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Title: Can superhorizon cosmological perturbations explain the acceleration of the universe?

Abstract

We investigate the recent suggestions by Barausse et al. and Kolb et al. that the acceleration of the universe could be explained by large superhorizon fluctuations generated by inflation. We show that no acceleration can be produced by this mechanism. We begin by showing how the application of Raychaudhuri equation to inhomogeneous cosmologies results in several 'no go' theorems for accelerated expansion. Next we derive an exact solution for a specific case of initial perturbations, for which application of the Kolb et al. expressions leads to an acceleration, while the exact solution reveals that no acceleration is present. We show that the discrepancy can be traced to higher-order terms that were dropped in the Kolb et al. analysis. We proceed with the analysis of initial value formulation of general relativity to argue that causality severely limits what observable effects can be derived from superhorizon perturbations. By constructing a Riemann normal coordinate system on initial slice we show that no infrared divergence terms arise in this coordinate system. Thus any divergences found previously can be eliminated by a local rescaling of coordinates and are unobservable. We perform an explicit analysis of the variance of the deceleration parameter for the case ofmore » single-field inflation using usual coordinates and show that the infrared-divergent terms found by Barausse et al. and Kolb et al. cancel against several additional terms not considered in their analysis. Finally, we argue that introducing isocurvature perturbations does not alter our conclusion that the accelerating expansion of the universe cannot be explained by superhorizon modes.« less

Authors:
 [1];  [1]
  1. Department of Physics, Jadwin Hall, Princeton University, Princeton, New Jersey 08544 (United States)
Publication Date:
OSTI Identifier:
20713701
Resource Type:
Journal Article
Journal Name:
Physical Review. D, Particles Fields
Additional Journal Information:
Journal Volume: 72; Journal Issue: 8; Other Information: DOI: 10.1103/PhysRevD.72.083501; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0556-2821
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACCELERATION; CAUSALITY; COORDINATES; COSMOLOGY; DISTURBANCES; EXACT SOLUTIONS; FLUCTUATIONS; GENERAL RELATIVITY THEORY; INFLATIONARY UNIVERSE; INFRARED DIVERGENCES; UNIVERSE

Citation Formats

Hirata, Christopher M, Seljak, Uros, and International Center for Theoretical Physics, Strada Costiera 11, 34014 Trieste. Can superhorizon cosmological perturbations explain the acceleration of the universe?. United States: N. p., 2005. Web. doi:10.1103/PhysRevD.72.083501.
Hirata, Christopher M, Seljak, Uros, & International Center for Theoretical Physics, Strada Costiera 11, 34014 Trieste. Can superhorizon cosmological perturbations explain the acceleration of the universe?. United States. https://doi.org/10.1103/PhysRevD.72.083501
Hirata, Christopher M, Seljak, Uros, and International Center for Theoretical Physics, Strada Costiera 11, 34014 Trieste. 2005. "Can superhorizon cosmological perturbations explain the acceleration of the universe?". United States. https://doi.org/10.1103/PhysRevD.72.083501.
@article{osti_20713701,
title = {Can superhorizon cosmological perturbations explain the acceleration of the universe?},
author = {Hirata, Christopher M and Seljak, Uros and International Center for Theoretical Physics, Strada Costiera 11, 34014 Trieste},
abstractNote = {We investigate the recent suggestions by Barausse et al. and Kolb et al. that the acceleration of the universe could be explained by large superhorizon fluctuations generated by inflation. We show that no acceleration can be produced by this mechanism. We begin by showing how the application of Raychaudhuri equation to inhomogeneous cosmologies results in several 'no go' theorems for accelerated expansion. Next we derive an exact solution for a specific case of initial perturbations, for which application of the Kolb et al. expressions leads to an acceleration, while the exact solution reveals that no acceleration is present. We show that the discrepancy can be traced to higher-order terms that were dropped in the Kolb et al. analysis. We proceed with the analysis of initial value formulation of general relativity to argue that causality severely limits what observable effects can be derived from superhorizon perturbations. By constructing a Riemann normal coordinate system on initial slice we show that no infrared divergence terms arise in this coordinate system. Thus any divergences found previously can be eliminated by a local rescaling of coordinates and are unobservable. We perform an explicit analysis of the variance of the deceleration parameter for the case of single-field inflation using usual coordinates and show that the infrared-divergent terms found by Barausse et al. and Kolb et al. cancel against several additional terms not considered in their analysis. Finally, we argue that introducing isocurvature perturbations does not alter our conclusion that the accelerating expansion of the universe cannot be explained by superhorizon modes.},
doi = {10.1103/PhysRevD.72.083501},
url = {https://www.osti.gov/biblio/20713701}, journal = {Physical Review. D, Particles Fields},
issn = {0556-2821},
number = 8,
volume = 72,
place = {United States},
year = {Sat Oct 15 00:00:00 EDT 2005},
month = {Sat Oct 15 00:00:00 EDT 2005}
}