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Testing Theories of the High-z and SuperEarly
Universe
Anthony Aguirre
On the front burners
• Me:
• Arrived 2003 (Postdoc IAS Princeton, PhD Astronomy Harvard.)
• Cosmology, broadly construed.
• Group(s):
• Scipp theory (Michael, Tom, Howie, Stefano)
• Astronomy (Piero Madau and others)
• Current students & postdocs:
• Jonathan Kozaczuk (with Stefano)
• Max Wainwright (with Stefano)
On the front burners
• Inflation and eternal inflation
• When and how does ‘eternal inflation’ occur?
• What is the large-scale structure of an eternal inflating
universe?
• Given inflation, need there be an initial singularity?
• How do transitions between inflationary ‘vacua’ occur?
• What is the inflationary “multiverse” and how can we test it?
• Might there be observable signatures of eternal inflation?
• Fundamental Physics
• How do we interpret quantum theory in an infinite universe?
• How do we think about time in eternal systems?
On the back burners
• Black holes:
• What fun things can happen in the interior of a realistic Kerr black hole?
• What to make of black hole complementarity and ‘firewalls’.
• Enrichment of the intergalactic medium (IGM)
• How did the IGM get enriched with the heavy elements?
• What does this tell us about feedback in galaxy formation?
• What does this tell us about Pop. III? About reionization?
• Dark matter:
• Dark matter annihilations and the first stars.
• Modified gravity and dark matter.
Inflation
Basic idea: exponential
expansion at very early
times.
Provides:
Expansion
Flatness
Uniformity
Fluctuations
Ending Inflation
Driven by vacuum energy,
but dynamical.
Leads to ‘field φ’, with
‘potential’ Λ(φ).
Handy: description is just
like a ball on a slope: gravity
and friction.
Field evolves toward Λobs,
where inflation ends.
Λ(φ)
φ
Failing to end inflation:
Is inflation everlasting?
The “double-well”:
Tunneling nucleations
bubble of new phase.
Inflation inside.
but new phase fails to take
over.
Λ(φ)
φ
Λinf
Λobs
Λinf Λobs
Λobs
Everlasting bubbly
inflation
Expanding sea of
inflation.
Pocket universes fill in
interstices, grow.
Can we observe other bubble “universes”?
Bubbles collide!
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y
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Can we observe other bubble “universes”?
What could we see?
• Bubble Collisions:
• Deeper analysis of link between collisions and cosmological
observables:
• Multiple collisions (Jon K.)
• 1+1D GR simulations of bubble collisions (Max W.)
• Analysis of Planck data (Matt Johnson, Hiranya Peiris and
UCL collaborators; Max W.)
• Other processes like decompactifications; collisions between
different #s of large dimensions; collisions between bubbles
with uncoupled fields.
Some current/possible/pondered projects:
Entropy decrease in closed systems
S~5 x 1026
S~5 x 1039
ultrahot soup
of photons
and leptons
(chemical equilibrium)
(Nuclear equilibrium)
(Proton decay)
Aguirre, Carroll & Johnson
Entropy decrease in closed systems
S~5 x 1026
S~5 x 1039
ultrahot soup
of photons
and leptons
(chemical equilibrium)
(Nuclear equilibrium)
(Proton decay)
Aguirre, Carroll & Johnson
• Relativistic closed systems in general (Jon K.)
Some current/possible/pondered projects:
Strange issues in infinite universes
Measure
Measure
LevelIII
Multiverse
Level I
Multiverse
Oldschool: Cosmological view:
Measure
Measure
Level I
Multiverse
Oldschool: Cosmological view:
EVERETT (NO WAVEFUNCTION COLLAPSE)
COPENHAGEN (WAVEFUNCTION COLLAPSES)
Some current/possible/pondered projects:
• Cosmological interpretation of quantum mechanics vs.
‘multiverse interpretation’ of quantum mechanics.
• Past-eternal cosmologies: which are possible and which are
not? (Emergent universe with John K@IPMU)
• A ‘double standard’ in the eternal inflationary arrow of time.
Some current/possible/pondered projects:
• Dark stars, Pop. III, and the IGM.
Some current/possible/pondered projects:
• Baby universes inside black holes. (Tegmark and Hamilton)
http://jila.colorado.edu/~ajsh/insidebh/realistic.html