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Title: Bubble collisions and measures of the multiverse

Abstract

To compute the spectrum of bubble collisions seen by an observer in an eternally-inflating multiverse, one must choose a measure over the diverging spacetime volume, including choosing an ''initial'' hypersurface below which there are no bubble nucleations. Previous calculations focused on the case where the initial hypersurface is pushed arbitrarily deep into the past. Interestingly, the observed spectrum depends on the orientation of the initial hypersurface, however one's ability observe the effect rapidly decreases with the ratio of inflationary Hubble rates inside and outside one's bubble. We investigate whether this conclusion might be avoided under more general circumstances, including placing the observer's bubble near the initial hypersurface. We find that it is not. As a point of reference, a substantial appendix reviews relevant aspects of the measure problem of eternal inflation.

Authors:
 [1]
  1. Department of Physics, Stanford University, Stanford, CA 94305 (United States)
Publication Date:
OSTI Identifier:
22279723
Resource Type:
Journal Article
Journal Name:
Journal of Cosmology and Astroparticle Physics
Additional Journal Information:
Journal Volume: 2012; Journal Issue: 01; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1475-7516
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; BUBBLES; COSMOLOGY; INFLATIONARY UNIVERSE; REVIEWS; SPACE-TIME

Citation Formats

Salem, Michael P., E-mail: salem@cosmos.phy.tufts.edu. Bubble collisions and measures of the multiverse. United States: N. p., 2012. Web. doi:10.1088/1475-7516/2012/01/021.
Salem, Michael P., E-mail: salem@cosmos.phy.tufts.edu. Bubble collisions and measures of the multiverse. United States. https://doi.org/10.1088/1475-7516/2012/01/021
Salem, Michael P., E-mail: salem@cosmos.phy.tufts.edu. 2012. "Bubble collisions and measures of the multiverse". United States. https://doi.org/10.1088/1475-7516/2012/01/021.
@article{osti_22279723,
title = {Bubble collisions and measures of the multiverse},
author = {Salem, Michael P., E-mail: salem@cosmos.phy.tufts.edu},
abstractNote = {To compute the spectrum of bubble collisions seen by an observer in an eternally-inflating multiverse, one must choose a measure over the diverging spacetime volume, including choosing an ''initial'' hypersurface below which there are no bubble nucleations. Previous calculations focused on the case where the initial hypersurface is pushed arbitrarily deep into the past. Interestingly, the observed spectrum depends on the orientation of the initial hypersurface, however one's ability observe the effect rapidly decreases with the ratio of inflationary Hubble rates inside and outside one's bubble. We investigate whether this conclusion might be avoided under more general circumstances, including placing the observer's bubble near the initial hypersurface. We find that it is not. As a point of reference, a substantial appendix reviews relevant aspects of the measure problem of eternal inflation.},
doi = {10.1088/1475-7516/2012/01/021},
url = {https://www.osti.gov/biblio/22279723}, journal = {Journal of Cosmology and Astroparticle Physics},
issn = {1475-7516},
number = 01,
volume = 2012,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2012},
month = {Sun Jan 01 00:00:00 EST 2012}
}