A status report on the observability of cosmic bubble collisions

Abstract

In the picture of eternal inflation as driven by a scalar potential with multiple minima, our observable universe resides inside one of many bubbles formed from transitions out of a false vacuum. These bubbles necessarily collide, upsetting the homogeneity and isotropy of our bubble interior, and possibly leading to detectable signatures in the observable portion of our bubble, potentially in the Cosmic Microwave Background or other precision cosmological probes. This constitutes a direct experimental test of eternal inflation and the landscape of string theory vacua. Assessing this possibility roughly splits into answering three questions: What happens in a generic bubble collision? What observational effects might be expected? How likely are we to observe a collision? In this review we report the current progress on each of these questions, improve upon a few of the existing results, and attempt to lay out directions for future work.

Review article; comments very welcome. 24 pages + 4 appendices; 19 color figures. (Revised version adds two figures, minor edits.)

References in corpus (14)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Eternal inflation and its implications
• A Holographic Framework for Eternal Inflation
• Thermal derivation of the Coleman-De Luccia tunneling prescription
• Eternal Inflation: The Inside Story
• Predicting the cosmological constant with the scale-factor cutoff measure
• Towards observable signatures of other bubble universes
• Eternal inflation, bubble collisions, and the persistence of memory
• Accidental Inflation in String Theory
• Towards observable signatures of other bubble universes II: Exact solutions for thin-wall bubble collisions
• Predictions in eternal inflation
• Transitions Between de Sitter Minima
• Future Foam
• Vacuum Bubble in an Inhomogeneous Cosmology

Cited by in corpus (41)

• First Observational Tests of Eternal Inflation
• Scattering of kinks of the sinh-deformed ${\phi }^4$ model
• First Observational Tests of Eternal Inflation: Analysis Methods and WMAP 7-Year Results
• The real shape of non-Gaussianities
• Determining the outcome of cosmic bubble collisions in full General Relativity
• Cosmic bubble and domain wall instabilities III: The role of oscillons in three-dimensional bubble collisions
• How unitary cosmology generalizes thermodynamics and solves the inflationary entropy problem
• Cosmic bubble and domain wall instabilities I: parametric amplification of linear fluctuations
• Simulating the universe(s): from cosmic bubble collisions to cosmological observables with numerical relativity
• Probing Two-Field Open Inflation by Resonant Signals in Correlation Functions
• Optimal filters for detecting cosmic bubble collisions
• Collision of two kinks with inner structure
• Observing the Multiverse with Cosmic Wakes
• Lorentzian Vacuum Transitions: Open or Closed Universes?
• Simulating the universe(s) II: phenomenology of cosmic bubble collisions in full General Relativity
• A perspective on the landscape problem
• Bubble collisions and measures of the multiverse
• A Clash of Kinks: Phase shifts in colliding non-integrable solitons
• Hierarchical Bayesian Detection Algorithm for Early-Universe Relics in the Cosmic Microwave Background
• False vacuum decay in kink scattering
• A scattering theory of ultrarelativistic solitons
• A signature of anisotropic bubble collisions
• Cosmology using numerical relativity
• Multiple Cosmic Collisions and the Microwave Background Power Spectrum
• Searches for other vacua I: bubbles in our universe
• Eternal inflation in a dissipative and radiation environment: Heated demise of eternity
• Scattering of metastable lumps in a model with a false vacuum
• Observable Signatures of a Classical Transition
• Topological Defects from the Multiverse
• A Simple System For Coleman-De Luccia Transitions
• Gravity waves from cosmic bubble collisions
• Constraints on Metastable Dark Energy Decaying into Dark Matter
• Repeated crossing of two concentric spherical thin-shells with charge
• Spectral Variations of the Sky: Constraints on Alternate Universes
• Rolling Through a Vacuum
• Eternal inflation near inflection points: a challenge to primordial black hole models
• Forecasting constraints from the cosmic microwave background on eternal inflation
• Entangled states as a probe of early universe history: a Higgs case study
• Radial derivatives as a test of pre-Big-Bang events on the Planck data
• Bubble Correlation in First-Order Phase Transitions
• Testing eternal inflation with the kinetic Sunyaev Zel'dovich effect