is the Hubble constant We also recall that the backgrounddensity of baryons 120576
119887generates a nonvanishingwormhole rest
mass119872119908= (43)120587119886
31198773120576119887(where119877(119905) is the scale factor of the
Universe and therefore 119872119908remains constant) for example
see [7] It produces the dark matter density related to thewormholes as 120576DM ≃ 119872
119908119899 The typical mass of a wormhole
119872119908is estimated as
119872119908sim 1 7 times (1 divide 125) times 10
2119872
⊙ΩDMℎ
2
75 (92)
where 119872⊙is the Solar mass We point out that this mass
has not the direct relation to the parameters of the gas ofwormholes However it defines the moment when wormholethroats separated from the cosmological expansion Theabove estimate shows that if wormholes form due to thedevelopment of perturbations in the exotic matter then thisprocess should start much earlier than the formation ofgalaxies
Thus we see that virtual wormholes should indeed leadto the regularization of all divergencies in QFT which agreeswith recent results [28] Therefore they form the local finitevalue of the cosmological constant In the absence of externalclassical fields such a value should be exactly zero at macro-scopic scales A some nonvanishing value for the cosmolog-ical constant appears as the result of vacuum polarization
effects in external fields Indeed external fields form anadditional distribution of virtual wormholes which possessan exotic stress energy tensor (some kind of dark energy)Only some part of it forms the cosmological constant whilethe rest reflects the symmetry of external fields and possessesinhomogeneitiesWe assume that during the evolution of ourUniverse inhomogeneities in the exotic matter develop andmay form actual wormholes Although this problem requiresthe further and more deep investigation we refer to [38]where the formation of a simplest wormhole-like object hasbeen considered In other words such polarization energyis reserved now in a gas of actual wormholes We estimatedparameters of such a gas and believe that such a gas mayindeed be responsible for both dark matter and dark energyphenomena
References
[1] J R Primack ldquoThe nature ofdark matterrdquo httparxivorgabsastro-ph0112255
[2] J Diemand M Zemp B Moore J Stadel and M CarolloldquoCusps in cold dark matter haloesrdquoMonthly Notices of the RoyalAstronomical Society vol 364 no 2 pp 665ndash673 2005
[3] E W Mielke and J A V Velez Perez ldquoAxion condensate as amodel for dark matter halosrdquo Physics Letters B vol 671 no 1pp 174ndash178 2009
[4] G Gentile P Salucci U Klein D Vergani and P Kalberla ldquoThecored distribution of dark matter in spiral galaxiesrdquo MonthlyNotices of the Royal Astronomical Society vol 351 no 3 pp 903ndash922 2004
[5] D T F Weldrake W J G de Blok and F Walter ldquoA high-resolution rotation curve of NGC 6822 a test-case for cold darkmatterrdquo Monthly Notices of the Royal Astronomical Society vol340 no 1 pp 12ndash28 2003
[6] W J G de Blok andA Bosma ldquoHigh-resolution rotation curvesof low surface brightness galaxiesrdquoAstronomy and Astrophysicsvol 385 pp 816ndash846 2002
[7] A Kirillov and E P Savelova ldquoDensity perturbations in a gas ofwormholesrdquoMonthly Notices of the Royal Astronomical Societyvol 412 no 3 pp 1710ndash1720 2011
[8] P Kanti B Kleihaus and J Kunz ldquoStable Lorentzianwormholesin dilatonic Einstein-Gauss-Bonnet theoryrdquo Physical Review Dvol 85 no 4 Article ID 044007 2012
[9] A A Kirillov and E P Savelova ldquoDark matter from a gas ofwormholesrdquo Physics Letters B vol 660 no 3 pp 93ndash99 2008
[10] A G Riess A V Filippenko P Challis et al ldquoObservationalevidence from supernovae for an accelerating universe and acosmological constantrdquo The Astronomical Journal vol 116 no3 p 1009 1998
[11] S Perlmutter G Aldering G Goldhaber et al ldquoMeasurementsofΩ andΛ from42high-redshift supernovaerdquoTheAstrophysicalJournal vol 517 no 2 p 565 1999
[12] J L Tonry B P Schmidt B Barris et al ldquoCosmological resultsfromhigh-z supernovaerdquoTheAstrophysical Journal vol 594 no1 p 594 2003
[13] N W Halverson E M Leitch C Pryke et al ldquoDegreeangular scale interferometer first results a measurement of thecosmic microwave background angular power spectrumrdquo TheAstrophysical Journal vol 568 no 1 p 38 2002
14 Journal of Astrophysics
[14] C B Netterfield P A R Ade J J Bock et al ldquoA measurementby BOOMERANGofmultiple peaks in the angular power spec-trum of the cosmic microwave backgroundrdquo The AstrophysicalJournal vol 571 no 2 p 604 2002
[15] S Coleman ldquoWhy there is nothing rather than something atheory of the cosmological constantrdquoNuclear Physics B vol 310no 3-4 pp 643ndash668 1988
[16] I Klebanov L Susskind and T Banks ldquoWormholes and thecosmological constantrdquo Nuclear Physics B vol 317 no 3 pp665ndash692 1989
[17] S W Hawking ldquoSpacetime foamrdquoNuclear Physics B vol 114 p349 1978
[18] T P Cheng and L F Li Gauge Theory of Elementary ParticlesClarendon Press Oxford UK 1984
[19] A H Taub ldquoSpace-times with distribution valued curvaturetensorsrdquo Journal ofMathematical Physics vol 21 no 6 pp 1423ndash1431 1980
[20] A Shatsky privite communications[21] V A Fock ldquoZur Theorie des Wasserstoffatomsrdquo Zeitschrift fur
Physik vol 98 no 3-4 pp 145ndash154 1935[22] E P Savelova ldquoGas of wormholes in Euclidean quantum field
theoryrdquo httparxivorgabs12115106[23] A A Kirillov and E P Savelova ldquoOn the behavior of
bosonic systems in the presence of topology fluctuationsrdquohttparxivorgabs08082478
[24] A A Kirillov ldquoViolation of the Pauli principle and dimensionof the Universe at very large distancesrdquo Physics Letters B vol555 no 1-2 pp 13ndash21 2003
[25] A A Kirillov ldquoDark matter dark charge and the fractalstructure of the Universerdquo Physics Letters B vol 535 no 1ndash4pp 22ndash24 2002
[26] J Ambjorn J Jurkiewicz and R Loll ldquoThe spectral dimensionof the universe is scale dependentrdquo Physical Review Letters vol95 no 17 Article ID 171301 4 pages 2005
[27] E Manrique S Rechenberger and F Saueressig ldquoAsymptoti-cally safe Lorentzian gravityrdquo Physical Review Letters vol 106no 25 Article ID 251302 4 pages 2011
[28] J Laiho and D Coumbe ldquoEvidence for asymptotic safety fromlattice quantum gravityrdquo Physical Review Letters vol 107 no 16Article ID 161301 2011
[29] A A Kirillov and D Turaev ldquoOn modification of the Newtonrsquoslaw of gravity at very large distancesrdquo Physics Letters B vol 532no 3-4 pp 185ndash192 2002
[30] A A Kirillov and D Turaev ldquoThe universal rotation curveof spiral galaxiesrdquo Monthly Notices of the Royal AstronomicalSociety vol 371 no 1 pp L31ndashL35 2006
[31] A A Kirillov and D Turaev ldquoFoam-like structure of theuniverserdquo Physics Letters B vol 656 pp 1ndash8 2007
[32] A A Kirillov ldquoThe nature of dark matterrdquo Physics Letters B vol632 no 4 pp 453ndash462 2006
[33] A A Kirillov and E P Savelova ldquoAstrophysical effects of space-time foamrdquo Gravitation and Cosmology vol 14 no 3 pp 256ndash261 2008
[34] S W Hawking and N Turok ldquoOpen inflation without falsevacuardquo Physics Letters B vol 425 no 1-2 pp 25ndash32 1998
[35] Z C Wu ldquoThe cosmological constant is probably zero and aproof is possibly rightrdquo Physics Letters B vol 659 no 5 pp 891ndash893 2008
[36] R Garattini ldquoEntropy and the cosmological constant aspacetime-foam approachrdquo Nuclear Physics B vol 88 no 1ndash3Article ID 991003 pp 297ndash300 2000
[37] MVisserLorentzianWormholes SpringerNewYorkNYUSA1996
[38] A A Kirillov and E P Savelova ldquoArtificial wormholerdquohttparxivorgabs12040351
[39] E W Mielke ldquoKnot wormholes in geometrodynamicsrdquo Gen-eral Relativity and Gravitation vol 8 no 3 pp 175ndash196 1977
[40] E B Gliner ldquoAlgebraic properties of the energy-momentumtensor and vacuum-like states of matterrdquo Journal of Experimen-tal and Theoretical Physics vol 22 p 378 1966
[41] A H Guth ldquoInflationary universe a possible solution to thehorizon and flatness problemsrdquo Physical Review D vol 23 no2 pp 347ndash356 1981
[42] A A Linde ldquoA new inflationary universe scenario a possiblesolution of the horizon flatness homogeneity isotropy andprimordial monopole problemsrdquo Physics Letters B vol 108 no6 pp 389ndash393 1982
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
![Page 5: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/5.jpg)
Journal of Astrophysics 5
where 119873119865 is given by (9) For a homogeneous and isotropicdistribution 119865(120585) = 119865(119886119883) and then for the bias we find
119887total (119909 minus 1199091015840)
= int1
21205872119886(
1
1198772
minus
minus1
1198772
+
)120575 (10038161003816100381610038161003816 minus
1015840minus
+
10038161003816100381610038161003816minus 119886)119873119865 (120585) 119889120585
(22)
Consider the Fourier transform 119865(119886119883) = int119865(119886 119896)119890minus119894119896119883
sdot
(1198894119896(2120587)
4) and using the integral 11199092
= int(41205872119896
2)119890
minus119894119896119909sdot
(1198894119896(2120587)
4) we find for 119887(119896) = int 119887(119909)119890
1198941198961199091198894119909 the expression
119887total (119896) = 119873int1198862 4120587
2
1198962(119865 (119886 119896) minus 119865 (119886 0))
1198691(119896119886)
1198961198862119889119886 (23)
(1) Example of a Finite Density of Wormholes Consider nowa particular (of a finite density) distribution of wormholes119865(119886119883) for example
119873119865 (119886119883) =119899
212058721199033
0
120575 (119886 minus 1198860) 120575 (119883 minus 119903
0) (24)
where 119899 = 119873119881 is the density of wormholes In the case119873 = 1 this function corresponds to a single wormhole withthe throat size 119886
0and the distance between throats 119903
0=
|119877+minus119877
minus|We recall that the action (6) remains invariant under
translations and rotations which straightforwardly leads tothe above function Then 119873119865(119886 119896) = int119873119865(119886119883)119890
1198941198961199091198894119909 re-
duces to 119873119865(119886 119896) = 119899(1198691(119896119903
0)(119896119903
02))120575(119886 minus 119886
0) Thus from
(23) we find
119887 (119896) = minus1198991198862 4120587
2
1198962(1 minus
1198691(119896119903
0)
11989611990302
)1198691(119896119886
0)
11989611988602
(25)
And for the true Green function we get
119866true = 1198660(119896)119873 (119896) = 119866
0(119896) (1 + 119887 (119896)) (26)
In the short-wave limit (119896119886 1198961199030≫ 1) 119887(119896) rarr 0 and
therefore 119873(119896) rarr 1 This means that at very small scalesthe space filled with a finite density of wormholes looks likethe ordinary Euclidean space In the long-wave limit 119896 rarr 0
we get 1198691(119896119903
0)(119896119903
02) asymp 1 minus (12) (119896119903
02)
2+ sdot sdot sdot which gives
119887(119896) asymp minus1205872119899119886
21199032
02 while in a more general case we find
119887(119896) asymp minus int(12058722)119886
21199032
0119899(119886 119903
0)119889119886 119889119903
0 where 119899(119886 119903
0) is the den-
sity of wormholes with a particular values of 119886 and 1199030 and for
the bias function (15) we get
119873(119896) 997888rarr 1 minus1205872
2int 119886
4119899 (119886 119903
0)1199032
0
1198862119889119886 119889119903
0le 1 (27)
In other words in the long-wave limit (119896119886 1198961199030≪ 1) the
presence of a particular set of virtual wormholes diminishesmerely the value of the charge values
(2) Limiting Topologies or Infinite Densities of WormholesConsider now the limiting distribution when the density of
wormholes 119899 rarr infin Since every throat cuts the finite portionof the volume (120587
22)119886
4 this case requires considering thelimit 119886 rarr 0 We assume that in this limit 1198862119873119865(119886119883) rarr
120575(119886)](119883) where ](119883) is a finite specific distribution Then(23) reduces to 119887total(119896) = (4120587
2119896
2) (](119896) minus ](0)) where ](119896) =
int ](119883)119890119894119896119883
1198894119883 and the bias (15) (18)119873(119896) becomes
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (28)
It is important that this limit still agrees with the rarefiedgas approximation for the basic gas parameter (ie theportion of volume cut by wormholes) tends to 120585 =
int(12058722)119886
4119865(119886119883)119889
4119883119889119886 rarr 0 The above expression is ob-
tained in the linear approximation only Taking into accountnext orders (eg see [22] where the case of a dense gas is alsoconsidered) we find 119873(119896) = 1 + 119887total(119896) + 119887
2
total(119896) + sdot sdot sdot andthe true Green function in a gas of wormholes becomes
119866true = 1198660(119896)119873 (119896) =
1
1198962 + 41205872(] (0) minus ] (119896))
(29)
In the long-wave limit 119896 rarr 0 the function ](119896) can beexpanded as ](119896) asymp ](0) + (12)]10158401015840(0)1198962 which also definesa renormalization of charge values119873(119896) rarr 1(1minus2120587
2]10158401015840(0))which coincides with (27) However in this limiting case wehave some freedom in the choice of ](119896) which we can useto assign 119873(119896) an arbitrary function of 119896 In other wordswe may get here a class of limiting topologies where Greenfunctions119866true = 119866
0(119896)119873(119896) have a good ultraviolet behavior
and quantumfield theories in such spaces turn out to be finiteIn particular this will certainly be the case when
119866true (119909 minus 1199091015840= 0) = int
1
1198962 + 41205872(] (0) minus ] (119896))
1198894119896
(2120587)4lt infin
(30)
This possibility however requires the further and more deepinvestigation
32 Green Function General Consideration The action (6)remains invariant under translations
1015840= + 119888 with an
arbitrary 119888 which means that the measure (11) does notactually depend on the position of the center of mass of thegas of wormholes and therefore we may restrict ourself withhomogeneous distributions 119865(120585) of wormholes in space onlyIndeed we may define 119889119873
120585 = 11988911987312058510158401198894119888 while the integration
over 1198894119888 gives the volume of1198774 that is int1198894
119888 = 1198714= 119881which
disappears from (11) due to the denominator (Technically wemay first restrict a portion of1198774 in (6) to a finite volume119881 andthen in final expressions consider the limit 119881 rarr infin (whichrepresents the standard tool in thermodynamics and QFT))In what follows we shall omit the prime from 120585
1015840Let us consider the Fourier representation119873(119909 119909
1015840 120585) rarr
119873(119896 1198961015840 120585) which in the case of a homogeneous distribution
of wormholes gives119873(119896 1198961015840) = 119873(119896 120585) 120575(119896 minus 119896
1015840) then we find
119866 (119896) = 1198660(119896)119873 (119896 120585) (31)
6 Journal of Astrophysics
and the Green function can be taken as
119866 =119873 (119896 120585)
1198962 + 1198982 (32)
Then for the total partition function we find
119885total (119869)
= int [119863119873 (119896)] 119890minus119868(119873)
119890minus(12)(119871
4
(2120587)4
) int((119873(119896)(1198962
+1198982
))|119869119896
|2
)119889119896
(33)
where [119863119873] = prod119896119889119873
119896and 120590(119873) comes from the integration
measure (ie from the Jacobian of transformation from 119865(120585)
to119873(119896))
119890minus119868(119873)
= int [119863119865]1198850(119873 (119896 120585)) 120575 (119873 (119896) minus 119873 (119896 120585)) (34)
We point out that 119868(119873) can be changed by means of addingto the action (6) of an arbitrary ldquonondynamicalrdquo constantterm which depends only on topology 119878 rarr 119878 + Δ119878 (119873(119896))
(eg a topological Euler term) The multiplier 1198850(119873) defines
the simplest measure for topologies Now by means of usingthe expression (32) and (33) we find the two-point Greenfunction in the form
119866 (119896) =119873 (119896)
1198962 + 1198982 (35)
where 119873(119896) is the cutoff function (the mean bias) whichis given by (We recall that in this integral contribute onlylimiting topologies in which density of wormholes diverges(119899 rarr infin))
119873(119896) =1
119885total (0)int [119863119873] 119890
minus119868(119873)119873(119896) (36)
At the present stage we still cannot evaluate the exactform for the cutoff function 119873(119896) in virtue of the ambiguityof Δ119878(119873(119896)) pointed out Such a term may include twoparts First part Δ
1119878 describes the proper dynamics of
wormholes and should be considered separately Indeedin general wormholes are dynamical self-gravitating objectswhich require considering the gravitational contribution tothe action Some part of such a contribution (mean curvatureinduced by wormholes) is discussed in Section 6 Howeversince a wormhole represents an extended nonlocal objectit possesses a rather complex dynamics and this problemrequires the further investigation The second part Δ
2119878 may
describe ldquoexternal conditionsrdquo (eg an external classicalfield in (33)) for the mean topology Actually the last termcan be used to prescribe an arbitrary particular value forthe cutoff function 119873(119896) = 119891(119896) Indeed the ldquoexternalconditionsrdquo can be accounted for by adding the term Δ
2119878 =
(120582119873) = int 120582(119896)119873(119896)1198894119896 where 120582(119896) plays the role of a
specific chemical potential which implicitly depends on 119891(119896)
through the equation
119891 (119896) =1
119885total (120582 0)int [119863119873] 119890
(120582119873)minus119868(119873)119873(119896) (37)
From (33) we see that the role of such a chemical potentialmay play the external current 120582(119896) = minus(12)(119871
4(2120587)
4)sdot
1198660(119896)|119869
ext119896|2 or equivalently an external classical field 120593
ext=
1198660(119896)119869
ext119896 In quantum field theory such a term leads merely
to a renormalization of the cosmological constant By otherwords the mean topology (ie the cutoff function or meandistribution of wormholes) is driven by the cosmologicalconstant Λ and vice versa
4 Topological Bias as a Projection Operator
By the construction the topological bias 119873(119909 1199091015840) plays the
role of a projection operator onto the space of functions (asubspace of functions on 119877
4) which obey the proper bound-ary conditions at throats of wormholes This means thatfor any particular topology (for a set of wormholes) thereexists the basis 119891
119894(119909) in which it takes the diagonal form
119873(119909 1199091015840) = sum119873
119894119891119894(119909)119891
lowast
119894(119909
1015840) with eigenvalues 119873
119894= 0 1
(since 1198732
119894= 119873
119894) In this section we illustrate this simple fact
(which is probably not obvious for readers) by the explicitconstruction of the reference system for a single wormholewhen physical functions become (due to the boundaryconditions) periodic functions of one of coordinates
Indeed consider a single wormhole with parameters 120585(ie 120585 = (119886 119877
+ 119877
minus) where 119886 is the throat radius and 119877
plusmn
are positions of throats in space (In general there existsan additional parameter Λ120572
120573which defines a rotation of one
of throats before gluing However it does not change thesubsequent constructionThere always exists a diffeomorphicmap of coordinates 1199091015840
= ℎ(119909) which sets such a matrix tounity)) Consider now a particular solution120601
0to the equation
Δ1206010= 0 (harmonic function) for 1198774 in the presence of the
wormhole which corresponds to the situation when throatspossess a unit chargemass but those have the opposite signsNow define the family of lines of force 119909(119904 119909
0) which obey
the equation 119889119909119889119904 = minusnabla1206010(119909) with initial conditions 119909(0) =
1199090 Physically such lines correspond to lines of force for a
two charged particles in positions 119877plusmn with charges plusmn1 Wenote that all points which lay on the trajectory 119909(119904 119909
0) may
be taken as initial conditions and they define the same lineof force with the obvious redefinition 119904 rarr 119904 minus 119904
0 By
other words we may take as a new coordinates the parameter119904 and portion of the coordinates orthogonal to the familyof lines 119909
perp
0 Coordinates 119909
perp
0can be taken as laying in the
hyperplane 1198773 which is orthogonal to the vector 119889 = minusminus
+
and goes through the point 0
= (minus+
+)2 (Instead
of the construction used here one may use also anothermethod Indeed consider two point charges and then thefunction 120601
0= 1(119909 minus 119909
+)2minus 1(119909 minus 119909
minus)2 can be taken as a
new coordinate Wormhole appears when we identify (glue)surfaces 120601
0= plusmn120596 We point out that such surfaces are not
spheres though they reduce to spheres in the limit |119909+minus
119909minus| rarr infin or 120596 rarr infin)Let 119904plusmn(119909perp
0) be the values of the parameter 119904 at which
the line intersects the throats 119877plusmn Then instead of 119904 we mayconsider a new parameter 120579 as 119904(120579) = 119904
minus+ (119904
+minus 119904
minus)1205792120587
so that when 120579 = 0 2120587 the parameter 119904 takes the values
Journal of Astrophysics 7
119904 = 119904minus 119904+ respectivelyThe gluing procedure at throatsmeans
merely that we identify points at 120579 = 0 and 120579 = 2120587 and allphysical functions in the space 119877
4 with a single wormhole120585 become periodic functions of 120579 Thus the coordinatetransformation 119909 = 119909(120579 119909
perp
0) gives the map of the above space
onto the cylinder with a specific metric 1198891198972 = (119889(120579 119909perp
0))
2
=
119892120572120573119889119910
120572119889119910
120573 (where 119910 = (120579 119909perp
0)) whose components are also
periodic in terms of 120579 Now we can continue the coordinatesto thewhole space1198774 (to construct a cover of the fundamentalregion 120579 isin [0 2120587]) simply admitting all valuesminusinfin lt 120579 lt +infin
this however requires to introduce the bias
1
radic119892120575 (120579 minus 120579
1015840) 997888rarr 119873(120579 minus 120579
1015840) =
+infin
sum
119899=minusinfin
1
radic119892120575 (120579 minus 120579
1015840+ 2120587119899)
(38)
since every point and every source in the fundamental regionacquires a countable set of images in the nonphysical region(inside of wormhole throats) Considering now the Fouriertransforms for 120579 we find
119873(119896 1198961015840) =
+infin
sum
119899=minusinfin
120575 (119896 minus 119899) 120575 (119896 minus 1198961015840) (39)
We point out that the above bias gives the unit operator in thespace of periodic functions of 120579 From the standpoint of allpossible functions on 1198774 it represents the projection operator
2= (120585) (taking an arbitrary function 119891 we find that upon
the projection 119891119873= 119891 119891
119873becomes a periodic function of
120579 that is only periodic functions survive)The above construction can be easily generalized to the
presence of a set of wormholes In the approximation of adilute gas of wormholes we may neglect the influence ofwormholes on each other (at least there always exists a suf-ficiently smooth map which transforms the family of linesof force for ldquoindependentrdquo wormholes onto the actual lines)Then the total bias (projection) may be considered as theproduct
119873total (119909 1199091015840) = int(prod
119894
radic1198921198941198894119910119894)119873(120585
1 119909 119910
1)
times 119873 (1205852 119910
1 119910
2) sdot sdot sdot 119873 (120585
119873 119910
119873minus1 119909
1015840)
(40)
where 119873(120585119894 119909 119909
1015840) is the bias for a single wormhole with
parameters 120585119894 Every such a particular bias119873(120585
119894 119909 119909
1015840) realizes
projection on a subspace of functions which are periodic withrespect to a particular coordinate 120579
119894(119909) while the total bias
gives the projection onto the intersection of such particularsubspaces (functions which are periodic with respect to everyparameter 120579
119894)
5 Cutoff
The projective nature of the bias operator 119873(119909 1199091015840) allows us
to express the cutoff function 119873(119896) via dynamic parametersof wormholes Indeed consider a box 1198714 in 119877
4 and periodic
boundary conditions which gives 119896 = 2120587119899119871 (in final expres-sions we consider the limit 119871 rarr infin which gives sum
119896rarr
(1198714(2120587)
4) int 119889
4119896) And let us consider the decomposition for
the integration measure in (33) as
119868 = 1198680+sum120582
1(119896)119873 (119896) +
1
2sum120582
2(119896 119896
1015840)119873 (119896)119873 (119896
1015840) + sdot sdot sdot
(41)
where 1205821(119896) includes also the contribution from 119885
0(119896) We
point out that this measure plays the role of the action for thebias119873(119896) Indeed the variation of the above expression givesthe equation of motions for the bias in the form
sum
1198961015840
1205822(119896 119896
1015840)119873 (119896
1015840) = minus120582
1(119896) (42)
which can be found by considering the proper dynamics ofwormholes We however do not consider the problem of thedynamic description of wormholes here and leave this forthe future research Moreover we may expect that in the firstapproximation one may retain the linear term only Indeedthis takes place when119873(119896) is not a dynamic variable or if wetake into account that 119873(119896) is a collective variable Then theprojective nature of the bias 119873(119896) = 0 1 means that it canbe phenomenologically expressed via some Fermionic ghostfield Ψ(119896) (eg 119873(119896 119896
1015840) = Ψ(119896)Ψ
+(119896
1015840)) where the negative
and positive frequency parts of the operator Ψ(119896) obey theanticommutation relationsΨ+
(119896)Ψ(1198961015840)+Ψ(119896
1015840) Ψ
+(119896) = 120575(119896minus
1198961015840) In the absence of ghost particles Ψ(119896)|0⟩ = 0 we get
119873(119896 1198961015840) = 120575(119896 minus 119896
1015840) that is 119873(119896) = 1 and wormholes
are absent In the term of the ghost field the action becomes119868(119873) = 119868
0+ (Ψ
1Ψ) + sdot sdot sdot Therefore in the leading approx-
imation equations of motion take the linear form 1Ψ = 0
Thus taken into account that 119873(119896) = 0 1 (1198732= 119873) we
find
119873(119896) =1
119885total (119896)sum
119873=01
119890minus1205821
(119896)119873(119896)119873(119896) =
119890minus1205821
(119896)
1 + 119890minus1205821(119896) (43)
The simplest choice gives merely 1205821(119896) = minussum ln119885
0(119896)
where the sum is taken over the number of fields and 1198850(119896)
is given by 1198850(119896) = radic120587(1198962 + 1198982) In the case of a set
of massless fields we find 119873(119896) = 119885(119896)(1 + 119885(119896)) where119885(119896) = (radic120587119896)
120572 and 120572 is the effective number of degreesof freedom (the number of boson minus fermion fields) Toensure the absence of divergencies one has to consider thenumber of fields 120572 gt 4 [23] However such a choice givesthe simplest estimate which in general cannot be correctIndeed while its behavior at very small scales (ie whenexceeding the Planckian scales 119885(119896) ≲ 1 and 119873(119896) = 119885(119896))may be physically accepted since it produces some kind of acutoff on the mass-shell 1198962 + 119898
2rarr 0 it gives the behavior
119873(119896) rarr 1 which is merely incorrect (eg from (27) we seethat the true behavior should be119873(119896) rarr const lt 1)
One may expect that the true cutoff function has a muchmore complex behavior Indeed some theoretical models inparticle physics (eg string theory) have the property tobe lower-dimensional at very small scales The mean cutoff
8 Journal of Astrophysics
119873(119896) gives the natural tool to describe a scale-dependantdimensional reduction [24 25] In fact this function definesthe spectral number of modes in the interval between 119896 and119896 + 119889119896 as
int119873 (119896)1198894119896
(2120587)4= int
119873 (119896) 1198964
(2120587)2
119889119896
119896 (44)
Hence we can define the effective spectral dimension 119863 ofspace as follows
1198964119873(119896) sim 119896
119863 (45)
From the empirical standpoint the dimension 119863 = 4 isverified at laboratory scales only while the rigorous tool todefine the spectral density of states (or the mean cutoff) cangive the lattice quantum gravity for example see [26 27]and references therein And indeed the spectral dimensionfor nonperturbative quantum gravity defined via Euclideandynamical triangulations was calculated recently in [28] Itturns out that it runs from a value of119863 = 32 at short distanceto 119863 = 4 at large distance scales We also point out that allobserved dark matter phenomena can be explained by thefractal dimension119863 asymp 2 starting from scales 119871 ≳ (1 divide 5)Kpcfor example [29ndash33]
6 Cosmological Constant
Let us consider the total Euclidean action [17]
119868119864= minus
1
16120587119866int (119877 minus 2Λ
0)radic119892119889
4119909 minus int119871
119898radic1198921198894119909 (46)
The variation of the above action leads to the Einstein equa-tions
119877119886119887minus1
2119892119886119887119877 + 119892
119886119887Λ
0= 8120587119866119879
119886119887 (47)
where 119879119886119887= (12)(119892)
minus12(120575119871
119898120575119892
119886119887) is the stress energy ten-
sor and Λ0is a naked cosmological constant In cosmology
such equations are considered from the classical standpointwhich means that they involve characteristic scales ℓ ≫ ℓplHowever the presence of virtual wormholes at Planckianscales defines some additional contribution in both parts ofthese equations which can be adsorbed into the cosmologicalconstant Therefore the total cosmological constant can bedefined as
Λ tot = Λ0+ Λ
119898+ Λ
119877= Λ
0+ 2120587119866 ⟨119879⟩ +
1
4⟨119877⟩119908 (48)
where ⟨119879⟩ is the energy of zero-point fluctuations (It includesalso the contribution of zero-point fluctuations of gravitons)That is themean vacuum value (we recall that in the standardQFTΛ
119898is infinite while wormholes form a finite value) and
⟨119877⟩119908
= Λ119877is a contribution of wormholes into the mean
curvature due to gluing (1)
61 Contribution of Virtual Wormholes into Mean CurvatureConsider a single wormhole whose metric is given by (1)
1198891199042= ℎ
2(119903)120575
120572120573119889119909
120572119889119909
120573 then the components of the Riccitensor are (We are much obliged to the Referee who pointedout to the subtleties when working with a step function in themetric)
119877120572120573
= 7 minus (ℎ1015840
ℎ)
1015840
(120575120572120573
+ (119873 minus 2) 119899120572119899120573)
minus1
119903
ℎ1015840
ℎ((119873 minus 2) Δ
120572120573+ 120575
120572120573(119873 minus 1))
minus (ℎ1015840
ℎ)
2
(119873 minus 2) Δ120572120573
(49)
where 119899]= 119909
]119886 is the unite normal vector to the throat
surface Δ120572120573
= 120575120572120573
minus 119899120572119899120573 ℎ1015840 = 120597ℎ120597119903 and119873 is the number
of dimensions The curvature scalar is
119877 = minus(119873 minus 1)
ℎ2[2
ℎ10158401015840
ℎ+ 2
1
119903
ℎ1015840
ℎ(119873 minus 1) + (
ℎ1015840
ℎ)
2
(119873 minus 4)]
(50)
Then substituting ℎ = 1 + (1198862119903
2minus 1)120579 in the above equation
we find
minusℎ4
119873 minus 1119877 = 4ℎ
1198862
1199033120575 +
2ℎ
119903119873minus1(119903
119873minus1120582)
1015840
+ (119873 minus 4)(1205822minus 4120579
1198862
1199033120582)
+ 4 (119873 minus 4)1198862
1199034120579 (120579 minus 1)
(51)
where 120579 is a smooth function which only in a limit becomesa step function 120582 = (1 minus 119886
2119903
2)120575 and 120575 = minus120579
1015840 In the limit120579 rarr 120579(119886 minus 119903) we find 120575 rarr 120575(119903 minus 119886) and the last two terms in(51) are negligible as compared to the first two terms while infour dimensions the last two terms vanishThen the curvatureis concentrated on the throat of the wormhole where 120579 differsfrom the step function In the limit of a vanishing throat sizewe have ℎ rarr 1 at the throat and we get
minus119877 =4 (119873 minus 1)
119886120575 (119903 minus 119886) +
2 (119873 minus 1)
119903119873minus1(119903
119873minus3(119903
2minus 119886
2) 120575)
1015840
(52)
In general all the terms together in (51) and analogous termsin the Ricci tensor provide that the Bianchi identity holdsand the energy is conserved [19] Therefore none of themcan be dropped out However it is easy to see the leadingcontribution to the integral over space comes from the firstterm only and in the limit of a vanishing throat size we findfor a single wormhole
1
4int119877radic119892119889
4119909 = minus6120587
21198862 (53)
Journal of Astrophysics 9
In the case of a set of wormholes (24) we find
1
4int119877radic119892119889
4119909 = minus6120587
2sum
119895
1198862
119895
= minus121205872int119899 (119886) 119886
2119889119886 119889
4119909 = intΛ
1198771198894119909
(54)
where 2119899(119886) = int 119899(119886 1199030)119889119903
0is the density of wormhole
throats with a fixed value of the throat size 119886 This definesthe contribution to the cosmological constant from the meancurvature as
Λ119877= minus12120587
2int119899 (119886) 119886
2119889119886 lt 0 (55)
We see that this quantity is always negative
62 Stress Energy Tensor In this section we consider thecontribution from matter fields In the case of a scalar fieldthe stress energy tensor has the form
minus119879120572120573
(119909) = 120597120572120593120597
120573120593 minus
1
2119892120572120573
(120597120583120593120597
120583120593 + 119898
21205932) (56)
Then the mean vacuum value of the stress energy tensor canbe obtained directly from the two-point green function (32)(35) as
minus ⟨119879120572120573
(119909)⟩
= lim1199091015840
rarr119909
(1205971205721205971015840
120573minus1
2119892120572120573
(1205971205831205971015840
120583+ 119898
2)) ⟨119866 (119909 119909
1015840 120585)⟩
(57)
By means of using the Fourier transform 119866(119909 1199091015840 120585) =
int 119890minus119894119896(119909minus119909
1015840
)119866(119896 120585) (119889
4119896(2120587)
4) and the expressions (32) (35)
we arrive at
⟨119879120572120573
(119909)⟩ =1
4119892120572120573
int(1 +119898
2
1198962 + 1198982)119873 (119896)
1198894119896
(2120587)4 (58)
where the property int 119896120572119896120573119891(119896
2)119889
4119896 = (14)119892
120572120573int 119896
2119891(119896
2)119889
4119896
has been used and 119873(119896) = ⟨119873(119896 120585)⟩ is the cutoff function(36)
For the sake of simplicity we consider the massless caseThen by the use of the cutoff 119873(119896) = 120587
1205722(120587
1205722+ 119896
120572) from
the previous section we get the finite estimate (120572 gt 4 is theeffective number of the field helicity states)
Λ119898=2120587119866sumint
1205871205722
1205871205722+119896120572
1198894119896
(2120587)4=120587119866
4Γ (
120572 minus 4
120572) Γ (
4
120572) sim 1
(59)
where the sum is taken over the number of fields Since theleading contribution comes here from very small scales wemay hope that this value will not essentially change if thetrue cutoff function changes the behavior on the mass-shellas 119896 rarr 0 (eg if we take 120582
1(119896) = minussum ln119885
0(119896) + 120575120582(119896) with
120575120582(119896) ≪ ln1198850(119896) as 119896 ≫ 1)
To understand how wormholes remove divergencies itwill be convenient to split the bias function into two parts119873(119896 120585) = 1 + 119887(119896 120585) where 1 corresponds to the standardEuclidean contribution while 119887(119896 120585) is the contribution ofwormholes The first part gives the well-known divergentcontribution of vacuumfield fluctuations 8120587119866⟨1198790
120572120573⟩ = Λ
lowast119892120572120573
with Λlowast
rarr +infin while the second part remains finite forany finite number of wormholes and due to the projectivenature of the bias described in the previous section itpartially compensates (reduces) the value of the cosmologicalconstant that is 8120587119866⟨Δ119879
120572120573⟩ = 120575Λ119892
120572120573 where 120575Λ =
sum119873120588119873120575Λ(119873) and 120575Λ(119873) is a negative finite contribution of
a finite set of wormholesConsider now the particular distribution of virtual
wormholes (24) and evaluate their contribution tothe cosmological constant which is given by 120575Λ(119873) =
2120587119866int 119887(119896) (1198894119896(2120587)
4) = 2120587119866119887total(0) Then from the ex-
pressions (22) and (24) we get
119887total (0) = minus119899
4120587411988631199033
0
int(1 minus1198862
1198772
minus
)120575 (119877+minus 119886)
times 120575 (1003816100381610038161003816119877+
minus 119877minus
1003816100381610038161003816 minus 1199030) 119889
4119877minus1198894119877+
(60)
which gives
119887total (0) = minus119899(1 minus 119891(119886
1199030
)) (61)
where
119891(119886
1199030
) =2
120587int
120587
0
1198862sin2
120579119889120579
1198862 + 21198861199030cos 120579 + 119903
2
0
(62)
For 1198861199030≪ 1 (we recall that by the construction 119886119903
0le 12)
this function has the value 119891(1198861199030) asymp 119886
2119903
2
0 Thus for the
contribution of wormholes we find
120575Λ119898= minus2120587119866int119899 (119886 119903
0) (1 minus 119891(
119886
1199030
))119889119886 1198891199030
= minus2120587119866119899 (1 minus ⟨119891⟩)
(63)
63 Vacuum Value of the Cosmological Constant From theabove expression we see that to get the finite value of thecosmological constant Λ
119898= Λ
lowast+ 120575Λ
119898lt infin one should
consider the limit 119899 rarr infin (infinite density of virtualwormholes) which requires considering the smaller andsmaller wormholes From the other handwe have the obviousrestriction int 2119899(119886 119903
0)(120587
22)119886
4119889119886 119889119903
0lt 1 where (120587
22)119886
4
is the volume of one throat (wormholes cannot cut morethan the total volume of space) (We also point out that inremoving divergencies the leading role plays the zero-pointenergy Indeed 120575Λ
119898sim minus2120587119866119899 while the mean curvature has
the order Λ119877sim minus119886
2119899 and for 119886 ≪ ℓpl we have 120575Λ119898
≫ Λ119877
Moreover in the limit 119899 rarr infin one gets 119886 rarr 0 and thereforeΛ
119877120575Λ
119898rarr 0)Therefore in the leading order it seems to be
sufficient to retain point-like wormholes only (ie consider
10 Journal of Astrophysics
the limit 119886 rarr 0) Then instead of (24) we may assume thevacuum distribution of virtual wormholes in the form
119873119865 (119886119883) =1
1198862120575 (119886) ] (119883) (64)
where ](119883) = int 1198862119873119865(119886119883)119889119886 and int(1119886
2)](119883)119889
4119883 =
119899 rarr infin has the meaning of the infinite density of point-like wormholes while ] sim 119886
2119899 remains a finite In this case
the volume cut by wormholes vanishes int 2119899(12058722)119886
4119889119886 119889119903
0=
1198862int ](119883)119889
4119883 rarr 0 and the rarefied gas approximationworks
wellThis defines the bias and themean cutoff (here we definethe Fourier transform ](119896) = int ](119883)119890
1198941198961198831198894119883) as
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (65)
The contribution to themean curvature (55) can be expressedvia the same function ](119896) as
Λ119877= minus12120587
2int119899 (119886 119903
0) 119886
2119889119886 119889119903
0
= minus121205872int ] (119883) 119889
4119883 = minus12120587
2] (0)
(66)
Thus for the total cosmological constant we get the expres-sion
Λ tot = Λ0
+ 2120587119866int(1minus4120587
2
1198962(] (0)minus] (119896)))
1198894119896
(2120587)4minus12120587
2] (0)
(67)
We stress that all these terms should be finite Indeed all dis-tributions of virtual wormholes ](119896) which lead to an infinitevalue of Λ tot are suppressed in (5) by the factor sim119890minusintΛ tot119889
4
119909while the minimal value is reached when wormholes cut allof the volume of space and the action is merely 119878 = 0(Frankly speaking this statement is not rigorous At first lookthe two last terms in (67) are independent and one may tryto take ](0) an arbitrary big If this were the case then theaction would not possess the minimum at all However ](0)cannot be arbitrary big since it will violate the rarefied gasapproximation and the linear expression (67) brakes downMoreover fermions give here a contribution of the oppositesign The rigorous investigation of this problem requires thefurther studying and we present it elsewhere) We also pointout that here we considered the real scalar field as the mattersource while in the general case the stress energy tensorshould include all existing Bose and Fermi fields (Fermi fieldsgive a negative contribution to Λ
119898)
The value of Λ0looks like a free parameter which in
quantum gravity runs with scales [27] However at largescales its asymptotic value may be uniquely fixed by thesimple arguments as follows Indeed in quantum field theoryproperties of the ground state (vacuum) change when weimply an external classical fields The same is true for thedistribution of virtualwormholes ](119896 119869) for example see (33)and (37) and therefore Λ tot = Λ tot(119869) which we describe
in the next subsection We recall that in gravity the role ofthe external current plays the stress energy tensor of matterfields 119869 = 119879
119886119887 However one believes that in the absence
of all classical fields the vacuum state should represent themost symmetric (Lorentz invariant) state which in our casecorresponds to the Euclidean space In order to be consistentwith the Einstein equations this requires Λ tot(119869 = 0) = 0
which uniquely fixes the value of Λ0in (67) We point out
that from somewhat different considerations such a choicewas advocated earlier in [15 34 35]
64 Vacuum Polarization in an External Field Consider nowtopology fluctuations in the presence of an external currentIn the presence of an external current 119869ext the distribution ofvirtual wormholes changes ](119896 119869) = ](119896) + 120575](119896 119869) Indeedin (33) for the case of a weak external field the contributionof the external current into the action can be expanded asexp(minus119881(119869)) ≃ 1 minus 119881 where
119881 = minus1
2int 119869 (119909) 119866 (119909 119910) 119869 (119910) 119889
4119909 119889
4119910
= minus1
2
1198714
(2120587)4int119866
0(119896)119873 (119896)
10038161003816100381610038161198691198961003816100381610038161003816
2
1198894119896
(68)
Then using (36) we find119873(119896 119869) = 119873(119896 0) + 120575119873(119896 119869) where
120575119873 (119896 119869) = 120575119887 (119869) ≃ minus1
2
1198714
(2120587)4int120590
2(119896 119901) 119866
0(119901)
10038161003816100381610038161003816119869119901
10038161003816100381610038161003816
2
1198894119901
(69)
is the bias related to an additional distribution of virtualwormholes and 120590
2(119896 119901) = Δ119873lowast(119896)Δ119873(119901)
1205902(119896 119901) =
1
119885total (0)int [119863119873] 119890
minus119868(119873)Δ119873
lowast(119896) Δ119873 (119901) (70)
defines the dispersion of vacuum topology fluctuations (hereΔ119873 = 119873 minus 119873) The exact definition of 1205902
(119896 119901) requires thefurther development of a fundamental theory In particular itcan be numerically calculated in lattice quantum gravity [28]However it can be shown that at scales 119896 119901 ≫ 119896pl it reducesto 1205902
(119896 119901) rarr 1205902
119896120575(119896 minus 119901) and therefore
120575119887 (119869) = minus1205902
119896
41205872
21198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(71)
Now comparing this function with (23) we relate the addi-tional distribution of virtual wormholes and the externalclassical field as
41205872
1198962(120575] (0 119869) minus 120575] (119896 119869)) =
1
21205902
119896
41205872
1198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(72)
where 120575](119896 119869) = int 1198862120575119873119865(119886 119896)119889119886 We point out that the
above expression does not define the value 120575](0 119869) whichrequires an additional considerationMoreover in general theexternal field 119869 does not possess a symmetry and therefore thecorrection ⟨120575119879
120572120573(119909)⟩ does not reduce to a single cosmological
Journal of Astrophysics 11
constant However such corrections always violate the aver-aged null energy condition [36 37] and may be considered assome kind of dark energy or by other words it represents anexotic matter Some portion of dark energy still has the formof the cosmological constant which defines a nonvanishingpresent day value (we recall that fermions give a contributionof the opposite sign)
120575Λ tot = minus2120587119866int4120587
2
1198962⟨120575] (0 119869) minus 120575] (119896 119869)⟩
1198894119896
(2120587)4
minus 121205872120575] (0 119869)
(73)
where ⟨120575](119896 119869)⟩ denotes an averaging over rotationsThe only unknown parameter in (72) is the dispersion
1205902
119896which defines the intensity of topology fluctuations in
the vacuum It has also the sense of the efficiency coefficientwhich defines the portion of the energy of the external fieldspent on the formation of additional wormholes Thoughthe evaluation of 1205902
119896requires the further development of a
fundamental theory one may expect that 1205902
119896= 119873(119896)(1 minus
119873(119896)) where 119873(119896) is the mean cutoff It is expected that119873(119896) rarr 0 as 119896 ≫ 119896pl and119873(119896) rarr 119873
0le 1 This means that
120590 rarr 0 as 119896 ≫ 119896pl and 120590 rarr 1205900≪ 1 as 119896 ≪ 119896pl while it takes
the maximum value 120590max sim 1 at Planckian scales 119896 sim 119896pl Byotherwords themost efficient transmission of the energy intowormholes takes place for wormholes of the Planckian sizeIn the case when external classical fields have characteristicscales 120582 = 2120587119896 ≫ ℓpl in (72) the efficiency coefficient 1205902
119896and
the cutoff 119873(119896) become constant 120590 ≃ 1205900 119873(119896) ≃ 119873
0 while
their ratiomay be estimated as 1205721205902
0119873
0= ΩDEΩ119887
where 120572 isthe effective number of fundamental fields which contributeto 120575Λ tot and ΩDE Ω119887
are dark energy and baryon energydensities respectively According to the modern picture thisratio gives ΩDEΩ119887
asymp 075005 = 15 while 1205902
0119873
0sim 1
(as 1198730≪ 1) and therefore this defines the estimate for the
effective number of fundamental fields (helicity states) as 120572 sim
15
65 Speculations on the Formation of Actual WormholesAs we already pointed out the additional distribution ofvirtual wormholes (72) reflects the symmetry of externalclassical fields and therefore it forms a homogeneous andisotropic background and perturbations We recall that vir-tual wormholes represent an exotic form of matter In theearly Universe such perturbations start to develop and mayform actual wormholes The rigorous description of sucha process represents an extremely complex and interestingproblemwhich requires the further study Some aspects of thebehavior of the exotic density perturbations were consideredin [7] while the simplest example of the formation of awormhole-type object was discussed recently by us in [38]Therefore we may expect that some portion of such a form ofdark energy is reserved now in actual wormholes which weconsider in the next section
7 Dark Energy from Actual Wormholes
Consider now the contribution to the dark energy fromthe gas of actual wormholes Unlike the virtual wormholesactual wormholes do exist at all times and therefore a singlewormhole can be viewed as a couple of conjugated cylinders1198793
plusmn= 119878
2
plusmntimes 119877
1 So that the number of parameters of an actualwormhole is less 120578 = (119886 119903
+ 119903
minus) where 119886 is the radius of 1198782
plusmn
and 119903plusmnisin 119877
3 is a spatial part of 119877plusmn
Actual wormholes also produce two kinds of contributionto the dark energy One comes from their contribution tothe mean curvature which corresponds to an exotic stressenergy momentum tensor Such a stress energy momentumtensor reflects the dark energy reserved by additional virtualwormholes discussed in the previous section Such energyis necessary to support actual wormholes as a solution tothe Einstein equations The second part comes from vacuumpolarization effects by actual wormholes The considerationin the previous section shows that for macroscopic worm-holes the second part has the order ⟨Δ119879
120572120573⟩ sim 8120587119866119899 and
is negligible as compared to the curvature 119877 sim 1198862119899 (since
macroscopic wormholes have throats 119886 ≫ ℓpl) Howeverfor the sake of completeness and for methodological aims wedescribe it as well
For rigorous evaluation of dark energy of the secondtype we first have to find the bias 119887
1(119909 119909
1015840 120578) analogous to
(19) for the topology 1198774(119879
3
+cup 119879
3
minus) There are many papers
treating different wormholes in this respect (eg see [36 37]and references therein) However in the present paper for anestimation we shall use a more simple trick
71 Beads of Virtual Wormholes (Quantum Wormhole)Indeed instead of the cylinders 1198793
plusmnwe consider a couple of
chains (beads of virtual wormholes 1198793
plusmnrarr cup
1198991198783
plusmn119899) Such an
idea was first suggested in [39] and one may call such anobject as quantum wormhole Then the bias can be writtenstraightforwardly
1198871(119909 119909
1015840 120578) =
+infin
sum
119899=minusinfin
1
41205872119886(
1
(119877minus119899
minus 1199091015840)2minus
1
(119877+119899
minus 1199091015840)2)
times [120575 (10038161003816100381610038161003816 minus
+119899
10038161003816100381610038161003816minus 119886) minus 120575 (
10038161003816100381610038161003816 minus
minus119899
10038161003816100381610038161003816minus 119886)]
(74)
where 119877plusmn119899
= (119905119899 119903
plusmn) with 119905
119899= 119905
0+ 2ℓ119899 and ℓ ge 119886 is the
step We may expect that upon averaging over the position1199050isin [minusℓ ℓ] the bias for the beads will reproduce the bias for
cylinders1198793
plusmn(at least it looks like a very good approximation)
We point out that the averaging out (12ℓ) intℓ
minusℓ119889119905
0and the
sum sum+infin
119899=minusinfinreduces to a single integral (12ℓ) intinfin
minusinfin119889119905 of the
zero term in (74) And moreover the resulting total biascorresponds merely to a specific choice of the distributionfunction 119865(120585) in (21) Namely we may take
119873119865 (120585) =1
2ℓ120575 (119905
+minus 119905
minus) 119891 (
1003816100381610038161003816119903+ minus 119903minus
1003816100381610038161003816 119886) (75)
12 Journal of Astrophysics
where119877plusmn= (119905
plusmn 119903
plusmn) and119891(119904 119886) is the distribution of cylinders
which can be taken as (119899 is 3-dimensional density)
119891 (120578) =119899 (119886)
41205871199032
0
120575 (119904 minus 1199030) (76)
Using the normalization condition int119873119865(120585)119889120585 = 119873 we findthe relation 119873 = (12ℓ)119899119881 = 119899119881 where 119899 is a 4-dimensional density of wormholes and 1(2ℓ) is the effectivenumber of wormholes on the unit length of the cylinder (iethe frequency with which the virtual wormhole appears atthe positions 119903
plusmn) This frequency is uniquely fixed by the
requirement that the volume which cuts the bead is equal tothat which cuts the cylinder (43)1205871198863 = (120587
22)119886
4(12ℓ) (ie
2ℓ = (31205878)119886 and 119899 = (83120587119886)119899) Thus we can use directlyexpression (23) and find (compare to (25))
119887 (119896) = minusint 119899 (119886) 1198862 4120587
2
1198962(1 minus
sin |k| 1199030|k| 1199030
)1198691(119896119886)
1198961198862119889119886 (77)
where 119896 = (1198960 k) Here the first term merely coincides with
that in (25) and therefore it gives the contribution to thecosmological constant 120575Λ(8120587119866) = minus1198994 = minus2119899(3120587119886)while the second term describes a correction which does notreduce to the cosmological constant and requires a separateconsideration
72 Stress Energy Tensor From (57) we find that the stressenergy tensor
minus⟨Δ119879120572120573
(119909)⟩ = int
119896120573119896120572minus (12) 119892
1205721205731198962
1198962119887 (119896 120585)
1198894119896
(2120587)4
(78)
reduces to the two functions
11987900
= 120576 = 1205821minus1
2120583
119879119894119895= 119901120575
119894119895 119901 =
1
31205822minus1
2120583
(79)
where 120576 + 3119901 = minus120583 and 1205821+ 120582
2= 120583 and these functions are
1205821= minusint
1198962
0
11989621198871198894119896
(2120587)4 120582
2= minusint
|k|2
11989621198871198894119896
(2120587)4 (80)
By means of the use of the spherical coordinates 11989620119896
2=
cos2120579 |k|21198962 = sin2120579 and 119889
4119896 = 4120587sin2
1205791198963119889119896119889120579 we get
120582119894=119899 (119886 119903
0)
4120573119894
(1 minus 2120573119894(119886
1199030
)
2
119891119894(119886
1199030
)) (81)
where 1205731= 1 120573
2= 13 and 119891
119894is given by
119891(1
2)(119910)
=2
120587int
1
minus1
int
infin
0
sin (119909 sin 120579)1198691(119910119909)
1199101199092(cos2120579sin2
120579) 119889119909 119889cos 120579
(82)
For 1198861199030≪ 1 we find
11989112
(119886
1199030
) asymp (1 + 11990012
(119886
1199030
)) (83)
Thus finally we find
120576 ≃ minus119899
4= minus
2119899
3120587119886 119901 ≃ 120576(1 minus
4
3(119886
1199030
)
2
) (84)
which upon the continuation to the Minkowsky space givesthe equation of state in the form (An arbitrary gas ofwormholes splits in fractions with a fixed 119886 and 119903
0)
119901 = minus(1 minus4
3(119886
1199030
)
2
) 120576 (85)
which in the case when 1198861199030≪ 1 behaves like a cosmological
constant However when 119886 ≫ ℓpl such a constant is extremelysmall and can be neglected while the leading contributioncomes from the mean curvature
73 Mean Curvature In this subsection we consider theMinkowsky spaceThen the simplest actual wormhole can bedescribed by the metric analogous to (1) for example see [7]
1198891199042= 119888
2119889119905
2minus ℎ
2(119903) 120575
120572120573119889119909
120572119889119909
120573 (86)
where ℎ(119903) = 1 + 120579(119886 minus 119903)(1198862119903
2minus 1) To avoid problems
with the Bianchi identity and the conservation of energy thestep function should be also smoothed as in (1) The stressenergy tensor which produces such a wormhole can be foundfrom the Einstein equation 8120587119866119879
120573
120572= 119877
120573
120572minus (12)120575
120573
120572119877 Both
regions 119903 gt 119886 and 119903 lt 119886 represent portions of the ordinaryflat Minkowsky space and therefore the curvature is 119877119896
119894equiv 0
However on the boundary 119903 = 119886 it has the singularity Sincethe metric (86) does not depend on time we find
1198770
0= 119877
0
120572= 0 119877
120573
120572=2
119886120575 (119886 minus 119903) 119899
120572119899120573+ 120575
120573
120572 + 120582
120573
120572 (87)
where 119899120572 = 119899120572= 119909
120572119903 is the outer normal to the throat 1198782
and 120582120573
120572are additional terms (eg see (49) and (51)) which
in the leading order are negligible upon averaging over someportion of space Δ119881 ≳ 119886
3 In the case of a set of wormholesthis gives in the leading order
1198770
0= 119877
0
120572= 0 119877
120573
120572= sum
2
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119903
119894
1003816100381610038161003816) 119899119894120572119899120573
119894+ 120575
120573
120572
(88)
where 119886119894is the radius of a throat and 119903
119894is the position of the
center of the throat in space and 119899120572
119894= (119909
120572minus 119903
120572
119894)|119903 minus 119903
119894|
In the case of a homogeneous and isotropic distribution ofsuch throats we find 119877
120573
120572= (13)119877120575
120573
120572(averaging over spatial
directions gives ⟨119899120572119899120573⟩ = (13)120575
120573
120572) where
119877 = minus8120587119866119879 = sum8
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119877
119894
1003816100381610038161003816) = 32120587int 119886119899 (119886) 119889119886
(89)
Journal of Astrophysics 13
where 119879 stands for the trace of the stress energy momentumtensor which one has to add to the Einstein equations tosupport such awormhole It is clear that such a source violatesthe weak energy condition and therefore it reproduces theformof dark energy (ie119879 = 120576+3119901 lt 0) If the density of suchsources (and resp the density of wormholes) is sufficientlyhigh then this results in the observed [10ndash14] accelerationof the scale factor for the Friedmann space as sim 119905
120572 with120572 = 21205763(120576 + 119901) = 2120576(2120576 + (120576 + 3119901)) gt 1 for examplesee also [40ndash42] In terms of the 4-dimensional density ofwormholes 119899 = (83120587119886)119899 we get 119877 sim 119886
2119899 ≫ 8120587119866119899 as 119886 ≫ ℓpl
and therefore the leading contribution indeed comes fromthe mean curvature
8 Estimates and Concluding Remarks
Now consider the simplest estimates Actual wormholes seemto be responsible for the dark matter [7 9] Therefore to getthe estimate to the number density of wormholes is ratherstraightforward First wormholes appear at scales when darkmatter effects start to display themselves that is at scales ofthe order 119871 sim (1 divide 5)Kpc which gives in that range thenumber density
119899 sim1
1198713sim (3 divide 0024) times 10
minus65cmminus3 (90)
The characteristic size of throats can be estimated from (89)120576DE sim (119866)
minus1119899119886 Since the density of dark energy is 120576DE1205760 =
ΩDE sim 075 where 1205760is the critical density then we find the
estimate
119886 sim2
3(1 divide 125) times 10
minus3119877⊙ΩDEℎ
2
75 (91)
where119877⊙is the Solar radius ℎ
75= 119867(75 km(secMpc)) and
119867 is the Hubble constant We also recall that the backgrounddensity of baryons 120576
119887generates a nonvanishingwormhole rest
mass119872119908= (43)120587119886
31198773120576119887(where119877(119905) is the scale factor of the
Universe and therefore 119872119908remains constant) for example
see [7] It produces the dark matter density related to thewormholes as 120576DM ≃ 119872
119908119899 The typical mass of a wormhole
119872119908is estimated as
119872119908sim 1 7 times (1 divide 125) times 10
2119872
⊙ΩDMℎ
2
75 (92)
where 119872⊙is the Solar mass We point out that this mass
has not the direct relation to the parameters of the gas ofwormholes However it defines the moment when wormholethroats separated from the cosmological expansion Theabove estimate shows that if wormholes form due to thedevelopment of perturbations in the exotic matter then thisprocess should start much earlier than the formation ofgalaxies
Thus we see that virtual wormholes should indeed leadto the regularization of all divergencies in QFT which agreeswith recent results [28] Therefore they form the local finitevalue of the cosmological constant In the absence of externalclassical fields such a value should be exactly zero at macro-scopic scales A some nonvanishing value for the cosmolog-ical constant appears as the result of vacuum polarization
effects in external fields Indeed external fields form anadditional distribution of virtual wormholes which possessan exotic stress energy tensor (some kind of dark energy)Only some part of it forms the cosmological constant whilethe rest reflects the symmetry of external fields and possessesinhomogeneitiesWe assume that during the evolution of ourUniverse inhomogeneities in the exotic matter develop andmay form actual wormholes Although this problem requiresthe further and more deep investigation we refer to [38]where the formation of a simplest wormhole-like object hasbeen considered In other words such polarization energyis reserved now in a gas of actual wormholes We estimatedparameters of such a gas and believe that such a gas mayindeed be responsible for both dark matter and dark energyphenomena
References
[1] J R Primack ldquoThe nature ofdark matterrdquo httparxivorgabsastro-ph0112255
[2] J Diemand M Zemp B Moore J Stadel and M CarolloldquoCusps in cold dark matter haloesrdquoMonthly Notices of the RoyalAstronomical Society vol 364 no 2 pp 665ndash673 2005
[3] E W Mielke and J A V Velez Perez ldquoAxion condensate as amodel for dark matter halosrdquo Physics Letters B vol 671 no 1pp 174ndash178 2009
[4] G Gentile P Salucci U Klein D Vergani and P Kalberla ldquoThecored distribution of dark matter in spiral galaxiesrdquo MonthlyNotices of the Royal Astronomical Society vol 351 no 3 pp 903ndash922 2004
[5] D T F Weldrake W J G de Blok and F Walter ldquoA high-resolution rotation curve of NGC 6822 a test-case for cold darkmatterrdquo Monthly Notices of the Royal Astronomical Society vol340 no 1 pp 12ndash28 2003
[6] W J G de Blok andA Bosma ldquoHigh-resolution rotation curvesof low surface brightness galaxiesrdquoAstronomy and Astrophysicsvol 385 pp 816ndash846 2002
[7] A Kirillov and E P Savelova ldquoDensity perturbations in a gas ofwormholesrdquoMonthly Notices of the Royal Astronomical Societyvol 412 no 3 pp 1710ndash1720 2011
[8] P Kanti B Kleihaus and J Kunz ldquoStable Lorentzianwormholesin dilatonic Einstein-Gauss-Bonnet theoryrdquo Physical Review Dvol 85 no 4 Article ID 044007 2012
[9] A A Kirillov and E P Savelova ldquoDark matter from a gas ofwormholesrdquo Physics Letters B vol 660 no 3 pp 93ndash99 2008
[10] A G Riess A V Filippenko P Challis et al ldquoObservationalevidence from supernovae for an accelerating universe and acosmological constantrdquo The Astronomical Journal vol 116 no3 p 1009 1998
[11] S Perlmutter G Aldering G Goldhaber et al ldquoMeasurementsofΩ andΛ from42high-redshift supernovaerdquoTheAstrophysicalJournal vol 517 no 2 p 565 1999
[12] J L Tonry B P Schmidt B Barris et al ldquoCosmological resultsfromhigh-z supernovaerdquoTheAstrophysical Journal vol 594 no1 p 594 2003
[13] N W Halverson E M Leitch C Pryke et al ldquoDegreeangular scale interferometer first results a measurement of thecosmic microwave background angular power spectrumrdquo TheAstrophysical Journal vol 568 no 1 p 38 2002
14 Journal of Astrophysics
[14] C B Netterfield P A R Ade J J Bock et al ldquoA measurementby BOOMERANGofmultiple peaks in the angular power spec-trum of the cosmic microwave backgroundrdquo The AstrophysicalJournal vol 571 no 2 p 604 2002
[15] S Coleman ldquoWhy there is nothing rather than something atheory of the cosmological constantrdquoNuclear Physics B vol 310no 3-4 pp 643ndash668 1988
[16] I Klebanov L Susskind and T Banks ldquoWormholes and thecosmological constantrdquo Nuclear Physics B vol 317 no 3 pp665ndash692 1989
[17] S W Hawking ldquoSpacetime foamrdquoNuclear Physics B vol 114 p349 1978
[18] T P Cheng and L F Li Gauge Theory of Elementary ParticlesClarendon Press Oxford UK 1984
[19] A H Taub ldquoSpace-times with distribution valued curvaturetensorsrdquo Journal ofMathematical Physics vol 21 no 6 pp 1423ndash1431 1980
[20] A Shatsky privite communications[21] V A Fock ldquoZur Theorie des Wasserstoffatomsrdquo Zeitschrift fur
Physik vol 98 no 3-4 pp 145ndash154 1935[22] E P Savelova ldquoGas of wormholes in Euclidean quantum field
theoryrdquo httparxivorgabs12115106[23] A A Kirillov and E P Savelova ldquoOn the behavior of
bosonic systems in the presence of topology fluctuationsrdquohttparxivorgabs08082478
[24] A A Kirillov ldquoViolation of the Pauli principle and dimensionof the Universe at very large distancesrdquo Physics Letters B vol555 no 1-2 pp 13ndash21 2003
[25] A A Kirillov ldquoDark matter dark charge and the fractalstructure of the Universerdquo Physics Letters B vol 535 no 1ndash4pp 22ndash24 2002
[26] J Ambjorn J Jurkiewicz and R Loll ldquoThe spectral dimensionof the universe is scale dependentrdquo Physical Review Letters vol95 no 17 Article ID 171301 4 pages 2005
[27] E Manrique S Rechenberger and F Saueressig ldquoAsymptoti-cally safe Lorentzian gravityrdquo Physical Review Letters vol 106no 25 Article ID 251302 4 pages 2011
[28] J Laiho and D Coumbe ldquoEvidence for asymptotic safety fromlattice quantum gravityrdquo Physical Review Letters vol 107 no 16Article ID 161301 2011
[29] A A Kirillov and D Turaev ldquoOn modification of the Newtonrsquoslaw of gravity at very large distancesrdquo Physics Letters B vol 532no 3-4 pp 185ndash192 2002
[30] A A Kirillov and D Turaev ldquoThe universal rotation curveof spiral galaxiesrdquo Monthly Notices of the Royal AstronomicalSociety vol 371 no 1 pp L31ndashL35 2006
[31] A A Kirillov and D Turaev ldquoFoam-like structure of theuniverserdquo Physics Letters B vol 656 pp 1ndash8 2007
[32] A A Kirillov ldquoThe nature of dark matterrdquo Physics Letters B vol632 no 4 pp 453ndash462 2006
[33] A A Kirillov and E P Savelova ldquoAstrophysical effects of space-time foamrdquo Gravitation and Cosmology vol 14 no 3 pp 256ndash261 2008
[34] S W Hawking and N Turok ldquoOpen inflation without falsevacuardquo Physics Letters B vol 425 no 1-2 pp 25ndash32 1998
[35] Z C Wu ldquoThe cosmological constant is probably zero and aproof is possibly rightrdquo Physics Letters B vol 659 no 5 pp 891ndash893 2008
[36] R Garattini ldquoEntropy and the cosmological constant aspacetime-foam approachrdquo Nuclear Physics B vol 88 no 1ndash3Article ID 991003 pp 297ndash300 2000
[37] MVisserLorentzianWormholes SpringerNewYorkNYUSA1996
[38] A A Kirillov and E P Savelova ldquoArtificial wormholerdquohttparxivorgabs12040351
[39] E W Mielke ldquoKnot wormholes in geometrodynamicsrdquo Gen-eral Relativity and Gravitation vol 8 no 3 pp 175ndash196 1977
[40] E B Gliner ldquoAlgebraic properties of the energy-momentumtensor and vacuum-like states of matterrdquo Journal of Experimen-tal and Theoretical Physics vol 22 p 378 1966
[41] A H Guth ldquoInflationary universe a possible solution to thehorizon and flatness problemsrdquo Physical Review D vol 23 no2 pp 347ndash356 1981
[42] A A Linde ldquoA new inflationary universe scenario a possiblesolution of the horizon flatness homogeneity isotropy andprimordial monopole problemsrdquo Physics Letters B vol 108 no6 pp 389ndash393 1982
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
![Page 6: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/6.jpg)
6 Journal of Astrophysics
and the Green function can be taken as
119866 =119873 (119896 120585)
1198962 + 1198982 (32)
Then for the total partition function we find
119885total (119869)
= int [119863119873 (119896)] 119890minus119868(119873)
119890minus(12)(119871
4
(2120587)4
) int((119873(119896)(1198962
+1198982
))|119869119896
|2
)119889119896
(33)
where [119863119873] = prod119896119889119873
119896and 120590(119873) comes from the integration
measure (ie from the Jacobian of transformation from 119865(120585)
to119873(119896))
119890minus119868(119873)
= int [119863119865]1198850(119873 (119896 120585)) 120575 (119873 (119896) minus 119873 (119896 120585)) (34)
We point out that 119868(119873) can be changed by means of addingto the action (6) of an arbitrary ldquonondynamicalrdquo constantterm which depends only on topology 119878 rarr 119878 + Δ119878 (119873(119896))
(eg a topological Euler term) The multiplier 1198850(119873) defines
the simplest measure for topologies Now by means of usingthe expression (32) and (33) we find the two-point Greenfunction in the form
119866 (119896) =119873 (119896)
1198962 + 1198982 (35)
where 119873(119896) is the cutoff function (the mean bias) whichis given by (We recall that in this integral contribute onlylimiting topologies in which density of wormholes diverges(119899 rarr infin))
119873(119896) =1
119885total (0)int [119863119873] 119890
minus119868(119873)119873(119896) (36)
At the present stage we still cannot evaluate the exactform for the cutoff function 119873(119896) in virtue of the ambiguityof Δ119878(119873(119896)) pointed out Such a term may include twoparts First part Δ
1119878 describes the proper dynamics of
wormholes and should be considered separately Indeedin general wormholes are dynamical self-gravitating objectswhich require considering the gravitational contribution tothe action Some part of such a contribution (mean curvatureinduced by wormholes) is discussed in Section 6 Howeversince a wormhole represents an extended nonlocal objectit possesses a rather complex dynamics and this problemrequires the further investigation The second part Δ
2119878 may
describe ldquoexternal conditionsrdquo (eg an external classicalfield in (33)) for the mean topology Actually the last termcan be used to prescribe an arbitrary particular value forthe cutoff function 119873(119896) = 119891(119896) Indeed the ldquoexternalconditionsrdquo can be accounted for by adding the term Δ
2119878 =
(120582119873) = int 120582(119896)119873(119896)1198894119896 where 120582(119896) plays the role of a
specific chemical potential which implicitly depends on 119891(119896)
through the equation
119891 (119896) =1
119885total (120582 0)int [119863119873] 119890
(120582119873)minus119868(119873)119873(119896) (37)
From (33) we see that the role of such a chemical potentialmay play the external current 120582(119896) = minus(12)(119871
4(2120587)
4)sdot
1198660(119896)|119869
ext119896|2 or equivalently an external classical field 120593
ext=
1198660(119896)119869
ext119896 In quantum field theory such a term leads merely
to a renormalization of the cosmological constant By otherwords the mean topology (ie the cutoff function or meandistribution of wormholes) is driven by the cosmologicalconstant Λ and vice versa
4 Topological Bias as a Projection Operator
By the construction the topological bias 119873(119909 1199091015840) plays the
role of a projection operator onto the space of functions (asubspace of functions on 119877
4) which obey the proper bound-ary conditions at throats of wormholes This means thatfor any particular topology (for a set of wormholes) thereexists the basis 119891
119894(119909) in which it takes the diagonal form
119873(119909 1199091015840) = sum119873
119894119891119894(119909)119891
lowast
119894(119909
1015840) with eigenvalues 119873
119894= 0 1
(since 1198732
119894= 119873
119894) In this section we illustrate this simple fact
(which is probably not obvious for readers) by the explicitconstruction of the reference system for a single wormholewhen physical functions become (due to the boundaryconditions) periodic functions of one of coordinates
Indeed consider a single wormhole with parameters 120585(ie 120585 = (119886 119877
+ 119877
minus) where 119886 is the throat radius and 119877
plusmn
are positions of throats in space (In general there existsan additional parameter Λ120572
120573which defines a rotation of one
of throats before gluing However it does not change thesubsequent constructionThere always exists a diffeomorphicmap of coordinates 1199091015840
= ℎ(119909) which sets such a matrix tounity)) Consider now a particular solution120601
0to the equation
Δ1206010= 0 (harmonic function) for 1198774 in the presence of the
wormhole which corresponds to the situation when throatspossess a unit chargemass but those have the opposite signsNow define the family of lines of force 119909(119904 119909
0) which obey
the equation 119889119909119889119904 = minusnabla1206010(119909) with initial conditions 119909(0) =
1199090 Physically such lines correspond to lines of force for a
two charged particles in positions 119877plusmn with charges plusmn1 Wenote that all points which lay on the trajectory 119909(119904 119909
0) may
be taken as initial conditions and they define the same lineof force with the obvious redefinition 119904 rarr 119904 minus 119904
0 By
other words we may take as a new coordinates the parameter119904 and portion of the coordinates orthogonal to the familyof lines 119909
perp
0 Coordinates 119909
perp
0can be taken as laying in the
hyperplane 1198773 which is orthogonal to the vector 119889 = minusminus
+
and goes through the point 0
= (minus+
+)2 (Instead
of the construction used here one may use also anothermethod Indeed consider two point charges and then thefunction 120601
0= 1(119909 minus 119909
+)2minus 1(119909 minus 119909
minus)2 can be taken as a
new coordinate Wormhole appears when we identify (glue)surfaces 120601
0= plusmn120596 We point out that such surfaces are not
spheres though they reduce to spheres in the limit |119909+minus
119909minus| rarr infin or 120596 rarr infin)Let 119904plusmn(119909perp
0) be the values of the parameter 119904 at which
the line intersects the throats 119877plusmn Then instead of 119904 we mayconsider a new parameter 120579 as 119904(120579) = 119904
minus+ (119904
+minus 119904
minus)1205792120587
so that when 120579 = 0 2120587 the parameter 119904 takes the values
Journal of Astrophysics 7
119904 = 119904minus 119904+ respectivelyThe gluing procedure at throatsmeans
merely that we identify points at 120579 = 0 and 120579 = 2120587 and allphysical functions in the space 119877
4 with a single wormhole120585 become periodic functions of 120579 Thus the coordinatetransformation 119909 = 119909(120579 119909
perp
0) gives the map of the above space
onto the cylinder with a specific metric 1198891198972 = (119889(120579 119909perp
0))
2
=
119892120572120573119889119910
120572119889119910
120573 (where 119910 = (120579 119909perp
0)) whose components are also
periodic in terms of 120579 Now we can continue the coordinatesto thewhole space1198774 (to construct a cover of the fundamentalregion 120579 isin [0 2120587]) simply admitting all valuesminusinfin lt 120579 lt +infin
this however requires to introduce the bias
1
radic119892120575 (120579 minus 120579
1015840) 997888rarr 119873(120579 minus 120579
1015840) =
+infin
sum
119899=minusinfin
1
radic119892120575 (120579 minus 120579
1015840+ 2120587119899)
(38)
since every point and every source in the fundamental regionacquires a countable set of images in the nonphysical region(inside of wormhole throats) Considering now the Fouriertransforms for 120579 we find
119873(119896 1198961015840) =
+infin
sum
119899=minusinfin
120575 (119896 minus 119899) 120575 (119896 minus 1198961015840) (39)
We point out that the above bias gives the unit operator in thespace of periodic functions of 120579 From the standpoint of allpossible functions on 1198774 it represents the projection operator
2= (120585) (taking an arbitrary function 119891 we find that upon
the projection 119891119873= 119891 119891
119873becomes a periodic function of
120579 that is only periodic functions survive)The above construction can be easily generalized to the
presence of a set of wormholes In the approximation of adilute gas of wormholes we may neglect the influence ofwormholes on each other (at least there always exists a suf-ficiently smooth map which transforms the family of linesof force for ldquoindependentrdquo wormholes onto the actual lines)Then the total bias (projection) may be considered as theproduct
119873total (119909 1199091015840) = int(prod
119894
radic1198921198941198894119910119894)119873(120585
1 119909 119910
1)
times 119873 (1205852 119910
1 119910
2) sdot sdot sdot 119873 (120585
119873 119910
119873minus1 119909
1015840)
(40)
where 119873(120585119894 119909 119909
1015840) is the bias for a single wormhole with
parameters 120585119894 Every such a particular bias119873(120585
119894 119909 119909
1015840) realizes
projection on a subspace of functions which are periodic withrespect to a particular coordinate 120579
119894(119909) while the total bias
gives the projection onto the intersection of such particularsubspaces (functions which are periodic with respect to everyparameter 120579
119894)
5 Cutoff
The projective nature of the bias operator 119873(119909 1199091015840) allows us
to express the cutoff function 119873(119896) via dynamic parametersof wormholes Indeed consider a box 1198714 in 119877
4 and periodic
boundary conditions which gives 119896 = 2120587119899119871 (in final expres-sions we consider the limit 119871 rarr infin which gives sum
119896rarr
(1198714(2120587)
4) int 119889
4119896) And let us consider the decomposition for
the integration measure in (33) as
119868 = 1198680+sum120582
1(119896)119873 (119896) +
1
2sum120582
2(119896 119896
1015840)119873 (119896)119873 (119896
1015840) + sdot sdot sdot
(41)
where 1205821(119896) includes also the contribution from 119885
0(119896) We
point out that this measure plays the role of the action for thebias119873(119896) Indeed the variation of the above expression givesthe equation of motions for the bias in the form
sum
1198961015840
1205822(119896 119896
1015840)119873 (119896
1015840) = minus120582
1(119896) (42)
which can be found by considering the proper dynamics ofwormholes We however do not consider the problem of thedynamic description of wormholes here and leave this forthe future research Moreover we may expect that in the firstapproximation one may retain the linear term only Indeedthis takes place when119873(119896) is not a dynamic variable or if wetake into account that 119873(119896) is a collective variable Then theprojective nature of the bias 119873(119896) = 0 1 means that it canbe phenomenologically expressed via some Fermionic ghostfield Ψ(119896) (eg 119873(119896 119896
1015840) = Ψ(119896)Ψ
+(119896
1015840)) where the negative
and positive frequency parts of the operator Ψ(119896) obey theanticommutation relationsΨ+
(119896)Ψ(1198961015840)+Ψ(119896
1015840) Ψ
+(119896) = 120575(119896minus
1198961015840) In the absence of ghost particles Ψ(119896)|0⟩ = 0 we get
119873(119896 1198961015840) = 120575(119896 minus 119896
1015840) that is 119873(119896) = 1 and wormholes
are absent In the term of the ghost field the action becomes119868(119873) = 119868
0+ (Ψ
1Ψ) + sdot sdot sdot Therefore in the leading approx-
imation equations of motion take the linear form 1Ψ = 0
Thus taken into account that 119873(119896) = 0 1 (1198732= 119873) we
find
119873(119896) =1
119885total (119896)sum
119873=01
119890minus1205821
(119896)119873(119896)119873(119896) =
119890minus1205821
(119896)
1 + 119890minus1205821(119896) (43)
The simplest choice gives merely 1205821(119896) = minussum ln119885
0(119896)
where the sum is taken over the number of fields and 1198850(119896)
is given by 1198850(119896) = radic120587(1198962 + 1198982) In the case of a set
of massless fields we find 119873(119896) = 119885(119896)(1 + 119885(119896)) where119885(119896) = (radic120587119896)
120572 and 120572 is the effective number of degreesof freedom (the number of boson minus fermion fields) Toensure the absence of divergencies one has to consider thenumber of fields 120572 gt 4 [23] However such a choice givesthe simplest estimate which in general cannot be correctIndeed while its behavior at very small scales (ie whenexceeding the Planckian scales 119885(119896) ≲ 1 and 119873(119896) = 119885(119896))may be physically accepted since it produces some kind of acutoff on the mass-shell 1198962 + 119898
2rarr 0 it gives the behavior
119873(119896) rarr 1 which is merely incorrect (eg from (27) we seethat the true behavior should be119873(119896) rarr const lt 1)
One may expect that the true cutoff function has a muchmore complex behavior Indeed some theoretical models inparticle physics (eg string theory) have the property tobe lower-dimensional at very small scales The mean cutoff
8 Journal of Astrophysics
119873(119896) gives the natural tool to describe a scale-dependantdimensional reduction [24 25] In fact this function definesthe spectral number of modes in the interval between 119896 and119896 + 119889119896 as
int119873 (119896)1198894119896
(2120587)4= int
119873 (119896) 1198964
(2120587)2
119889119896
119896 (44)
Hence we can define the effective spectral dimension 119863 ofspace as follows
1198964119873(119896) sim 119896
119863 (45)
From the empirical standpoint the dimension 119863 = 4 isverified at laboratory scales only while the rigorous tool todefine the spectral density of states (or the mean cutoff) cangive the lattice quantum gravity for example see [26 27]and references therein And indeed the spectral dimensionfor nonperturbative quantum gravity defined via Euclideandynamical triangulations was calculated recently in [28] Itturns out that it runs from a value of119863 = 32 at short distanceto 119863 = 4 at large distance scales We also point out that allobserved dark matter phenomena can be explained by thefractal dimension119863 asymp 2 starting from scales 119871 ≳ (1 divide 5)Kpcfor example [29ndash33]
6 Cosmological Constant
Let us consider the total Euclidean action [17]
119868119864= minus
1
16120587119866int (119877 minus 2Λ
0)radic119892119889
4119909 minus int119871
119898radic1198921198894119909 (46)
The variation of the above action leads to the Einstein equa-tions
119877119886119887minus1
2119892119886119887119877 + 119892
119886119887Λ
0= 8120587119866119879
119886119887 (47)
where 119879119886119887= (12)(119892)
minus12(120575119871
119898120575119892
119886119887) is the stress energy ten-
sor and Λ0is a naked cosmological constant In cosmology
such equations are considered from the classical standpointwhich means that they involve characteristic scales ℓ ≫ ℓplHowever the presence of virtual wormholes at Planckianscales defines some additional contribution in both parts ofthese equations which can be adsorbed into the cosmologicalconstant Therefore the total cosmological constant can bedefined as
Λ tot = Λ0+ Λ
119898+ Λ
119877= Λ
0+ 2120587119866 ⟨119879⟩ +
1
4⟨119877⟩119908 (48)
where ⟨119879⟩ is the energy of zero-point fluctuations (It includesalso the contribution of zero-point fluctuations of gravitons)That is themean vacuum value (we recall that in the standardQFTΛ
119898is infinite while wormholes form a finite value) and
⟨119877⟩119908
= Λ119877is a contribution of wormholes into the mean
curvature due to gluing (1)
61 Contribution of Virtual Wormholes into Mean CurvatureConsider a single wormhole whose metric is given by (1)
1198891199042= ℎ
2(119903)120575
120572120573119889119909
120572119889119909
120573 then the components of the Riccitensor are (We are much obliged to the Referee who pointedout to the subtleties when working with a step function in themetric)
119877120572120573
= 7 minus (ℎ1015840
ℎ)
1015840
(120575120572120573
+ (119873 minus 2) 119899120572119899120573)
minus1
119903
ℎ1015840
ℎ((119873 minus 2) Δ
120572120573+ 120575
120572120573(119873 minus 1))
minus (ℎ1015840
ℎ)
2
(119873 minus 2) Δ120572120573
(49)
where 119899]= 119909
]119886 is the unite normal vector to the throat
surface Δ120572120573
= 120575120572120573
minus 119899120572119899120573 ℎ1015840 = 120597ℎ120597119903 and119873 is the number
of dimensions The curvature scalar is
119877 = minus(119873 minus 1)
ℎ2[2
ℎ10158401015840
ℎ+ 2
1
119903
ℎ1015840
ℎ(119873 minus 1) + (
ℎ1015840
ℎ)
2
(119873 minus 4)]
(50)
Then substituting ℎ = 1 + (1198862119903
2minus 1)120579 in the above equation
we find
minusℎ4
119873 minus 1119877 = 4ℎ
1198862
1199033120575 +
2ℎ
119903119873minus1(119903
119873minus1120582)
1015840
+ (119873 minus 4)(1205822minus 4120579
1198862
1199033120582)
+ 4 (119873 minus 4)1198862
1199034120579 (120579 minus 1)
(51)
where 120579 is a smooth function which only in a limit becomesa step function 120582 = (1 minus 119886
2119903
2)120575 and 120575 = minus120579
1015840 In the limit120579 rarr 120579(119886 minus 119903) we find 120575 rarr 120575(119903 minus 119886) and the last two terms in(51) are negligible as compared to the first two terms while infour dimensions the last two terms vanishThen the curvatureis concentrated on the throat of the wormhole where 120579 differsfrom the step function In the limit of a vanishing throat sizewe have ℎ rarr 1 at the throat and we get
minus119877 =4 (119873 minus 1)
119886120575 (119903 minus 119886) +
2 (119873 minus 1)
119903119873minus1(119903
119873minus3(119903
2minus 119886
2) 120575)
1015840
(52)
In general all the terms together in (51) and analogous termsin the Ricci tensor provide that the Bianchi identity holdsand the energy is conserved [19] Therefore none of themcan be dropped out However it is easy to see the leadingcontribution to the integral over space comes from the firstterm only and in the limit of a vanishing throat size we findfor a single wormhole
1
4int119877radic119892119889
4119909 = minus6120587
21198862 (53)
Journal of Astrophysics 9
In the case of a set of wormholes (24) we find
1
4int119877radic119892119889
4119909 = minus6120587
2sum
119895
1198862
119895
= minus121205872int119899 (119886) 119886
2119889119886 119889
4119909 = intΛ
1198771198894119909
(54)
where 2119899(119886) = int 119899(119886 1199030)119889119903
0is the density of wormhole
throats with a fixed value of the throat size 119886 This definesthe contribution to the cosmological constant from the meancurvature as
Λ119877= minus12120587
2int119899 (119886) 119886
2119889119886 lt 0 (55)
We see that this quantity is always negative
62 Stress Energy Tensor In this section we consider thecontribution from matter fields In the case of a scalar fieldthe stress energy tensor has the form
minus119879120572120573
(119909) = 120597120572120593120597
120573120593 minus
1
2119892120572120573
(120597120583120593120597
120583120593 + 119898
21205932) (56)
Then the mean vacuum value of the stress energy tensor canbe obtained directly from the two-point green function (32)(35) as
minus ⟨119879120572120573
(119909)⟩
= lim1199091015840
rarr119909
(1205971205721205971015840
120573minus1
2119892120572120573
(1205971205831205971015840
120583+ 119898
2)) ⟨119866 (119909 119909
1015840 120585)⟩
(57)
By means of using the Fourier transform 119866(119909 1199091015840 120585) =
int 119890minus119894119896(119909minus119909
1015840
)119866(119896 120585) (119889
4119896(2120587)
4) and the expressions (32) (35)
we arrive at
⟨119879120572120573
(119909)⟩ =1
4119892120572120573
int(1 +119898
2
1198962 + 1198982)119873 (119896)
1198894119896
(2120587)4 (58)
where the property int 119896120572119896120573119891(119896
2)119889
4119896 = (14)119892
120572120573int 119896
2119891(119896
2)119889
4119896
has been used and 119873(119896) = ⟨119873(119896 120585)⟩ is the cutoff function(36)
For the sake of simplicity we consider the massless caseThen by the use of the cutoff 119873(119896) = 120587
1205722(120587
1205722+ 119896
120572) from
the previous section we get the finite estimate (120572 gt 4 is theeffective number of the field helicity states)
Λ119898=2120587119866sumint
1205871205722
1205871205722+119896120572
1198894119896
(2120587)4=120587119866
4Γ (
120572 minus 4
120572) Γ (
4
120572) sim 1
(59)
where the sum is taken over the number of fields Since theleading contribution comes here from very small scales wemay hope that this value will not essentially change if thetrue cutoff function changes the behavior on the mass-shellas 119896 rarr 0 (eg if we take 120582
1(119896) = minussum ln119885
0(119896) + 120575120582(119896) with
120575120582(119896) ≪ ln1198850(119896) as 119896 ≫ 1)
To understand how wormholes remove divergencies itwill be convenient to split the bias function into two parts119873(119896 120585) = 1 + 119887(119896 120585) where 1 corresponds to the standardEuclidean contribution while 119887(119896 120585) is the contribution ofwormholes The first part gives the well-known divergentcontribution of vacuumfield fluctuations 8120587119866⟨1198790
120572120573⟩ = Λ
lowast119892120572120573
with Λlowast
rarr +infin while the second part remains finite forany finite number of wormholes and due to the projectivenature of the bias described in the previous section itpartially compensates (reduces) the value of the cosmologicalconstant that is 8120587119866⟨Δ119879
120572120573⟩ = 120575Λ119892
120572120573 where 120575Λ =
sum119873120588119873120575Λ(119873) and 120575Λ(119873) is a negative finite contribution of
a finite set of wormholesConsider now the particular distribution of virtual
wormholes (24) and evaluate their contribution tothe cosmological constant which is given by 120575Λ(119873) =
2120587119866int 119887(119896) (1198894119896(2120587)
4) = 2120587119866119887total(0) Then from the ex-
pressions (22) and (24) we get
119887total (0) = minus119899
4120587411988631199033
0
int(1 minus1198862
1198772
minus
)120575 (119877+minus 119886)
times 120575 (1003816100381610038161003816119877+
minus 119877minus
1003816100381610038161003816 minus 1199030) 119889
4119877minus1198894119877+
(60)
which gives
119887total (0) = minus119899(1 minus 119891(119886
1199030
)) (61)
where
119891(119886
1199030
) =2
120587int
120587
0
1198862sin2
120579119889120579
1198862 + 21198861199030cos 120579 + 119903
2
0
(62)
For 1198861199030≪ 1 (we recall that by the construction 119886119903
0le 12)
this function has the value 119891(1198861199030) asymp 119886
2119903
2
0 Thus for the
contribution of wormholes we find
120575Λ119898= minus2120587119866int119899 (119886 119903
0) (1 minus 119891(
119886
1199030
))119889119886 1198891199030
= minus2120587119866119899 (1 minus ⟨119891⟩)
(63)
63 Vacuum Value of the Cosmological Constant From theabove expression we see that to get the finite value of thecosmological constant Λ
119898= Λ
lowast+ 120575Λ
119898lt infin one should
consider the limit 119899 rarr infin (infinite density of virtualwormholes) which requires considering the smaller andsmaller wormholes From the other handwe have the obviousrestriction int 2119899(119886 119903
0)(120587
22)119886
4119889119886 119889119903
0lt 1 where (120587
22)119886
4
is the volume of one throat (wormholes cannot cut morethan the total volume of space) (We also point out that inremoving divergencies the leading role plays the zero-pointenergy Indeed 120575Λ
119898sim minus2120587119866119899 while the mean curvature has
the order Λ119877sim minus119886
2119899 and for 119886 ≪ ℓpl we have 120575Λ119898
≫ Λ119877
Moreover in the limit 119899 rarr infin one gets 119886 rarr 0 and thereforeΛ
119877120575Λ
119898rarr 0)Therefore in the leading order it seems to be
sufficient to retain point-like wormholes only (ie consider
10 Journal of Astrophysics
the limit 119886 rarr 0) Then instead of (24) we may assume thevacuum distribution of virtual wormholes in the form
119873119865 (119886119883) =1
1198862120575 (119886) ] (119883) (64)
where ](119883) = int 1198862119873119865(119886119883)119889119886 and int(1119886
2)](119883)119889
4119883 =
119899 rarr infin has the meaning of the infinite density of point-like wormholes while ] sim 119886
2119899 remains a finite In this case
the volume cut by wormholes vanishes int 2119899(12058722)119886
4119889119886 119889119903
0=
1198862int ](119883)119889
4119883 rarr 0 and the rarefied gas approximationworks
wellThis defines the bias and themean cutoff (here we definethe Fourier transform ](119896) = int ](119883)119890
1198941198961198831198894119883) as
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (65)
The contribution to themean curvature (55) can be expressedvia the same function ](119896) as
Λ119877= minus12120587
2int119899 (119886 119903
0) 119886
2119889119886 119889119903
0
= minus121205872int ] (119883) 119889
4119883 = minus12120587
2] (0)
(66)
Thus for the total cosmological constant we get the expres-sion
Λ tot = Λ0
+ 2120587119866int(1minus4120587
2
1198962(] (0)minus] (119896)))
1198894119896
(2120587)4minus12120587
2] (0)
(67)
We stress that all these terms should be finite Indeed all dis-tributions of virtual wormholes ](119896) which lead to an infinitevalue of Λ tot are suppressed in (5) by the factor sim119890minusintΛ tot119889
4
119909while the minimal value is reached when wormholes cut allof the volume of space and the action is merely 119878 = 0(Frankly speaking this statement is not rigorous At first lookthe two last terms in (67) are independent and one may tryto take ](0) an arbitrary big If this were the case then theaction would not possess the minimum at all However ](0)cannot be arbitrary big since it will violate the rarefied gasapproximation and the linear expression (67) brakes downMoreover fermions give here a contribution of the oppositesign The rigorous investigation of this problem requires thefurther studying and we present it elsewhere) We also pointout that here we considered the real scalar field as the mattersource while in the general case the stress energy tensorshould include all existing Bose and Fermi fields (Fermi fieldsgive a negative contribution to Λ
119898)
The value of Λ0looks like a free parameter which in
quantum gravity runs with scales [27] However at largescales its asymptotic value may be uniquely fixed by thesimple arguments as follows Indeed in quantum field theoryproperties of the ground state (vacuum) change when weimply an external classical fields The same is true for thedistribution of virtualwormholes ](119896 119869) for example see (33)and (37) and therefore Λ tot = Λ tot(119869) which we describe
in the next subsection We recall that in gravity the role ofthe external current plays the stress energy tensor of matterfields 119869 = 119879
119886119887 However one believes that in the absence
of all classical fields the vacuum state should represent themost symmetric (Lorentz invariant) state which in our casecorresponds to the Euclidean space In order to be consistentwith the Einstein equations this requires Λ tot(119869 = 0) = 0
which uniquely fixes the value of Λ0in (67) We point out
that from somewhat different considerations such a choicewas advocated earlier in [15 34 35]
64 Vacuum Polarization in an External Field Consider nowtopology fluctuations in the presence of an external currentIn the presence of an external current 119869ext the distribution ofvirtual wormholes changes ](119896 119869) = ](119896) + 120575](119896 119869) Indeedin (33) for the case of a weak external field the contributionof the external current into the action can be expanded asexp(minus119881(119869)) ≃ 1 minus 119881 where
119881 = minus1
2int 119869 (119909) 119866 (119909 119910) 119869 (119910) 119889
4119909 119889
4119910
= minus1
2
1198714
(2120587)4int119866
0(119896)119873 (119896)
10038161003816100381610038161198691198961003816100381610038161003816
2
1198894119896
(68)
Then using (36) we find119873(119896 119869) = 119873(119896 0) + 120575119873(119896 119869) where
120575119873 (119896 119869) = 120575119887 (119869) ≃ minus1
2
1198714
(2120587)4int120590
2(119896 119901) 119866
0(119901)
10038161003816100381610038161003816119869119901
10038161003816100381610038161003816
2
1198894119901
(69)
is the bias related to an additional distribution of virtualwormholes and 120590
2(119896 119901) = Δ119873lowast(119896)Δ119873(119901)
1205902(119896 119901) =
1
119885total (0)int [119863119873] 119890
minus119868(119873)Δ119873
lowast(119896) Δ119873 (119901) (70)
defines the dispersion of vacuum topology fluctuations (hereΔ119873 = 119873 minus 119873) The exact definition of 1205902
(119896 119901) requires thefurther development of a fundamental theory In particular itcan be numerically calculated in lattice quantum gravity [28]However it can be shown that at scales 119896 119901 ≫ 119896pl it reducesto 1205902
(119896 119901) rarr 1205902
119896120575(119896 minus 119901) and therefore
120575119887 (119869) = minus1205902
119896
41205872
21198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(71)
Now comparing this function with (23) we relate the addi-tional distribution of virtual wormholes and the externalclassical field as
41205872
1198962(120575] (0 119869) minus 120575] (119896 119869)) =
1
21205902
119896
41205872
1198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(72)
where 120575](119896 119869) = int 1198862120575119873119865(119886 119896)119889119886 We point out that the
above expression does not define the value 120575](0 119869) whichrequires an additional considerationMoreover in general theexternal field 119869 does not possess a symmetry and therefore thecorrection ⟨120575119879
120572120573(119909)⟩ does not reduce to a single cosmological
Journal of Astrophysics 11
constant However such corrections always violate the aver-aged null energy condition [36 37] and may be considered assome kind of dark energy or by other words it represents anexotic matter Some portion of dark energy still has the formof the cosmological constant which defines a nonvanishingpresent day value (we recall that fermions give a contributionof the opposite sign)
120575Λ tot = minus2120587119866int4120587
2
1198962⟨120575] (0 119869) minus 120575] (119896 119869)⟩
1198894119896
(2120587)4
minus 121205872120575] (0 119869)
(73)
where ⟨120575](119896 119869)⟩ denotes an averaging over rotationsThe only unknown parameter in (72) is the dispersion
1205902
119896which defines the intensity of topology fluctuations in
the vacuum It has also the sense of the efficiency coefficientwhich defines the portion of the energy of the external fieldspent on the formation of additional wormholes Thoughthe evaluation of 1205902
119896requires the further development of a
fundamental theory one may expect that 1205902
119896= 119873(119896)(1 minus
119873(119896)) where 119873(119896) is the mean cutoff It is expected that119873(119896) rarr 0 as 119896 ≫ 119896pl and119873(119896) rarr 119873
0le 1 This means that
120590 rarr 0 as 119896 ≫ 119896pl and 120590 rarr 1205900≪ 1 as 119896 ≪ 119896pl while it takes
the maximum value 120590max sim 1 at Planckian scales 119896 sim 119896pl Byotherwords themost efficient transmission of the energy intowormholes takes place for wormholes of the Planckian sizeIn the case when external classical fields have characteristicscales 120582 = 2120587119896 ≫ ℓpl in (72) the efficiency coefficient 1205902
119896and
the cutoff 119873(119896) become constant 120590 ≃ 1205900 119873(119896) ≃ 119873
0 while
their ratiomay be estimated as 1205721205902
0119873
0= ΩDEΩ119887
where 120572 isthe effective number of fundamental fields which contributeto 120575Λ tot and ΩDE Ω119887
are dark energy and baryon energydensities respectively According to the modern picture thisratio gives ΩDEΩ119887
asymp 075005 = 15 while 1205902
0119873
0sim 1
(as 1198730≪ 1) and therefore this defines the estimate for the
effective number of fundamental fields (helicity states) as 120572 sim
15
65 Speculations on the Formation of Actual WormholesAs we already pointed out the additional distribution ofvirtual wormholes (72) reflects the symmetry of externalclassical fields and therefore it forms a homogeneous andisotropic background and perturbations We recall that vir-tual wormholes represent an exotic form of matter In theearly Universe such perturbations start to develop and mayform actual wormholes The rigorous description of sucha process represents an extremely complex and interestingproblemwhich requires the further study Some aspects of thebehavior of the exotic density perturbations were consideredin [7] while the simplest example of the formation of awormhole-type object was discussed recently by us in [38]Therefore we may expect that some portion of such a form ofdark energy is reserved now in actual wormholes which weconsider in the next section
7 Dark Energy from Actual Wormholes
Consider now the contribution to the dark energy fromthe gas of actual wormholes Unlike the virtual wormholesactual wormholes do exist at all times and therefore a singlewormhole can be viewed as a couple of conjugated cylinders1198793
plusmn= 119878
2
plusmntimes 119877
1 So that the number of parameters of an actualwormhole is less 120578 = (119886 119903
+ 119903
minus) where 119886 is the radius of 1198782
plusmn
and 119903plusmnisin 119877
3 is a spatial part of 119877plusmn
Actual wormholes also produce two kinds of contributionto the dark energy One comes from their contribution tothe mean curvature which corresponds to an exotic stressenergy momentum tensor Such a stress energy momentumtensor reflects the dark energy reserved by additional virtualwormholes discussed in the previous section Such energyis necessary to support actual wormholes as a solution tothe Einstein equations The second part comes from vacuumpolarization effects by actual wormholes The considerationin the previous section shows that for macroscopic worm-holes the second part has the order ⟨Δ119879
120572120573⟩ sim 8120587119866119899 and
is negligible as compared to the curvature 119877 sim 1198862119899 (since
macroscopic wormholes have throats 119886 ≫ ℓpl) Howeverfor the sake of completeness and for methodological aims wedescribe it as well
For rigorous evaluation of dark energy of the secondtype we first have to find the bias 119887
1(119909 119909
1015840 120578) analogous to
(19) for the topology 1198774(119879
3
+cup 119879
3
minus) There are many papers
treating different wormholes in this respect (eg see [36 37]and references therein) However in the present paper for anestimation we shall use a more simple trick
71 Beads of Virtual Wormholes (Quantum Wormhole)Indeed instead of the cylinders 1198793
plusmnwe consider a couple of
chains (beads of virtual wormholes 1198793
plusmnrarr cup
1198991198783
plusmn119899) Such an
idea was first suggested in [39] and one may call such anobject as quantum wormhole Then the bias can be writtenstraightforwardly
1198871(119909 119909
1015840 120578) =
+infin
sum
119899=minusinfin
1
41205872119886(
1
(119877minus119899
minus 1199091015840)2minus
1
(119877+119899
minus 1199091015840)2)
times [120575 (10038161003816100381610038161003816 minus
+119899
10038161003816100381610038161003816minus 119886) minus 120575 (
10038161003816100381610038161003816 minus
minus119899
10038161003816100381610038161003816minus 119886)]
(74)
where 119877plusmn119899
= (119905119899 119903
plusmn) with 119905
119899= 119905
0+ 2ℓ119899 and ℓ ge 119886 is the
step We may expect that upon averaging over the position1199050isin [minusℓ ℓ] the bias for the beads will reproduce the bias for
cylinders1198793
plusmn(at least it looks like a very good approximation)
We point out that the averaging out (12ℓ) intℓ
minusℓ119889119905
0and the
sum sum+infin
119899=minusinfinreduces to a single integral (12ℓ) intinfin
minusinfin119889119905 of the
zero term in (74) And moreover the resulting total biascorresponds merely to a specific choice of the distributionfunction 119865(120585) in (21) Namely we may take
119873119865 (120585) =1
2ℓ120575 (119905
+minus 119905
minus) 119891 (
1003816100381610038161003816119903+ minus 119903minus
1003816100381610038161003816 119886) (75)
12 Journal of Astrophysics
where119877plusmn= (119905
plusmn 119903
plusmn) and119891(119904 119886) is the distribution of cylinders
which can be taken as (119899 is 3-dimensional density)
119891 (120578) =119899 (119886)
41205871199032
0
120575 (119904 minus 1199030) (76)
Using the normalization condition int119873119865(120585)119889120585 = 119873 we findthe relation 119873 = (12ℓ)119899119881 = 119899119881 where 119899 is a 4-dimensional density of wormholes and 1(2ℓ) is the effectivenumber of wormholes on the unit length of the cylinder (iethe frequency with which the virtual wormhole appears atthe positions 119903
plusmn) This frequency is uniquely fixed by the
requirement that the volume which cuts the bead is equal tothat which cuts the cylinder (43)1205871198863 = (120587
22)119886
4(12ℓ) (ie
2ℓ = (31205878)119886 and 119899 = (83120587119886)119899) Thus we can use directlyexpression (23) and find (compare to (25))
119887 (119896) = minusint 119899 (119886) 1198862 4120587
2
1198962(1 minus
sin |k| 1199030|k| 1199030
)1198691(119896119886)
1198961198862119889119886 (77)
where 119896 = (1198960 k) Here the first term merely coincides with
that in (25) and therefore it gives the contribution to thecosmological constant 120575Λ(8120587119866) = minus1198994 = minus2119899(3120587119886)while the second term describes a correction which does notreduce to the cosmological constant and requires a separateconsideration
72 Stress Energy Tensor From (57) we find that the stressenergy tensor
minus⟨Δ119879120572120573
(119909)⟩ = int
119896120573119896120572minus (12) 119892
1205721205731198962
1198962119887 (119896 120585)
1198894119896
(2120587)4
(78)
reduces to the two functions
11987900
= 120576 = 1205821minus1
2120583
119879119894119895= 119901120575
119894119895 119901 =
1
31205822minus1
2120583
(79)
where 120576 + 3119901 = minus120583 and 1205821+ 120582
2= 120583 and these functions are
1205821= minusint
1198962
0
11989621198871198894119896
(2120587)4 120582
2= minusint
|k|2
11989621198871198894119896
(2120587)4 (80)
By means of the use of the spherical coordinates 11989620119896
2=
cos2120579 |k|21198962 = sin2120579 and 119889
4119896 = 4120587sin2
1205791198963119889119896119889120579 we get
120582119894=119899 (119886 119903
0)
4120573119894
(1 minus 2120573119894(119886
1199030
)
2
119891119894(119886
1199030
)) (81)
where 1205731= 1 120573
2= 13 and 119891
119894is given by
119891(1
2)(119910)
=2
120587int
1
minus1
int
infin
0
sin (119909 sin 120579)1198691(119910119909)
1199101199092(cos2120579sin2
120579) 119889119909 119889cos 120579
(82)
For 1198861199030≪ 1 we find
11989112
(119886
1199030
) asymp (1 + 11990012
(119886
1199030
)) (83)
Thus finally we find
120576 ≃ minus119899
4= minus
2119899
3120587119886 119901 ≃ 120576(1 minus
4
3(119886
1199030
)
2
) (84)
which upon the continuation to the Minkowsky space givesthe equation of state in the form (An arbitrary gas ofwormholes splits in fractions with a fixed 119886 and 119903
0)
119901 = minus(1 minus4
3(119886
1199030
)
2
) 120576 (85)
which in the case when 1198861199030≪ 1 behaves like a cosmological
constant However when 119886 ≫ ℓpl such a constant is extremelysmall and can be neglected while the leading contributioncomes from the mean curvature
73 Mean Curvature In this subsection we consider theMinkowsky spaceThen the simplest actual wormhole can bedescribed by the metric analogous to (1) for example see [7]
1198891199042= 119888
2119889119905
2minus ℎ
2(119903) 120575
120572120573119889119909
120572119889119909
120573 (86)
where ℎ(119903) = 1 + 120579(119886 minus 119903)(1198862119903
2minus 1) To avoid problems
with the Bianchi identity and the conservation of energy thestep function should be also smoothed as in (1) The stressenergy tensor which produces such a wormhole can be foundfrom the Einstein equation 8120587119866119879
120573
120572= 119877
120573
120572minus (12)120575
120573
120572119877 Both
regions 119903 gt 119886 and 119903 lt 119886 represent portions of the ordinaryflat Minkowsky space and therefore the curvature is 119877119896
119894equiv 0
However on the boundary 119903 = 119886 it has the singularity Sincethe metric (86) does not depend on time we find
1198770
0= 119877
0
120572= 0 119877
120573
120572=2
119886120575 (119886 minus 119903) 119899
120572119899120573+ 120575
120573
120572 + 120582
120573
120572 (87)
where 119899120572 = 119899120572= 119909
120572119903 is the outer normal to the throat 1198782
and 120582120573
120572are additional terms (eg see (49) and (51)) which
in the leading order are negligible upon averaging over someportion of space Δ119881 ≳ 119886
3 In the case of a set of wormholesthis gives in the leading order
1198770
0= 119877
0
120572= 0 119877
120573
120572= sum
2
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119903
119894
1003816100381610038161003816) 119899119894120572119899120573
119894+ 120575
120573
120572
(88)
where 119886119894is the radius of a throat and 119903
119894is the position of the
center of the throat in space and 119899120572
119894= (119909
120572minus 119903
120572
119894)|119903 minus 119903
119894|
In the case of a homogeneous and isotropic distribution ofsuch throats we find 119877
120573
120572= (13)119877120575
120573
120572(averaging over spatial
directions gives ⟨119899120572119899120573⟩ = (13)120575
120573
120572) where
119877 = minus8120587119866119879 = sum8
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119877
119894
1003816100381610038161003816) = 32120587int 119886119899 (119886) 119889119886
(89)
Journal of Astrophysics 13
where 119879 stands for the trace of the stress energy momentumtensor which one has to add to the Einstein equations tosupport such awormhole It is clear that such a source violatesthe weak energy condition and therefore it reproduces theformof dark energy (ie119879 = 120576+3119901 lt 0) If the density of suchsources (and resp the density of wormholes) is sufficientlyhigh then this results in the observed [10ndash14] accelerationof the scale factor for the Friedmann space as sim 119905
120572 with120572 = 21205763(120576 + 119901) = 2120576(2120576 + (120576 + 3119901)) gt 1 for examplesee also [40ndash42] In terms of the 4-dimensional density ofwormholes 119899 = (83120587119886)119899 we get 119877 sim 119886
2119899 ≫ 8120587119866119899 as 119886 ≫ ℓpl
and therefore the leading contribution indeed comes fromthe mean curvature
8 Estimates and Concluding Remarks
Now consider the simplest estimates Actual wormholes seemto be responsible for the dark matter [7 9] Therefore to getthe estimate to the number density of wormholes is ratherstraightforward First wormholes appear at scales when darkmatter effects start to display themselves that is at scales ofthe order 119871 sim (1 divide 5)Kpc which gives in that range thenumber density
119899 sim1
1198713sim (3 divide 0024) times 10
minus65cmminus3 (90)
The characteristic size of throats can be estimated from (89)120576DE sim (119866)
minus1119899119886 Since the density of dark energy is 120576DE1205760 =
ΩDE sim 075 where 1205760is the critical density then we find the
estimate
119886 sim2
3(1 divide 125) times 10
minus3119877⊙ΩDEℎ
2
75 (91)
where119877⊙is the Solar radius ℎ
75= 119867(75 km(secMpc)) and
119867 is the Hubble constant We also recall that the backgrounddensity of baryons 120576
119887generates a nonvanishingwormhole rest
mass119872119908= (43)120587119886
31198773120576119887(where119877(119905) is the scale factor of the
Universe and therefore 119872119908remains constant) for example
see [7] It produces the dark matter density related to thewormholes as 120576DM ≃ 119872
119908119899 The typical mass of a wormhole
119872119908is estimated as
119872119908sim 1 7 times (1 divide 125) times 10
2119872
⊙ΩDMℎ
2
75 (92)
where 119872⊙is the Solar mass We point out that this mass
has not the direct relation to the parameters of the gas ofwormholes However it defines the moment when wormholethroats separated from the cosmological expansion Theabove estimate shows that if wormholes form due to thedevelopment of perturbations in the exotic matter then thisprocess should start much earlier than the formation ofgalaxies
Thus we see that virtual wormholes should indeed leadto the regularization of all divergencies in QFT which agreeswith recent results [28] Therefore they form the local finitevalue of the cosmological constant In the absence of externalclassical fields such a value should be exactly zero at macro-scopic scales A some nonvanishing value for the cosmolog-ical constant appears as the result of vacuum polarization
effects in external fields Indeed external fields form anadditional distribution of virtual wormholes which possessan exotic stress energy tensor (some kind of dark energy)Only some part of it forms the cosmological constant whilethe rest reflects the symmetry of external fields and possessesinhomogeneitiesWe assume that during the evolution of ourUniverse inhomogeneities in the exotic matter develop andmay form actual wormholes Although this problem requiresthe further and more deep investigation we refer to [38]where the formation of a simplest wormhole-like object hasbeen considered In other words such polarization energyis reserved now in a gas of actual wormholes We estimatedparameters of such a gas and believe that such a gas mayindeed be responsible for both dark matter and dark energyphenomena
References
[1] J R Primack ldquoThe nature ofdark matterrdquo httparxivorgabsastro-ph0112255
[2] J Diemand M Zemp B Moore J Stadel and M CarolloldquoCusps in cold dark matter haloesrdquoMonthly Notices of the RoyalAstronomical Society vol 364 no 2 pp 665ndash673 2005
[3] E W Mielke and J A V Velez Perez ldquoAxion condensate as amodel for dark matter halosrdquo Physics Letters B vol 671 no 1pp 174ndash178 2009
[4] G Gentile P Salucci U Klein D Vergani and P Kalberla ldquoThecored distribution of dark matter in spiral galaxiesrdquo MonthlyNotices of the Royal Astronomical Society vol 351 no 3 pp 903ndash922 2004
[5] D T F Weldrake W J G de Blok and F Walter ldquoA high-resolution rotation curve of NGC 6822 a test-case for cold darkmatterrdquo Monthly Notices of the Royal Astronomical Society vol340 no 1 pp 12ndash28 2003
[6] W J G de Blok andA Bosma ldquoHigh-resolution rotation curvesof low surface brightness galaxiesrdquoAstronomy and Astrophysicsvol 385 pp 816ndash846 2002
[7] A Kirillov and E P Savelova ldquoDensity perturbations in a gas ofwormholesrdquoMonthly Notices of the Royal Astronomical Societyvol 412 no 3 pp 1710ndash1720 2011
[8] P Kanti B Kleihaus and J Kunz ldquoStable Lorentzianwormholesin dilatonic Einstein-Gauss-Bonnet theoryrdquo Physical Review Dvol 85 no 4 Article ID 044007 2012
[9] A A Kirillov and E P Savelova ldquoDark matter from a gas ofwormholesrdquo Physics Letters B vol 660 no 3 pp 93ndash99 2008
[10] A G Riess A V Filippenko P Challis et al ldquoObservationalevidence from supernovae for an accelerating universe and acosmological constantrdquo The Astronomical Journal vol 116 no3 p 1009 1998
[11] S Perlmutter G Aldering G Goldhaber et al ldquoMeasurementsofΩ andΛ from42high-redshift supernovaerdquoTheAstrophysicalJournal vol 517 no 2 p 565 1999
[12] J L Tonry B P Schmidt B Barris et al ldquoCosmological resultsfromhigh-z supernovaerdquoTheAstrophysical Journal vol 594 no1 p 594 2003
[13] N W Halverson E M Leitch C Pryke et al ldquoDegreeangular scale interferometer first results a measurement of thecosmic microwave background angular power spectrumrdquo TheAstrophysical Journal vol 568 no 1 p 38 2002
14 Journal of Astrophysics
[14] C B Netterfield P A R Ade J J Bock et al ldquoA measurementby BOOMERANGofmultiple peaks in the angular power spec-trum of the cosmic microwave backgroundrdquo The AstrophysicalJournal vol 571 no 2 p 604 2002
[15] S Coleman ldquoWhy there is nothing rather than something atheory of the cosmological constantrdquoNuclear Physics B vol 310no 3-4 pp 643ndash668 1988
[16] I Klebanov L Susskind and T Banks ldquoWormholes and thecosmological constantrdquo Nuclear Physics B vol 317 no 3 pp665ndash692 1989
[17] S W Hawking ldquoSpacetime foamrdquoNuclear Physics B vol 114 p349 1978
[18] T P Cheng and L F Li Gauge Theory of Elementary ParticlesClarendon Press Oxford UK 1984
[19] A H Taub ldquoSpace-times with distribution valued curvaturetensorsrdquo Journal ofMathematical Physics vol 21 no 6 pp 1423ndash1431 1980
[20] A Shatsky privite communications[21] V A Fock ldquoZur Theorie des Wasserstoffatomsrdquo Zeitschrift fur
Physik vol 98 no 3-4 pp 145ndash154 1935[22] E P Savelova ldquoGas of wormholes in Euclidean quantum field
theoryrdquo httparxivorgabs12115106[23] A A Kirillov and E P Savelova ldquoOn the behavior of
bosonic systems in the presence of topology fluctuationsrdquohttparxivorgabs08082478
[24] A A Kirillov ldquoViolation of the Pauli principle and dimensionof the Universe at very large distancesrdquo Physics Letters B vol555 no 1-2 pp 13ndash21 2003
[25] A A Kirillov ldquoDark matter dark charge and the fractalstructure of the Universerdquo Physics Letters B vol 535 no 1ndash4pp 22ndash24 2002
[26] J Ambjorn J Jurkiewicz and R Loll ldquoThe spectral dimensionof the universe is scale dependentrdquo Physical Review Letters vol95 no 17 Article ID 171301 4 pages 2005
[27] E Manrique S Rechenberger and F Saueressig ldquoAsymptoti-cally safe Lorentzian gravityrdquo Physical Review Letters vol 106no 25 Article ID 251302 4 pages 2011
[28] J Laiho and D Coumbe ldquoEvidence for asymptotic safety fromlattice quantum gravityrdquo Physical Review Letters vol 107 no 16Article ID 161301 2011
[29] A A Kirillov and D Turaev ldquoOn modification of the Newtonrsquoslaw of gravity at very large distancesrdquo Physics Letters B vol 532no 3-4 pp 185ndash192 2002
[30] A A Kirillov and D Turaev ldquoThe universal rotation curveof spiral galaxiesrdquo Monthly Notices of the Royal AstronomicalSociety vol 371 no 1 pp L31ndashL35 2006
[31] A A Kirillov and D Turaev ldquoFoam-like structure of theuniverserdquo Physics Letters B vol 656 pp 1ndash8 2007
[32] A A Kirillov ldquoThe nature of dark matterrdquo Physics Letters B vol632 no 4 pp 453ndash462 2006
[33] A A Kirillov and E P Savelova ldquoAstrophysical effects of space-time foamrdquo Gravitation and Cosmology vol 14 no 3 pp 256ndash261 2008
[34] S W Hawking and N Turok ldquoOpen inflation without falsevacuardquo Physics Letters B vol 425 no 1-2 pp 25ndash32 1998
[35] Z C Wu ldquoThe cosmological constant is probably zero and aproof is possibly rightrdquo Physics Letters B vol 659 no 5 pp 891ndash893 2008
[36] R Garattini ldquoEntropy and the cosmological constant aspacetime-foam approachrdquo Nuclear Physics B vol 88 no 1ndash3Article ID 991003 pp 297ndash300 2000
[37] MVisserLorentzianWormholes SpringerNewYorkNYUSA1996
[38] A A Kirillov and E P Savelova ldquoArtificial wormholerdquohttparxivorgabs12040351
[39] E W Mielke ldquoKnot wormholes in geometrodynamicsrdquo Gen-eral Relativity and Gravitation vol 8 no 3 pp 175ndash196 1977
[40] E B Gliner ldquoAlgebraic properties of the energy-momentumtensor and vacuum-like states of matterrdquo Journal of Experimen-tal and Theoretical Physics vol 22 p 378 1966
[41] A H Guth ldquoInflationary universe a possible solution to thehorizon and flatness problemsrdquo Physical Review D vol 23 no2 pp 347ndash356 1981
[42] A A Linde ldquoA new inflationary universe scenario a possiblesolution of the horizon flatness homogeneity isotropy andprimordial monopole problemsrdquo Physics Letters B vol 108 no6 pp 389ndash393 1982
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
![Page 7: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/7.jpg)
Journal of Astrophysics 7
119904 = 119904minus 119904+ respectivelyThe gluing procedure at throatsmeans
merely that we identify points at 120579 = 0 and 120579 = 2120587 and allphysical functions in the space 119877
4 with a single wormhole120585 become periodic functions of 120579 Thus the coordinatetransformation 119909 = 119909(120579 119909
perp
0) gives the map of the above space
onto the cylinder with a specific metric 1198891198972 = (119889(120579 119909perp
0))
2
=
119892120572120573119889119910
120572119889119910
120573 (where 119910 = (120579 119909perp
0)) whose components are also
periodic in terms of 120579 Now we can continue the coordinatesto thewhole space1198774 (to construct a cover of the fundamentalregion 120579 isin [0 2120587]) simply admitting all valuesminusinfin lt 120579 lt +infin
this however requires to introduce the bias
1
radic119892120575 (120579 minus 120579
1015840) 997888rarr 119873(120579 minus 120579
1015840) =
+infin
sum
119899=minusinfin
1
radic119892120575 (120579 minus 120579
1015840+ 2120587119899)
(38)
since every point and every source in the fundamental regionacquires a countable set of images in the nonphysical region(inside of wormhole throats) Considering now the Fouriertransforms for 120579 we find
119873(119896 1198961015840) =
+infin
sum
119899=minusinfin
120575 (119896 minus 119899) 120575 (119896 minus 1198961015840) (39)
We point out that the above bias gives the unit operator in thespace of periodic functions of 120579 From the standpoint of allpossible functions on 1198774 it represents the projection operator
2= (120585) (taking an arbitrary function 119891 we find that upon
the projection 119891119873= 119891 119891
119873becomes a periodic function of
120579 that is only periodic functions survive)The above construction can be easily generalized to the
presence of a set of wormholes In the approximation of adilute gas of wormholes we may neglect the influence ofwormholes on each other (at least there always exists a suf-ficiently smooth map which transforms the family of linesof force for ldquoindependentrdquo wormholes onto the actual lines)Then the total bias (projection) may be considered as theproduct
119873total (119909 1199091015840) = int(prod
119894
radic1198921198941198894119910119894)119873(120585
1 119909 119910
1)
times 119873 (1205852 119910
1 119910
2) sdot sdot sdot 119873 (120585
119873 119910
119873minus1 119909
1015840)
(40)
where 119873(120585119894 119909 119909
1015840) is the bias for a single wormhole with
parameters 120585119894 Every such a particular bias119873(120585
119894 119909 119909
1015840) realizes
projection on a subspace of functions which are periodic withrespect to a particular coordinate 120579
119894(119909) while the total bias
gives the projection onto the intersection of such particularsubspaces (functions which are periodic with respect to everyparameter 120579
119894)
5 Cutoff
The projective nature of the bias operator 119873(119909 1199091015840) allows us
to express the cutoff function 119873(119896) via dynamic parametersof wormholes Indeed consider a box 1198714 in 119877
4 and periodic
boundary conditions which gives 119896 = 2120587119899119871 (in final expres-sions we consider the limit 119871 rarr infin which gives sum
119896rarr
(1198714(2120587)
4) int 119889
4119896) And let us consider the decomposition for
the integration measure in (33) as
119868 = 1198680+sum120582
1(119896)119873 (119896) +
1
2sum120582
2(119896 119896
1015840)119873 (119896)119873 (119896
1015840) + sdot sdot sdot
(41)
where 1205821(119896) includes also the contribution from 119885
0(119896) We
point out that this measure plays the role of the action for thebias119873(119896) Indeed the variation of the above expression givesthe equation of motions for the bias in the form
sum
1198961015840
1205822(119896 119896
1015840)119873 (119896
1015840) = minus120582
1(119896) (42)
which can be found by considering the proper dynamics ofwormholes We however do not consider the problem of thedynamic description of wormholes here and leave this forthe future research Moreover we may expect that in the firstapproximation one may retain the linear term only Indeedthis takes place when119873(119896) is not a dynamic variable or if wetake into account that 119873(119896) is a collective variable Then theprojective nature of the bias 119873(119896) = 0 1 means that it canbe phenomenologically expressed via some Fermionic ghostfield Ψ(119896) (eg 119873(119896 119896
1015840) = Ψ(119896)Ψ
+(119896
1015840)) where the negative
and positive frequency parts of the operator Ψ(119896) obey theanticommutation relationsΨ+
(119896)Ψ(1198961015840)+Ψ(119896
1015840) Ψ
+(119896) = 120575(119896minus
1198961015840) In the absence of ghost particles Ψ(119896)|0⟩ = 0 we get
119873(119896 1198961015840) = 120575(119896 minus 119896
1015840) that is 119873(119896) = 1 and wormholes
are absent In the term of the ghost field the action becomes119868(119873) = 119868
0+ (Ψ
1Ψ) + sdot sdot sdot Therefore in the leading approx-
imation equations of motion take the linear form 1Ψ = 0
Thus taken into account that 119873(119896) = 0 1 (1198732= 119873) we
find
119873(119896) =1
119885total (119896)sum
119873=01
119890minus1205821
(119896)119873(119896)119873(119896) =
119890minus1205821
(119896)
1 + 119890minus1205821(119896) (43)
The simplest choice gives merely 1205821(119896) = minussum ln119885
0(119896)
where the sum is taken over the number of fields and 1198850(119896)
is given by 1198850(119896) = radic120587(1198962 + 1198982) In the case of a set
of massless fields we find 119873(119896) = 119885(119896)(1 + 119885(119896)) where119885(119896) = (radic120587119896)
120572 and 120572 is the effective number of degreesof freedom (the number of boson minus fermion fields) Toensure the absence of divergencies one has to consider thenumber of fields 120572 gt 4 [23] However such a choice givesthe simplest estimate which in general cannot be correctIndeed while its behavior at very small scales (ie whenexceeding the Planckian scales 119885(119896) ≲ 1 and 119873(119896) = 119885(119896))may be physically accepted since it produces some kind of acutoff on the mass-shell 1198962 + 119898
2rarr 0 it gives the behavior
119873(119896) rarr 1 which is merely incorrect (eg from (27) we seethat the true behavior should be119873(119896) rarr const lt 1)
One may expect that the true cutoff function has a muchmore complex behavior Indeed some theoretical models inparticle physics (eg string theory) have the property tobe lower-dimensional at very small scales The mean cutoff
8 Journal of Astrophysics
119873(119896) gives the natural tool to describe a scale-dependantdimensional reduction [24 25] In fact this function definesthe spectral number of modes in the interval between 119896 and119896 + 119889119896 as
int119873 (119896)1198894119896
(2120587)4= int
119873 (119896) 1198964
(2120587)2
119889119896
119896 (44)
Hence we can define the effective spectral dimension 119863 ofspace as follows
1198964119873(119896) sim 119896
119863 (45)
From the empirical standpoint the dimension 119863 = 4 isverified at laboratory scales only while the rigorous tool todefine the spectral density of states (or the mean cutoff) cangive the lattice quantum gravity for example see [26 27]and references therein And indeed the spectral dimensionfor nonperturbative quantum gravity defined via Euclideandynamical triangulations was calculated recently in [28] Itturns out that it runs from a value of119863 = 32 at short distanceto 119863 = 4 at large distance scales We also point out that allobserved dark matter phenomena can be explained by thefractal dimension119863 asymp 2 starting from scales 119871 ≳ (1 divide 5)Kpcfor example [29ndash33]
6 Cosmological Constant
Let us consider the total Euclidean action [17]
119868119864= minus
1
16120587119866int (119877 minus 2Λ
0)radic119892119889
4119909 minus int119871
119898radic1198921198894119909 (46)
The variation of the above action leads to the Einstein equa-tions
119877119886119887minus1
2119892119886119887119877 + 119892
119886119887Λ
0= 8120587119866119879
119886119887 (47)
where 119879119886119887= (12)(119892)
minus12(120575119871
119898120575119892
119886119887) is the stress energy ten-
sor and Λ0is a naked cosmological constant In cosmology
such equations are considered from the classical standpointwhich means that they involve characteristic scales ℓ ≫ ℓplHowever the presence of virtual wormholes at Planckianscales defines some additional contribution in both parts ofthese equations which can be adsorbed into the cosmologicalconstant Therefore the total cosmological constant can bedefined as
Λ tot = Λ0+ Λ
119898+ Λ
119877= Λ
0+ 2120587119866 ⟨119879⟩ +
1
4⟨119877⟩119908 (48)
where ⟨119879⟩ is the energy of zero-point fluctuations (It includesalso the contribution of zero-point fluctuations of gravitons)That is themean vacuum value (we recall that in the standardQFTΛ
119898is infinite while wormholes form a finite value) and
⟨119877⟩119908
= Λ119877is a contribution of wormholes into the mean
curvature due to gluing (1)
61 Contribution of Virtual Wormholes into Mean CurvatureConsider a single wormhole whose metric is given by (1)
1198891199042= ℎ
2(119903)120575
120572120573119889119909
120572119889119909
120573 then the components of the Riccitensor are (We are much obliged to the Referee who pointedout to the subtleties when working with a step function in themetric)
119877120572120573
= 7 minus (ℎ1015840
ℎ)
1015840
(120575120572120573
+ (119873 minus 2) 119899120572119899120573)
minus1
119903
ℎ1015840
ℎ((119873 minus 2) Δ
120572120573+ 120575
120572120573(119873 minus 1))
minus (ℎ1015840
ℎ)
2
(119873 minus 2) Δ120572120573
(49)
where 119899]= 119909
]119886 is the unite normal vector to the throat
surface Δ120572120573
= 120575120572120573
minus 119899120572119899120573 ℎ1015840 = 120597ℎ120597119903 and119873 is the number
of dimensions The curvature scalar is
119877 = minus(119873 minus 1)
ℎ2[2
ℎ10158401015840
ℎ+ 2
1
119903
ℎ1015840
ℎ(119873 minus 1) + (
ℎ1015840
ℎ)
2
(119873 minus 4)]
(50)
Then substituting ℎ = 1 + (1198862119903
2minus 1)120579 in the above equation
we find
minusℎ4
119873 minus 1119877 = 4ℎ
1198862
1199033120575 +
2ℎ
119903119873minus1(119903
119873minus1120582)
1015840
+ (119873 minus 4)(1205822minus 4120579
1198862
1199033120582)
+ 4 (119873 minus 4)1198862
1199034120579 (120579 minus 1)
(51)
where 120579 is a smooth function which only in a limit becomesa step function 120582 = (1 minus 119886
2119903
2)120575 and 120575 = minus120579
1015840 In the limit120579 rarr 120579(119886 minus 119903) we find 120575 rarr 120575(119903 minus 119886) and the last two terms in(51) are negligible as compared to the first two terms while infour dimensions the last two terms vanishThen the curvatureis concentrated on the throat of the wormhole where 120579 differsfrom the step function In the limit of a vanishing throat sizewe have ℎ rarr 1 at the throat and we get
minus119877 =4 (119873 minus 1)
119886120575 (119903 minus 119886) +
2 (119873 minus 1)
119903119873minus1(119903
119873minus3(119903
2minus 119886
2) 120575)
1015840
(52)
In general all the terms together in (51) and analogous termsin the Ricci tensor provide that the Bianchi identity holdsand the energy is conserved [19] Therefore none of themcan be dropped out However it is easy to see the leadingcontribution to the integral over space comes from the firstterm only and in the limit of a vanishing throat size we findfor a single wormhole
1
4int119877radic119892119889
4119909 = minus6120587
21198862 (53)
Journal of Astrophysics 9
In the case of a set of wormholes (24) we find
1
4int119877radic119892119889
4119909 = minus6120587
2sum
119895
1198862
119895
= minus121205872int119899 (119886) 119886
2119889119886 119889
4119909 = intΛ
1198771198894119909
(54)
where 2119899(119886) = int 119899(119886 1199030)119889119903
0is the density of wormhole
throats with a fixed value of the throat size 119886 This definesthe contribution to the cosmological constant from the meancurvature as
Λ119877= minus12120587
2int119899 (119886) 119886
2119889119886 lt 0 (55)
We see that this quantity is always negative
62 Stress Energy Tensor In this section we consider thecontribution from matter fields In the case of a scalar fieldthe stress energy tensor has the form
minus119879120572120573
(119909) = 120597120572120593120597
120573120593 minus
1
2119892120572120573
(120597120583120593120597
120583120593 + 119898
21205932) (56)
Then the mean vacuum value of the stress energy tensor canbe obtained directly from the two-point green function (32)(35) as
minus ⟨119879120572120573
(119909)⟩
= lim1199091015840
rarr119909
(1205971205721205971015840
120573minus1
2119892120572120573
(1205971205831205971015840
120583+ 119898
2)) ⟨119866 (119909 119909
1015840 120585)⟩
(57)
By means of using the Fourier transform 119866(119909 1199091015840 120585) =
int 119890minus119894119896(119909minus119909
1015840
)119866(119896 120585) (119889
4119896(2120587)
4) and the expressions (32) (35)
we arrive at
⟨119879120572120573
(119909)⟩ =1
4119892120572120573
int(1 +119898
2
1198962 + 1198982)119873 (119896)
1198894119896
(2120587)4 (58)
where the property int 119896120572119896120573119891(119896
2)119889
4119896 = (14)119892
120572120573int 119896
2119891(119896
2)119889
4119896
has been used and 119873(119896) = ⟨119873(119896 120585)⟩ is the cutoff function(36)
For the sake of simplicity we consider the massless caseThen by the use of the cutoff 119873(119896) = 120587
1205722(120587
1205722+ 119896
120572) from
the previous section we get the finite estimate (120572 gt 4 is theeffective number of the field helicity states)
Λ119898=2120587119866sumint
1205871205722
1205871205722+119896120572
1198894119896
(2120587)4=120587119866
4Γ (
120572 minus 4
120572) Γ (
4
120572) sim 1
(59)
where the sum is taken over the number of fields Since theleading contribution comes here from very small scales wemay hope that this value will not essentially change if thetrue cutoff function changes the behavior on the mass-shellas 119896 rarr 0 (eg if we take 120582
1(119896) = minussum ln119885
0(119896) + 120575120582(119896) with
120575120582(119896) ≪ ln1198850(119896) as 119896 ≫ 1)
To understand how wormholes remove divergencies itwill be convenient to split the bias function into two parts119873(119896 120585) = 1 + 119887(119896 120585) where 1 corresponds to the standardEuclidean contribution while 119887(119896 120585) is the contribution ofwormholes The first part gives the well-known divergentcontribution of vacuumfield fluctuations 8120587119866⟨1198790
120572120573⟩ = Λ
lowast119892120572120573
with Λlowast
rarr +infin while the second part remains finite forany finite number of wormholes and due to the projectivenature of the bias described in the previous section itpartially compensates (reduces) the value of the cosmologicalconstant that is 8120587119866⟨Δ119879
120572120573⟩ = 120575Λ119892
120572120573 where 120575Λ =
sum119873120588119873120575Λ(119873) and 120575Λ(119873) is a negative finite contribution of
a finite set of wormholesConsider now the particular distribution of virtual
wormholes (24) and evaluate their contribution tothe cosmological constant which is given by 120575Λ(119873) =
2120587119866int 119887(119896) (1198894119896(2120587)
4) = 2120587119866119887total(0) Then from the ex-
pressions (22) and (24) we get
119887total (0) = minus119899
4120587411988631199033
0
int(1 minus1198862
1198772
minus
)120575 (119877+minus 119886)
times 120575 (1003816100381610038161003816119877+
minus 119877minus
1003816100381610038161003816 minus 1199030) 119889
4119877minus1198894119877+
(60)
which gives
119887total (0) = minus119899(1 minus 119891(119886
1199030
)) (61)
where
119891(119886
1199030
) =2
120587int
120587
0
1198862sin2
120579119889120579
1198862 + 21198861199030cos 120579 + 119903
2
0
(62)
For 1198861199030≪ 1 (we recall that by the construction 119886119903
0le 12)
this function has the value 119891(1198861199030) asymp 119886
2119903
2
0 Thus for the
contribution of wormholes we find
120575Λ119898= minus2120587119866int119899 (119886 119903
0) (1 minus 119891(
119886
1199030
))119889119886 1198891199030
= minus2120587119866119899 (1 minus ⟨119891⟩)
(63)
63 Vacuum Value of the Cosmological Constant From theabove expression we see that to get the finite value of thecosmological constant Λ
119898= Λ
lowast+ 120575Λ
119898lt infin one should
consider the limit 119899 rarr infin (infinite density of virtualwormholes) which requires considering the smaller andsmaller wormholes From the other handwe have the obviousrestriction int 2119899(119886 119903
0)(120587
22)119886
4119889119886 119889119903
0lt 1 where (120587
22)119886
4
is the volume of one throat (wormholes cannot cut morethan the total volume of space) (We also point out that inremoving divergencies the leading role plays the zero-pointenergy Indeed 120575Λ
119898sim minus2120587119866119899 while the mean curvature has
the order Λ119877sim minus119886
2119899 and for 119886 ≪ ℓpl we have 120575Λ119898
≫ Λ119877
Moreover in the limit 119899 rarr infin one gets 119886 rarr 0 and thereforeΛ
119877120575Λ
119898rarr 0)Therefore in the leading order it seems to be
sufficient to retain point-like wormholes only (ie consider
10 Journal of Astrophysics
the limit 119886 rarr 0) Then instead of (24) we may assume thevacuum distribution of virtual wormholes in the form
119873119865 (119886119883) =1
1198862120575 (119886) ] (119883) (64)
where ](119883) = int 1198862119873119865(119886119883)119889119886 and int(1119886
2)](119883)119889
4119883 =
119899 rarr infin has the meaning of the infinite density of point-like wormholes while ] sim 119886
2119899 remains a finite In this case
the volume cut by wormholes vanishes int 2119899(12058722)119886
4119889119886 119889119903
0=
1198862int ](119883)119889
4119883 rarr 0 and the rarefied gas approximationworks
wellThis defines the bias and themean cutoff (here we definethe Fourier transform ](119896) = int ](119883)119890
1198941198961198831198894119883) as
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (65)
The contribution to themean curvature (55) can be expressedvia the same function ](119896) as
Λ119877= minus12120587
2int119899 (119886 119903
0) 119886
2119889119886 119889119903
0
= minus121205872int ] (119883) 119889
4119883 = minus12120587
2] (0)
(66)
Thus for the total cosmological constant we get the expres-sion
Λ tot = Λ0
+ 2120587119866int(1minus4120587
2
1198962(] (0)minus] (119896)))
1198894119896
(2120587)4minus12120587
2] (0)
(67)
We stress that all these terms should be finite Indeed all dis-tributions of virtual wormholes ](119896) which lead to an infinitevalue of Λ tot are suppressed in (5) by the factor sim119890minusintΛ tot119889
4
119909while the minimal value is reached when wormholes cut allof the volume of space and the action is merely 119878 = 0(Frankly speaking this statement is not rigorous At first lookthe two last terms in (67) are independent and one may tryto take ](0) an arbitrary big If this were the case then theaction would not possess the minimum at all However ](0)cannot be arbitrary big since it will violate the rarefied gasapproximation and the linear expression (67) brakes downMoreover fermions give here a contribution of the oppositesign The rigorous investigation of this problem requires thefurther studying and we present it elsewhere) We also pointout that here we considered the real scalar field as the mattersource while in the general case the stress energy tensorshould include all existing Bose and Fermi fields (Fermi fieldsgive a negative contribution to Λ
119898)
The value of Λ0looks like a free parameter which in
quantum gravity runs with scales [27] However at largescales its asymptotic value may be uniquely fixed by thesimple arguments as follows Indeed in quantum field theoryproperties of the ground state (vacuum) change when weimply an external classical fields The same is true for thedistribution of virtualwormholes ](119896 119869) for example see (33)and (37) and therefore Λ tot = Λ tot(119869) which we describe
in the next subsection We recall that in gravity the role ofthe external current plays the stress energy tensor of matterfields 119869 = 119879
119886119887 However one believes that in the absence
of all classical fields the vacuum state should represent themost symmetric (Lorentz invariant) state which in our casecorresponds to the Euclidean space In order to be consistentwith the Einstein equations this requires Λ tot(119869 = 0) = 0
which uniquely fixes the value of Λ0in (67) We point out
that from somewhat different considerations such a choicewas advocated earlier in [15 34 35]
64 Vacuum Polarization in an External Field Consider nowtopology fluctuations in the presence of an external currentIn the presence of an external current 119869ext the distribution ofvirtual wormholes changes ](119896 119869) = ](119896) + 120575](119896 119869) Indeedin (33) for the case of a weak external field the contributionof the external current into the action can be expanded asexp(minus119881(119869)) ≃ 1 minus 119881 where
119881 = minus1
2int 119869 (119909) 119866 (119909 119910) 119869 (119910) 119889
4119909 119889
4119910
= minus1
2
1198714
(2120587)4int119866
0(119896)119873 (119896)
10038161003816100381610038161198691198961003816100381610038161003816
2
1198894119896
(68)
Then using (36) we find119873(119896 119869) = 119873(119896 0) + 120575119873(119896 119869) where
120575119873 (119896 119869) = 120575119887 (119869) ≃ minus1
2
1198714
(2120587)4int120590
2(119896 119901) 119866
0(119901)
10038161003816100381610038161003816119869119901
10038161003816100381610038161003816
2
1198894119901
(69)
is the bias related to an additional distribution of virtualwormholes and 120590
2(119896 119901) = Δ119873lowast(119896)Δ119873(119901)
1205902(119896 119901) =
1
119885total (0)int [119863119873] 119890
minus119868(119873)Δ119873
lowast(119896) Δ119873 (119901) (70)
defines the dispersion of vacuum topology fluctuations (hereΔ119873 = 119873 minus 119873) The exact definition of 1205902
(119896 119901) requires thefurther development of a fundamental theory In particular itcan be numerically calculated in lattice quantum gravity [28]However it can be shown that at scales 119896 119901 ≫ 119896pl it reducesto 1205902
(119896 119901) rarr 1205902
119896120575(119896 minus 119901) and therefore
120575119887 (119869) = minus1205902
119896
41205872
21198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(71)
Now comparing this function with (23) we relate the addi-tional distribution of virtual wormholes and the externalclassical field as
41205872
1198962(120575] (0 119869) minus 120575] (119896 119869)) =
1
21205902
119896
41205872
1198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(72)
where 120575](119896 119869) = int 1198862120575119873119865(119886 119896)119889119886 We point out that the
above expression does not define the value 120575](0 119869) whichrequires an additional considerationMoreover in general theexternal field 119869 does not possess a symmetry and therefore thecorrection ⟨120575119879
120572120573(119909)⟩ does not reduce to a single cosmological
Journal of Astrophysics 11
constant However such corrections always violate the aver-aged null energy condition [36 37] and may be considered assome kind of dark energy or by other words it represents anexotic matter Some portion of dark energy still has the formof the cosmological constant which defines a nonvanishingpresent day value (we recall that fermions give a contributionof the opposite sign)
120575Λ tot = minus2120587119866int4120587
2
1198962⟨120575] (0 119869) minus 120575] (119896 119869)⟩
1198894119896
(2120587)4
minus 121205872120575] (0 119869)
(73)
where ⟨120575](119896 119869)⟩ denotes an averaging over rotationsThe only unknown parameter in (72) is the dispersion
1205902
119896which defines the intensity of topology fluctuations in
the vacuum It has also the sense of the efficiency coefficientwhich defines the portion of the energy of the external fieldspent on the formation of additional wormholes Thoughthe evaluation of 1205902
119896requires the further development of a
fundamental theory one may expect that 1205902
119896= 119873(119896)(1 minus
119873(119896)) where 119873(119896) is the mean cutoff It is expected that119873(119896) rarr 0 as 119896 ≫ 119896pl and119873(119896) rarr 119873
0le 1 This means that
120590 rarr 0 as 119896 ≫ 119896pl and 120590 rarr 1205900≪ 1 as 119896 ≪ 119896pl while it takes
the maximum value 120590max sim 1 at Planckian scales 119896 sim 119896pl Byotherwords themost efficient transmission of the energy intowormholes takes place for wormholes of the Planckian sizeIn the case when external classical fields have characteristicscales 120582 = 2120587119896 ≫ ℓpl in (72) the efficiency coefficient 1205902
119896and
the cutoff 119873(119896) become constant 120590 ≃ 1205900 119873(119896) ≃ 119873
0 while
their ratiomay be estimated as 1205721205902
0119873
0= ΩDEΩ119887
where 120572 isthe effective number of fundamental fields which contributeto 120575Λ tot and ΩDE Ω119887
are dark energy and baryon energydensities respectively According to the modern picture thisratio gives ΩDEΩ119887
asymp 075005 = 15 while 1205902
0119873
0sim 1
(as 1198730≪ 1) and therefore this defines the estimate for the
effective number of fundamental fields (helicity states) as 120572 sim
15
65 Speculations on the Formation of Actual WormholesAs we already pointed out the additional distribution ofvirtual wormholes (72) reflects the symmetry of externalclassical fields and therefore it forms a homogeneous andisotropic background and perturbations We recall that vir-tual wormholes represent an exotic form of matter In theearly Universe such perturbations start to develop and mayform actual wormholes The rigorous description of sucha process represents an extremely complex and interestingproblemwhich requires the further study Some aspects of thebehavior of the exotic density perturbations were consideredin [7] while the simplest example of the formation of awormhole-type object was discussed recently by us in [38]Therefore we may expect that some portion of such a form ofdark energy is reserved now in actual wormholes which weconsider in the next section
7 Dark Energy from Actual Wormholes
Consider now the contribution to the dark energy fromthe gas of actual wormholes Unlike the virtual wormholesactual wormholes do exist at all times and therefore a singlewormhole can be viewed as a couple of conjugated cylinders1198793
plusmn= 119878
2
plusmntimes 119877
1 So that the number of parameters of an actualwormhole is less 120578 = (119886 119903
+ 119903
minus) where 119886 is the radius of 1198782
plusmn
and 119903plusmnisin 119877
3 is a spatial part of 119877plusmn
Actual wormholes also produce two kinds of contributionto the dark energy One comes from their contribution tothe mean curvature which corresponds to an exotic stressenergy momentum tensor Such a stress energy momentumtensor reflects the dark energy reserved by additional virtualwormholes discussed in the previous section Such energyis necessary to support actual wormholes as a solution tothe Einstein equations The second part comes from vacuumpolarization effects by actual wormholes The considerationin the previous section shows that for macroscopic worm-holes the second part has the order ⟨Δ119879
120572120573⟩ sim 8120587119866119899 and
is negligible as compared to the curvature 119877 sim 1198862119899 (since
macroscopic wormholes have throats 119886 ≫ ℓpl) Howeverfor the sake of completeness and for methodological aims wedescribe it as well
For rigorous evaluation of dark energy of the secondtype we first have to find the bias 119887
1(119909 119909
1015840 120578) analogous to
(19) for the topology 1198774(119879
3
+cup 119879
3
minus) There are many papers
treating different wormholes in this respect (eg see [36 37]and references therein) However in the present paper for anestimation we shall use a more simple trick
71 Beads of Virtual Wormholes (Quantum Wormhole)Indeed instead of the cylinders 1198793
plusmnwe consider a couple of
chains (beads of virtual wormholes 1198793
plusmnrarr cup
1198991198783
plusmn119899) Such an
idea was first suggested in [39] and one may call such anobject as quantum wormhole Then the bias can be writtenstraightforwardly
1198871(119909 119909
1015840 120578) =
+infin
sum
119899=minusinfin
1
41205872119886(
1
(119877minus119899
minus 1199091015840)2minus
1
(119877+119899
minus 1199091015840)2)
times [120575 (10038161003816100381610038161003816 minus
+119899
10038161003816100381610038161003816minus 119886) minus 120575 (
10038161003816100381610038161003816 minus
minus119899
10038161003816100381610038161003816minus 119886)]
(74)
where 119877plusmn119899
= (119905119899 119903
plusmn) with 119905
119899= 119905
0+ 2ℓ119899 and ℓ ge 119886 is the
step We may expect that upon averaging over the position1199050isin [minusℓ ℓ] the bias for the beads will reproduce the bias for
cylinders1198793
plusmn(at least it looks like a very good approximation)
We point out that the averaging out (12ℓ) intℓ
minusℓ119889119905
0and the
sum sum+infin
119899=minusinfinreduces to a single integral (12ℓ) intinfin
minusinfin119889119905 of the
zero term in (74) And moreover the resulting total biascorresponds merely to a specific choice of the distributionfunction 119865(120585) in (21) Namely we may take
119873119865 (120585) =1
2ℓ120575 (119905
+minus 119905
minus) 119891 (
1003816100381610038161003816119903+ minus 119903minus
1003816100381610038161003816 119886) (75)
12 Journal of Astrophysics
where119877plusmn= (119905
plusmn 119903
plusmn) and119891(119904 119886) is the distribution of cylinders
which can be taken as (119899 is 3-dimensional density)
119891 (120578) =119899 (119886)
41205871199032
0
120575 (119904 minus 1199030) (76)
Using the normalization condition int119873119865(120585)119889120585 = 119873 we findthe relation 119873 = (12ℓ)119899119881 = 119899119881 where 119899 is a 4-dimensional density of wormholes and 1(2ℓ) is the effectivenumber of wormholes on the unit length of the cylinder (iethe frequency with which the virtual wormhole appears atthe positions 119903
plusmn) This frequency is uniquely fixed by the
requirement that the volume which cuts the bead is equal tothat which cuts the cylinder (43)1205871198863 = (120587
22)119886
4(12ℓ) (ie
2ℓ = (31205878)119886 and 119899 = (83120587119886)119899) Thus we can use directlyexpression (23) and find (compare to (25))
119887 (119896) = minusint 119899 (119886) 1198862 4120587
2
1198962(1 minus
sin |k| 1199030|k| 1199030
)1198691(119896119886)
1198961198862119889119886 (77)
where 119896 = (1198960 k) Here the first term merely coincides with
that in (25) and therefore it gives the contribution to thecosmological constant 120575Λ(8120587119866) = minus1198994 = minus2119899(3120587119886)while the second term describes a correction which does notreduce to the cosmological constant and requires a separateconsideration
72 Stress Energy Tensor From (57) we find that the stressenergy tensor
minus⟨Δ119879120572120573
(119909)⟩ = int
119896120573119896120572minus (12) 119892
1205721205731198962
1198962119887 (119896 120585)
1198894119896
(2120587)4
(78)
reduces to the two functions
11987900
= 120576 = 1205821minus1
2120583
119879119894119895= 119901120575
119894119895 119901 =
1
31205822minus1
2120583
(79)
where 120576 + 3119901 = minus120583 and 1205821+ 120582
2= 120583 and these functions are
1205821= minusint
1198962
0
11989621198871198894119896
(2120587)4 120582
2= minusint
|k|2
11989621198871198894119896
(2120587)4 (80)
By means of the use of the spherical coordinates 11989620119896
2=
cos2120579 |k|21198962 = sin2120579 and 119889
4119896 = 4120587sin2
1205791198963119889119896119889120579 we get
120582119894=119899 (119886 119903
0)
4120573119894
(1 minus 2120573119894(119886
1199030
)
2
119891119894(119886
1199030
)) (81)
where 1205731= 1 120573
2= 13 and 119891
119894is given by
119891(1
2)(119910)
=2
120587int
1
minus1
int
infin
0
sin (119909 sin 120579)1198691(119910119909)
1199101199092(cos2120579sin2
120579) 119889119909 119889cos 120579
(82)
For 1198861199030≪ 1 we find
11989112
(119886
1199030
) asymp (1 + 11990012
(119886
1199030
)) (83)
Thus finally we find
120576 ≃ minus119899
4= minus
2119899
3120587119886 119901 ≃ 120576(1 minus
4
3(119886
1199030
)
2
) (84)
which upon the continuation to the Minkowsky space givesthe equation of state in the form (An arbitrary gas ofwormholes splits in fractions with a fixed 119886 and 119903
0)
119901 = minus(1 minus4
3(119886
1199030
)
2
) 120576 (85)
which in the case when 1198861199030≪ 1 behaves like a cosmological
constant However when 119886 ≫ ℓpl such a constant is extremelysmall and can be neglected while the leading contributioncomes from the mean curvature
73 Mean Curvature In this subsection we consider theMinkowsky spaceThen the simplest actual wormhole can bedescribed by the metric analogous to (1) for example see [7]
1198891199042= 119888
2119889119905
2minus ℎ
2(119903) 120575
120572120573119889119909
120572119889119909
120573 (86)
where ℎ(119903) = 1 + 120579(119886 minus 119903)(1198862119903
2minus 1) To avoid problems
with the Bianchi identity and the conservation of energy thestep function should be also smoothed as in (1) The stressenergy tensor which produces such a wormhole can be foundfrom the Einstein equation 8120587119866119879
120573
120572= 119877
120573
120572minus (12)120575
120573
120572119877 Both
regions 119903 gt 119886 and 119903 lt 119886 represent portions of the ordinaryflat Minkowsky space and therefore the curvature is 119877119896
119894equiv 0
However on the boundary 119903 = 119886 it has the singularity Sincethe metric (86) does not depend on time we find
1198770
0= 119877
0
120572= 0 119877
120573
120572=2
119886120575 (119886 minus 119903) 119899
120572119899120573+ 120575
120573
120572 + 120582
120573
120572 (87)
where 119899120572 = 119899120572= 119909
120572119903 is the outer normal to the throat 1198782
and 120582120573
120572are additional terms (eg see (49) and (51)) which
in the leading order are negligible upon averaging over someportion of space Δ119881 ≳ 119886
3 In the case of a set of wormholesthis gives in the leading order
1198770
0= 119877
0
120572= 0 119877
120573
120572= sum
2
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119903
119894
1003816100381610038161003816) 119899119894120572119899120573
119894+ 120575
120573
120572
(88)
where 119886119894is the radius of a throat and 119903
119894is the position of the
center of the throat in space and 119899120572
119894= (119909
120572minus 119903
120572
119894)|119903 minus 119903
119894|
In the case of a homogeneous and isotropic distribution ofsuch throats we find 119877
120573
120572= (13)119877120575
120573
120572(averaging over spatial
directions gives ⟨119899120572119899120573⟩ = (13)120575
120573
120572) where
119877 = minus8120587119866119879 = sum8
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119877
119894
1003816100381610038161003816) = 32120587int 119886119899 (119886) 119889119886
(89)
Journal of Astrophysics 13
where 119879 stands for the trace of the stress energy momentumtensor which one has to add to the Einstein equations tosupport such awormhole It is clear that such a source violatesthe weak energy condition and therefore it reproduces theformof dark energy (ie119879 = 120576+3119901 lt 0) If the density of suchsources (and resp the density of wormholes) is sufficientlyhigh then this results in the observed [10ndash14] accelerationof the scale factor for the Friedmann space as sim 119905
120572 with120572 = 21205763(120576 + 119901) = 2120576(2120576 + (120576 + 3119901)) gt 1 for examplesee also [40ndash42] In terms of the 4-dimensional density ofwormholes 119899 = (83120587119886)119899 we get 119877 sim 119886
2119899 ≫ 8120587119866119899 as 119886 ≫ ℓpl
and therefore the leading contribution indeed comes fromthe mean curvature
8 Estimates and Concluding Remarks
Now consider the simplest estimates Actual wormholes seemto be responsible for the dark matter [7 9] Therefore to getthe estimate to the number density of wormholes is ratherstraightforward First wormholes appear at scales when darkmatter effects start to display themselves that is at scales ofthe order 119871 sim (1 divide 5)Kpc which gives in that range thenumber density
119899 sim1
1198713sim (3 divide 0024) times 10
minus65cmminus3 (90)
The characteristic size of throats can be estimated from (89)120576DE sim (119866)
minus1119899119886 Since the density of dark energy is 120576DE1205760 =
ΩDE sim 075 where 1205760is the critical density then we find the
estimate
119886 sim2
3(1 divide 125) times 10
minus3119877⊙ΩDEℎ
2
75 (91)
where119877⊙is the Solar radius ℎ
75= 119867(75 km(secMpc)) and
119867 is the Hubble constant We also recall that the backgrounddensity of baryons 120576
119887generates a nonvanishingwormhole rest
mass119872119908= (43)120587119886
31198773120576119887(where119877(119905) is the scale factor of the
Universe and therefore 119872119908remains constant) for example
see [7] It produces the dark matter density related to thewormholes as 120576DM ≃ 119872
119908119899 The typical mass of a wormhole
119872119908is estimated as
119872119908sim 1 7 times (1 divide 125) times 10
2119872
⊙ΩDMℎ
2
75 (92)
where 119872⊙is the Solar mass We point out that this mass
has not the direct relation to the parameters of the gas ofwormholes However it defines the moment when wormholethroats separated from the cosmological expansion Theabove estimate shows that if wormholes form due to thedevelopment of perturbations in the exotic matter then thisprocess should start much earlier than the formation ofgalaxies
Thus we see that virtual wormholes should indeed leadto the regularization of all divergencies in QFT which agreeswith recent results [28] Therefore they form the local finitevalue of the cosmological constant In the absence of externalclassical fields such a value should be exactly zero at macro-scopic scales A some nonvanishing value for the cosmolog-ical constant appears as the result of vacuum polarization
effects in external fields Indeed external fields form anadditional distribution of virtual wormholes which possessan exotic stress energy tensor (some kind of dark energy)Only some part of it forms the cosmological constant whilethe rest reflects the symmetry of external fields and possessesinhomogeneitiesWe assume that during the evolution of ourUniverse inhomogeneities in the exotic matter develop andmay form actual wormholes Although this problem requiresthe further and more deep investigation we refer to [38]where the formation of a simplest wormhole-like object hasbeen considered In other words such polarization energyis reserved now in a gas of actual wormholes We estimatedparameters of such a gas and believe that such a gas mayindeed be responsible for both dark matter and dark energyphenomena
References
[1] J R Primack ldquoThe nature ofdark matterrdquo httparxivorgabsastro-ph0112255
[2] J Diemand M Zemp B Moore J Stadel and M CarolloldquoCusps in cold dark matter haloesrdquoMonthly Notices of the RoyalAstronomical Society vol 364 no 2 pp 665ndash673 2005
[3] E W Mielke and J A V Velez Perez ldquoAxion condensate as amodel for dark matter halosrdquo Physics Letters B vol 671 no 1pp 174ndash178 2009
[4] G Gentile P Salucci U Klein D Vergani and P Kalberla ldquoThecored distribution of dark matter in spiral galaxiesrdquo MonthlyNotices of the Royal Astronomical Society vol 351 no 3 pp 903ndash922 2004
[5] D T F Weldrake W J G de Blok and F Walter ldquoA high-resolution rotation curve of NGC 6822 a test-case for cold darkmatterrdquo Monthly Notices of the Royal Astronomical Society vol340 no 1 pp 12ndash28 2003
[6] W J G de Blok andA Bosma ldquoHigh-resolution rotation curvesof low surface brightness galaxiesrdquoAstronomy and Astrophysicsvol 385 pp 816ndash846 2002
[7] A Kirillov and E P Savelova ldquoDensity perturbations in a gas ofwormholesrdquoMonthly Notices of the Royal Astronomical Societyvol 412 no 3 pp 1710ndash1720 2011
[8] P Kanti B Kleihaus and J Kunz ldquoStable Lorentzianwormholesin dilatonic Einstein-Gauss-Bonnet theoryrdquo Physical Review Dvol 85 no 4 Article ID 044007 2012
[9] A A Kirillov and E P Savelova ldquoDark matter from a gas ofwormholesrdquo Physics Letters B vol 660 no 3 pp 93ndash99 2008
[10] A G Riess A V Filippenko P Challis et al ldquoObservationalevidence from supernovae for an accelerating universe and acosmological constantrdquo The Astronomical Journal vol 116 no3 p 1009 1998
[11] S Perlmutter G Aldering G Goldhaber et al ldquoMeasurementsofΩ andΛ from42high-redshift supernovaerdquoTheAstrophysicalJournal vol 517 no 2 p 565 1999
[12] J L Tonry B P Schmidt B Barris et al ldquoCosmological resultsfromhigh-z supernovaerdquoTheAstrophysical Journal vol 594 no1 p 594 2003
[13] N W Halverson E M Leitch C Pryke et al ldquoDegreeangular scale interferometer first results a measurement of thecosmic microwave background angular power spectrumrdquo TheAstrophysical Journal vol 568 no 1 p 38 2002
14 Journal of Astrophysics
[14] C B Netterfield P A R Ade J J Bock et al ldquoA measurementby BOOMERANGofmultiple peaks in the angular power spec-trum of the cosmic microwave backgroundrdquo The AstrophysicalJournal vol 571 no 2 p 604 2002
[15] S Coleman ldquoWhy there is nothing rather than something atheory of the cosmological constantrdquoNuclear Physics B vol 310no 3-4 pp 643ndash668 1988
[16] I Klebanov L Susskind and T Banks ldquoWormholes and thecosmological constantrdquo Nuclear Physics B vol 317 no 3 pp665ndash692 1989
[17] S W Hawking ldquoSpacetime foamrdquoNuclear Physics B vol 114 p349 1978
[18] T P Cheng and L F Li Gauge Theory of Elementary ParticlesClarendon Press Oxford UK 1984
[19] A H Taub ldquoSpace-times with distribution valued curvaturetensorsrdquo Journal ofMathematical Physics vol 21 no 6 pp 1423ndash1431 1980
[20] A Shatsky privite communications[21] V A Fock ldquoZur Theorie des Wasserstoffatomsrdquo Zeitschrift fur
Physik vol 98 no 3-4 pp 145ndash154 1935[22] E P Savelova ldquoGas of wormholes in Euclidean quantum field
theoryrdquo httparxivorgabs12115106[23] A A Kirillov and E P Savelova ldquoOn the behavior of
bosonic systems in the presence of topology fluctuationsrdquohttparxivorgabs08082478
[24] A A Kirillov ldquoViolation of the Pauli principle and dimensionof the Universe at very large distancesrdquo Physics Letters B vol555 no 1-2 pp 13ndash21 2003
[25] A A Kirillov ldquoDark matter dark charge and the fractalstructure of the Universerdquo Physics Letters B vol 535 no 1ndash4pp 22ndash24 2002
[26] J Ambjorn J Jurkiewicz and R Loll ldquoThe spectral dimensionof the universe is scale dependentrdquo Physical Review Letters vol95 no 17 Article ID 171301 4 pages 2005
[27] E Manrique S Rechenberger and F Saueressig ldquoAsymptoti-cally safe Lorentzian gravityrdquo Physical Review Letters vol 106no 25 Article ID 251302 4 pages 2011
[28] J Laiho and D Coumbe ldquoEvidence for asymptotic safety fromlattice quantum gravityrdquo Physical Review Letters vol 107 no 16Article ID 161301 2011
[29] A A Kirillov and D Turaev ldquoOn modification of the Newtonrsquoslaw of gravity at very large distancesrdquo Physics Letters B vol 532no 3-4 pp 185ndash192 2002
[30] A A Kirillov and D Turaev ldquoThe universal rotation curveof spiral galaxiesrdquo Monthly Notices of the Royal AstronomicalSociety vol 371 no 1 pp L31ndashL35 2006
[31] A A Kirillov and D Turaev ldquoFoam-like structure of theuniverserdquo Physics Letters B vol 656 pp 1ndash8 2007
[32] A A Kirillov ldquoThe nature of dark matterrdquo Physics Letters B vol632 no 4 pp 453ndash462 2006
[33] A A Kirillov and E P Savelova ldquoAstrophysical effects of space-time foamrdquo Gravitation and Cosmology vol 14 no 3 pp 256ndash261 2008
[34] S W Hawking and N Turok ldquoOpen inflation without falsevacuardquo Physics Letters B vol 425 no 1-2 pp 25ndash32 1998
[35] Z C Wu ldquoThe cosmological constant is probably zero and aproof is possibly rightrdquo Physics Letters B vol 659 no 5 pp 891ndash893 2008
[36] R Garattini ldquoEntropy and the cosmological constant aspacetime-foam approachrdquo Nuclear Physics B vol 88 no 1ndash3Article ID 991003 pp 297ndash300 2000
[37] MVisserLorentzianWormholes SpringerNewYorkNYUSA1996
[38] A A Kirillov and E P Savelova ldquoArtificial wormholerdquohttparxivorgabs12040351
[39] E W Mielke ldquoKnot wormholes in geometrodynamicsrdquo Gen-eral Relativity and Gravitation vol 8 no 3 pp 175ndash196 1977
[40] E B Gliner ldquoAlgebraic properties of the energy-momentumtensor and vacuum-like states of matterrdquo Journal of Experimen-tal and Theoretical Physics vol 22 p 378 1966
[41] A H Guth ldquoInflationary universe a possible solution to thehorizon and flatness problemsrdquo Physical Review D vol 23 no2 pp 347ndash356 1981
[42] A A Linde ldquoA new inflationary universe scenario a possiblesolution of the horizon flatness homogeneity isotropy andprimordial monopole problemsrdquo Physics Letters B vol 108 no6 pp 389ndash393 1982
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
![Page 8: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/8.jpg)
8 Journal of Astrophysics
119873(119896) gives the natural tool to describe a scale-dependantdimensional reduction [24 25] In fact this function definesthe spectral number of modes in the interval between 119896 and119896 + 119889119896 as
int119873 (119896)1198894119896
(2120587)4= int
119873 (119896) 1198964
(2120587)2
119889119896
119896 (44)
Hence we can define the effective spectral dimension 119863 ofspace as follows
1198964119873(119896) sim 119896
119863 (45)
From the empirical standpoint the dimension 119863 = 4 isverified at laboratory scales only while the rigorous tool todefine the spectral density of states (or the mean cutoff) cangive the lattice quantum gravity for example see [26 27]and references therein And indeed the spectral dimensionfor nonperturbative quantum gravity defined via Euclideandynamical triangulations was calculated recently in [28] Itturns out that it runs from a value of119863 = 32 at short distanceto 119863 = 4 at large distance scales We also point out that allobserved dark matter phenomena can be explained by thefractal dimension119863 asymp 2 starting from scales 119871 ≳ (1 divide 5)Kpcfor example [29ndash33]
6 Cosmological Constant
Let us consider the total Euclidean action [17]
119868119864= minus
1
16120587119866int (119877 minus 2Λ
0)radic119892119889
4119909 minus int119871
119898radic1198921198894119909 (46)
The variation of the above action leads to the Einstein equa-tions
119877119886119887minus1
2119892119886119887119877 + 119892
119886119887Λ
0= 8120587119866119879
119886119887 (47)
where 119879119886119887= (12)(119892)
minus12(120575119871
119898120575119892
119886119887) is the stress energy ten-
sor and Λ0is a naked cosmological constant In cosmology
such equations are considered from the classical standpointwhich means that they involve characteristic scales ℓ ≫ ℓplHowever the presence of virtual wormholes at Planckianscales defines some additional contribution in both parts ofthese equations which can be adsorbed into the cosmologicalconstant Therefore the total cosmological constant can bedefined as
Λ tot = Λ0+ Λ
119898+ Λ
119877= Λ
0+ 2120587119866 ⟨119879⟩ +
1
4⟨119877⟩119908 (48)
where ⟨119879⟩ is the energy of zero-point fluctuations (It includesalso the contribution of zero-point fluctuations of gravitons)That is themean vacuum value (we recall that in the standardQFTΛ
119898is infinite while wormholes form a finite value) and
⟨119877⟩119908
= Λ119877is a contribution of wormholes into the mean
curvature due to gluing (1)
61 Contribution of Virtual Wormholes into Mean CurvatureConsider a single wormhole whose metric is given by (1)
1198891199042= ℎ
2(119903)120575
120572120573119889119909
120572119889119909
120573 then the components of the Riccitensor are (We are much obliged to the Referee who pointedout to the subtleties when working with a step function in themetric)
119877120572120573
= 7 minus (ℎ1015840
ℎ)
1015840
(120575120572120573
+ (119873 minus 2) 119899120572119899120573)
minus1
119903
ℎ1015840
ℎ((119873 minus 2) Δ
120572120573+ 120575
120572120573(119873 minus 1))
minus (ℎ1015840
ℎ)
2
(119873 minus 2) Δ120572120573
(49)
where 119899]= 119909
]119886 is the unite normal vector to the throat
surface Δ120572120573
= 120575120572120573
minus 119899120572119899120573 ℎ1015840 = 120597ℎ120597119903 and119873 is the number
of dimensions The curvature scalar is
119877 = minus(119873 minus 1)
ℎ2[2
ℎ10158401015840
ℎ+ 2
1
119903
ℎ1015840
ℎ(119873 minus 1) + (
ℎ1015840
ℎ)
2
(119873 minus 4)]
(50)
Then substituting ℎ = 1 + (1198862119903
2minus 1)120579 in the above equation
we find
minusℎ4
119873 minus 1119877 = 4ℎ
1198862
1199033120575 +
2ℎ
119903119873minus1(119903
119873minus1120582)
1015840
+ (119873 minus 4)(1205822minus 4120579
1198862
1199033120582)
+ 4 (119873 minus 4)1198862
1199034120579 (120579 minus 1)
(51)
where 120579 is a smooth function which only in a limit becomesa step function 120582 = (1 minus 119886
2119903
2)120575 and 120575 = minus120579
1015840 In the limit120579 rarr 120579(119886 minus 119903) we find 120575 rarr 120575(119903 minus 119886) and the last two terms in(51) are negligible as compared to the first two terms while infour dimensions the last two terms vanishThen the curvatureis concentrated on the throat of the wormhole where 120579 differsfrom the step function In the limit of a vanishing throat sizewe have ℎ rarr 1 at the throat and we get
minus119877 =4 (119873 minus 1)
119886120575 (119903 minus 119886) +
2 (119873 minus 1)
119903119873minus1(119903
119873minus3(119903
2minus 119886
2) 120575)
1015840
(52)
In general all the terms together in (51) and analogous termsin the Ricci tensor provide that the Bianchi identity holdsand the energy is conserved [19] Therefore none of themcan be dropped out However it is easy to see the leadingcontribution to the integral over space comes from the firstterm only and in the limit of a vanishing throat size we findfor a single wormhole
1
4int119877radic119892119889
4119909 = minus6120587
21198862 (53)
Journal of Astrophysics 9
In the case of a set of wormholes (24) we find
1
4int119877radic119892119889
4119909 = minus6120587
2sum
119895
1198862
119895
= minus121205872int119899 (119886) 119886
2119889119886 119889
4119909 = intΛ
1198771198894119909
(54)
where 2119899(119886) = int 119899(119886 1199030)119889119903
0is the density of wormhole
throats with a fixed value of the throat size 119886 This definesthe contribution to the cosmological constant from the meancurvature as
Λ119877= minus12120587
2int119899 (119886) 119886
2119889119886 lt 0 (55)
We see that this quantity is always negative
62 Stress Energy Tensor In this section we consider thecontribution from matter fields In the case of a scalar fieldthe stress energy tensor has the form
minus119879120572120573
(119909) = 120597120572120593120597
120573120593 minus
1
2119892120572120573
(120597120583120593120597
120583120593 + 119898
21205932) (56)
Then the mean vacuum value of the stress energy tensor canbe obtained directly from the two-point green function (32)(35) as
minus ⟨119879120572120573
(119909)⟩
= lim1199091015840
rarr119909
(1205971205721205971015840
120573minus1
2119892120572120573
(1205971205831205971015840
120583+ 119898
2)) ⟨119866 (119909 119909
1015840 120585)⟩
(57)
By means of using the Fourier transform 119866(119909 1199091015840 120585) =
int 119890minus119894119896(119909minus119909
1015840
)119866(119896 120585) (119889
4119896(2120587)
4) and the expressions (32) (35)
we arrive at
⟨119879120572120573
(119909)⟩ =1
4119892120572120573
int(1 +119898
2
1198962 + 1198982)119873 (119896)
1198894119896
(2120587)4 (58)
where the property int 119896120572119896120573119891(119896
2)119889
4119896 = (14)119892
120572120573int 119896
2119891(119896
2)119889
4119896
has been used and 119873(119896) = ⟨119873(119896 120585)⟩ is the cutoff function(36)
For the sake of simplicity we consider the massless caseThen by the use of the cutoff 119873(119896) = 120587
1205722(120587
1205722+ 119896
120572) from
the previous section we get the finite estimate (120572 gt 4 is theeffective number of the field helicity states)
Λ119898=2120587119866sumint
1205871205722
1205871205722+119896120572
1198894119896
(2120587)4=120587119866
4Γ (
120572 minus 4
120572) Γ (
4
120572) sim 1
(59)
where the sum is taken over the number of fields Since theleading contribution comes here from very small scales wemay hope that this value will not essentially change if thetrue cutoff function changes the behavior on the mass-shellas 119896 rarr 0 (eg if we take 120582
1(119896) = minussum ln119885
0(119896) + 120575120582(119896) with
120575120582(119896) ≪ ln1198850(119896) as 119896 ≫ 1)
To understand how wormholes remove divergencies itwill be convenient to split the bias function into two parts119873(119896 120585) = 1 + 119887(119896 120585) where 1 corresponds to the standardEuclidean contribution while 119887(119896 120585) is the contribution ofwormholes The first part gives the well-known divergentcontribution of vacuumfield fluctuations 8120587119866⟨1198790
120572120573⟩ = Λ
lowast119892120572120573
with Λlowast
rarr +infin while the second part remains finite forany finite number of wormholes and due to the projectivenature of the bias described in the previous section itpartially compensates (reduces) the value of the cosmologicalconstant that is 8120587119866⟨Δ119879
120572120573⟩ = 120575Λ119892
120572120573 where 120575Λ =
sum119873120588119873120575Λ(119873) and 120575Λ(119873) is a negative finite contribution of
a finite set of wormholesConsider now the particular distribution of virtual
wormholes (24) and evaluate their contribution tothe cosmological constant which is given by 120575Λ(119873) =
2120587119866int 119887(119896) (1198894119896(2120587)
4) = 2120587119866119887total(0) Then from the ex-
pressions (22) and (24) we get
119887total (0) = minus119899
4120587411988631199033
0
int(1 minus1198862
1198772
minus
)120575 (119877+minus 119886)
times 120575 (1003816100381610038161003816119877+
minus 119877minus
1003816100381610038161003816 minus 1199030) 119889
4119877minus1198894119877+
(60)
which gives
119887total (0) = minus119899(1 minus 119891(119886
1199030
)) (61)
where
119891(119886
1199030
) =2
120587int
120587
0
1198862sin2
120579119889120579
1198862 + 21198861199030cos 120579 + 119903
2
0
(62)
For 1198861199030≪ 1 (we recall that by the construction 119886119903
0le 12)
this function has the value 119891(1198861199030) asymp 119886
2119903
2
0 Thus for the
contribution of wormholes we find
120575Λ119898= minus2120587119866int119899 (119886 119903
0) (1 minus 119891(
119886
1199030
))119889119886 1198891199030
= minus2120587119866119899 (1 minus ⟨119891⟩)
(63)
63 Vacuum Value of the Cosmological Constant From theabove expression we see that to get the finite value of thecosmological constant Λ
119898= Λ
lowast+ 120575Λ
119898lt infin one should
consider the limit 119899 rarr infin (infinite density of virtualwormholes) which requires considering the smaller andsmaller wormholes From the other handwe have the obviousrestriction int 2119899(119886 119903
0)(120587
22)119886
4119889119886 119889119903
0lt 1 where (120587
22)119886
4
is the volume of one throat (wormholes cannot cut morethan the total volume of space) (We also point out that inremoving divergencies the leading role plays the zero-pointenergy Indeed 120575Λ
119898sim minus2120587119866119899 while the mean curvature has
the order Λ119877sim minus119886
2119899 and for 119886 ≪ ℓpl we have 120575Λ119898
≫ Λ119877
Moreover in the limit 119899 rarr infin one gets 119886 rarr 0 and thereforeΛ
119877120575Λ
119898rarr 0)Therefore in the leading order it seems to be
sufficient to retain point-like wormholes only (ie consider
10 Journal of Astrophysics
the limit 119886 rarr 0) Then instead of (24) we may assume thevacuum distribution of virtual wormholes in the form
119873119865 (119886119883) =1
1198862120575 (119886) ] (119883) (64)
where ](119883) = int 1198862119873119865(119886119883)119889119886 and int(1119886
2)](119883)119889
4119883 =
119899 rarr infin has the meaning of the infinite density of point-like wormholes while ] sim 119886
2119899 remains a finite In this case
the volume cut by wormholes vanishes int 2119899(12058722)119886
4119889119886 119889119903
0=
1198862int ](119883)119889
4119883 rarr 0 and the rarefied gas approximationworks
wellThis defines the bias and themean cutoff (here we definethe Fourier transform ](119896) = int ](119883)119890
1198941198961198831198894119883) as
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (65)
The contribution to themean curvature (55) can be expressedvia the same function ](119896) as
Λ119877= minus12120587
2int119899 (119886 119903
0) 119886
2119889119886 119889119903
0
= minus121205872int ] (119883) 119889
4119883 = minus12120587
2] (0)
(66)
Thus for the total cosmological constant we get the expres-sion
Λ tot = Λ0
+ 2120587119866int(1minus4120587
2
1198962(] (0)minus] (119896)))
1198894119896
(2120587)4minus12120587
2] (0)
(67)
We stress that all these terms should be finite Indeed all dis-tributions of virtual wormholes ](119896) which lead to an infinitevalue of Λ tot are suppressed in (5) by the factor sim119890minusintΛ tot119889
4
119909while the minimal value is reached when wormholes cut allof the volume of space and the action is merely 119878 = 0(Frankly speaking this statement is not rigorous At first lookthe two last terms in (67) are independent and one may tryto take ](0) an arbitrary big If this were the case then theaction would not possess the minimum at all However ](0)cannot be arbitrary big since it will violate the rarefied gasapproximation and the linear expression (67) brakes downMoreover fermions give here a contribution of the oppositesign The rigorous investigation of this problem requires thefurther studying and we present it elsewhere) We also pointout that here we considered the real scalar field as the mattersource while in the general case the stress energy tensorshould include all existing Bose and Fermi fields (Fermi fieldsgive a negative contribution to Λ
119898)
The value of Λ0looks like a free parameter which in
quantum gravity runs with scales [27] However at largescales its asymptotic value may be uniquely fixed by thesimple arguments as follows Indeed in quantum field theoryproperties of the ground state (vacuum) change when weimply an external classical fields The same is true for thedistribution of virtualwormholes ](119896 119869) for example see (33)and (37) and therefore Λ tot = Λ tot(119869) which we describe
in the next subsection We recall that in gravity the role ofthe external current plays the stress energy tensor of matterfields 119869 = 119879
119886119887 However one believes that in the absence
of all classical fields the vacuum state should represent themost symmetric (Lorentz invariant) state which in our casecorresponds to the Euclidean space In order to be consistentwith the Einstein equations this requires Λ tot(119869 = 0) = 0
which uniquely fixes the value of Λ0in (67) We point out
that from somewhat different considerations such a choicewas advocated earlier in [15 34 35]
64 Vacuum Polarization in an External Field Consider nowtopology fluctuations in the presence of an external currentIn the presence of an external current 119869ext the distribution ofvirtual wormholes changes ](119896 119869) = ](119896) + 120575](119896 119869) Indeedin (33) for the case of a weak external field the contributionof the external current into the action can be expanded asexp(minus119881(119869)) ≃ 1 minus 119881 where
119881 = minus1
2int 119869 (119909) 119866 (119909 119910) 119869 (119910) 119889
4119909 119889
4119910
= minus1
2
1198714
(2120587)4int119866
0(119896)119873 (119896)
10038161003816100381610038161198691198961003816100381610038161003816
2
1198894119896
(68)
Then using (36) we find119873(119896 119869) = 119873(119896 0) + 120575119873(119896 119869) where
120575119873 (119896 119869) = 120575119887 (119869) ≃ minus1
2
1198714
(2120587)4int120590
2(119896 119901) 119866
0(119901)
10038161003816100381610038161003816119869119901
10038161003816100381610038161003816
2
1198894119901
(69)
is the bias related to an additional distribution of virtualwormholes and 120590
2(119896 119901) = Δ119873lowast(119896)Δ119873(119901)
1205902(119896 119901) =
1
119885total (0)int [119863119873] 119890
minus119868(119873)Δ119873
lowast(119896) Δ119873 (119901) (70)
defines the dispersion of vacuum topology fluctuations (hereΔ119873 = 119873 minus 119873) The exact definition of 1205902
(119896 119901) requires thefurther development of a fundamental theory In particular itcan be numerically calculated in lattice quantum gravity [28]However it can be shown that at scales 119896 119901 ≫ 119896pl it reducesto 1205902
(119896 119901) rarr 1205902
119896120575(119896 minus 119901) and therefore
120575119887 (119869) = minus1205902
119896
41205872
21198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(71)
Now comparing this function with (23) we relate the addi-tional distribution of virtual wormholes and the externalclassical field as
41205872
1198962(120575] (0 119869) minus 120575] (119896 119869)) =
1
21205902
119896
41205872
1198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(72)
where 120575](119896 119869) = int 1198862120575119873119865(119886 119896)119889119886 We point out that the
above expression does not define the value 120575](0 119869) whichrequires an additional considerationMoreover in general theexternal field 119869 does not possess a symmetry and therefore thecorrection ⟨120575119879
120572120573(119909)⟩ does not reduce to a single cosmological
Journal of Astrophysics 11
constant However such corrections always violate the aver-aged null energy condition [36 37] and may be considered assome kind of dark energy or by other words it represents anexotic matter Some portion of dark energy still has the formof the cosmological constant which defines a nonvanishingpresent day value (we recall that fermions give a contributionof the opposite sign)
120575Λ tot = minus2120587119866int4120587
2
1198962⟨120575] (0 119869) minus 120575] (119896 119869)⟩
1198894119896
(2120587)4
minus 121205872120575] (0 119869)
(73)
where ⟨120575](119896 119869)⟩ denotes an averaging over rotationsThe only unknown parameter in (72) is the dispersion
1205902
119896which defines the intensity of topology fluctuations in
the vacuum It has also the sense of the efficiency coefficientwhich defines the portion of the energy of the external fieldspent on the formation of additional wormholes Thoughthe evaluation of 1205902
119896requires the further development of a
fundamental theory one may expect that 1205902
119896= 119873(119896)(1 minus
119873(119896)) where 119873(119896) is the mean cutoff It is expected that119873(119896) rarr 0 as 119896 ≫ 119896pl and119873(119896) rarr 119873
0le 1 This means that
120590 rarr 0 as 119896 ≫ 119896pl and 120590 rarr 1205900≪ 1 as 119896 ≪ 119896pl while it takes
the maximum value 120590max sim 1 at Planckian scales 119896 sim 119896pl Byotherwords themost efficient transmission of the energy intowormholes takes place for wormholes of the Planckian sizeIn the case when external classical fields have characteristicscales 120582 = 2120587119896 ≫ ℓpl in (72) the efficiency coefficient 1205902
119896and
the cutoff 119873(119896) become constant 120590 ≃ 1205900 119873(119896) ≃ 119873
0 while
their ratiomay be estimated as 1205721205902
0119873
0= ΩDEΩ119887
where 120572 isthe effective number of fundamental fields which contributeto 120575Λ tot and ΩDE Ω119887
are dark energy and baryon energydensities respectively According to the modern picture thisratio gives ΩDEΩ119887
asymp 075005 = 15 while 1205902
0119873
0sim 1
(as 1198730≪ 1) and therefore this defines the estimate for the
effective number of fundamental fields (helicity states) as 120572 sim
15
65 Speculations on the Formation of Actual WormholesAs we already pointed out the additional distribution ofvirtual wormholes (72) reflects the symmetry of externalclassical fields and therefore it forms a homogeneous andisotropic background and perturbations We recall that vir-tual wormholes represent an exotic form of matter In theearly Universe such perturbations start to develop and mayform actual wormholes The rigorous description of sucha process represents an extremely complex and interestingproblemwhich requires the further study Some aspects of thebehavior of the exotic density perturbations were consideredin [7] while the simplest example of the formation of awormhole-type object was discussed recently by us in [38]Therefore we may expect that some portion of such a form ofdark energy is reserved now in actual wormholes which weconsider in the next section
7 Dark Energy from Actual Wormholes
Consider now the contribution to the dark energy fromthe gas of actual wormholes Unlike the virtual wormholesactual wormholes do exist at all times and therefore a singlewormhole can be viewed as a couple of conjugated cylinders1198793
plusmn= 119878
2
plusmntimes 119877
1 So that the number of parameters of an actualwormhole is less 120578 = (119886 119903
+ 119903
minus) where 119886 is the radius of 1198782
plusmn
and 119903plusmnisin 119877
3 is a spatial part of 119877plusmn
Actual wormholes also produce two kinds of contributionto the dark energy One comes from their contribution tothe mean curvature which corresponds to an exotic stressenergy momentum tensor Such a stress energy momentumtensor reflects the dark energy reserved by additional virtualwormholes discussed in the previous section Such energyis necessary to support actual wormholes as a solution tothe Einstein equations The second part comes from vacuumpolarization effects by actual wormholes The considerationin the previous section shows that for macroscopic worm-holes the second part has the order ⟨Δ119879
120572120573⟩ sim 8120587119866119899 and
is negligible as compared to the curvature 119877 sim 1198862119899 (since
macroscopic wormholes have throats 119886 ≫ ℓpl) Howeverfor the sake of completeness and for methodological aims wedescribe it as well
For rigorous evaluation of dark energy of the secondtype we first have to find the bias 119887
1(119909 119909
1015840 120578) analogous to
(19) for the topology 1198774(119879
3
+cup 119879
3
minus) There are many papers
treating different wormholes in this respect (eg see [36 37]and references therein) However in the present paper for anestimation we shall use a more simple trick
71 Beads of Virtual Wormholes (Quantum Wormhole)Indeed instead of the cylinders 1198793
plusmnwe consider a couple of
chains (beads of virtual wormholes 1198793
plusmnrarr cup
1198991198783
plusmn119899) Such an
idea was first suggested in [39] and one may call such anobject as quantum wormhole Then the bias can be writtenstraightforwardly
1198871(119909 119909
1015840 120578) =
+infin
sum
119899=minusinfin
1
41205872119886(
1
(119877minus119899
minus 1199091015840)2minus
1
(119877+119899
minus 1199091015840)2)
times [120575 (10038161003816100381610038161003816 minus
+119899
10038161003816100381610038161003816minus 119886) minus 120575 (
10038161003816100381610038161003816 minus
minus119899
10038161003816100381610038161003816minus 119886)]
(74)
where 119877plusmn119899
= (119905119899 119903
plusmn) with 119905
119899= 119905
0+ 2ℓ119899 and ℓ ge 119886 is the
step We may expect that upon averaging over the position1199050isin [minusℓ ℓ] the bias for the beads will reproduce the bias for
cylinders1198793
plusmn(at least it looks like a very good approximation)
We point out that the averaging out (12ℓ) intℓ
minusℓ119889119905
0and the
sum sum+infin
119899=minusinfinreduces to a single integral (12ℓ) intinfin
minusinfin119889119905 of the
zero term in (74) And moreover the resulting total biascorresponds merely to a specific choice of the distributionfunction 119865(120585) in (21) Namely we may take
119873119865 (120585) =1
2ℓ120575 (119905
+minus 119905
minus) 119891 (
1003816100381610038161003816119903+ minus 119903minus
1003816100381610038161003816 119886) (75)
12 Journal of Astrophysics
where119877plusmn= (119905
plusmn 119903
plusmn) and119891(119904 119886) is the distribution of cylinders
which can be taken as (119899 is 3-dimensional density)
119891 (120578) =119899 (119886)
41205871199032
0
120575 (119904 minus 1199030) (76)
Using the normalization condition int119873119865(120585)119889120585 = 119873 we findthe relation 119873 = (12ℓ)119899119881 = 119899119881 where 119899 is a 4-dimensional density of wormholes and 1(2ℓ) is the effectivenumber of wormholes on the unit length of the cylinder (iethe frequency with which the virtual wormhole appears atthe positions 119903
plusmn) This frequency is uniquely fixed by the
requirement that the volume which cuts the bead is equal tothat which cuts the cylinder (43)1205871198863 = (120587
22)119886
4(12ℓ) (ie
2ℓ = (31205878)119886 and 119899 = (83120587119886)119899) Thus we can use directlyexpression (23) and find (compare to (25))
119887 (119896) = minusint 119899 (119886) 1198862 4120587
2
1198962(1 minus
sin |k| 1199030|k| 1199030
)1198691(119896119886)
1198961198862119889119886 (77)
where 119896 = (1198960 k) Here the first term merely coincides with
that in (25) and therefore it gives the contribution to thecosmological constant 120575Λ(8120587119866) = minus1198994 = minus2119899(3120587119886)while the second term describes a correction which does notreduce to the cosmological constant and requires a separateconsideration
72 Stress Energy Tensor From (57) we find that the stressenergy tensor
minus⟨Δ119879120572120573
(119909)⟩ = int
119896120573119896120572minus (12) 119892
1205721205731198962
1198962119887 (119896 120585)
1198894119896
(2120587)4
(78)
reduces to the two functions
11987900
= 120576 = 1205821minus1
2120583
119879119894119895= 119901120575
119894119895 119901 =
1
31205822minus1
2120583
(79)
where 120576 + 3119901 = minus120583 and 1205821+ 120582
2= 120583 and these functions are
1205821= minusint
1198962
0
11989621198871198894119896
(2120587)4 120582
2= minusint
|k|2
11989621198871198894119896
(2120587)4 (80)
By means of the use of the spherical coordinates 11989620119896
2=
cos2120579 |k|21198962 = sin2120579 and 119889
4119896 = 4120587sin2
1205791198963119889119896119889120579 we get
120582119894=119899 (119886 119903
0)
4120573119894
(1 minus 2120573119894(119886
1199030
)
2
119891119894(119886
1199030
)) (81)
where 1205731= 1 120573
2= 13 and 119891
119894is given by
119891(1
2)(119910)
=2
120587int
1
minus1
int
infin
0
sin (119909 sin 120579)1198691(119910119909)
1199101199092(cos2120579sin2
120579) 119889119909 119889cos 120579
(82)
For 1198861199030≪ 1 we find
11989112
(119886
1199030
) asymp (1 + 11990012
(119886
1199030
)) (83)
Thus finally we find
120576 ≃ minus119899
4= minus
2119899
3120587119886 119901 ≃ 120576(1 minus
4
3(119886
1199030
)
2
) (84)
which upon the continuation to the Minkowsky space givesthe equation of state in the form (An arbitrary gas ofwormholes splits in fractions with a fixed 119886 and 119903
0)
119901 = minus(1 minus4
3(119886
1199030
)
2
) 120576 (85)
which in the case when 1198861199030≪ 1 behaves like a cosmological
constant However when 119886 ≫ ℓpl such a constant is extremelysmall and can be neglected while the leading contributioncomes from the mean curvature
73 Mean Curvature In this subsection we consider theMinkowsky spaceThen the simplest actual wormhole can bedescribed by the metric analogous to (1) for example see [7]
1198891199042= 119888
2119889119905
2minus ℎ
2(119903) 120575
120572120573119889119909
120572119889119909
120573 (86)
where ℎ(119903) = 1 + 120579(119886 minus 119903)(1198862119903
2minus 1) To avoid problems
with the Bianchi identity and the conservation of energy thestep function should be also smoothed as in (1) The stressenergy tensor which produces such a wormhole can be foundfrom the Einstein equation 8120587119866119879
120573
120572= 119877
120573
120572minus (12)120575
120573
120572119877 Both
regions 119903 gt 119886 and 119903 lt 119886 represent portions of the ordinaryflat Minkowsky space and therefore the curvature is 119877119896
119894equiv 0
However on the boundary 119903 = 119886 it has the singularity Sincethe metric (86) does not depend on time we find
1198770
0= 119877
0
120572= 0 119877
120573
120572=2
119886120575 (119886 minus 119903) 119899
120572119899120573+ 120575
120573
120572 + 120582
120573
120572 (87)
where 119899120572 = 119899120572= 119909
120572119903 is the outer normal to the throat 1198782
and 120582120573
120572are additional terms (eg see (49) and (51)) which
in the leading order are negligible upon averaging over someportion of space Δ119881 ≳ 119886
3 In the case of a set of wormholesthis gives in the leading order
1198770
0= 119877
0
120572= 0 119877
120573
120572= sum
2
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119903
119894
1003816100381610038161003816) 119899119894120572119899120573
119894+ 120575
120573
120572
(88)
where 119886119894is the radius of a throat and 119903
119894is the position of the
center of the throat in space and 119899120572
119894= (119909
120572minus 119903
120572
119894)|119903 minus 119903
119894|
In the case of a homogeneous and isotropic distribution ofsuch throats we find 119877
120573
120572= (13)119877120575
120573
120572(averaging over spatial
directions gives ⟨119899120572119899120573⟩ = (13)120575
120573
120572) where
119877 = minus8120587119866119879 = sum8
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119877
119894
1003816100381610038161003816) = 32120587int 119886119899 (119886) 119889119886
(89)
Journal of Astrophysics 13
where 119879 stands for the trace of the stress energy momentumtensor which one has to add to the Einstein equations tosupport such awormhole It is clear that such a source violatesthe weak energy condition and therefore it reproduces theformof dark energy (ie119879 = 120576+3119901 lt 0) If the density of suchsources (and resp the density of wormholes) is sufficientlyhigh then this results in the observed [10ndash14] accelerationof the scale factor for the Friedmann space as sim 119905
120572 with120572 = 21205763(120576 + 119901) = 2120576(2120576 + (120576 + 3119901)) gt 1 for examplesee also [40ndash42] In terms of the 4-dimensional density ofwormholes 119899 = (83120587119886)119899 we get 119877 sim 119886
2119899 ≫ 8120587119866119899 as 119886 ≫ ℓpl
and therefore the leading contribution indeed comes fromthe mean curvature
8 Estimates and Concluding Remarks
Now consider the simplest estimates Actual wormholes seemto be responsible for the dark matter [7 9] Therefore to getthe estimate to the number density of wormholes is ratherstraightforward First wormholes appear at scales when darkmatter effects start to display themselves that is at scales ofthe order 119871 sim (1 divide 5)Kpc which gives in that range thenumber density
119899 sim1
1198713sim (3 divide 0024) times 10
minus65cmminus3 (90)
The characteristic size of throats can be estimated from (89)120576DE sim (119866)
minus1119899119886 Since the density of dark energy is 120576DE1205760 =
ΩDE sim 075 where 1205760is the critical density then we find the
estimate
119886 sim2
3(1 divide 125) times 10
minus3119877⊙ΩDEℎ
2
75 (91)
where119877⊙is the Solar radius ℎ
75= 119867(75 km(secMpc)) and
119867 is the Hubble constant We also recall that the backgrounddensity of baryons 120576
119887generates a nonvanishingwormhole rest
mass119872119908= (43)120587119886
31198773120576119887(where119877(119905) is the scale factor of the
Universe and therefore 119872119908remains constant) for example
see [7] It produces the dark matter density related to thewormholes as 120576DM ≃ 119872
119908119899 The typical mass of a wormhole
119872119908is estimated as
119872119908sim 1 7 times (1 divide 125) times 10
2119872
⊙ΩDMℎ
2
75 (92)
where 119872⊙is the Solar mass We point out that this mass
has not the direct relation to the parameters of the gas ofwormholes However it defines the moment when wormholethroats separated from the cosmological expansion Theabove estimate shows that if wormholes form due to thedevelopment of perturbations in the exotic matter then thisprocess should start much earlier than the formation ofgalaxies
Thus we see that virtual wormholes should indeed leadto the regularization of all divergencies in QFT which agreeswith recent results [28] Therefore they form the local finitevalue of the cosmological constant In the absence of externalclassical fields such a value should be exactly zero at macro-scopic scales A some nonvanishing value for the cosmolog-ical constant appears as the result of vacuum polarization
effects in external fields Indeed external fields form anadditional distribution of virtual wormholes which possessan exotic stress energy tensor (some kind of dark energy)Only some part of it forms the cosmological constant whilethe rest reflects the symmetry of external fields and possessesinhomogeneitiesWe assume that during the evolution of ourUniverse inhomogeneities in the exotic matter develop andmay form actual wormholes Although this problem requiresthe further and more deep investigation we refer to [38]where the formation of a simplest wormhole-like object hasbeen considered In other words such polarization energyis reserved now in a gas of actual wormholes We estimatedparameters of such a gas and believe that such a gas mayindeed be responsible for both dark matter and dark energyphenomena
References
[1] J R Primack ldquoThe nature ofdark matterrdquo httparxivorgabsastro-ph0112255
[2] J Diemand M Zemp B Moore J Stadel and M CarolloldquoCusps in cold dark matter haloesrdquoMonthly Notices of the RoyalAstronomical Society vol 364 no 2 pp 665ndash673 2005
[3] E W Mielke and J A V Velez Perez ldquoAxion condensate as amodel for dark matter halosrdquo Physics Letters B vol 671 no 1pp 174ndash178 2009
[4] G Gentile P Salucci U Klein D Vergani and P Kalberla ldquoThecored distribution of dark matter in spiral galaxiesrdquo MonthlyNotices of the Royal Astronomical Society vol 351 no 3 pp 903ndash922 2004
[5] D T F Weldrake W J G de Blok and F Walter ldquoA high-resolution rotation curve of NGC 6822 a test-case for cold darkmatterrdquo Monthly Notices of the Royal Astronomical Society vol340 no 1 pp 12ndash28 2003
[6] W J G de Blok andA Bosma ldquoHigh-resolution rotation curvesof low surface brightness galaxiesrdquoAstronomy and Astrophysicsvol 385 pp 816ndash846 2002
[7] A Kirillov and E P Savelova ldquoDensity perturbations in a gas ofwormholesrdquoMonthly Notices of the Royal Astronomical Societyvol 412 no 3 pp 1710ndash1720 2011
[8] P Kanti B Kleihaus and J Kunz ldquoStable Lorentzianwormholesin dilatonic Einstein-Gauss-Bonnet theoryrdquo Physical Review Dvol 85 no 4 Article ID 044007 2012
[9] A A Kirillov and E P Savelova ldquoDark matter from a gas ofwormholesrdquo Physics Letters B vol 660 no 3 pp 93ndash99 2008
[10] A G Riess A V Filippenko P Challis et al ldquoObservationalevidence from supernovae for an accelerating universe and acosmological constantrdquo The Astronomical Journal vol 116 no3 p 1009 1998
[11] S Perlmutter G Aldering G Goldhaber et al ldquoMeasurementsofΩ andΛ from42high-redshift supernovaerdquoTheAstrophysicalJournal vol 517 no 2 p 565 1999
[12] J L Tonry B P Schmidt B Barris et al ldquoCosmological resultsfromhigh-z supernovaerdquoTheAstrophysical Journal vol 594 no1 p 594 2003
[13] N W Halverson E M Leitch C Pryke et al ldquoDegreeangular scale interferometer first results a measurement of thecosmic microwave background angular power spectrumrdquo TheAstrophysical Journal vol 568 no 1 p 38 2002
14 Journal of Astrophysics
[14] C B Netterfield P A R Ade J J Bock et al ldquoA measurementby BOOMERANGofmultiple peaks in the angular power spec-trum of the cosmic microwave backgroundrdquo The AstrophysicalJournal vol 571 no 2 p 604 2002
[15] S Coleman ldquoWhy there is nothing rather than something atheory of the cosmological constantrdquoNuclear Physics B vol 310no 3-4 pp 643ndash668 1988
[16] I Klebanov L Susskind and T Banks ldquoWormholes and thecosmological constantrdquo Nuclear Physics B vol 317 no 3 pp665ndash692 1989
[17] S W Hawking ldquoSpacetime foamrdquoNuclear Physics B vol 114 p349 1978
[18] T P Cheng and L F Li Gauge Theory of Elementary ParticlesClarendon Press Oxford UK 1984
[19] A H Taub ldquoSpace-times with distribution valued curvaturetensorsrdquo Journal ofMathematical Physics vol 21 no 6 pp 1423ndash1431 1980
[20] A Shatsky privite communications[21] V A Fock ldquoZur Theorie des Wasserstoffatomsrdquo Zeitschrift fur
Physik vol 98 no 3-4 pp 145ndash154 1935[22] E P Savelova ldquoGas of wormholes in Euclidean quantum field
theoryrdquo httparxivorgabs12115106[23] A A Kirillov and E P Savelova ldquoOn the behavior of
bosonic systems in the presence of topology fluctuationsrdquohttparxivorgabs08082478
[24] A A Kirillov ldquoViolation of the Pauli principle and dimensionof the Universe at very large distancesrdquo Physics Letters B vol555 no 1-2 pp 13ndash21 2003
[25] A A Kirillov ldquoDark matter dark charge and the fractalstructure of the Universerdquo Physics Letters B vol 535 no 1ndash4pp 22ndash24 2002
[26] J Ambjorn J Jurkiewicz and R Loll ldquoThe spectral dimensionof the universe is scale dependentrdquo Physical Review Letters vol95 no 17 Article ID 171301 4 pages 2005
[27] E Manrique S Rechenberger and F Saueressig ldquoAsymptoti-cally safe Lorentzian gravityrdquo Physical Review Letters vol 106no 25 Article ID 251302 4 pages 2011
[28] J Laiho and D Coumbe ldquoEvidence for asymptotic safety fromlattice quantum gravityrdquo Physical Review Letters vol 107 no 16Article ID 161301 2011
[29] A A Kirillov and D Turaev ldquoOn modification of the Newtonrsquoslaw of gravity at very large distancesrdquo Physics Letters B vol 532no 3-4 pp 185ndash192 2002
[30] A A Kirillov and D Turaev ldquoThe universal rotation curveof spiral galaxiesrdquo Monthly Notices of the Royal AstronomicalSociety vol 371 no 1 pp L31ndashL35 2006
[31] A A Kirillov and D Turaev ldquoFoam-like structure of theuniverserdquo Physics Letters B vol 656 pp 1ndash8 2007
[32] A A Kirillov ldquoThe nature of dark matterrdquo Physics Letters B vol632 no 4 pp 453ndash462 2006
[33] A A Kirillov and E P Savelova ldquoAstrophysical effects of space-time foamrdquo Gravitation and Cosmology vol 14 no 3 pp 256ndash261 2008
[34] S W Hawking and N Turok ldquoOpen inflation without falsevacuardquo Physics Letters B vol 425 no 1-2 pp 25ndash32 1998
[35] Z C Wu ldquoThe cosmological constant is probably zero and aproof is possibly rightrdquo Physics Letters B vol 659 no 5 pp 891ndash893 2008
[36] R Garattini ldquoEntropy and the cosmological constant aspacetime-foam approachrdquo Nuclear Physics B vol 88 no 1ndash3Article ID 991003 pp 297ndash300 2000
[37] MVisserLorentzianWormholes SpringerNewYorkNYUSA1996
[38] A A Kirillov and E P Savelova ldquoArtificial wormholerdquohttparxivorgabs12040351
[39] E W Mielke ldquoKnot wormholes in geometrodynamicsrdquo Gen-eral Relativity and Gravitation vol 8 no 3 pp 175ndash196 1977
[40] E B Gliner ldquoAlgebraic properties of the energy-momentumtensor and vacuum-like states of matterrdquo Journal of Experimen-tal and Theoretical Physics vol 22 p 378 1966
[41] A H Guth ldquoInflationary universe a possible solution to thehorizon and flatness problemsrdquo Physical Review D vol 23 no2 pp 347ndash356 1981
[42] A A Linde ldquoA new inflationary universe scenario a possiblesolution of the horizon flatness homogeneity isotropy andprimordial monopole problemsrdquo Physics Letters B vol 108 no6 pp 389ndash393 1982
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
![Page 9: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/9.jpg)
Journal of Astrophysics 9
In the case of a set of wormholes (24) we find
1
4int119877radic119892119889
4119909 = minus6120587
2sum
119895
1198862
119895
= minus121205872int119899 (119886) 119886
2119889119886 119889
4119909 = intΛ
1198771198894119909
(54)
where 2119899(119886) = int 119899(119886 1199030)119889119903
0is the density of wormhole
throats with a fixed value of the throat size 119886 This definesthe contribution to the cosmological constant from the meancurvature as
Λ119877= minus12120587
2int119899 (119886) 119886
2119889119886 lt 0 (55)
We see that this quantity is always negative
62 Stress Energy Tensor In this section we consider thecontribution from matter fields In the case of a scalar fieldthe stress energy tensor has the form
minus119879120572120573
(119909) = 120597120572120593120597
120573120593 minus
1
2119892120572120573
(120597120583120593120597
120583120593 + 119898
21205932) (56)
Then the mean vacuum value of the stress energy tensor canbe obtained directly from the two-point green function (32)(35) as
minus ⟨119879120572120573
(119909)⟩
= lim1199091015840
rarr119909
(1205971205721205971015840
120573minus1
2119892120572120573
(1205971205831205971015840
120583+ 119898
2)) ⟨119866 (119909 119909
1015840 120585)⟩
(57)
By means of using the Fourier transform 119866(119909 1199091015840 120585) =
int 119890minus119894119896(119909minus119909
1015840
)119866(119896 120585) (119889
4119896(2120587)
4) and the expressions (32) (35)
we arrive at
⟨119879120572120573
(119909)⟩ =1
4119892120572120573
int(1 +119898
2
1198962 + 1198982)119873 (119896)
1198894119896
(2120587)4 (58)
where the property int 119896120572119896120573119891(119896
2)119889
4119896 = (14)119892
120572120573int 119896
2119891(119896
2)119889
4119896
has been used and 119873(119896) = ⟨119873(119896 120585)⟩ is the cutoff function(36)
For the sake of simplicity we consider the massless caseThen by the use of the cutoff 119873(119896) = 120587
1205722(120587
1205722+ 119896
120572) from
the previous section we get the finite estimate (120572 gt 4 is theeffective number of the field helicity states)
Λ119898=2120587119866sumint
1205871205722
1205871205722+119896120572
1198894119896
(2120587)4=120587119866
4Γ (
120572 minus 4
120572) Γ (
4
120572) sim 1
(59)
where the sum is taken over the number of fields Since theleading contribution comes here from very small scales wemay hope that this value will not essentially change if thetrue cutoff function changes the behavior on the mass-shellas 119896 rarr 0 (eg if we take 120582
1(119896) = minussum ln119885
0(119896) + 120575120582(119896) with
120575120582(119896) ≪ ln1198850(119896) as 119896 ≫ 1)
To understand how wormholes remove divergencies itwill be convenient to split the bias function into two parts119873(119896 120585) = 1 + 119887(119896 120585) where 1 corresponds to the standardEuclidean contribution while 119887(119896 120585) is the contribution ofwormholes The first part gives the well-known divergentcontribution of vacuumfield fluctuations 8120587119866⟨1198790
120572120573⟩ = Λ
lowast119892120572120573
with Λlowast
rarr +infin while the second part remains finite forany finite number of wormholes and due to the projectivenature of the bias described in the previous section itpartially compensates (reduces) the value of the cosmologicalconstant that is 8120587119866⟨Δ119879
120572120573⟩ = 120575Λ119892
120572120573 where 120575Λ =
sum119873120588119873120575Λ(119873) and 120575Λ(119873) is a negative finite contribution of
a finite set of wormholesConsider now the particular distribution of virtual
wormholes (24) and evaluate their contribution tothe cosmological constant which is given by 120575Λ(119873) =
2120587119866int 119887(119896) (1198894119896(2120587)
4) = 2120587119866119887total(0) Then from the ex-
pressions (22) and (24) we get
119887total (0) = minus119899
4120587411988631199033
0
int(1 minus1198862
1198772
minus
)120575 (119877+minus 119886)
times 120575 (1003816100381610038161003816119877+
minus 119877minus
1003816100381610038161003816 minus 1199030) 119889
4119877minus1198894119877+
(60)
which gives
119887total (0) = minus119899(1 minus 119891(119886
1199030
)) (61)
where
119891(119886
1199030
) =2
120587int
120587
0
1198862sin2
120579119889120579
1198862 + 21198861199030cos 120579 + 119903
2
0
(62)
For 1198861199030≪ 1 (we recall that by the construction 119886119903
0le 12)
this function has the value 119891(1198861199030) asymp 119886
2119903
2
0 Thus for the
contribution of wormholes we find
120575Λ119898= minus2120587119866int119899 (119886 119903
0) (1 minus 119891(
119886
1199030
))119889119886 1198891199030
= minus2120587119866119899 (1 minus ⟨119891⟩)
(63)
63 Vacuum Value of the Cosmological Constant From theabove expression we see that to get the finite value of thecosmological constant Λ
119898= Λ
lowast+ 120575Λ
119898lt infin one should
consider the limit 119899 rarr infin (infinite density of virtualwormholes) which requires considering the smaller andsmaller wormholes From the other handwe have the obviousrestriction int 2119899(119886 119903
0)(120587
22)119886
4119889119886 119889119903
0lt 1 where (120587
22)119886
4
is the volume of one throat (wormholes cannot cut morethan the total volume of space) (We also point out that inremoving divergencies the leading role plays the zero-pointenergy Indeed 120575Λ
119898sim minus2120587119866119899 while the mean curvature has
the order Λ119877sim minus119886
2119899 and for 119886 ≪ ℓpl we have 120575Λ119898
≫ Λ119877
Moreover in the limit 119899 rarr infin one gets 119886 rarr 0 and thereforeΛ
119877120575Λ
119898rarr 0)Therefore in the leading order it seems to be
sufficient to retain point-like wormholes only (ie consider
10 Journal of Astrophysics
the limit 119886 rarr 0) Then instead of (24) we may assume thevacuum distribution of virtual wormholes in the form
119873119865 (119886119883) =1
1198862120575 (119886) ] (119883) (64)
where ](119883) = int 1198862119873119865(119886119883)119889119886 and int(1119886
2)](119883)119889
4119883 =
119899 rarr infin has the meaning of the infinite density of point-like wormholes while ] sim 119886
2119899 remains a finite In this case
the volume cut by wormholes vanishes int 2119899(12058722)119886
4119889119886 119889119903
0=
1198862int ](119883)119889
4119883 rarr 0 and the rarefied gas approximationworks
wellThis defines the bias and themean cutoff (here we definethe Fourier transform ](119896) = int ](119883)119890
1198941198961198831198894119883) as
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (65)
The contribution to themean curvature (55) can be expressedvia the same function ](119896) as
Λ119877= minus12120587
2int119899 (119886 119903
0) 119886
2119889119886 119889119903
0
= minus121205872int ] (119883) 119889
4119883 = minus12120587
2] (0)
(66)
Thus for the total cosmological constant we get the expres-sion
Λ tot = Λ0
+ 2120587119866int(1minus4120587
2
1198962(] (0)minus] (119896)))
1198894119896
(2120587)4minus12120587
2] (0)
(67)
We stress that all these terms should be finite Indeed all dis-tributions of virtual wormholes ](119896) which lead to an infinitevalue of Λ tot are suppressed in (5) by the factor sim119890minusintΛ tot119889
4
119909while the minimal value is reached when wormholes cut allof the volume of space and the action is merely 119878 = 0(Frankly speaking this statement is not rigorous At first lookthe two last terms in (67) are independent and one may tryto take ](0) an arbitrary big If this were the case then theaction would not possess the minimum at all However ](0)cannot be arbitrary big since it will violate the rarefied gasapproximation and the linear expression (67) brakes downMoreover fermions give here a contribution of the oppositesign The rigorous investigation of this problem requires thefurther studying and we present it elsewhere) We also pointout that here we considered the real scalar field as the mattersource while in the general case the stress energy tensorshould include all existing Bose and Fermi fields (Fermi fieldsgive a negative contribution to Λ
119898)
The value of Λ0looks like a free parameter which in
quantum gravity runs with scales [27] However at largescales its asymptotic value may be uniquely fixed by thesimple arguments as follows Indeed in quantum field theoryproperties of the ground state (vacuum) change when weimply an external classical fields The same is true for thedistribution of virtualwormholes ](119896 119869) for example see (33)and (37) and therefore Λ tot = Λ tot(119869) which we describe
in the next subsection We recall that in gravity the role ofthe external current plays the stress energy tensor of matterfields 119869 = 119879
119886119887 However one believes that in the absence
of all classical fields the vacuum state should represent themost symmetric (Lorentz invariant) state which in our casecorresponds to the Euclidean space In order to be consistentwith the Einstein equations this requires Λ tot(119869 = 0) = 0
which uniquely fixes the value of Λ0in (67) We point out
that from somewhat different considerations such a choicewas advocated earlier in [15 34 35]
64 Vacuum Polarization in an External Field Consider nowtopology fluctuations in the presence of an external currentIn the presence of an external current 119869ext the distribution ofvirtual wormholes changes ](119896 119869) = ](119896) + 120575](119896 119869) Indeedin (33) for the case of a weak external field the contributionof the external current into the action can be expanded asexp(minus119881(119869)) ≃ 1 minus 119881 where
119881 = minus1
2int 119869 (119909) 119866 (119909 119910) 119869 (119910) 119889
4119909 119889
4119910
= minus1
2
1198714
(2120587)4int119866
0(119896)119873 (119896)
10038161003816100381610038161198691198961003816100381610038161003816
2
1198894119896
(68)
Then using (36) we find119873(119896 119869) = 119873(119896 0) + 120575119873(119896 119869) where
120575119873 (119896 119869) = 120575119887 (119869) ≃ minus1
2
1198714
(2120587)4int120590
2(119896 119901) 119866
0(119901)
10038161003816100381610038161003816119869119901
10038161003816100381610038161003816
2
1198894119901
(69)
is the bias related to an additional distribution of virtualwormholes and 120590
2(119896 119901) = Δ119873lowast(119896)Δ119873(119901)
1205902(119896 119901) =
1
119885total (0)int [119863119873] 119890
minus119868(119873)Δ119873
lowast(119896) Δ119873 (119901) (70)
defines the dispersion of vacuum topology fluctuations (hereΔ119873 = 119873 minus 119873) The exact definition of 1205902
(119896 119901) requires thefurther development of a fundamental theory In particular itcan be numerically calculated in lattice quantum gravity [28]However it can be shown that at scales 119896 119901 ≫ 119896pl it reducesto 1205902
(119896 119901) rarr 1205902
119896120575(119896 minus 119901) and therefore
120575119887 (119869) = minus1205902
119896
41205872
21198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(71)
Now comparing this function with (23) we relate the addi-tional distribution of virtual wormholes and the externalclassical field as
41205872
1198962(120575] (0 119869) minus 120575] (119896 119869)) =
1
21205902
119896
41205872
1198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(72)
where 120575](119896 119869) = int 1198862120575119873119865(119886 119896)119889119886 We point out that the
above expression does not define the value 120575](0 119869) whichrequires an additional considerationMoreover in general theexternal field 119869 does not possess a symmetry and therefore thecorrection ⟨120575119879
120572120573(119909)⟩ does not reduce to a single cosmological
Journal of Astrophysics 11
constant However such corrections always violate the aver-aged null energy condition [36 37] and may be considered assome kind of dark energy or by other words it represents anexotic matter Some portion of dark energy still has the formof the cosmological constant which defines a nonvanishingpresent day value (we recall that fermions give a contributionof the opposite sign)
120575Λ tot = minus2120587119866int4120587
2
1198962⟨120575] (0 119869) minus 120575] (119896 119869)⟩
1198894119896
(2120587)4
minus 121205872120575] (0 119869)
(73)
where ⟨120575](119896 119869)⟩ denotes an averaging over rotationsThe only unknown parameter in (72) is the dispersion
1205902
119896which defines the intensity of topology fluctuations in
the vacuum It has also the sense of the efficiency coefficientwhich defines the portion of the energy of the external fieldspent on the formation of additional wormholes Thoughthe evaluation of 1205902
119896requires the further development of a
fundamental theory one may expect that 1205902
119896= 119873(119896)(1 minus
119873(119896)) where 119873(119896) is the mean cutoff It is expected that119873(119896) rarr 0 as 119896 ≫ 119896pl and119873(119896) rarr 119873
0le 1 This means that
120590 rarr 0 as 119896 ≫ 119896pl and 120590 rarr 1205900≪ 1 as 119896 ≪ 119896pl while it takes
the maximum value 120590max sim 1 at Planckian scales 119896 sim 119896pl Byotherwords themost efficient transmission of the energy intowormholes takes place for wormholes of the Planckian sizeIn the case when external classical fields have characteristicscales 120582 = 2120587119896 ≫ ℓpl in (72) the efficiency coefficient 1205902
119896and
the cutoff 119873(119896) become constant 120590 ≃ 1205900 119873(119896) ≃ 119873
0 while
their ratiomay be estimated as 1205721205902
0119873
0= ΩDEΩ119887
where 120572 isthe effective number of fundamental fields which contributeto 120575Λ tot and ΩDE Ω119887
are dark energy and baryon energydensities respectively According to the modern picture thisratio gives ΩDEΩ119887
asymp 075005 = 15 while 1205902
0119873
0sim 1
(as 1198730≪ 1) and therefore this defines the estimate for the
effective number of fundamental fields (helicity states) as 120572 sim
15
65 Speculations on the Formation of Actual WormholesAs we already pointed out the additional distribution ofvirtual wormholes (72) reflects the symmetry of externalclassical fields and therefore it forms a homogeneous andisotropic background and perturbations We recall that vir-tual wormholes represent an exotic form of matter In theearly Universe such perturbations start to develop and mayform actual wormholes The rigorous description of sucha process represents an extremely complex and interestingproblemwhich requires the further study Some aspects of thebehavior of the exotic density perturbations were consideredin [7] while the simplest example of the formation of awormhole-type object was discussed recently by us in [38]Therefore we may expect that some portion of such a form ofdark energy is reserved now in actual wormholes which weconsider in the next section
7 Dark Energy from Actual Wormholes
Consider now the contribution to the dark energy fromthe gas of actual wormholes Unlike the virtual wormholesactual wormholes do exist at all times and therefore a singlewormhole can be viewed as a couple of conjugated cylinders1198793
plusmn= 119878
2
plusmntimes 119877
1 So that the number of parameters of an actualwormhole is less 120578 = (119886 119903
+ 119903
minus) where 119886 is the radius of 1198782
plusmn
and 119903plusmnisin 119877
3 is a spatial part of 119877plusmn
Actual wormholes also produce two kinds of contributionto the dark energy One comes from their contribution tothe mean curvature which corresponds to an exotic stressenergy momentum tensor Such a stress energy momentumtensor reflects the dark energy reserved by additional virtualwormholes discussed in the previous section Such energyis necessary to support actual wormholes as a solution tothe Einstein equations The second part comes from vacuumpolarization effects by actual wormholes The considerationin the previous section shows that for macroscopic worm-holes the second part has the order ⟨Δ119879
120572120573⟩ sim 8120587119866119899 and
is negligible as compared to the curvature 119877 sim 1198862119899 (since
macroscopic wormholes have throats 119886 ≫ ℓpl) Howeverfor the sake of completeness and for methodological aims wedescribe it as well
For rigorous evaluation of dark energy of the secondtype we first have to find the bias 119887
1(119909 119909
1015840 120578) analogous to
(19) for the topology 1198774(119879
3
+cup 119879
3
minus) There are many papers
treating different wormholes in this respect (eg see [36 37]and references therein) However in the present paper for anestimation we shall use a more simple trick
71 Beads of Virtual Wormholes (Quantum Wormhole)Indeed instead of the cylinders 1198793
plusmnwe consider a couple of
chains (beads of virtual wormholes 1198793
plusmnrarr cup
1198991198783
plusmn119899) Such an
idea was first suggested in [39] and one may call such anobject as quantum wormhole Then the bias can be writtenstraightforwardly
1198871(119909 119909
1015840 120578) =
+infin
sum
119899=minusinfin
1
41205872119886(
1
(119877minus119899
minus 1199091015840)2minus
1
(119877+119899
minus 1199091015840)2)
times [120575 (10038161003816100381610038161003816 minus
+119899
10038161003816100381610038161003816minus 119886) minus 120575 (
10038161003816100381610038161003816 minus
minus119899
10038161003816100381610038161003816minus 119886)]
(74)
where 119877plusmn119899
= (119905119899 119903
plusmn) with 119905
119899= 119905
0+ 2ℓ119899 and ℓ ge 119886 is the
step We may expect that upon averaging over the position1199050isin [minusℓ ℓ] the bias for the beads will reproduce the bias for
cylinders1198793
plusmn(at least it looks like a very good approximation)
We point out that the averaging out (12ℓ) intℓ
minusℓ119889119905
0and the
sum sum+infin
119899=minusinfinreduces to a single integral (12ℓ) intinfin
minusinfin119889119905 of the
zero term in (74) And moreover the resulting total biascorresponds merely to a specific choice of the distributionfunction 119865(120585) in (21) Namely we may take
119873119865 (120585) =1
2ℓ120575 (119905
+minus 119905
minus) 119891 (
1003816100381610038161003816119903+ minus 119903minus
1003816100381610038161003816 119886) (75)
12 Journal of Astrophysics
where119877plusmn= (119905
plusmn 119903
plusmn) and119891(119904 119886) is the distribution of cylinders
which can be taken as (119899 is 3-dimensional density)
119891 (120578) =119899 (119886)
41205871199032
0
120575 (119904 minus 1199030) (76)
Using the normalization condition int119873119865(120585)119889120585 = 119873 we findthe relation 119873 = (12ℓ)119899119881 = 119899119881 where 119899 is a 4-dimensional density of wormholes and 1(2ℓ) is the effectivenumber of wormholes on the unit length of the cylinder (iethe frequency with which the virtual wormhole appears atthe positions 119903
plusmn) This frequency is uniquely fixed by the
requirement that the volume which cuts the bead is equal tothat which cuts the cylinder (43)1205871198863 = (120587
22)119886
4(12ℓ) (ie
2ℓ = (31205878)119886 and 119899 = (83120587119886)119899) Thus we can use directlyexpression (23) and find (compare to (25))
119887 (119896) = minusint 119899 (119886) 1198862 4120587
2
1198962(1 minus
sin |k| 1199030|k| 1199030
)1198691(119896119886)
1198961198862119889119886 (77)
where 119896 = (1198960 k) Here the first term merely coincides with
that in (25) and therefore it gives the contribution to thecosmological constant 120575Λ(8120587119866) = minus1198994 = minus2119899(3120587119886)while the second term describes a correction which does notreduce to the cosmological constant and requires a separateconsideration
72 Stress Energy Tensor From (57) we find that the stressenergy tensor
minus⟨Δ119879120572120573
(119909)⟩ = int
119896120573119896120572minus (12) 119892
1205721205731198962
1198962119887 (119896 120585)
1198894119896
(2120587)4
(78)
reduces to the two functions
11987900
= 120576 = 1205821minus1
2120583
119879119894119895= 119901120575
119894119895 119901 =
1
31205822minus1
2120583
(79)
where 120576 + 3119901 = minus120583 and 1205821+ 120582
2= 120583 and these functions are
1205821= minusint
1198962
0
11989621198871198894119896
(2120587)4 120582
2= minusint
|k|2
11989621198871198894119896
(2120587)4 (80)
By means of the use of the spherical coordinates 11989620119896
2=
cos2120579 |k|21198962 = sin2120579 and 119889
4119896 = 4120587sin2
1205791198963119889119896119889120579 we get
120582119894=119899 (119886 119903
0)
4120573119894
(1 minus 2120573119894(119886
1199030
)
2
119891119894(119886
1199030
)) (81)
where 1205731= 1 120573
2= 13 and 119891
119894is given by
119891(1
2)(119910)
=2
120587int
1
minus1
int
infin
0
sin (119909 sin 120579)1198691(119910119909)
1199101199092(cos2120579sin2
120579) 119889119909 119889cos 120579
(82)
For 1198861199030≪ 1 we find
11989112
(119886
1199030
) asymp (1 + 11990012
(119886
1199030
)) (83)
Thus finally we find
120576 ≃ minus119899
4= minus
2119899
3120587119886 119901 ≃ 120576(1 minus
4
3(119886
1199030
)
2
) (84)
which upon the continuation to the Minkowsky space givesthe equation of state in the form (An arbitrary gas ofwormholes splits in fractions with a fixed 119886 and 119903
0)
119901 = minus(1 minus4
3(119886
1199030
)
2
) 120576 (85)
which in the case when 1198861199030≪ 1 behaves like a cosmological
constant However when 119886 ≫ ℓpl such a constant is extremelysmall and can be neglected while the leading contributioncomes from the mean curvature
73 Mean Curvature In this subsection we consider theMinkowsky spaceThen the simplest actual wormhole can bedescribed by the metric analogous to (1) for example see [7]
1198891199042= 119888
2119889119905
2minus ℎ
2(119903) 120575
120572120573119889119909
120572119889119909
120573 (86)
where ℎ(119903) = 1 + 120579(119886 minus 119903)(1198862119903
2minus 1) To avoid problems
with the Bianchi identity and the conservation of energy thestep function should be also smoothed as in (1) The stressenergy tensor which produces such a wormhole can be foundfrom the Einstein equation 8120587119866119879
120573
120572= 119877
120573
120572minus (12)120575
120573
120572119877 Both
regions 119903 gt 119886 and 119903 lt 119886 represent portions of the ordinaryflat Minkowsky space and therefore the curvature is 119877119896
119894equiv 0
However on the boundary 119903 = 119886 it has the singularity Sincethe metric (86) does not depend on time we find
1198770
0= 119877
0
120572= 0 119877
120573
120572=2
119886120575 (119886 minus 119903) 119899
120572119899120573+ 120575
120573
120572 + 120582
120573
120572 (87)
where 119899120572 = 119899120572= 119909
120572119903 is the outer normal to the throat 1198782
and 120582120573
120572are additional terms (eg see (49) and (51)) which
in the leading order are negligible upon averaging over someportion of space Δ119881 ≳ 119886
3 In the case of a set of wormholesthis gives in the leading order
1198770
0= 119877
0
120572= 0 119877
120573
120572= sum
2
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119903
119894
1003816100381610038161003816) 119899119894120572119899120573
119894+ 120575
120573
120572
(88)
where 119886119894is the radius of a throat and 119903
119894is the position of the
center of the throat in space and 119899120572
119894= (119909
120572minus 119903
120572
119894)|119903 minus 119903
119894|
In the case of a homogeneous and isotropic distribution ofsuch throats we find 119877
120573
120572= (13)119877120575
120573
120572(averaging over spatial
directions gives ⟨119899120572119899120573⟩ = (13)120575
120573
120572) where
119877 = minus8120587119866119879 = sum8
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119877
119894
1003816100381610038161003816) = 32120587int 119886119899 (119886) 119889119886
(89)
Journal of Astrophysics 13
where 119879 stands for the trace of the stress energy momentumtensor which one has to add to the Einstein equations tosupport such awormhole It is clear that such a source violatesthe weak energy condition and therefore it reproduces theformof dark energy (ie119879 = 120576+3119901 lt 0) If the density of suchsources (and resp the density of wormholes) is sufficientlyhigh then this results in the observed [10ndash14] accelerationof the scale factor for the Friedmann space as sim 119905
120572 with120572 = 21205763(120576 + 119901) = 2120576(2120576 + (120576 + 3119901)) gt 1 for examplesee also [40ndash42] In terms of the 4-dimensional density ofwormholes 119899 = (83120587119886)119899 we get 119877 sim 119886
2119899 ≫ 8120587119866119899 as 119886 ≫ ℓpl
and therefore the leading contribution indeed comes fromthe mean curvature
8 Estimates and Concluding Remarks
Now consider the simplest estimates Actual wormholes seemto be responsible for the dark matter [7 9] Therefore to getthe estimate to the number density of wormholes is ratherstraightforward First wormholes appear at scales when darkmatter effects start to display themselves that is at scales ofthe order 119871 sim (1 divide 5)Kpc which gives in that range thenumber density
119899 sim1
1198713sim (3 divide 0024) times 10
minus65cmminus3 (90)
The characteristic size of throats can be estimated from (89)120576DE sim (119866)
minus1119899119886 Since the density of dark energy is 120576DE1205760 =
ΩDE sim 075 where 1205760is the critical density then we find the
estimate
119886 sim2
3(1 divide 125) times 10
minus3119877⊙ΩDEℎ
2
75 (91)
where119877⊙is the Solar radius ℎ
75= 119867(75 km(secMpc)) and
119867 is the Hubble constant We also recall that the backgrounddensity of baryons 120576
119887generates a nonvanishingwormhole rest
mass119872119908= (43)120587119886
31198773120576119887(where119877(119905) is the scale factor of the
Universe and therefore 119872119908remains constant) for example
see [7] It produces the dark matter density related to thewormholes as 120576DM ≃ 119872
119908119899 The typical mass of a wormhole
119872119908is estimated as
119872119908sim 1 7 times (1 divide 125) times 10
2119872
⊙ΩDMℎ
2
75 (92)
where 119872⊙is the Solar mass We point out that this mass
has not the direct relation to the parameters of the gas ofwormholes However it defines the moment when wormholethroats separated from the cosmological expansion Theabove estimate shows that if wormholes form due to thedevelopment of perturbations in the exotic matter then thisprocess should start much earlier than the formation ofgalaxies
Thus we see that virtual wormholes should indeed leadto the regularization of all divergencies in QFT which agreeswith recent results [28] Therefore they form the local finitevalue of the cosmological constant In the absence of externalclassical fields such a value should be exactly zero at macro-scopic scales A some nonvanishing value for the cosmolog-ical constant appears as the result of vacuum polarization
effects in external fields Indeed external fields form anadditional distribution of virtual wormholes which possessan exotic stress energy tensor (some kind of dark energy)Only some part of it forms the cosmological constant whilethe rest reflects the symmetry of external fields and possessesinhomogeneitiesWe assume that during the evolution of ourUniverse inhomogeneities in the exotic matter develop andmay form actual wormholes Although this problem requiresthe further and more deep investigation we refer to [38]where the formation of a simplest wormhole-like object hasbeen considered In other words such polarization energyis reserved now in a gas of actual wormholes We estimatedparameters of such a gas and believe that such a gas mayindeed be responsible for both dark matter and dark energyphenomena
References
[1] J R Primack ldquoThe nature ofdark matterrdquo httparxivorgabsastro-ph0112255
[2] J Diemand M Zemp B Moore J Stadel and M CarolloldquoCusps in cold dark matter haloesrdquoMonthly Notices of the RoyalAstronomical Society vol 364 no 2 pp 665ndash673 2005
[3] E W Mielke and J A V Velez Perez ldquoAxion condensate as amodel for dark matter halosrdquo Physics Letters B vol 671 no 1pp 174ndash178 2009
[4] G Gentile P Salucci U Klein D Vergani and P Kalberla ldquoThecored distribution of dark matter in spiral galaxiesrdquo MonthlyNotices of the Royal Astronomical Society vol 351 no 3 pp 903ndash922 2004
[5] D T F Weldrake W J G de Blok and F Walter ldquoA high-resolution rotation curve of NGC 6822 a test-case for cold darkmatterrdquo Monthly Notices of the Royal Astronomical Society vol340 no 1 pp 12ndash28 2003
[6] W J G de Blok andA Bosma ldquoHigh-resolution rotation curvesof low surface brightness galaxiesrdquoAstronomy and Astrophysicsvol 385 pp 816ndash846 2002
[7] A Kirillov and E P Savelova ldquoDensity perturbations in a gas ofwormholesrdquoMonthly Notices of the Royal Astronomical Societyvol 412 no 3 pp 1710ndash1720 2011
[8] P Kanti B Kleihaus and J Kunz ldquoStable Lorentzianwormholesin dilatonic Einstein-Gauss-Bonnet theoryrdquo Physical Review Dvol 85 no 4 Article ID 044007 2012
[9] A A Kirillov and E P Savelova ldquoDark matter from a gas ofwormholesrdquo Physics Letters B vol 660 no 3 pp 93ndash99 2008
[10] A G Riess A V Filippenko P Challis et al ldquoObservationalevidence from supernovae for an accelerating universe and acosmological constantrdquo The Astronomical Journal vol 116 no3 p 1009 1998
[11] S Perlmutter G Aldering G Goldhaber et al ldquoMeasurementsofΩ andΛ from42high-redshift supernovaerdquoTheAstrophysicalJournal vol 517 no 2 p 565 1999
[12] J L Tonry B P Schmidt B Barris et al ldquoCosmological resultsfromhigh-z supernovaerdquoTheAstrophysical Journal vol 594 no1 p 594 2003
[13] N W Halverson E M Leitch C Pryke et al ldquoDegreeangular scale interferometer first results a measurement of thecosmic microwave background angular power spectrumrdquo TheAstrophysical Journal vol 568 no 1 p 38 2002
14 Journal of Astrophysics
[14] C B Netterfield P A R Ade J J Bock et al ldquoA measurementby BOOMERANGofmultiple peaks in the angular power spec-trum of the cosmic microwave backgroundrdquo The AstrophysicalJournal vol 571 no 2 p 604 2002
[15] S Coleman ldquoWhy there is nothing rather than something atheory of the cosmological constantrdquoNuclear Physics B vol 310no 3-4 pp 643ndash668 1988
[16] I Klebanov L Susskind and T Banks ldquoWormholes and thecosmological constantrdquo Nuclear Physics B vol 317 no 3 pp665ndash692 1989
[17] S W Hawking ldquoSpacetime foamrdquoNuclear Physics B vol 114 p349 1978
[18] T P Cheng and L F Li Gauge Theory of Elementary ParticlesClarendon Press Oxford UK 1984
[19] A H Taub ldquoSpace-times with distribution valued curvaturetensorsrdquo Journal ofMathematical Physics vol 21 no 6 pp 1423ndash1431 1980
[20] A Shatsky privite communications[21] V A Fock ldquoZur Theorie des Wasserstoffatomsrdquo Zeitschrift fur
Physik vol 98 no 3-4 pp 145ndash154 1935[22] E P Savelova ldquoGas of wormholes in Euclidean quantum field
theoryrdquo httparxivorgabs12115106[23] A A Kirillov and E P Savelova ldquoOn the behavior of
bosonic systems in the presence of topology fluctuationsrdquohttparxivorgabs08082478
[24] A A Kirillov ldquoViolation of the Pauli principle and dimensionof the Universe at very large distancesrdquo Physics Letters B vol555 no 1-2 pp 13ndash21 2003
[25] A A Kirillov ldquoDark matter dark charge and the fractalstructure of the Universerdquo Physics Letters B vol 535 no 1ndash4pp 22ndash24 2002
[26] J Ambjorn J Jurkiewicz and R Loll ldquoThe spectral dimensionof the universe is scale dependentrdquo Physical Review Letters vol95 no 17 Article ID 171301 4 pages 2005
[27] E Manrique S Rechenberger and F Saueressig ldquoAsymptoti-cally safe Lorentzian gravityrdquo Physical Review Letters vol 106no 25 Article ID 251302 4 pages 2011
[28] J Laiho and D Coumbe ldquoEvidence for asymptotic safety fromlattice quantum gravityrdquo Physical Review Letters vol 107 no 16Article ID 161301 2011
[29] A A Kirillov and D Turaev ldquoOn modification of the Newtonrsquoslaw of gravity at very large distancesrdquo Physics Letters B vol 532no 3-4 pp 185ndash192 2002
[30] A A Kirillov and D Turaev ldquoThe universal rotation curveof spiral galaxiesrdquo Monthly Notices of the Royal AstronomicalSociety vol 371 no 1 pp L31ndashL35 2006
[31] A A Kirillov and D Turaev ldquoFoam-like structure of theuniverserdquo Physics Letters B vol 656 pp 1ndash8 2007
[32] A A Kirillov ldquoThe nature of dark matterrdquo Physics Letters B vol632 no 4 pp 453ndash462 2006
[33] A A Kirillov and E P Savelova ldquoAstrophysical effects of space-time foamrdquo Gravitation and Cosmology vol 14 no 3 pp 256ndash261 2008
[34] S W Hawking and N Turok ldquoOpen inflation without falsevacuardquo Physics Letters B vol 425 no 1-2 pp 25ndash32 1998
[35] Z C Wu ldquoThe cosmological constant is probably zero and aproof is possibly rightrdquo Physics Letters B vol 659 no 5 pp 891ndash893 2008
[36] R Garattini ldquoEntropy and the cosmological constant aspacetime-foam approachrdquo Nuclear Physics B vol 88 no 1ndash3Article ID 991003 pp 297ndash300 2000
[37] MVisserLorentzianWormholes SpringerNewYorkNYUSA1996
[38] A A Kirillov and E P Savelova ldquoArtificial wormholerdquohttparxivorgabs12040351
[39] E W Mielke ldquoKnot wormholes in geometrodynamicsrdquo Gen-eral Relativity and Gravitation vol 8 no 3 pp 175ndash196 1977
[40] E B Gliner ldquoAlgebraic properties of the energy-momentumtensor and vacuum-like states of matterrdquo Journal of Experimen-tal and Theoretical Physics vol 22 p 378 1966
[41] A H Guth ldquoInflationary universe a possible solution to thehorizon and flatness problemsrdquo Physical Review D vol 23 no2 pp 347ndash356 1981
[42] A A Linde ldquoA new inflationary universe scenario a possiblesolution of the horizon flatness homogeneity isotropy andprimordial monopole problemsrdquo Physics Letters B vol 108 no6 pp 389ndash393 1982
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
![Page 10: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/10.jpg)
10 Journal of Astrophysics
the limit 119886 rarr 0) Then instead of (24) we may assume thevacuum distribution of virtual wormholes in the form
119873119865 (119886119883) =1
1198862120575 (119886) ] (119883) (64)
where ](119883) = int 1198862119873119865(119886119883)119889119886 and int(1119886
2)](119883)119889
4119883 =
119899 rarr infin has the meaning of the infinite density of point-like wormholes while ] sim 119886
2119899 remains a finite In this case
the volume cut by wormholes vanishes int 2119899(12058722)119886
4119889119886 119889119903
0=
1198862int ](119883)119889
4119883 rarr 0 and the rarefied gas approximationworks
wellThis defines the bias and themean cutoff (here we definethe Fourier transform ](119896) = int ](119883)119890
1198941198961198831198894119883) as
119873(119896) = 1 minus4120587
2
1198962(] (0) minus ] (119896)) (65)
The contribution to themean curvature (55) can be expressedvia the same function ](119896) as
Λ119877= minus12120587
2int119899 (119886 119903
0) 119886
2119889119886 119889119903
0
= minus121205872int ] (119883) 119889
4119883 = minus12120587
2] (0)
(66)
Thus for the total cosmological constant we get the expres-sion
Λ tot = Λ0
+ 2120587119866int(1minus4120587
2
1198962(] (0)minus] (119896)))
1198894119896
(2120587)4minus12120587
2] (0)
(67)
We stress that all these terms should be finite Indeed all dis-tributions of virtual wormholes ](119896) which lead to an infinitevalue of Λ tot are suppressed in (5) by the factor sim119890minusintΛ tot119889
4
119909while the minimal value is reached when wormholes cut allof the volume of space and the action is merely 119878 = 0(Frankly speaking this statement is not rigorous At first lookthe two last terms in (67) are independent and one may tryto take ](0) an arbitrary big If this were the case then theaction would not possess the minimum at all However ](0)cannot be arbitrary big since it will violate the rarefied gasapproximation and the linear expression (67) brakes downMoreover fermions give here a contribution of the oppositesign The rigorous investigation of this problem requires thefurther studying and we present it elsewhere) We also pointout that here we considered the real scalar field as the mattersource while in the general case the stress energy tensorshould include all existing Bose and Fermi fields (Fermi fieldsgive a negative contribution to Λ
119898)
The value of Λ0looks like a free parameter which in
quantum gravity runs with scales [27] However at largescales its asymptotic value may be uniquely fixed by thesimple arguments as follows Indeed in quantum field theoryproperties of the ground state (vacuum) change when weimply an external classical fields The same is true for thedistribution of virtualwormholes ](119896 119869) for example see (33)and (37) and therefore Λ tot = Λ tot(119869) which we describe
in the next subsection We recall that in gravity the role ofthe external current plays the stress energy tensor of matterfields 119869 = 119879
119886119887 However one believes that in the absence
of all classical fields the vacuum state should represent themost symmetric (Lorentz invariant) state which in our casecorresponds to the Euclidean space In order to be consistentwith the Einstein equations this requires Λ tot(119869 = 0) = 0
which uniquely fixes the value of Λ0in (67) We point out
that from somewhat different considerations such a choicewas advocated earlier in [15 34 35]
64 Vacuum Polarization in an External Field Consider nowtopology fluctuations in the presence of an external currentIn the presence of an external current 119869ext the distribution ofvirtual wormholes changes ](119896 119869) = ](119896) + 120575](119896 119869) Indeedin (33) for the case of a weak external field the contributionof the external current into the action can be expanded asexp(minus119881(119869)) ≃ 1 minus 119881 where
119881 = minus1
2int 119869 (119909) 119866 (119909 119910) 119869 (119910) 119889
4119909 119889
4119910
= minus1
2
1198714
(2120587)4int119866
0(119896)119873 (119896)
10038161003816100381610038161198691198961003816100381610038161003816
2
1198894119896
(68)
Then using (36) we find119873(119896 119869) = 119873(119896 0) + 120575119873(119896 119869) where
120575119873 (119896 119869) = 120575119887 (119869) ≃ minus1
2
1198714
(2120587)4int120590
2(119896 119901) 119866
0(119901)
10038161003816100381610038161003816119869119901
10038161003816100381610038161003816
2
1198894119901
(69)
is the bias related to an additional distribution of virtualwormholes and 120590
2(119896 119901) = Δ119873lowast(119896)Δ119873(119901)
1205902(119896 119901) =
1
119885total (0)int [119863119873] 119890
minus119868(119873)Δ119873
lowast(119896) Δ119873 (119901) (70)
defines the dispersion of vacuum topology fluctuations (hereΔ119873 = 119873 minus 119873) The exact definition of 1205902
(119896 119901) requires thefurther development of a fundamental theory In particular itcan be numerically calculated in lattice quantum gravity [28]However it can be shown that at scales 119896 119901 ≫ 119896pl it reducesto 1205902
(119896 119901) rarr 1205902
119896120575(119896 minus 119901) and therefore
120575119887 (119869) = minus1205902
119896
41205872
21198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(71)
Now comparing this function with (23) we relate the addi-tional distribution of virtual wormholes and the externalclassical field as
41205872
1198962(120575] (0 119869) minus 120575] (119896 119869)) =
1
21205902
119896
41205872
1198962
10038161003816100381610038161003816119869ext119896
10038161003816100381610038161003816
2
(72)
where 120575](119896 119869) = int 1198862120575119873119865(119886 119896)119889119886 We point out that the
above expression does not define the value 120575](0 119869) whichrequires an additional considerationMoreover in general theexternal field 119869 does not possess a symmetry and therefore thecorrection ⟨120575119879
120572120573(119909)⟩ does not reduce to a single cosmological
Journal of Astrophysics 11
constant However such corrections always violate the aver-aged null energy condition [36 37] and may be considered assome kind of dark energy or by other words it represents anexotic matter Some portion of dark energy still has the formof the cosmological constant which defines a nonvanishingpresent day value (we recall that fermions give a contributionof the opposite sign)
120575Λ tot = minus2120587119866int4120587
2
1198962⟨120575] (0 119869) minus 120575] (119896 119869)⟩
1198894119896
(2120587)4
minus 121205872120575] (0 119869)
(73)
where ⟨120575](119896 119869)⟩ denotes an averaging over rotationsThe only unknown parameter in (72) is the dispersion
1205902
119896which defines the intensity of topology fluctuations in
the vacuum It has also the sense of the efficiency coefficientwhich defines the portion of the energy of the external fieldspent on the formation of additional wormholes Thoughthe evaluation of 1205902
119896requires the further development of a
fundamental theory one may expect that 1205902
119896= 119873(119896)(1 minus
119873(119896)) where 119873(119896) is the mean cutoff It is expected that119873(119896) rarr 0 as 119896 ≫ 119896pl and119873(119896) rarr 119873
0le 1 This means that
120590 rarr 0 as 119896 ≫ 119896pl and 120590 rarr 1205900≪ 1 as 119896 ≪ 119896pl while it takes
the maximum value 120590max sim 1 at Planckian scales 119896 sim 119896pl Byotherwords themost efficient transmission of the energy intowormholes takes place for wormholes of the Planckian sizeIn the case when external classical fields have characteristicscales 120582 = 2120587119896 ≫ ℓpl in (72) the efficiency coefficient 1205902
119896and
the cutoff 119873(119896) become constant 120590 ≃ 1205900 119873(119896) ≃ 119873
0 while
their ratiomay be estimated as 1205721205902
0119873
0= ΩDEΩ119887
where 120572 isthe effective number of fundamental fields which contributeto 120575Λ tot and ΩDE Ω119887
are dark energy and baryon energydensities respectively According to the modern picture thisratio gives ΩDEΩ119887
asymp 075005 = 15 while 1205902
0119873
0sim 1
(as 1198730≪ 1) and therefore this defines the estimate for the
effective number of fundamental fields (helicity states) as 120572 sim
15
65 Speculations on the Formation of Actual WormholesAs we already pointed out the additional distribution ofvirtual wormholes (72) reflects the symmetry of externalclassical fields and therefore it forms a homogeneous andisotropic background and perturbations We recall that vir-tual wormholes represent an exotic form of matter In theearly Universe such perturbations start to develop and mayform actual wormholes The rigorous description of sucha process represents an extremely complex and interestingproblemwhich requires the further study Some aspects of thebehavior of the exotic density perturbations were consideredin [7] while the simplest example of the formation of awormhole-type object was discussed recently by us in [38]Therefore we may expect that some portion of such a form ofdark energy is reserved now in actual wormholes which weconsider in the next section
7 Dark Energy from Actual Wormholes
Consider now the contribution to the dark energy fromthe gas of actual wormholes Unlike the virtual wormholesactual wormholes do exist at all times and therefore a singlewormhole can be viewed as a couple of conjugated cylinders1198793
plusmn= 119878
2
plusmntimes 119877
1 So that the number of parameters of an actualwormhole is less 120578 = (119886 119903
+ 119903
minus) where 119886 is the radius of 1198782
plusmn
and 119903plusmnisin 119877
3 is a spatial part of 119877plusmn
Actual wormholes also produce two kinds of contributionto the dark energy One comes from their contribution tothe mean curvature which corresponds to an exotic stressenergy momentum tensor Such a stress energy momentumtensor reflects the dark energy reserved by additional virtualwormholes discussed in the previous section Such energyis necessary to support actual wormholes as a solution tothe Einstein equations The second part comes from vacuumpolarization effects by actual wormholes The considerationin the previous section shows that for macroscopic worm-holes the second part has the order ⟨Δ119879
120572120573⟩ sim 8120587119866119899 and
is negligible as compared to the curvature 119877 sim 1198862119899 (since
macroscopic wormholes have throats 119886 ≫ ℓpl) Howeverfor the sake of completeness and for methodological aims wedescribe it as well
For rigorous evaluation of dark energy of the secondtype we first have to find the bias 119887
1(119909 119909
1015840 120578) analogous to
(19) for the topology 1198774(119879
3
+cup 119879
3
minus) There are many papers
treating different wormholes in this respect (eg see [36 37]and references therein) However in the present paper for anestimation we shall use a more simple trick
71 Beads of Virtual Wormholes (Quantum Wormhole)Indeed instead of the cylinders 1198793
plusmnwe consider a couple of
chains (beads of virtual wormholes 1198793
plusmnrarr cup
1198991198783
plusmn119899) Such an
idea was first suggested in [39] and one may call such anobject as quantum wormhole Then the bias can be writtenstraightforwardly
1198871(119909 119909
1015840 120578) =
+infin
sum
119899=minusinfin
1
41205872119886(
1
(119877minus119899
minus 1199091015840)2minus
1
(119877+119899
minus 1199091015840)2)
times [120575 (10038161003816100381610038161003816 minus
+119899
10038161003816100381610038161003816minus 119886) minus 120575 (
10038161003816100381610038161003816 minus
minus119899
10038161003816100381610038161003816minus 119886)]
(74)
where 119877plusmn119899
= (119905119899 119903
plusmn) with 119905
119899= 119905
0+ 2ℓ119899 and ℓ ge 119886 is the
step We may expect that upon averaging over the position1199050isin [minusℓ ℓ] the bias for the beads will reproduce the bias for
cylinders1198793
plusmn(at least it looks like a very good approximation)
We point out that the averaging out (12ℓ) intℓ
minusℓ119889119905
0and the
sum sum+infin
119899=minusinfinreduces to a single integral (12ℓ) intinfin
minusinfin119889119905 of the
zero term in (74) And moreover the resulting total biascorresponds merely to a specific choice of the distributionfunction 119865(120585) in (21) Namely we may take
119873119865 (120585) =1
2ℓ120575 (119905
+minus 119905
minus) 119891 (
1003816100381610038161003816119903+ minus 119903minus
1003816100381610038161003816 119886) (75)
12 Journal of Astrophysics
where119877plusmn= (119905
plusmn 119903
plusmn) and119891(119904 119886) is the distribution of cylinders
which can be taken as (119899 is 3-dimensional density)
119891 (120578) =119899 (119886)
41205871199032
0
120575 (119904 minus 1199030) (76)
Using the normalization condition int119873119865(120585)119889120585 = 119873 we findthe relation 119873 = (12ℓ)119899119881 = 119899119881 where 119899 is a 4-dimensional density of wormholes and 1(2ℓ) is the effectivenumber of wormholes on the unit length of the cylinder (iethe frequency with which the virtual wormhole appears atthe positions 119903
plusmn) This frequency is uniquely fixed by the
requirement that the volume which cuts the bead is equal tothat which cuts the cylinder (43)1205871198863 = (120587
22)119886
4(12ℓ) (ie
2ℓ = (31205878)119886 and 119899 = (83120587119886)119899) Thus we can use directlyexpression (23) and find (compare to (25))
119887 (119896) = minusint 119899 (119886) 1198862 4120587
2
1198962(1 minus
sin |k| 1199030|k| 1199030
)1198691(119896119886)
1198961198862119889119886 (77)
where 119896 = (1198960 k) Here the first term merely coincides with
that in (25) and therefore it gives the contribution to thecosmological constant 120575Λ(8120587119866) = minus1198994 = minus2119899(3120587119886)while the second term describes a correction which does notreduce to the cosmological constant and requires a separateconsideration
72 Stress Energy Tensor From (57) we find that the stressenergy tensor
minus⟨Δ119879120572120573
(119909)⟩ = int
119896120573119896120572minus (12) 119892
1205721205731198962
1198962119887 (119896 120585)
1198894119896
(2120587)4
(78)
reduces to the two functions
11987900
= 120576 = 1205821minus1
2120583
119879119894119895= 119901120575
119894119895 119901 =
1
31205822minus1
2120583
(79)
where 120576 + 3119901 = minus120583 and 1205821+ 120582
2= 120583 and these functions are
1205821= minusint
1198962
0
11989621198871198894119896
(2120587)4 120582
2= minusint
|k|2
11989621198871198894119896
(2120587)4 (80)
By means of the use of the spherical coordinates 11989620119896
2=
cos2120579 |k|21198962 = sin2120579 and 119889
4119896 = 4120587sin2
1205791198963119889119896119889120579 we get
120582119894=119899 (119886 119903
0)
4120573119894
(1 minus 2120573119894(119886
1199030
)
2
119891119894(119886
1199030
)) (81)
where 1205731= 1 120573
2= 13 and 119891
119894is given by
119891(1
2)(119910)
=2
120587int
1
minus1
int
infin
0
sin (119909 sin 120579)1198691(119910119909)
1199101199092(cos2120579sin2
120579) 119889119909 119889cos 120579
(82)
For 1198861199030≪ 1 we find
11989112
(119886
1199030
) asymp (1 + 11990012
(119886
1199030
)) (83)
Thus finally we find
120576 ≃ minus119899
4= minus
2119899
3120587119886 119901 ≃ 120576(1 minus
4
3(119886
1199030
)
2
) (84)
which upon the continuation to the Minkowsky space givesthe equation of state in the form (An arbitrary gas ofwormholes splits in fractions with a fixed 119886 and 119903
0)
119901 = minus(1 minus4
3(119886
1199030
)
2
) 120576 (85)
which in the case when 1198861199030≪ 1 behaves like a cosmological
constant However when 119886 ≫ ℓpl such a constant is extremelysmall and can be neglected while the leading contributioncomes from the mean curvature
73 Mean Curvature In this subsection we consider theMinkowsky spaceThen the simplest actual wormhole can bedescribed by the metric analogous to (1) for example see [7]
1198891199042= 119888
2119889119905
2minus ℎ
2(119903) 120575
120572120573119889119909
120572119889119909
120573 (86)
where ℎ(119903) = 1 + 120579(119886 minus 119903)(1198862119903
2minus 1) To avoid problems
with the Bianchi identity and the conservation of energy thestep function should be also smoothed as in (1) The stressenergy tensor which produces such a wormhole can be foundfrom the Einstein equation 8120587119866119879
120573
120572= 119877
120573
120572minus (12)120575
120573
120572119877 Both
regions 119903 gt 119886 and 119903 lt 119886 represent portions of the ordinaryflat Minkowsky space and therefore the curvature is 119877119896
119894equiv 0
However on the boundary 119903 = 119886 it has the singularity Sincethe metric (86) does not depend on time we find
1198770
0= 119877
0
120572= 0 119877
120573
120572=2
119886120575 (119886 minus 119903) 119899
120572119899120573+ 120575
120573
120572 + 120582
120573
120572 (87)
where 119899120572 = 119899120572= 119909
120572119903 is the outer normal to the throat 1198782
and 120582120573
120572are additional terms (eg see (49) and (51)) which
in the leading order are negligible upon averaging over someportion of space Δ119881 ≳ 119886
3 In the case of a set of wormholesthis gives in the leading order
1198770
0= 119877
0
120572= 0 119877
120573
120572= sum
2
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119903
119894
1003816100381610038161003816) 119899119894120572119899120573
119894+ 120575
120573
120572
(88)
where 119886119894is the radius of a throat and 119903
119894is the position of the
center of the throat in space and 119899120572
119894= (119909
120572minus 119903
120572
119894)|119903 minus 119903
119894|
In the case of a homogeneous and isotropic distribution ofsuch throats we find 119877
120573
120572= (13)119877120575
120573
120572(averaging over spatial
directions gives ⟨119899120572119899120573⟩ = (13)120575
120573
120572) where
119877 = minus8120587119866119879 = sum8
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119877
119894
1003816100381610038161003816) = 32120587int 119886119899 (119886) 119889119886
(89)
Journal of Astrophysics 13
where 119879 stands for the trace of the stress energy momentumtensor which one has to add to the Einstein equations tosupport such awormhole It is clear that such a source violatesthe weak energy condition and therefore it reproduces theformof dark energy (ie119879 = 120576+3119901 lt 0) If the density of suchsources (and resp the density of wormholes) is sufficientlyhigh then this results in the observed [10ndash14] accelerationof the scale factor for the Friedmann space as sim 119905
120572 with120572 = 21205763(120576 + 119901) = 2120576(2120576 + (120576 + 3119901)) gt 1 for examplesee also [40ndash42] In terms of the 4-dimensional density ofwormholes 119899 = (83120587119886)119899 we get 119877 sim 119886
2119899 ≫ 8120587119866119899 as 119886 ≫ ℓpl
and therefore the leading contribution indeed comes fromthe mean curvature
8 Estimates and Concluding Remarks
Now consider the simplest estimates Actual wormholes seemto be responsible for the dark matter [7 9] Therefore to getthe estimate to the number density of wormholes is ratherstraightforward First wormholes appear at scales when darkmatter effects start to display themselves that is at scales ofthe order 119871 sim (1 divide 5)Kpc which gives in that range thenumber density
119899 sim1
1198713sim (3 divide 0024) times 10
minus65cmminus3 (90)
The characteristic size of throats can be estimated from (89)120576DE sim (119866)
minus1119899119886 Since the density of dark energy is 120576DE1205760 =
ΩDE sim 075 where 1205760is the critical density then we find the
estimate
119886 sim2
3(1 divide 125) times 10
minus3119877⊙ΩDEℎ
2
75 (91)
where119877⊙is the Solar radius ℎ
75= 119867(75 km(secMpc)) and
119867 is the Hubble constant We also recall that the backgrounddensity of baryons 120576
119887generates a nonvanishingwormhole rest
mass119872119908= (43)120587119886
31198773120576119887(where119877(119905) is the scale factor of the
Universe and therefore 119872119908remains constant) for example
see [7] It produces the dark matter density related to thewormholes as 120576DM ≃ 119872
119908119899 The typical mass of a wormhole
119872119908is estimated as
119872119908sim 1 7 times (1 divide 125) times 10
2119872
⊙ΩDMℎ
2
75 (92)
where 119872⊙is the Solar mass We point out that this mass
has not the direct relation to the parameters of the gas ofwormholes However it defines the moment when wormholethroats separated from the cosmological expansion Theabove estimate shows that if wormholes form due to thedevelopment of perturbations in the exotic matter then thisprocess should start much earlier than the formation ofgalaxies
Thus we see that virtual wormholes should indeed leadto the regularization of all divergencies in QFT which agreeswith recent results [28] Therefore they form the local finitevalue of the cosmological constant In the absence of externalclassical fields such a value should be exactly zero at macro-scopic scales A some nonvanishing value for the cosmolog-ical constant appears as the result of vacuum polarization
effects in external fields Indeed external fields form anadditional distribution of virtual wormholes which possessan exotic stress energy tensor (some kind of dark energy)Only some part of it forms the cosmological constant whilethe rest reflects the symmetry of external fields and possessesinhomogeneitiesWe assume that during the evolution of ourUniverse inhomogeneities in the exotic matter develop andmay form actual wormholes Although this problem requiresthe further and more deep investigation we refer to [38]where the formation of a simplest wormhole-like object hasbeen considered In other words such polarization energyis reserved now in a gas of actual wormholes We estimatedparameters of such a gas and believe that such a gas mayindeed be responsible for both dark matter and dark energyphenomena
References
[1] J R Primack ldquoThe nature ofdark matterrdquo httparxivorgabsastro-ph0112255
[2] J Diemand M Zemp B Moore J Stadel and M CarolloldquoCusps in cold dark matter haloesrdquoMonthly Notices of the RoyalAstronomical Society vol 364 no 2 pp 665ndash673 2005
[3] E W Mielke and J A V Velez Perez ldquoAxion condensate as amodel for dark matter halosrdquo Physics Letters B vol 671 no 1pp 174ndash178 2009
[4] G Gentile P Salucci U Klein D Vergani and P Kalberla ldquoThecored distribution of dark matter in spiral galaxiesrdquo MonthlyNotices of the Royal Astronomical Society vol 351 no 3 pp 903ndash922 2004
[5] D T F Weldrake W J G de Blok and F Walter ldquoA high-resolution rotation curve of NGC 6822 a test-case for cold darkmatterrdquo Monthly Notices of the Royal Astronomical Society vol340 no 1 pp 12ndash28 2003
[6] W J G de Blok andA Bosma ldquoHigh-resolution rotation curvesof low surface brightness galaxiesrdquoAstronomy and Astrophysicsvol 385 pp 816ndash846 2002
[7] A Kirillov and E P Savelova ldquoDensity perturbations in a gas ofwormholesrdquoMonthly Notices of the Royal Astronomical Societyvol 412 no 3 pp 1710ndash1720 2011
[8] P Kanti B Kleihaus and J Kunz ldquoStable Lorentzianwormholesin dilatonic Einstein-Gauss-Bonnet theoryrdquo Physical Review Dvol 85 no 4 Article ID 044007 2012
[9] A A Kirillov and E P Savelova ldquoDark matter from a gas ofwormholesrdquo Physics Letters B vol 660 no 3 pp 93ndash99 2008
[10] A G Riess A V Filippenko P Challis et al ldquoObservationalevidence from supernovae for an accelerating universe and acosmological constantrdquo The Astronomical Journal vol 116 no3 p 1009 1998
[11] S Perlmutter G Aldering G Goldhaber et al ldquoMeasurementsofΩ andΛ from42high-redshift supernovaerdquoTheAstrophysicalJournal vol 517 no 2 p 565 1999
[12] J L Tonry B P Schmidt B Barris et al ldquoCosmological resultsfromhigh-z supernovaerdquoTheAstrophysical Journal vol 594 no1 p 594 2003
[13] N W Halverson E M Leitch C Pryke et al ldquoDegreeangular scale interferometer first results a measurement of thecosmic microwave background angular power spectrumrdquo TheAstrophysical Journal vol 568 no 1 p 38 2002
14 Journal of Astrophysics
[14] C B Netterfield P A R Ade J J Bock et al ldquoA measurementby BOOMERANGofmultiple peaks in the angular power spec-trum of the cosmic microwave backgroundrdquo The AstrophysicalJournal vol 571 no 2 p 604 2002
[15] S Coleman ldquoWhy there is nothing rather than something atheory of the cosmological constantrdquoNuclear Physics B vol 310no 3-4 pp 643ndash668 1988
[16] I Klebanov L Susskind and T Banks ldquoWormholes and thecosmological constantrdquo Nuclear Physics B vol 317 no 3 pp665ndash692 1989
[17] S W Hawking ldquoSpacetime foamrdquoNuclear Physics B vol 114 p349 1978
[18] T P Cheng and L F Li Gauge Theory of Elementary ParticlesClarendon Press Oxford UK 1984
[19] A H Taub ldquoSpace-times with distribution valued curvaturetensorsrdquo Journal ofMathematical Physics vol 21 no 6 pp 1423ndash1431 1980
[20] A Shatsky privite communications[21] V A Fock ldquoZur Theorie des Wasserstoffatomsrdquo Zeitschrift fur
Physik vol 98 no 3-4 pp 145ndash154 1935[22] E P Savelova ldquoGas of wormholes in Euclidean quantum field
theoryrdquo httparxivorgabs12115106[23] A A Kirillov and E P Savelova ldquoOn the behavior of
bosonic systems in the presence of topology fluctuationsrdquohttparxivorgabs08082478
[24] A A Kirillov ldquoViolation of the Pauli principle and dimensionof the Universe at very large distancesrdquo Physics Letters B vol555 no 1-2 pp 13ndash21 2003
[25] A A Kirillov ldquoDark matter dark charge and the fractalstructure of the Universerdquo Physics Letters B vol 535 no 1ndash4pp 22ndash24 2002
[26] J Ambjorn J Jurkiewicz and R Loll ldquoThe spectral dimensionof the universe is scale dependentrdquo Physical Review Letters vol95 no 17 Article ID 171301 4 pages 2005
[27] E Manrique S Rechenberger and F Saueressig ldquoAsymptoti-cally safe Lorentzian gravityrdquo Physical Review Letters vol 106no 25 Article ID 251302 4 pages 2011
[28] J Laiho and D Coumbe ldquoEvidence for asymptotic safety fromlattice quantum gravityrdquo Physical Review Letters vol 107 no 16Article ID 161301 2011
[29] A A Kirillov and D Turaev ldquoOn modification of the Newtonrsquoslaw of gravity at very large distancesrdquo Physics Letters B vol 532no 3-4 pp 185ndash192 2002
[30] A A Kirillov and D Turaev ldquoThe universal rotation curveof spiral galaxiesrdquo Monthly Notices of the Royal AstronomicalSociety vol 371 no 1 pp L31ndashL35 2006
[31] A A Kirillov and D Turaev ldquoFoam-like structure of theuniverserdquo Physics Letters B vol 656 pp 1ndash8 2007
[32] A A Kirillov ldquoThe nature of dark matterrdquo Physics Letters B vol632 no 4 pp 453ndash462 2006
[33] A A Kirillov and E P Savelova ldquoAstrophysical effects of space-time foamrdquo Gravitation and Cosmology vol 14 no 3 pp 256ndash261 2008
[34] S W Hawking and N Turok ldquoOpen inflation without falsevacuardquo Physics Letters B vol 425 no 1-2 pp 25ndash32 1998
[35] Z C Wu ldquoThe cosmological constant is probably zero and aproof is possibly rightrdquo Physics Letters B vol 659 no 5 pp 891ndash893 2008
[36] R Garattini ldquoEntropy and the cosmological constant aspacetime-foam approachrdquo Nuclear Physics B vol 88 no 1ndash3Article ID 991003 pp 297ndash300 2000
[37] MVisserLorentzianWormholes SpringerNewYorkNYUSA1996
[38] A A Kirillov and E P Savelova ldquoArtificial wormholerdquohttparxivorgabs12040351
[39] E W Mielke ldquoKnot wormholes in geometrodynamicsrdquo Gen-eral Relativity and Gravitation vol 8 no 3 pp 175ndash196 1977
[40] E B Gliner ldquoAlgebraic properties of the energy-momentumtensor and vacuum-like states of matterrdquo Journal of Experimen-tal and Theoretical Physics vol 22 p 378 1966
[41] A H Guth ldquoInflationary universe a possible solution to thehorizon and flatness problemsrdquo Physical Review D vol 23 no2 pp 347ndash356 1981
[42] A A Linde ldquoA new inflationary universe scenario a possiblesolution of the horizon flatness homogeneity isotropy andprimordial monopole problemsrdquo Physics Letters B vol 108 no6 pp 389ndash393 1982
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
![Page 11: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/11.jpg)
Journal of Astrophysics 11
constant However such corrections always violate the aver-aged null energy condition [36 37] and may be considered assome kind of dark energy or by other words it represents anexotic matter Some portion of dark energy still has the formof the cosmological constant which defines a nonvanishingpresent day value (we recall that fermions give a contributionof the opposite sign)
120575Λ tot = minus2120587119866int4120587
2
1198962⟨120575] (0 119869) minus 120575] (119896 119869)⟩
1198894119896
(2120587)4
minus 121205872120575] (0 119869)
(73)
where ⟨120575](119896 119869)⟩ denotes an averaging over rotationsThe only unknown parameter in (72) is the dispersion
1205902
119896which defines the intensity of topology fluctuations in
the vacuum It has also the sense of the efficiency coefficientwhich defines the portion of the energy of the external fieldspent on the formation of additional wormholes Thoughthe evaluation of 1205902
119896requires the further development of a
fundamental theory one may expect that 1205902
119896= 119873(119896)(1 minus
119873(119896)) where 119873(119896) is the mean cutoff It is expected that119873(119896) rarr 0 as 119896 ≫ 119896pl and119873(119896) rarr 119873
0le 1 This means that
120590 rarr 0 as 119896 ≫ 119896pl and 120590 rarr 1205900≪ 1 as 119896 ≪ 119896pl while it takes
the maximum value 120590max sim 1 at Planckian scales 119896 sim 119896pl Byotherwords themost efficient transmission of the energy intowormholes takes place for wormholes of the Planckian sizeIn the case when external classical fields have characteristicscales 120582 = 2120587119896 ≫ ℓpl in (72) the efficiency coefficient 1205902
119896and
the cutoff 119873(119896) become constant 120590 ≃ 1205900 119873(119896) ≃ 119873
0 while
their ratiomay be estimated as 1205721205902
0119873
0= ΩDEΩ119887
where 120572 isthe effective number of fundamental fields which contributeto 120575Λ tot and ΩDE Ω119887
are dark energy and baryon energydensities respectively According to the modern picture thisratio gives ΩDEΩ119887
asymp 075005 = 15 while 1205902
0119873
0sim 1
(as 1198730≪ 1) and therefore this defines the estimate for the
effective number of fundamental fields (helicity states) as 120572 sim
15
65 Speculations on the Formation of Actual WormholesAs we already pointed out the additional distribution ofvirtual wormholes (72) reflects the symmetry of externalclassical fields and therefore it forms a homogeneous andisotropic background and perturbations We recall that vir-tual wormholes represent an exotic form of matter In theearly Universe such perturbations start to develop and mayform actual wormholes The rigorous description of sucha process represents an extremely complex and interestingproblemwhich requires the further study Some aspects of thebehavior of the exotic density perturbations were consideredin [7] while the simplest example of the formation of awormhole-type object was discussed recently by us in [38]Therefore we may expect that some portion of such a form ofdark energy is reserved now in actual wormholes which weconsider in the next section
7 Dark Energy from Actual Wormholes
Consider now the contribution to the dark energy fromthe gas of actual wormholes Unlike the virtual wormholesactual wormholes do exist at all times and therefore a singlewormhole can be viewed as a couple of conjugated cylinders1198793
plusmn= 119878
2
plusmntimes 119877
1 So that the number of parameters of an actualwormhole is less 120578 = (119886 119903
+ 119903
minus) where 119886 is the radius of 1198782
plusmn
and 119903plusmnisin 119877
3 is a spatial part of 119877plusmn
Actual wormholes also produce two kinds of contributionto the dark energy One comes from their contribution tothe mean curvature which corresponds to an exotic stressenergy momentum tensor Such a stress energy momentumtensor reflects the dark energy reserved by additional virtualwormholes discussed in the previous section Such energyis necessary to support actual wormholes as a solution tothe Einstein equations The second part comes from vacuumpolarization effects by actual wormholes The considerationin the previous section shows that for macroscopic worm-holes the second part has the order ⟨Δ119879
120572120573⟩ sim 8120587119866119899 and
is negligible as compared to the curvature 119877 sim 1198862119899 (since
macroscopic wormholes have throats 119886 ≫ ℓpl) Howeverfor the sake of completeness and for methodological aims wedescribe it as well
For rigorous evaluation of dark energy of the secondtype we first have to find the bias 119887
1(119909 119909
1015840 120578) analogous to
(19) for the topology 1198774(119879
3
+cup 119879
3
minus) There are many papers
treating different wormholes in this respect (eg see [36 37]and references therein) However in the present paper for anestimation we shall use a more simple trick
71 Beads of Virtual Wormholes (Quantum Wormhole)Indeed instead of the cylinders 1198793
plusmnwe consider a couple of
chains (beads of virtual wormholes 1198793
plusmnrarr cup
1198991198783
plusmn119899) Such an
idea was first suggested in [39] and one may call such anobject as quantum wormhole Then the bias can be writtenstraightforwardly
1198871(119909 119909
1015840 120578) =
+infin
sum
119899=minusinfin
1
41205872119886(
1
(119877minus119899
minus 1199091015840)2minus
1
(119877+119899
minus 1199091015840)2)
times [120575 (10038161003816100381610038161003816 minus
+119899
10038161003816100381610038161003816minus 119886) minus 120575 (
10038161003816100381610038161003816 minus
minus119899
10038161003816100381610038161003816minus 119886)]
(74)
where 119877plusmn119899
= (119905119899 119903
plusmn) with 119905
119899= 119905
0+ 2ℓ119899 and ℓ ge 119886 is the
step We may expect that upon averaging over the position1199050isin [minusℓ ℓ] the bias for the beads will reproduce the bias for
cylinders1198793
plusmn(at least it looks like a very good approximation)
We point out that the averaging out (12ℓ) intℓ
minusℓ119889119905
0and the
sum sum+infin
119899=minusinfinreduces to a single integral (12ℓ) intinfin
minusinfin119889119905 of the
zero term in (74) And moreover the resulting total biascorresponds merely to a specific choice of the distributionfunction 119865(120585) in (21) Namely we may take
119873119865 (120585) =1
2ℓ120575 (119905
+minus 119905
minus) 119891 (
1003816100381610038161003816119903+ minus 119903minus
1003816100381610038161003816 119886) (75)
12 Journal of Astrophysics
where119877plusmn= (119905
plusmn 119903
plusmn) and119891(119904 119886) is the distribution of cylinders
which can be taken as (119899 is 3-dimensional density)
119891 (120578) =119899 (119886)
41205871199032
0
120575 (119904 minus 1199030) (76)
Using the normalization condition int119873119865(120585)119889120585 = 119873 we findthe relation 119873 = (12ℓ)119899119881 = 119899119881 where 119899 is a 4-dimensional density of wormholes and 1(2ℓ) is the effectivenumber of wormholes on the unit length of the cylinder (iethe frequency with which the virtual wormhole appears atthe positions 119903
plusmn) This frequency is uniquely fixed by the
requirement that the volume which cuts the bead is equal tothat which cuts the cylinder (43)1205871198863 = (120587
22)119886
4(12ℓ) (ie
2ℓ = (31205878)119886 and 119899 = (83120587119886)119899) Thus we can use directlyexpression (23) and find (compare to (25))
119887 (119896) = minusint 119899 (119886) 1198862 4120587
2
1198962(1 minus
sin |k| 1199030|k| 1199030
)1198691(119896119886)
1198961198862119889119886 (77)
where 119896 = (1198960 k) Here the first term merely coincides with
that in (25) and therefore it gives the contribution to thecosmological constant 120575Λ(8120587119866) = minus1198994 = minus2119899(3120587119886)while the second term describes a correction which does notreduce to the cosmological constant and requires a separateconsideration
72 Stress Energy Tensor From (57) we find that the stressenergy tensor
minus⟨Δ119879120572120573
(119909)⟩ = int
119896120573119896120572minus (12) 119892
1205721205731198962
1198962119887 (119896 120585)
1198894119896
(2120587)4
(78)
reduces to the two functions
11987900
= 120576 = 1205821minus1
2120583
119879119894119895= 119901120575
119894119895 119901 =
1
31205822minus1
2120583
(79)
where 120576 + 3119901 = minus120583 and 1205821+ 120582
2= 120583 and these functions are
1205821= minusint
1198962
0
11989621198871198894119896
(2120587)4 120582
2= minusint
|k|2
11989621198871198894119896
(2120587)4 (80)
By means of the use of the spherical coordinates 11989620119896
2=
cos2120579 |k|21198962 = sin2120579 and 119889
4119896 = 4120587sin2
1205791198963119889119896119889120579 we get
120582119894=119899 (119886 119903
0)
4120573119894
(1 minus 2120573119894(119886
1199030
)
2
119891119894(119886
1199030
)) (81)
where 1205731= 1 120573
2= 13 and 119891
119894is given by
119891(1
2)(119910)
=2
120587int
1
minus1
int
infin
0
sin (119909 sin 120579)1198691(119910119909)
1199101199092(cos2120579sin2
120579) 119889119909 119889cos 120579
(82)
For 1198861199030≪ 1 we find
11989112
(119886
1199030
) asymp (1 + 11990012
(119886
1199030
)) (83)
Thus finally we find
120576 ≃ minus119899
4= minus
2119899
3120587119886 119901 ≃ 120576(1 minus
4
3(119886
1199030
)
2
) (84)
which upon the continuation to the Minkowsky space givesthe equation of state in the form (An arbitrary gas ofwormholes splits in fractions with a fixed 119886 and 119903
0)
119901 = minus(1 minus4
3(119886
1199030
)
2
) 120576 (85)
which in the case when 1198861199030≪ 1 behaves like a cosmological
constant However when 119886 ≫ ℓpl such a constant is extremelysmall and can be neglected while the leading contributioncomes from the mean curvature
73 Mean Curvature In this subsection we consider theMinkowsky spaceThen the simplest actual wormhole can bedescribed by the metric analogous to (1) for example see [7]
1198891199042= 119888
2119889119905
2minus ℎ
2(119903) 120575
120572120573119889119909
120572119889119909
120573 (86)
where ℎ(119903) = 1 + 120579(119886 minus 119903)(1198862119903
2minus 1) To avoid problems
with the Bianchi identity and the conservation of energy thestep function should be also smoothed as in (1) The stressenergy tensor which produces such a wormhole can be foundfrom the Einstein equation 8120587119866119879
120573
120572= 119877
120573
120572minus (12)120575
120573
120572119877 Both
regions 119903 gt 119886 and 119903 lt 119886 represent portions of the ordinaryflat Minkowsky space and therefore the curvature is 119877119896
119894equiv 0
However on the boundary 119903 = 119886 it has the singularity Sincethe metric (86) does not depend on time we find
1198770
0= 119877
0
120572= 0 119877
120573
120572=2
119886120575 (119886 minus 119903) 119899
120572119899120573+ 120575
120573
120572 + 120582
120573
120572 (87)
where 119899120572 = 119899120572= 119909
120572119903 is the outer normal to the throat 1198782
and 120582120573
120572are additional terms (eg see (49) and (51)) which
in the leading order are negligible upon averaging over someportion of space Δ119881 ≳ 119886
3 In the case of a set of wormholesthis gives in the leading order
1198770
0= 119877
0
120572= 0 119877
120573
120572= sum
2
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119903
119894
1003816100381610038161003816) 119899119894120572119899120573
119894+ 120575
120573
120572
(88)
where 119886119894is the radius of a throat and 119903
119894is the position of the
center of the throat in space and 119899120572
119894= (119909
120572minus 119903
120572
119894)|119903 minus 119903
119894|
In the case of a homogeneous and isotropic distribution ofsuch throats we find 119877
120573
120572= (13)119877120575
120573
120572(averaging over spatial
directions gives ⟨119899120572119899120573⟩ = (13)120575
120573
120572) where
119877 = minus8120587119866119879 = sum8
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119877
119894
1003816100381610038161003816) = 32120587int 119886119899 (119886) 119889119886
(89)
Journal of Astrophysics 13
where 119879 stands for the trace of the stress energy momentumtensor which one has to add to the Einstein equations tosupport such awormhole It is clear that such a source violatesthe weak energy condition and therefore it reproduces theformof dark energy (ie119879 = 120576+3119901 lt 0) If the density of suchsources (and resp the density of wormholes) is sufficientlyhigh then this results in the observed [10ndash14] accelerationof the scale factor for the Friedmann space as sim 119905
120572 with120572 = 21205763(120576 + 119901) = 2120576(2120576 + (120576 + 3119901)) gt 1 for examplesee also [40ndash42] In terms of the 4-dimensional density ofwormholes 119899 = (83120587119886)119899 we get 119877 sim 119886
2119899 ≫ 8120587119866119899 as 119886 ≫ ℓpl
and therefore the leading contribution indeed comes fromthe mean curvature
8 Estimates and Concluding Remarks
Now consider the simplest estimates Actual wormholes seemto be responsible for the dark matter [7 9] Therefore to getthe estimate to the number density of wormholes is ratherstraightforward First wormholes appear at scales when darkmatter effects start to display themselves that is at scales ofthe order 119871 sim (1 divide 5)Kpc which gives in that range thenumber density
119899 sim1
1198713sim (3 divide 0024) times 10
minus65cmminus3 (90)
The characteristic size of throats can be estimated from (89)120576DE sim (119866)
minus1119899119886 Since the density of dark energy is 120576DE1205760 =
ΩDE sim 075 where 1205760is the critical density then we find the
estimate
119886 sim2
3(1 divide 125) times 10
minus3119877⊙ΩDEℎ
2
75 (91)
where119877⊙is the Solar radius ℎ
75= 119867(75 km(secMpc)) and
119867 is the Hubble constant We also recall that the backgrounddensity of baryons 120576
119887generates a nonvanishingwormhole rest
mass119872119908= (43)120587119886
31198773120576119887(where119877(119905) is the scale factor of the
Universe and therefore 119872119908remains constant) for example
see [7] It produces the dark matter density related to thewormholes as 120576DM ≃ 119872
119908119899 The typical mass of a wormhole
119872119908is estimated as
119872119908sim 1 7 times (1 divide 125) times 10
2119872
⊙ΩDMℎ
2
75 (92)
where 119872⊙is the Solar mass We point out that this mass
has not the direct relation to the parameters of the gas ofwormholes However it defines the moment when wormholethroats separated from the cosmological expansion Theabove estimate shows that if wormholes form due to thedevelopment of perturbations in the exotic matter then thisprocess should start much earlier than the formation ofgalaxies
Thus we see that virtual wormholes should indeed leadto the regularization of all divergencies in QFT which agreeswith recent results [28] Therefore they form the local finitevalue of the cosmological constant In the absence of externalclassical fields such a value should be exactly zero at macro-scopic scales A some nonvanishing value for the cosmolog-ical constant appears as the result of vacuum polarization
effects in external fields Indeed external fields form anadditional distribution of virtual wormholes which possessan exotic stress energy tensor (some kind of dark energy)Only some part of it forms the cosmological constant whilethe rest reflects the symmetry of external fields and possessesinhomogeneitiesWe assume that during the evolution of ourUniverse inhomogeneities in the exotic matter develop andmay form actual wormholes Although this problem requiresthe further and more deep investigation we refer to [38]where the formation of a simplest wormhole-like object hasbeen considered In other words such polarization energyis reserved now in a gas of actual wormholes We estimatedparameters of such a gas and believe that such a gas mayindeed be responsible for both dark matter and dark energyphenomena
References
[1] J R Primack ldquoThe nature ofdark matterrdquo httparxivorgabsastro-ph0112255
[2] J Diemand M Zemp B Moore J Stadel and M CarolloldquoCusps in cold dark matter haloesrdquoMonthly Notices of the RoyalAstronomical Society vol 364 no 2 pp 665ndash673 2005
[3] E W Mielke and J A V Velez Perez ldquoAxion condensate as amodel for dark matter halosrdquo Physics Letters B vol 671 no 1pp 174ndash178 2009
[4] G Gentile P Salucci U Klein D Vergani and P Kalberla ldquoThecored distribution of dark matter in spiral galaxiesrdquo MonthlyNotices of the Royal Astronomical Society vol 351 no 3 pp 903ndash922 2004
[5] D T F Weldrake W J G de Blok and F Walter ldquoA high-resolution rotation curve of NGC 6822 a test-case for cold darkmatterrdquo Monthly Notices of the Royal Astronomical Society vol340 no 1 pp 12ndash28 2003
[6] W J G de Blok andA Bosma ldquoHigh-resolution rotation curvesof low surface brightness galaxiesrdquoAstronomy and Astrophysicsvol 385 pp 816ndash846 2002
[7] A Kirillov and E P Savelova ldquoDensity perturbations in a gas ofwormholesrdquoMonthly Notices of the Royal Astronomical Societyvol 412 no 3 pp 1710ndash1720 2011
[8] P Kanti B Kleihaus and J Kunz ldquoStable Lorentzianwormholesin dilatonic Einstein-Gauss-Bonnet theoryrdquo Physical Review Dvol 85 no 4 Article ID 044007 2012
[9] A A Kirillov and E P Savelova ldquoDark matter from a gas ofwormholesrdquo Physics Letters B vol 660 no 3 pp 93ndash99 2008
[10] A G Riess A V Filippenko P Challis et al ldquoObservationalevidence from supernovae for an accelerating universe and acosmological constantrdquo The Astronomical Journal vol 116 no3 p 1009 1998
[11] S Perlmutter G Aldering G Goldhaber et al ldquoMeasurementsofΩ andΛ from42high-redshift supernovaerdquoTheAstrophysicalJournal vol 517 no 2 p 565 1999
[12] J L Tonry B P Schmidt B Barris et al ldquoCosmological resultsfromhigh-z supernovaerdquoTheAstrophysical Journal vol 594 no1 p 594 2003
[13] N W Halverson E M Leitch C Pryke et al ldquoDegreeangular scale interferometer first results a measurement of thecosmic microwave background angular power spectrumrdquo TheAstrophysical Journal vol 568 no 1 p 38 2002
14 Journal of Astrophysics
[14] C B Netterfield P A R Ade J J Bock et al ldquoA measurementby BOOMERANGofmultiple peaks in the angular power spec-trum of the cosmic microwave backgroundrdquo The AstrophysicalJournal vol 571 no 2 p 604 2002
[15] S Coleman ldquoWhy there is nothing rather than something atheory of the cosmological constantrdquoNuclear Physics B vol 310no 3-4 pp 643ndash668 1988
[16] I Klebanov L Susskind and T Banks ldquoWormholes and thecosmological constantrdquo Nuclear Physics B vol 317 no 3 pp665ndash692 1989
[17] S W Hawking ldquoSpacetime foamrdquoNuclear Physics B vol 114 p349 1978
[18] T P Cheng and L F Li Gauge Theory of Elementary ParticlesClarendon Press Oxford UK 1984
[19] A H Taub ldquoSpace-times with distribution valued curvaturetensorsrdquo Journal ofMathematical Physics vol 21 no 6 pp 1423ndash1431 1980
[20] A Shatsky privite communications[21] V A Fock ldquoZur Theorie des Wasserstoffatomsrdquo Zeitschrift fur
Physik vol 98 no 3-4 pp 145ndash154 1935[22] E P Savelova ldquoGas of wormholes in Euclidean quantum field
theoryrdquo httparxivorgabs12115106[23] A A Kirillov and E P Savelova ldquoOn the behavior of
bosonic systems in the presence of topology fluctuationsrdquohttparxivorgabs08082478
[24] A A Kirillov ldquoViolation of the Pauli principle and dimensionof the Universe at very large distancesrdquo Physics Letters B vol555 no 1-2 pp 13ndash21 2003
[25] A A Kirillov ldquoDark matter dark charge and the fractalstructure of the Universerdquo Physics Letters B vol 535 no 1ndash4pp 22ndash24 2002
[26] J Ambjorn J Jurkiewicz and R Loll ldquoThe spectral dimensionof the universe is scale dependentrdquo Physical Review Letters vol95 no 17 Article ID 171301 4 pages 2005
[27] E Manrique S Rechenberger and F Saueressig ldquoAsymptoti-cally safe Lorentzian gravityrdquo Physical Review Letters vol 106no 25 Article ID 251302 4 pages 2011
[28] J Laiho and D Coumbe ldquoEvidence for asymptotic safety fromlattice quantum gravityrdquo Physical Review Letters vol 107 no 16Article ID 161301 2011
[29] A A Kirillov and D Turaev ldquoOn modification of the Newtonrsquoslaw of gravity at very large distancesrdquo Physics Letters B vol 532no 3-4 pp 185ndash192 2002
[30] A A Kirillov and D Turaev ldquoThe universal rotation curveof spiral galaxiesrdquo Monthly Notices of the Royal AstronomicalSociety vol 371 no 1 pp L31ndashL35 2006
[31] A A Kirillov and D Turaev ldquoFoam-like structure of theuniverserdquo Physics Letters B vol 656 pp 1ndash8 2007
[32] A A Kirillov ldquoThe nature of dark matterrdquo Physics Letters B vol632 no 4 pp 453ndash462 2006
[33] A A Kirillov and E P Savelova ldquoAstrophysical effects of space-time foamrdquo Gravitation and Cosmology vol 14 no 3 pp 256ndash261 2008
[34] S W Hawking and N Turok ldquoOpen inflation without falsevacuardquo Physics Letters B vol 425 no 1-2 pp 25ndash32 1998
[35] Z C Wu ldquoThe cosmological constant is probably zero and aproof is possibly rightrdquo Physics Letters B vol 659 no 5 pp 891ndash893 2008
[36] R Garattini ldquoEntropy and the cosmological constant aspacetime-foam approachrdquo Nuclear Physics B vol 88 no 1ndash3Article ID 991003 pp 297ndash300 2000
[37] MVisserLorentzianWormholes SpringerNewYorkNYUSA1996
[38] A A Kirillov and E P Savelova ldquoArtificial wormholerdquohttparxivorgabs12040351
[39] E W Mielke ldquoKnot wormholes in geometrodynamicsrdquo Gen-eral Relativity and Gravitation vol 8 no 3 pp 175ndash196 1977
[40] E B Gliner ldquoAlgebraic properties of the energy-momentumtensor and vacuum-like states of matterrdquo Journal of Experimen-tal and Theoretical Physics vol 22 p 378 1966
[41] A H Guth ldquoInflationary universe a possible solution to thehorizon and flatness problemsrdquo Physical Review D vol 23 no2 pp 347ndash356 1981
[42] A A Linde ldquoA new inflationary universe scenario a possiblesolution of the horizon flatness homogeneity isotropy andprimordial monopole problemsrdquo Physics Letters B vol 108 no6 pp 389ndash393 1982
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
![Page 12: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/12.jpg)
12 Journal of Astrophysics
where119877plusmn= (119905
plusmn 119903
plusmn) and119891(119904 119886) is the distribution of cylinders
which can be taken as (119899 is 3-dimensional density)
119891 (120578) =119899 (119886)
41205871199032
0
120575 (119904 minus 1199030) (76)
Using the normalization condition int119873119865(120585)119889120585 = 119873 we findthe relation 119873 = (12ℓ)119899119881 = 119899119881 where 119899 is a 4-dimensional density of wormholes and 1(2ℓ) is the effectivenumber of wormholes on the unit length of the cylinder (iethe frequency with which the virtual wormhole appears atthe positions 119903
plusmn) This frequency is uniquely fixed by the
requirement that the volume which cuts the bead is equal tothat which cuts the cylinder (43)1205871198863 = (120587
22)119886
4(12ℓ) (ie
2ℓ = (31205878)119886 and 119899 = (83120587119886)119899) Thus we can use directlyexpression (23) and find (compare to (25))
119887 (119896) = minusint 119899 (119886) 1198862 4120587
2
1198962(1 minus
sin |k| 1199030|k| 1199030
)1198691(119896119886)
1198961198862119889119886 (77)
where 119896 = (1198960 k) Here the first term merely coincides with
that in (25) and therefore it gives the contribution to thecosmological constant 120575Λ(8120587119866) = minus1198994 = minus2119899(3120587119886)while the second term describes a correction which does notreduce to the cosmological constant and requires a separateconsideration
72 Stress Energy Tensor From (57) we find that the stressenergy tensor
minus⟨Δ119879120572120573
(119909)⟩ = int
119896120573119896120572minus (12) 119892
1205721205731198962
1198962119887 (119896 120585)
1198894119896
(2120587)4
(78)
reduces to the two functions
11987900
= 120576 = 1205821minus1
2120583
119879119894119895= 119901120575
119894119895 119901 =
1
31205822minus1
2120583
(79)
where 120576 + 3119901 = minus120583 and 1205821+ 120582
2= 120583 and these functions are
1205821= minusint
1198962
0
11989621198871198894119896
(2120587)4 120582
2= minusint
|k|2
11989621198871198894119896
(2120587)4 (80)
By means of the use of the spherical coordinates 11989620119896
2=
cos2120579 |k|21198962 = sin2120579 and 119889
4119896 = 4120587sin2
1205791198963119889119896119889120579 we get
120582119894=119899 (119886 119903
0)
4120573119894
(1 minus 2120573119894(119886
1199030
)
2
119891119894(119886
1199030
)) (81)
where 1205731= 1 120573
2= 13 and 119891
119894is given by
119891(1
2)(119910)
=2
120587int
1
minus1
int
infin
0
sin (119909 sin 120579)1198691(119910119909)
1199101199092(cos2120579sin2
120579) 119889119909 119889cos 120579
(82)
For 1198861199030≪ 1 we find
11989112
(119886
1199030
) asymp (1 + 11990012
(119886
1199030
)) (83)
Thus finally we find
120576 ≃ minus119899
4= minus
2119899
3120587119886 119901 ≃ 120576(1 minus
4
3(119886
1199030
)
2
) (84)
which upon the continuation to the Minkowsky space givesthe equation of state in the form (An arbitrary gas ofwormholes splits in fractions with a fixed 119886 and 119903
0)
119901 = minus(1 minus4
3(119886
1199030
)
2
) 120576 (85)
which in the case when 1198861199030≪ 1 behaves like a cosmological
constant However when 119886 ≫ ℓpl such a constant is extremelysmall and can be neglected while the leading contributioncomes from the mean curvature
73 Mean Curvature In this subsection we consider theMinkowsky spaceThen the simplest actual wormhole can bedescribed by the metric analogous to (1) for example see [7]
1198891199042= 119888
2119889119905
2minus ℎ
2(119903) 120575
120572120573119889119909
120572119889119909
120573 (86)
where ℎ(119903) = 1 + 120579(119886 minus 119903)(1198862119903
2minus 1) To avoid problems
with the Bianchi identity and the conservation of energy thestep function should be also smoothed as in (1) The stressenergy tensor which produces such a wormhole can be foundfrom the Einstein equation 8120587119866119879
120573
120572= 119877
120573
120572minus (12)120575
120573
120572119877 Both
regions 119903 gt 119886 and 119903 lt 119886 represent portions of the ordinaryflat Minkowsky space and therefore the curvature is 119877119896
119894equiv 0
However on the boundary 119903 = 119886 it has the singularity Sincethe metric (86) does not depend on time we find
1198770
0= 119877
0
120572= 0 119877
120573
120572=2
119886120575 (119886 minus 119903) 119899
120572119899120573+ 120575
120573
120572 + 120582
120573
120572 (87)
where 119899120572 = 119899120572= 119909
120572119903 is the outer normal to the throat 1198782
and 120582120573
120572are additional terms (eg see (49) and (51)) which
in the leading order are negligible upon averaging over someportion of space Δ119881 ≳ 119886
3 In the case of a set of wormholesthis gives in the leading order
1198770
0= 119877
0
120572= 0 119877
120573
120572= sum
2
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119903
119894
1003816100381610038161003816) 119899119894120572119899120573
119894+ 120575
120573
120572
(88)
where 119886119894is the radius of a throat and 119903
119894is the position of the
center of the throat in space and 119899120572
119894= (119909
120572minus 119903
120572
119894)|119903 minus 119903
119894|
In the case of a homogeneous and isotropic distribution ofsuch throats we find 119877
120573
120572= (13)119877120575
120573
120572(averaging over spatial
directions gives ⟨119899120572119899120573⟩ = (13)120575
120573
120572) where
119877 = minus8120587119866119879 = sum8
119886119894
120575 (119886119894minus1003816100381610038161003816119903 minus 119877
119894
1003816100381610038161003816) = 32120587int 119886119899 (119886) 119889119886
(89)
Journal of Astrophysics 13
where 119879 stands for the trace of the stress energy momentumtensor which one has to add to the Einstein equations tosupport such awormhole It is clear that such a source violatesthe weak energy condition and therefore it reproduces theformof dark energy (ie119879 = 120576+3119901 lt 0) If the density of suchsources (and resp the density of wormholes) is sufficientlyhigh then this results in the observed [10ndash14] accelerationof the scale factor for the Friedmann space as sim 119905
120572 with120572 = 21205763(120576 + 119901) = 2120576(2120576 + (120576 + 3119901)) gt 1 for examplesee also [40ndash42] In terms of the 4-dimensional density ofwormholes 119899 = (83120587119886)119899 we get 119877 sim 119886
2119899 ≫ 8120587119866119899 as 119886 ≫ ℓpl
and therefore the leading contribution indeed comes fromthe mean curvature
8 Estimates and Concluding Remarks
Now consider the simplest estimates Actual wormholes seemto be responsible for the dark matter [7 9] Therefore to getthe estimate to the number density of wormholes is ratherstraightforward First wormholes appear at scales when darkmatter effects start to display themselves that is at scales ofthe order 119871 sim (1 divide 5)Kpc which gives in that range thenumber density
119899 sim1
1198713sim (3 divide 0024) times 10
minus65cmminus3 (90)
The characteristic size of throats can be estimated from (89)120576DE sim (119866)
minus1119899119886 Since the density of dark energy is 120576DE1205760 =
ΩDE sim 075 where 1205760is the critical density then we find the
estimate
119886 sim2
3(1 divide 125) times 10
minus3119877⊙ΩDEℎ
2
75 (91)
where119877⊙is the Solar radius ℎ
75= 119867(75 km(secMpc)) and
119867 is the Hubble constant We also recall that the backgrounddensity of baryons 120576
119887generates a nonvanishingwormhole rest
mass119872119908= (43)120587119886
31198773120576119887(where119877(119905) is the scale factor of the
Universe and therefore 119872119908remains constant) for example
see [7] It produces the dark matter density related to thewormholes as 120576DM ≃ 119872
119908119899 The typical mass of a wormhole
119872119908is estimated as
119872119908sim 1 7 times (1 divide 125) times 10
2119872
⊙ΩDMℎ
2
75 (92)
where 119872⊙is the Solar mass We point out that this mass
has not the direct relation to the parameters of the gas ofwormholes However it defines the moment when wormholethroats separated from the cosmological expansion Theabove estimate shows that if wormholes form due to thedevelopment of perturbations in the exotic matter then thisprocess should start much earlier than the formation ofgalaxies
Thus we see that virtual wormholes should indeed leadto the regularization of all divergencies in QFT which agreeswith recent results [28] Therefore they form the local finitevalue of the cosmological constant In the absence of externalclassical fields such a value should be exactly zero at macro-scopic scales A some nonvanishing value for the cosmolog-ical constant appears as the result of vacuum polarization
effects in external fields Indeed external fields form anadditional distribution of virtual wormholes which possessan exotic stress energy tensor (some kind of dark energy)Only some part of it forms the cosmological constant whilethe rest reflects the symmetry of external fields and possessesinhomogeneitiesWe assume that during the evolution of ourUniverse inhomogeneities in the exotic matter develop andmay form actual wormholes Although this problem requiresthe further and more deep investigation we refer to [38]where the formation of a simplest wormhole-like object hasbeen considered In other words such polarization energyis reserved now in a gas of actual wormholes We estimatedparameters of such a gas and believe that such a gas mayindeed be responsible for both dark matter and dark energyphenomena
References
[1] J R Primack ldquoThe nature ofdark matterrdquo httparxivorgabsastro-ph0112255
[2] J Diemand M Zemp B Moore J Stadel and M CarolloldquoCusps in cold dark matter haloesrdquoMonthly Notices of the RoyalAstronomical Society vol 364 no 2 pp 665ndash673 2005
[3] E W Mielke and J A V Velez Perez ldquoAxion condensate as amodel for dark matter halosrdquo Physics Letters B vol 671 no 1pp 174ndash178 2009
[4] G Gentile P Salucci U Klein D Vergani and P Kalberla ldquoThecored distribution of dark matter in spiral galaxiesrdquo MonthlyNotices of the Royal Astronomical Society vol 351 no 3 pp 903ndash922 2004
[5] D T F Weldrake W J G de Blok and F Walter ldquoA high-resolution rotation curve of NGC 6822 a test-case for cold darkmatterrdquo Monthly Notices of the Royal Astronomical Society vol340 no 1 pp 12ndash28 2003
[6] W J G de Blok andA Bosma ldquoHigh-resolution rotation curvesof low surface brightness galaxiesrdquoAstronomy and Astrophysicsvol 385 pp 816ndash846 2002
[7] A Kirillov and E P Savelova ldquoDensity perturbations in a gas ofwormholesrdquoMonthly Notices of the Royal Astronomical Societyvol 412 no 3 pp 1710ndash1720 2011
[8] P Kanti B Kleihaus and J Kunz ldquoStable Lorentzianwormholesin dilatonic Einstein-Gauss-Bonnet theoryrdquo Physical Review Dvol 85 no 4 Article ID 044007 2012
[9] A A Kirillov and E P Savelova ldquoDark matter from a gas ofwormholesrdquo Physics Letters B vol 660 no 3 pp 93ndash99 2008
[10] A G Riess A V Filippenko P Challis et al ldquoObservationalevidence from supernovae for an accelerating universe and acosmological constantrdquo The Astronomical Journal vol 116 no3 p 1009 1998
[11] S Perlmutter G Aldering G Goldhaber et al ldquoMeasurementsofΩ andΛ from42high-redshift supernovaerdquoTheAstrophysicalJournal vol 517 no 2 p 565 1999
[12] J L Tonry B P Schmidt B Barris et al ldquoCosmological resultsfromhigh-z supernovaerdquoTheAstrophysical Journal vol 594 no1 p 594 2003
[13] N W Halverson E M Leitch C Pryke et al ldquoDegreeangular scale interferometer first results a measurement of thecosmic microwave background angular power spectrumrdquo TheAstrophysical Journal vol 568 no 1 p 38 2002
14 Journal of Astrophysics
[14] C B Netterfield P A R Ade J J Bock et al ldquoA measurementby BOOMERANGofmultiple peaks in the angular power spec-trum of the cosmic microwave backgroundrdquo The AstrophysicalJournal vol 571 no 2 p 604 2002
[15] S Coleman ldquoWhy there is nothing rather than something atheory of the cosmological constantrdquoNuclear Physics B vol 310no 3-4 pp 643ndash668 1988
[16] I Klebanov L Susskind and T Banks ldquoWormholes and thecosmological constantrdquo Nuclear Physics B vol 317 no 3 pp665ndash692 1989
[17] S W Hawking ldquoSpacetime foamrdquoNuclear Physics B vol 114 p349 1978
[18] T P Cheng and L F Li Gauge Theory of Elementary ParticlesClarendon Press Oxford UK 1984
[19] A H Taub ldquoSpace-times with distribution valued curvaturetensorsrdquo Journal ofMathematical Physics vol 21 no 6 pp 1423ndash1431 1980
[20] A Shatsky privite communications[21] V A Fock ldquoZur Theorie des Wasserstoffatomsrdquo Zeitschrift fur
Physik vol 98 no 3-4 pp 145ndash154 1935[22] E P Savelova ldquoGas of wormholes in Euclidean quantum field
theoryrdquo httparxivorgabs12115106[23] A A Kirillov and E P Savelova ldquoOn the behavior of
bosonic systems in the presence of topology fluctuationsrdquohttparxivorgabs08082478
[24] A A Kirillov ldquoViolation of the Pauli principle and dimensionof the Universe at very large distancesrdquo Physics Letters B vol555 no 1-2 pp 13ndash21 2003
[25] A A Kirillov ldquoDark matter dark charge and the fractalstructure of the Universerdquo Physics Letters B vol 535 no 1ndash4pp 22ndash24 2002
[26] J Ambjorn J Jurkiewicz and R Loll ldquoThe spectral dimensionof the universe is scale dependentrdquo Physical Review Letters vol95 no 17 Article ID 171301 4 pages 2005
[27] E Manrique S Rechenberger and F Saueressig ldquoAsymptoti-cally safe Lorentzian gravityrdquo Physical Review Letters vol 106no 25 Article ID 251302 4 pages 2011
[28] J Laiho and D Coumbe ldquoEvidence for asymptotic safety fromlattice quantum gravityrdquo Physical Review Letters vol 107 no 16Article ID 161301 2011
[29] A A Kirillov and D Turaev ldquoOn modification of the Newtonrsquoslaw of gravity at very large distancesrdquo Physics Letters B vol 532no 3-4 pp 185ndash192 2002
[30] A A Kirillov and D Turaev ldquoThe universal rotation curveof spiral galaxiesrdquo Monthly Notices of the Royal AstronomicalSociety vol 371 no 1 pp L31ndashL35 2006
[31] A A Kirillov and D Turaev ldquoFoam-like structure of theuniverserdquo Physics Letters B vol 656 pp 1ndash8 2007
[32] A A Kirillov ldquoThe nature of dark matterrdquo Physics Letters B vol632 no 4 pp 453ndash462 2006
[33] A A Kirillov and E P Savelova ldquoAstrophysical effects of space-time foamrdquo Gravitation and Cosmology vol 14 no 3 pp 256ndash261 2008
[34] S W Hawking and N Turok ldquoOpen inflation without falsevacuardquo Physics Letters B vol 425 no 1-2 pp 25ndash32 1998
[35] Z C Wu ldquoThe cosmological constant is probably zero and aproof is possibly rightrdquo Physics Letters B vol 659 no 5 pp 891ndash893 2008
[36] R Garattini ldquoEntropy and the cosmological constant aspacetime-foam approachrdquo Nuclear Physics B vol 88 no 1ndash3Article ID 991003 pp 297ndash300 2000
[37] MVisserLorentzianWormholes SpringerNewYorkNYUSA1996
[38] A A Kirillov and E P Savelova ldquoArtificial wormholerdquohttparxivorgabs12040351
[39] E W Mielke ldquoKnot wormholes in geometrodynamicsrdquo Gen-eral Relativity and Gravitation vol 8 no 3 pp 175ndash196 1977
[40] E B Gliner ldquoAlgebraic properties of the energy-momentumtensor and vacuum-like states of matterrdquo Journal of Experimen-tal and Theoretical Physics vol 22 p 378 1966
[41] A H Guth ldquoInflationary universe a possible solution to thehorizon and flatness problemsrdquo Physical Review D vol 23 no2 pp 347ndash356 1981
[42] A A Linde ldquoA new inflationary universe scenario a possiblesolution of the horizon flatness homogeneity isotropy andprimordial monopole problemsrdquo Physics Letters B vol 108 no6 pp 389ndash393 1982
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
![Page 13: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/13.jpg)
Journal of Astrophysics 13
where 119879 stands for the trace of the stress energy momentumtensor which one has to add to the Einstein equations tosupport such awormhole It is clear that such a source violatesthe weak energy condition and therefore it reproduces theformof dark energy (ie119879 = 120576+3119901 lt 0) If the density of suchsources (and resp the density of wormholes) is sufficientlyhigh then this results in the observed [10ndash14] accelerationof the scale factor for the Friedmann space as sim 119905
120572 with120572 = 21205763(120576 + 119901) = 2120576(2120576 + (120576 + 3119901)) gt 1 for examplesee also [40ndash42] In terms of the 4-dimensional density ofwormholes 119899 = (83120587119886)119899 we get 119877 sim 119886
2119899 ≫ 8120587119866119899 as 119886 ≫ ℓpl
and therefore the leading contribution indeed comes fromthe mean curvature
8 Estimates and Concluding Remarks
Now consider the simplest estimates Actual wormholes seemto be responsible for the dark matter [7 9] Therefore to getthe estimate to the number density of wormholes is ratherstraightforward First wormholes appear at scales when darkmatter effects start to display themselves that is at scales ofthe order 119871 sim (1 divide 5)Kpc which gives in that range thenumber density
119899 sim1
1198713sim (3 divide 0024) times 10
minus65cmminus3 (90)
The characteristic size of throats can be estimated from (89)120576DE sim (119866)
minus1119899119886 Since the density of dark energy is 120576DE1205760 =
ΩDE sim 075 where 1205760is the critical density then we find the
estimate
119886 sim2
3(1 divide 125) times 10
minus3119877⊙ΩDEℎ
2
75 (91)
where119877⊙is the Solar radius ℎ
75= 119867(75 km(secMpc)) and
119867 is the Hubble constant We also recall that the backgrounddensity of baryons 120576
119887generates a nonvanishingwormhole rest
mass119872119908= (43)120587119886
31198773120576119887(where119877(119905) is the scale factor of the
Universe and therefore 119872119908remains constant) for example
see [7] It produces the dark matter density related to thewormholes as 120576DM ≃ 119872
119908119899 The typical mass of a wormhole
119872119908is estimated as
119872119908sim 1 7 times (1 divide 125) times 10
2119872
⊙ΩDMℎ
2
75 (92)
where 119872⊙is the Solar mass We point out that this mass
has not the direct relation to the parameters of the gas ofwormholes However it defines the moment when wormholethroats separated from the cosmological expansion Theabove estimate shows that if wormholes form due to thedevelopment of perturbations in the exotic matter then thisprocess should start much earlier than the formation ofgalaxies
Thus we see that virtual wormholes should indeed leadto the regularization of all divergencies in QFT which agreeswith recent results [28] Therefore they form the local finitevalue of the cosmological constant In the absence of externalclassical fields such a value should be exactly zero at macro-scopic scales A some nonvanishing value for the cosmolog-ical constant appears as the result of vacuum polarization
effects in external fields Indeed external fields form anadditional distribution of virtual wormholes which possessan exotic stress energy tensor (some kind of dark energy)Only some part of it forms the cosmological constant whilethe rest reflects the symmetry of external fields and possessesinhomogeneitiesWe assume that during the evolution of ourUniverse inhomogeneities in the exotic matter develop andmay form actual wormholes Although this problem requiresthe further and more deep investigation we refer to [38]where the formation of a simplest wormhole-like object hasbeen considered In other words such polarization energyis reserved now in a gas of actual wormholes We estimatedparameters of such a gas and believe that such a gas mayindeed be responsible for both dark matter and dark energyphenomena
References
[1] J R Primack ldquoThe nature ofdark matterrdquo httparxivorgabsastro-ph0112255
[2] J Diemand M Zemp B Moore J Stadel and M CarolloldquoCusps in cold dark matter haloesrdquoMonthly Notices of the RoyalAstronomical Society vol 364 no 2 pp 665ndash673 2005
[3] E W Mielke and J A V Velez Perez ldquoAxion condensate as amodel for dark matter halosrdquo Physics Letters B vol 671 no 1pp 174ndash178 2009
[4] G Gentile P Salucci U Klein D Vergani and P Kalberla ldquoThecored distribution of dark matter in spiral galaxiesrdquo MonthlyNotices of the Royal Astronomical Society vol 351 no 3 pp 903ndash922 2004
[5] D T F Weldrake W J G de Blok and F Walter ldquoA high-resolution rotation curve of NGC 6822 a test-case for cold darkmatterrdquo Monthly Notices of the Royal Astronomical Society vol340 no 1 pp 12ndash28 2003
[6] W J G de Blok andA Bosma ldquoHigh-resolution rotation curvesof low surface brightness galaxiesrdquoAstronomy and Astrophysicsvol 385 pp 816ndash846 2002
[7] A Kirillov and E P Savelova ldquoDensity perturbations in a gas ofwormholesrdquoMonthly Notices of the Royal Astronomical Societyvol 412 no 3 pp 1710ndash1720 2011
[8] P Kanti B Kleihaus and J Kunz ldquoStable Lorentzianwormholesin dilatonic Einstein-Gauss-Bonnet theoryrdquo Physical Review Dvol 85 no 4 Article ID 044007 2012
[9] A A Kirillov and E P Savelova ldquoDark matter from a gas ofwormholesrdquo Physics Letters B vol 660 no 3 pp 93ndash99 2008
[10] A G Riess A V Filippenko P Challis et al ldquoObservationalevidence from supernovae for an accelerating universe and acosmological constantrdquo The Astronomical Journal vol 116 no3 p 1009 1998
[11] S Perlmutter G Aldering G Goldhaber et al ldquoMeasurementsofΩ andΛ from42high-redshift supernovaerdquoTheAstrophysicalJournal vol 517 no 2 p 565 1999
[12] J L Tonry B P Schmidt B Barris et al ldquoCosmological resultsfromhigh-z supernovaerdquoTheAstrophysical Journal vol 594 no1 p 594 2003
[13] N W Halverson E M Leitch C Pryke et al ldquoDegreeangular scale interferometer first results a measurement of thecosmic microwave background angular power spectrumrdquo TheAstrophysical Journal vol 568 no 1 p 38 2002
14 Journal of Astrophysics
[14] C B Netterfield P A R Ade J J Bock et al ldquoA measurementby BOOMERANGofmultiple peaks in the angular power spec-trum of the cosmic microwave backgroundrdquo The AstrophysicalJournal vol 571 no 2 p 604 2002
[15] S Coleman ldquoWhy there is nothing rather than something atheory of the cosmological constantrdquoNuclear Physics B vol 310no 3-4 pp 643ndash668 1988
[16] I Klebanov L Susskind and T Banks ldquoWormholes and thecosmological constantrdquo Nuclear Physics B vol 317 no 3 pp665ndash692 1989
[17] S W Hawking ldquoSpacetime foamrdquoNuclear Physics B vol 114 p349 1978
[18] T P Cheng and L F Li Gauge Theory of Elementary ParticlesClarendon Press Oxford UK 1984
[19] A H Taub ldquoSpace-times with distribution valued curvaturetensorsrdquo Journal ofMathematical Physics vol 21 no 6 pp 1423ndash1431 1980
[20] A Shatsky privite communications[21] V A Fock ldquoZur Theorie des Wasserstoffatomsrdquo Zeitschrift fur
Physik vol 98 no 3-4 pp 145ndash154 1935[22] E P Savelova ldquoGas of wormholes in Euclidean quantum field
theoryrdquo httparxivorgabs12115106[23] A A Kirillov and E P Savelova ldquoOn the behavior of
bosonic systems in the presence of topology fluctuationsrdquohttparxivorgabs08082478
[24] A A Kirillov ldquoViolation of the Pauli principle and dimensionof the Universe at very large distancesrdquo Physics Letters B vol555 no 1-2 pp 13ndash21 2003
[25] A A Kirillov ldquoDark matter dark charge and the fractalstructure of the Universerdquo Physics Letters B vol 535 no 1ndash4pp 22ndash24 2002
[26] J Ambjorn J Jurkiewicz and R Loll ldquoThe spectral dimensionof the universe is scale dependentrdquo Physical Review Letters vol95 no 17 Article ID 171301 4 pages 2005
[27] E Manrique S Rechenberger and F Saueressig ldquoAsymptoti-cally safe Lorentzian gravityrdquo Physical Review Letters vol 106no 25 Article ID 251302 4 pages 2011
[28] J Laiho and D Coumbe ldquoEvidence for asymptotic safety fromlattice quantum gravityrdquo Physical Review Letters vol 107 no 16Article ID 161301 2011
[29] A A Kirillov and D Turaev ldquoOn modification of the Newtonrsquoslaw of gravity at very large distancesrdquo Physics Letters B vol 532no 3-4 pp 185ndash192 2002
[30] A A Kirillov and D Turaev ldquoThe universal rotation curveof spiral galaxiesrdquo Monthly Notices of the Royal AstronomicalSociety vol 371 no 1 pp L31ndashL35 2006
[31] A A Kirillov and D Turaev ldquoFoam-like structure of theuniverserdquo Physics Letters B vol 656 pp 1ndash8 2007
[32] A A Kirillov ldquoThe nature of dark matterrdquo Physics Letters B vol632 no 4 pp 453ndash462 2006
[33] A A Kirillov and E P Savelova ldquoAstrophysical effects of space-time foamrdquo Gravitation and Cosmology vol 14 no 3 pp 256ndash261 2008
[34] S W Hawking and N Turok ldquoOpen inflation without falsevacuardquo Physics Letters B vol 425 no 1-2 pp 25ndash32 1998
[35] Z C Wu ldquoThe cosmological constant is probably zero and aproof is possibly rightrdquo Physics Letters B vol 659 no 5 pp 891ndash893 2008
[36] R Garattini ldquoEntropy and the cosmological constant aspacetime-foam approachrdquo Nuclear Physics B vol 88 no 1ndash3Article ID 991003 pp 297ndash300 2000
[37] MVisserLorentzianWormholes SpringerNewYorkNYUSA1996
[38] A A Kirillov and E P Savelova ldquoArtificial wormholerdquohttparxivorgabs12040351
[39] E W Mielke ldquoKnot wormholes in geometrodynamicsrdquo Gen-eral Relativity and Gravitation vol 8 no 3 pp 175ndash196 1977
[40] E B Gliner ldquoAlgebraic properties of the energy-momentumtensor and vacuum-like states of matterrdquo Journal of Experimen-tal and Theoretical Physics vol 22 p 378 1966
[41] A H Guth ldquoInflationary universe a possible solution to thehorizon and flatness problemsrdquo Physical Review D vol 23 no2 pp 347ndash356 1981
[42] A A Linde ldquoA new inflationary universe scenario a possiblesolution of the horizon flatness homogeneity isotropy andprimordial monopole problemsrdquo Physics Letters B vol 108 no6 pp 389ndash393 1982
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
![Page 14: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/14.jpg)
14 Journal of Astrophysics
[14] C B Netterfield P A R Ade J J Bock et al ldquoA measurementby BOOMERANGofmultiple peaks in the angular power spec-trum of the cosmic microwave backgroundrdquo The AstrophysicalJournal vol 571 no 2 p 604 2002
[15] S Coleman ldquoWhy there is nothing rather than something atheory of the cosmological constantrdquoNuclear Physics B vol 310no 3-4 pp 643ndash668 1988
[16] I Klebanov L Susskind and T Banks ldquoWormholes and thecosmological constantrdquo Nuclear Physics B vol 317 no 3 pp665ndash692 1989
[17] S W Hawking ldquoSpacetime foamrdquoNuclear Physics B vol 114 p349 1978
[18] T P Cheng and L F Li Gauge Theory of Elementary ParticlesClarendon Press Oxford UK 1984
[19] A H Taub ldquoSpace-times with distribution valued curvaturetensorsrdquo Journal ofMathematical Physics vol 21 no 6 pp 1423ndash1431 1980
[20] A Shatsky privite communications[21] V A Fock ldquoZur Theorie des Wasserstoffatomsrdquo Zeitschrift fur
Physik vol 98 no 3-4 pp 145ndash154 1935[22] E P Savelova ldquoGas of wormholes in Euclidean quantum field
theoryrdquo httparxivorgabs12115106[23] A A Kirillov and E P Savelova ldquoOn the behavior of
bosonic systems in the presence of topology fluctuationsrdquohttparxivorgabs08082478
[24] A A Kirillov ldquoViolation of the Pauli principle and dimensionof the Universe at very large distancesrdquo Physics Letters B vol555 no 1-2 pp 13ndash21 2003
[25] A A Kirillov ldquoDark matter dark charge and the fractalstructure of the Universerdquo Physics Letters B vol 535 no 1ndash4pp 22ndash24 2002
[26] J Ambjorn J Jurkiewicz and R Loll ldquoThe spectral dimensionof the universe is scale dependentrdquo Physical Review Letters vol95 no 17 Article ID 171301 4 pages 2005
[27] E Manrique S Rechenberger and F Saueressig ldquoAsymptoti-cally safe Lorentzian gravityrdquo Physical Review Letters vol 106no 25 Article ID 251302 4 pages 2011
[28] J Laiho and D Coumbe ldquoEvidence for asymptotic safety fromlattice quantum gravityrdquo Physical Review Letters vol 107 no 16Article ID 161301 2011
[29] A A Kirillov and D Turaev ldquoOn modification of the Newtonrsquoslaw of gravity at very large distancesrdquo Physics Letters B vol 532no 3-4 pp 185ndash192 2002
[30] A A Kirillov and D Turaev ldquoThe universal rotation curveof spiral galaxiesrdquo Monthly Notices of the Royal AstronomicalSociety vol 371 no 1 pp L31ndashL35 2006
[31] A A Kirillov and D Turaev ldquoFoam-like structure of theuniverserdquo Physics Letters B vol 656 pp 1ndash8 2007
[32] A A Kirillov ldquoThe nature of dark matterrdquo Physics Letters B vol632 no 4 pp 453ndash462 2006
[33] A A Kirillov and E P Savelova ldquoAstrophysical effects of space-time foamrdquo Gravitation and Cosmology vol 14 no 3 pp 256ndash261 2008
[34] S W Hawking and N Turok ldquoOpen inflation without falsevacuardquo Physics Letters B vol 425 no 1-2 pp 25ndash32 1998
[35] Z C Wu ldquoThe cosmological constant is probably zero and aproof is possibly rightrdquo Physics Letters B vol 659 no 5 pp 891ndash893 2008
[36] R Garattini ldquoEntropy and the cosmological constant aspacetime-foam approachrdquo Nuclear Physics B vol 88 no 1ndash3Article ID 991003 pp 297ndash300 2000
[37] MVisserLorentzianWormholes SpringerNewYorkNYUSA1996
[38] A A Kirillov and E P Savelova ldquoArtificial wormholerdquohttparxivorgabs12040351
[39] E W Mielke ldquoKnot wormholes in geometrodynamicsrdquo Gen-eral Relativity and Gravitation vol 8 no 3 pp 175ndash196 1977
[40] E B Gliner ldquoAlgebraic properties of the energy-momentumtensor and vacuum-like states of matterrdquo Journal of Experimen-tal and Theoretical Physics vol 22 p 378 1966
[41] A H Guth ldquoInflationary universe a possible solution to thehorizon and flatness problemsrdquo Physical Review D vol 23 no2 pp 347ndash356 1981
[42] A A Linde ldquoA new inflationary universe scenario a possiblesolution of the horizon flatness homogeneity isotropy andprimordial monopole problemsrdquo Physics Letters B vol 108 no6 pp 389ndash393 1982
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
![Page 15: Research Article Dark Energy from the Gas of Wormholes · 2017. 7. 17. · is called as the Bronnikov-Ellis metric, or the metric = (1+( /)+( 2 / 2)) which includes an additional](https://reader035.vdocuments.site/reader035/viewer/2022071406/60fb4d28fd919414b2044be6/html5/thumbnails/15.jpg)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of