where will einstein fail?

WHERE WILL EINSTEIN FAIL?AND WHY ASTRONOMERS SHOULD CARE

Niayesh Afshordi

Super Jedi 2013, Mauritius4 July 2013

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1Thursday, 4 July, 13

Super Jedi 2013, Mauritius, 4 July, 2013

OUTLINE

Why will Einstein fail?

Solving the Cosmological Constant Problem

Astrophysical Tests

Where will Einstein Fail?



EINSTEIN’S LEGACY

Lorentz symmetry: geometry of flat spacetime

Equivalence Principle: gravity is spacetime geometry

special and general relativity

Most precise theories, period!



LORENTZ WAS RIGHT!

Liberati 2012



SO WAS EINSTEIN!Tests of equivalence principle Tests of strong gravity

(Parametrized Post Newtonian)



Well, for the most part!


IUCAA, Oct. 15, 2011

(ASTROPHYSICIST’S)

QUANTUM GRAVITY PROBLEMS

Finiteness/Renormalizability Big Bang Singularity/Initial ConditionsOld Cosmological Constant Problem (Pauli 1920’s)

|ρvac| ≳ 1033 kg/m3 (Standard Model of Particle Physics)

New Cosmological Constant Problem: Dark Energy ρvac = (7.1 ± 0.9) ⨉ 10-27 kg/m3

Coincidence Problem ρvac ≈ 2.7 ρm,0

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COSMOLOGICAL CONSTANT PROBLEM

Einstein Equation:

(Planck Mass)2 × Einstein Curvature = Energy-Momentum

spacetime curvature

(103eV)4standard model

(100 GeV)4 + excitations

Anthropic Solution: We live in a rare but habitable part of Cosmos*

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Astronomer: But what’s wrong with a small constant?




Particle Physicist: No symmetry protects its smallness; would be the first time in the history of Physics!




Particle Physicist: No symmetry protects its smallness; would be the first time in the history of Physics!

Alternative: Landscape/Multiverse Conundrum



WHICH PRINCIPLES TO KEEP?

• Lorentz symmetry• Locality

• Action principle• Unitarity

• Falsifiability• Predictivity

710



“A GLORIOUS HISTORICAL ACCIDENT!”

Barbour: Mach suggested that Physics only depends on the change in observables. Relativity (and Lorentz Invariance) emerges as a consistency condition

Horava: A transition to Lifshitz symmetry: E ∝p3, makes gravity power-counting renormalizable


A LESSON FROM PERIHELION PRECESSION OF MERCURY

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http://www.google.ca/url?q=http://en.wikipedia.org/wiki/Tests_of_general_relativity%23Perihelion_precession_of_Mercury&usg=AFQjCNEqLd5n3AQL5hMW1ghjpvy7t6mINg&sa=X&ei=krXETfaaKcjx0gGQh_2TCA&ved=0CCYQygQwAA



Newtonian Gravity has a symmetry between angular and radial coord’s: r ↔ θ, Ωr = Ωθ

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Is this fundamental?

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No. It only emerges at low energies, but is broken at high energies → perihelion precession of Mercury

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Same could happen to Lorentz symmetry

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Same could happen to Lorentz symmetry

Cosmologist:Universe has already done this!

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COSMOLOGICAL CONSTANT PROBLEM

Einstein Equation:

(Planck Mass)2 × Einstein Curvature = Energy-Momentum

spacetime curvature

(103eV)4standard model

(100 GeV)4 + excitations

MODIFY GRAVITY!!

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MODIFIED GRAVITY:PHENOMENOLOGICAL APPROACH

Idea: We didn’t see Dark Energy coming. Maybe gravity is also different.

Why we don’t see it in the solar system? Screening Mechanisms: Chameleon (Khoury & Weltman), Symmetron (Khoury & Hinterbichler), Vainshtein

Let’s parametrize it in cosmology: Hu & Sawicki; Pogosian,Hojjati & Zhao; Narimani & Scott ...

Equivalence principle violation for stars, dwarf galaxies: Hui, Jain, Sakstein, Nicolis ...

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DANGER!

Searches for modified gravity are bound to find them!

It’s important to know what you’re looking for!

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JCAP 0908:030,2009


DE-GRAVITATION

Idea: Modifications of gravity should address the cosmological constant problem, i.e. de-gravitate the Quantum Vacuum

Cascading gravity (Khoury, Dvali, Tolley, de Rham, Pujolas, ...)

(Partially) Massive Gravity (Hoffman, Hinterbichler, Tolley, de Rham, Rosen, ...)

Supersymmetric Large Extra dimensions (C.P. Burgess, ...)

Problem: Why radiation era happened?

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WHAT IF NEWTON KNEW QUANTUM FIELD THEORY

(AND SPECIAL RELATIVITY)?!

2 = 4G( + p/c2))

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2 = 4G( + p/c2)

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2 = 4G( + p/c2)

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•Quantum vacuum degravitates





2 = 4G( + p/c2)

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•Quantum vacuum degravitates•This can be made covariant (NA 2008), a.k.a Gravitational Aether



Deviations from GR sourced by Pressure or Vorticity

Neutron Star Structure

Cosmology

Intrinsic Gravitomagnetic Effect (LAGEOS, GPB)

(Kamiab & NA, 2011)(Aslanbeigi, Robbers, Foster, Kohri, NA, 2011)

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COINCIDENCE PROBLEM:WHAT SETS THE OBSERVED SCALE OF DARK ENERGY?

Neutrino mass ～ meV? (see Valeria)

Large extra dimensions ～ 0.1 mm

Stellar Black Hole scale ～ 10 M

Radiation-Matter Transition (k-essence)



WHERE WILL EINSTEIN FAIL?

Usual Suspects:

Early Universe, Inside Black Holes

Unusual Suspects: Cosmological Constant Problem →

Cosmic Microwave Background, Matter-Radiation transition

Neutron star structure, Mergers: Gravitational Wave astronomy

Gravitomagnetic effect; Tests of Equivalence Principle

Black Holes⇔Dark Energy: cosmic evolution and structure formation, astronomical probes of BH horizon

Neutrino Physics

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ON SCIENTIFIC METHOD

In spite of all our prejudices, Physics is an Empirical Science

Credibility of a theory is only judged by its concrete predictions against Nature, NOT its popularity, elegance, parsimony, etc.

Do you hold your favourite theories to this standard?!

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POSSIBLE PROJECTS:

Aether v.s. Planck

Inflation with Gravitational Aether

Stable Dark Energy/Neutrino Coupling

Phenomenology of Black Holes/ Dark Energy Coupling

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BLACK HOLES: ENTROPY AND DARK ENERGY

2012: Unitary evolution leads to firewalls @ BH horizons: Almheiri, Marolf, Polchinski & Sully

Empty Black Holes, Firewalls, Fuzzballs:

Israel Junction condition ⇒An incompressible fluid sits at the horizon

Thermal entropy per unit area = 1/4 (Saravani, NA, Mann 2012)

Resolving the singularity at horizon ties Dark Energy scale to Black Hole mass

Dark Energy as a Quantum hair of astrophysical Black Holes (Prescod-Weinstein, NA, Balogh 2009)


http://arxiv.org/find/hep-th/1/au:+Almheiri_A/0/1/0/all/0/1

http://arxiv.org/find/hep-th/1/au:+Almheiri_A/0/1/0/all/0/1

http://arxiv.org/find/hep-th/1/au:+Marolf_D/0/1/0/all/0/1

http://arxiv.org/find/hep-th/1/au:+Marolf_D/0/1/0/all/0/1

http://arxiv.org/find/hep-th/1/au:+Polchinski_J/0/1/0/all/0/1

http://arxiv.org/find/hep-th/1/au:+Polchinski_J/0/1/0/all/0/1

http://arxiv.org/find/hep-th/1/au:+Sully_J/0/1/0/all/0/1

http://arxiv.org/find/hep-th/1/au:+Sully_J/0/1/0/all/0/1


NEUTRON STARS AND AETHER

Deviations from Einstein gravity are sourced by relativistic pressure or vorticity

Neutron Stars are perfect laboratories to test Aether!

Aether decreases the maximum mass (effectively so%ens EOS), so discovery of very massive Neutron Stars can rule it out

Uncertainty in nuclear equation of states !

Can test with Gravitational Wave detection from NS-NS mergers

Aether

General Relativity

Kamiab & NA 2011

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COSMOLOGY (GN/GR = 0.75 OR 1?)

0.0210 0.0215 0.0220 0.0225 0.0230 0.0235 0.02400.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

b h2

G N / G R

General Relativity

Gravitational Aether

X

X

Big Bang Nucleosynthesis

(Aslanbeigi, Robbers, Foster, Kohri, NA, 2011)

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Cosmic Microwave Background



COSMOLOGY (GN/GR = 0.75 OR 1?) 27


AETHER AND BLACK HOLES

We can solve for the black hole spacetime in this theory

p0 is the aether pressure at infinity

f(r) is an analytic function of r that diverges at r≈2m & r→∞

UV-IR coupling thru aether pressure, p0

Finite redshi% at r=2m

No Horizon(similar to Fuzzba( models)

ds2 =

1 2m

r

[1 + 4p0f(r)]2 dt2

1 2m

r

1

dr2 r2d2

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... AND DARK ENERGY!

Let us propose that maximum redshift at “horizon” is set to Planck Temperature/Hawking Temperature by quantum gravity effects:

Aether pressure has the same sign and magnitude as Dark Energy for stellar mass black holes!

Conjecture: Formation of stellar black holes causes cosmic acceleration

Conjecture: Evolution of Astrophysical black holes leads to dynamical Dark Energy

p0 = 12562m3

m

74 M

3

pDE,obs!!

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... AND DARK ENERGY!

Let us propose that maximum redshift at “horizon” is set to Planck Temperature/Hawking Temperature by quantum gravity effects:

Aether pressure has the same sign and magnitude as Dark Energy for stellar mass black holes!

Conjecture: Formation of stellar black holes causes cosmic acceleration

Conjecture: Evolution of Astrophysical black holes leads to dynamical Dark Energy

p0 = 12562m3

m

74 M

3

pDE,obs!!

Prescod-Weinstein, NA, Balogh 2009

Dar

k En

ergy

equ

atio

n of

stat

eM

ean

Blac

k H

ole

Mas

s (M

⨀)

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JOINT DARK ENERGY MISSIONS:(WFIRST, LSST, EUCLID)

Probe Dark Energy history with incredible precision over the next decade

 →confirm/rule out aether predictions

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THERMODYNAMIC ARGUMENT

NA 2010

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What if gravitational aether has a thermal pressure?Let’s consider QG corrections to BH thermal properties:

Entropy:Energy/Mass:Volume:

Pressure becomes:

THERMODYNAMIC ARGUMENT

!

NA 2010

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INCOMPRESSIBLE AETHER IN HISTORY!

“Similar to Newton, but mathematically in greater detail, Bernhard Riemann assumed in 1853 that the gravitational aether is an incompressible fluid and normal matter represents sinks in this aether ...” http://en.wikipedia.org/wiki/Mechanical_explanations_of_gravitation

Riemann, B. (1876), "Neue mathematische Prinzipien der Naturphilosophie", Bernhard Riemanns Werke und gesammelter Nachlass (Leipzig): 528–538

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http://en.wikipedia.org/wiki/Mechanical_explanations_of_gravitation

http://en.wikipedia.org/wiki/Mechanical_explanations_of_gravitation

http://en.wikipedia.org/wiki/Bernhard_Riemann

http://en.wikipedia.org/wiki/Bernhard_Riemann

http://quod.lib.umich.edu/cgi/t/text/pageviewer-idx?c=umhistmath&cc=umhistmath&idno=abw1043.0001.001&frm=frameset&view=image&seq=6





AETHER & MISSING BARYONS!

NA, Lin, Nagai & Sanderson 2007

WMAPWMAP+ACT+SPT

WMAP+ACT+SPT+SNe+BAO+H0

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A SIDE ON LITHIUM!

Observations of Lithium in old stars is 3-5 times lower than predictions of standard Big Bang Nucleosynthesis

Aether diminishes the discrepancy, but doesn’t remove it

Lithium remains ionized throughout the cosmic history, and so diffuses out of first dark matter haloes (Pospelov & NA 2012) redshift =20

Monaco, et al. 2010



MEET PROF. LORENTZ!

Hendrik Antoon Lorentz (1853-1928)

Nobel prize (w/ Zeeman) in 1902, for explaining Zeeman effect

In 1892 and 1895, he discovered a group of transformations of space and “local time” that left Maxwell equations of electromagnetism unchanged.



Let us propose (NA 2008):

The metric is now blind to vacuum energy

In order to satisfy Bianchi identity:

Further assume an incompressible fluid (or gravitational aether)

**Disclaimer: The field equations do not follow from an Action principle

HOW TO DO IT COVARIANTLY?

Tµ = vacgµ + excitations

(8G)1Gµ = Tµ 14T

gµ + ...

(8G)1Gµ = Tµ 14T

gµ + T µ , T µ

;µ =14T

,

T µ = p(u

µu gµ)

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where will einstein fail?

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