Odds of observing the multiverse

Abstract

Eternal inflation predicts our observable universe lies within a bubble (or pocket universe) embedded in a volume of inflating space. The interior of the bubble undergoes inflation and standard cosmology, while the bubble walls expand outward and collide with other neighboring bubbles. The collisions provide either an opportunity to make a direct observation of the multiverse or, if they produce unacceptable anisotropy, a threat to inflationary theory. The probability of an observer in our bubble detecting the effects of collisions has an absolute upper bound set by the odds of being in the part of our bubble that lies in the forward light-cone of a collision; in the case of collisions with bubbles of identical vacua, this bound given by the bubble nucleation rate times ($H_{\mathrm{O}}/H_{\mathrm{I}}{)}^2$, where $H_{\mathrm{O}}$ is the Hubble scale outside the bubbles and $H_{\mathrm{I}}$ is the scale of the second round of inflation that occurs inside our bubble. Similar results were obtained by Freigovel \emph{et al.} using a different method for the case of collisions with bubbles of much larger cosmological constant; here it is shown to hold in the case of collisions with identical bubbles as well. A significant error in a previous draft was corrected in order to arrive at this result.

21 pages, 12 figures; a significant error was corrected

References in corpus (15)

• Eternal inflation and its implications
• Sinks in the Landscape, Boltzmann Brains, and the Cosmological Constant Problem
• Holographic probabilities in eternal inflation
• Boltzmann brains and the scale-factor cutoff measure of the multiverse
• When Worlds Collide
• Towards observable signatures of other bubble universes
• Eternal inflation, bubble collisions, and the persistence of memory
• Colliding with a Crunching Bubble
• Hurdles for Recent Measures in Eternal Inflation
• Watching Worlds Collide: Effects on the CMB from Cosmological Bubble Collisions
• A measure of the multiverse
• Towards observable signatures of other bubble universes II: Exact solutions for thin-wall bubble collisions
• Predictions in eternal inflation
• Surviving the crash: assessing the aftermath of cosmic bubble collisions
• Eternal Inflation, Bubble Collisions, and the Disintegration of the Persistence of Memory

Cited by in corpus (10)

• First Observational Tests of Eternal Inflation: Analysis Methods and WMAP 7-Year Results
• Determining the outcome of cosmic bubble collisions in full General Relativity
• Eternal Inflation, Bubble Collisions, and the Disintegration of the Persistence of Memory
• Probing Two-Field Open Inflation by Resonant Signals in Correlation Functions
• Optimal filters for detecting cosmic bubble collisions
• Bubble collisions and measures of the multiverse
• Multiple Cosmic Collisions and the Microwave Background Power Spectrum
• A signature of anisotropic bubble collisions
• Gravity waves from cosmic bubble collisions
• Multiverse rate equation including bubble collisions