Vacuum structure and the arrow of time

2011/12/31 by Raphael Bousso
Physics and Astronomy · #Arrow #Arrow of time #Black Holes and Theoretical Physics #Classical mechanics #Computer science #Cosmology and Gravitation Theories #Entropy (arrow of time) #Galaxies: Formation, Evolution, Phenomena #Physics #Quantum #Quantum mechanics #Scalar field #Spacetime #Theoretical physics #Vacuum energy #astro-ph.CO #gr-qc #hep-ph #hep-th

paper · pdf · doi:10.1103/physrevd.86.123509

31 pages JHEP format, 3 figures

arxiv created 2012/06/11 · openalex publication_date 2012/12/07 · arxiv updated 2013/05/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We find ourselves in an extended era of entropy production. Unlike most other observations, the arrow of time is usually regarded as a constraint on initial conditions. I argue, however, that it primarily constrains the vacuum structure of the theory. I exhibit simple scalar field potentials in which low-entropy initial conditions are not necessary, or not sufficient, for an arrow of time to arise. In particular, in some models an arrow of time obtains even if the initial vacuum has arbitrarily large entropy. In such examples, the dynamical resolution of the arrow of time problem arises from properties of the vacuum structure similar to those that allow the string landscape to solve the cosmological constant problem without producing an empty universe, particularly its high dimensionality and the large difference in vacuum energy between neighboring vacua.

Citations

• Entropy and initial conditions in cosmology
• Birth of inflationary universes
• Unitary Evolution and Cosmological Fine-Tuning
• Measurements of Ω and Λ from 42 High‐Redshift Supernovae
• Predictions from star formation in the multiverse
• Predictions of the causal entropic principle for environmental conditions of the universe
• Positive vacuum energy and the N-bound
• Can the universe afford inflation?
• A Geometric Solution to the Coincidence Problem, and the Size of the Landscape as the Origin of Hierarchy
• Time without end: Physics and biology in an open universe
• de Sitter equilibrium as a fundamental framework for cosmology
• The holographic principle
• Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
• de Sitter vacua in string theory
• The Stretched Horizon and Black Hole Complementarity
• Effects of inhomogeneity on the causal entropic prediction ofΛ
• Disturbing Implications of a Cosmological Constant
• The Cosmological Constant and the String Landscape
• Complementarity in the multiverse
• Spontaneous Inflation and the Origin of the Arrow of Time
• A covariant entropy conjecture
• Holographic Probabilities in Eternal Inflation