Luke ConlinAssistant Professor

Department of Chemistry and PhysicsSalem State University

DO WE LIVE IN A BLACK HOLE?Modern conceptions of the multiverse

Big Questions in Physics

Whyistheuniversethewayitis?

Whatisinsideablackhole?

To answer these questions…Weneedtoresolveourbiggest(andsmallest)theoriesofphysics

GeneralRelativity(BIGstuff)

StandardModelofParticlePhysics(small stuff)

Equation:𝐺,- = 8𝜋𝑇,- Equation:

Theoryofgravity Theoryofallotherforces

Where it all comes together:Boththeoriesmustbeatworkwheregravitationalfieldsarestrong,butthingsaresmall…

Blackholes

TheBigBang

Current best guess:We could be living in a black hole!

Our“bigbang”couldbesomeoneelse’sblackhole

In this talk…1. What’sinsideofablackhole?2. Whyistheuniversethewayitis?3. Conclusions

Part 1. What’s Inside of a Black Hole?

?

First, what is a black hole?Anobjectsodense,nothingcan escape itsgravity(notevenlight…hencethe‘black’hole)

Imagecredit:CCASAimagebyJohnstone

Spacetime curvaturenearEarth Spacetime curvaturenearblackhole

Needtotravelfasttoorbit;evenfastertoescape Pastthepointofnoreturn,

nothing canescape

First, what is a black hole?Anobjectsodense,nothingcan escape itsgravity(notevenlight…hencethe‘black’hole)

Imagecredit:CCASAimagebyJohnstone

Spacetime curvaturenearblackhole

Pastthepointofnoreturn,nothing canescape

Ananalogy:

Anatomy of a black holeBlackholeshavedifferent“regions”

Accretiondisk(stufffallingin)

Gasjets(Stuffflungaway)

Eventhorizon(noreturn)

Photonsphere(smallestorbits)

What’s inside a black hole?Shortanswer:Nobodyknows

Inside,thingsgetsquashedtoextremelyhighdensity

𝐷 =𝑀𝑉

WhathappenswhenV=0?

Say…what’stheequationfordensity?

Thetheoryblowsup!

What’s inside a black hole?Longanswer:Wehavesomeideas…

Thebounce hypothesis:QuantummechanicsforbidsV=0

Instead,thematterwill“bounce”intoanewexpandingregionofspacetime,connectedtotheoldregionbyawormhole(Smolin,1998)

Allblackholesaboveacriticalmassshould“bounce”intoababyuniverse

(Garriga,Vilenkin,&Zhang,2015)

Do black holes exist? YES!

Stellar blackholes• Mass:

• ~5-60Suns• Radius:

• ~10-100miles• Howmany?

• Therearedozensofcandidatesjustwithin10,000lightyearsofEarth

• (so,billionsandbillions)

Thereisconvincingevidencefortwokinds ofblackholes:

Do black holes exist? YES!

Galactic blackholes• Mass:

• ~4million-150billionSuns• Radius:

• ~.10-150xearth-sundist.• Howmany?

• Astronomersnowthinkjustabouteverygalaxy(evenours)hasablackholeatthecenter

• (So,billionsandbillions)

Thereisconvincingevidencefortwokindsofblackholes:

Case Study: Cygnus X-1Themoststudiedstellar blackhole

• StrongX-Raysignaldiscoveredin1964

• StephenHawkingfamouslybetagainstitbeingablackhole• (Helostthebet)

Cygnus(theswan)

Cyg X-1

• Mass:14.8solarmasses• Sizeofeventhorizon:~25miles

• DistancefromEarth:~6,070lightyears

• :s

Anartist'simpressionoftheHDE 226868–Cygnus X-1binarysystem. ESA/Hubbleillustration

Case Study: Cygnus X-1

ChandraX-rayimage

Case Study: M87

• Mass:~6.4billionM☉• Sizeofeventhorizon:~150xearth-sunorbit

• DistancefromEarth:53.5millionlight-years

Oneofthebiggestgalacticblackholes

M87 Supermassive Black Hole

ImageCredit:NASA,ESA,andJ.Madrid(McMasterUniversity)

Thegasjetsareactive

How do black holes form?

Stellar blackholes• Formfromcollapsedstars,atleast5xthemassofthesun

• Starrunsoutoffueltoburn,gravitywins

• Squashesdownuntilitexplodesintoasupernova

• Compressedcore=blackhole

Theanswerdependsonthekindofblackhole

How do black holes form?

Galacticblackholes• Nobodyknowshowtheyformed!

• Someideas:• Accumulationofstellarblackholes(tooslow)

• Densityfluctuationsleftoverfromthebigbang(toosmall)

• Primordialblackholes!(formedduringbigbang)

Theanswerdependsonthekindofblackhole

Theanswerdependsonhowtheuniverse“banged”

Part 2. Why Is the Universe the Way It Is?

“WhatIamreallyinterestediniswhetherGodcouldhavemadetheworldinadifferentway;thatis,whetherthelogicalsimplicityleavesanyfreedomatall”

Could The Universe Be Any Other Way?

ParticlePhysics:Yes,easily.Butitwouldn’tbepretty!

Einstein:Maybenot.

Could The Universe Be Any Other Way?

• ThelogicalsimplicityofEinstein’stheoryofgravitygavehimgreatconfidence

• Nofreeparameters• Predictedbendingangleofstarlightduringeclipse

• Appliedtotheuniverse,Einsteinwasnotsoconfidentinhistheory

• Equationsimpliedanexpanding/contractinguniverse• Headded aparameter(cosmologicalconstant)toadjusttheexpansionrate

Thecosmologicalconstantisnowbelievedtobetherepulsivegravitythatfueledtheuniverse’sinflation

NoWay!

Okay,maybealittle…

Could The Universe Be Any Other Way?

Particlephysicsisnotsologicallysimple• ~20freeparameters• Ifanyofthemwereslightlydifferent,wewouldnotlikelyexisttowonderaboutit

• E.g.ifelectronchargewereslightlydifferent,starswouldn’tshine(Hawking,1988)

Itseemsouruniverseisfinelytunedforustobeheretowonderaboutit!

Combining gravity and quantum physicsGeneralRelativity• Universebeginswithabang,keepsexpanding

Quantumphysics• Anythingthatcanhappendoes

• It’sjustamatterofhowoften

Introducing…the MULTIVERSE

Ananalogy:

Eachuniversehasprimordialblackholes,connectingtoeachotherviawormholes

A“bubbling”multiverse

FromLinde(2015)

Explaining the Fine Tuning

Option #1: The anthropic principle

Theuniverseisthewayitis,becauseifitweren’t,wewouldn’tbeheretocomplain!

Explaining the Fine Tuning

Theuniverseisthewayitis,becauseitisall theotherwaystoo;buttherearemoreuniverseslikeoursthannot

Option #2: The mediocrity principle

Explaining the Fine Tuning

Eachuniversethathastherightparameterstomakeblackholeswillspawnotheruniverseswithsimilarparameters

Verysoon,we’remostlikelytofindourselvesinauniversewithBH’s

Themultiversetunesitselftomakethemostpossibleblackholes!(we’rejustalongfortherideJ)

Option #2a: Cosmic Natural Selection

Part 3. Summary & Conclusions

Nobody knows what’s inside a black hole…

…butitcouldbeus!

Nobody knows why the universe is the way it is…

…butitbebecausetherearemanyuniverses...andoursisthemostcommontype

But this is just mere speculation, right?Speculative?Yes.Butnot“merespeculation”…

...thereareobservationalconsequences!

Open Question:Howarewesupposedtosleepatnight?!?

In the center of every galaxy, there could be another universe

“Soyoudon’thavetobeachump”

Thank you!!

References• Garriga,Vilenkin,&Zhang(2015).Blackholesandthemultiverse.

• Hawking(1988).Abriefhistoryoftime

• Linde(2015).Abriefhistoryofthemultiverse.

• Vilenkin,A.ManyWorldsinOne

• Smolin,L.TheLifeoftheCosmos

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