Can we see other universes? based on work by Anthony Aguirre, Matt Johnson & Assaf Shomer

Transcription

1 Can we see other universes? based on work by Anthony Aguirre, Matt Johnson & Assaf Shomer

2 Everlasting inflation (Multiple minima) + (slow transitions) = eternal inflation vf vt

3 Everlasting inflation (Multiple minima) + (slow transitions) = eternal inflation T=const. slice infinite negatively curved, homogenous space. Each bubble has open FRW cosmology inside. True vacuum False vacuum t=const. slice space with expanding finite-size bubble

4 Everlasting inflation (Multiple minima) + (slow transitions) = eternal inflation Constant Φ slices Each bubble has open FRW cosmology inside. t True vacuum Bubble wall x False vacuum Nucleation event

5 Everlasting inflation (Multiple minima) + (slow transitions) = eternal inflation Each bubble has open FRW cosmology inside. Infinitely many other bubbles, potentially different properties J P F

6 Everlasting inflation (Multiple minima) + (slow transitions) = eternal inflation Each bubble has open FRW cosmology inside. Infinitely many other bubbles, potentially different properties How do we test this picture?

7 Everlasting inflation Each bubble has open FRW cosmology inside. Constant Φ slices Can t get out. t True vacuum Bubble wall x False vacuum Nucleation event

8 Bubbles collide. Can we see the other ones? Probability: Most observers must have collisions in past. Suvivability: The collisions must not preclude the existence of the observers in question. Constant t slices True vacuum Observability: The collision must be significant enough to be observable. Bubble wall Nucleation events False vacuum

9 The setup Present (ξ,τ ) o o T= π/2 Recombination Reheating Past Light Cone T co End Inflation Begin Inflation (r,t ) n n Want to compute: dn dψd(cosθ)dφ (θ, φ, ξ 0, τ 0 ) Observation Bubble Initial Conditions η = 0 η = π T= π/2

10 The setup (θ,φ) }ψ Present Recombination Reheating (ξ,τ ) o o Past Light Cone T= T co π/2 End Inflation Begin Inflation (r,t ) n n Want to compute: dn dψd(cosθ)dφ (θ, φ, ξ 0, τ 0 ) Observation Bubble Initial Conditions η = 0 η = π T= π/2

11 Horrible geometry problem... Present Reheating (ξ,τ o o ) Past Light Cone T= π/2 T co End Inflation Begin Inflation (r,t ) n Observation Bubble Initial Conditions n (ξ0,τ0) η = 0 T= π/2 η = π α 1 α 2 ρ Δρ θ 1 θ 2 2π ψ

12 Results Two large-n regimes: Late, small bubbles (as τo, N and ψ 0) Early, large bubbles (as ξo, N and ψ ) Anisotropic distribution (divergences where θ=θo) dn dψ n dφ n d cos Θ n Increasing observation time 5 Π 2 Π 3 Π 2 2 Π Ψ

13 Results Two large-n regimes: Late, small bubbles (as τo, N and ψ 0) Early, large bubbles (as ξo, N and ψ ) Anisotropic distribution (divergences where θ=θo) dn dψ n dφ n d cos Θ n Π 2 Π 3 Π 2 2 Π Ψ

14 Implications Small late bubbles: Almost certainly perturbative. Only seen if λhf -4 > (HT/HF) 2 ~ Œ Essentially point sources, isotropically distributed.œ Large early bubbles: Seen at all but set of measure zero of points in open universe. But not perturbative.œ

15 Key open questions What does a general bubble collision (including inflation inside bubbles) look like? Can the observers with big observable collisions survive to observe them? Are there reasonable scenarios with small observable bubbles? How would bubbles appear in the CMB? What other consequences might they have? and/or, can any scenarios can be ruled out given the CMB we see?