Four-volume cutoff measure of the multiverse

Journal Article · 14 February 2020 · Physical Review. D.

DOI: https://doi.org/10.1103/physrevd.101.043520 · OSTI ID:1599687

Vilenkin, Alexander  ^[1]; Yamada, Masaki ^[2]

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1. Tufts Univ., Medford, MA (United States)
2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

Predictions in an eternally inflating multiverse are meaningless unless we specify the probability measure. The scale-factor cutoff is perhaps the simplest and most successful measure which avoids catastrophic problems such as the youngness paradox, runaway problem, and Boltzmann brain problem, but it is not well defined in contracting regions with a negative cosmological constant. In this paper, we propose a new measure with properties similar to the scale-factor cutoff which is well-defined everywhere. The measure is defined by a cutoff in the four volume spanned by infinitesimal comoving neighborhoods in a congruence of timelike geodesics. The probability distributions for the cosmological constant and for the curvature parameter in this measure are similar to those for the scale-factor cutoff and are in a good agreement with observations.

• Research Organization: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
• Sponsoring Organization: National Science Foundation (NSF); Japan Society for the Promotion of Science (JSPS); USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: SC0012567; PHY-1820872
• OSTI ID: 1599687
• Alternate ID(s): OSTI ID: 1802389
• Journal Information: Physical Review. D., Vol. 101, Issue 4; ISSN 2470-0010
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English