Cosmological backreaction and its dependence on spacetime foliation
Abstract
The subject of cosmological backreaction in General Relativity is often approached by coordinate-dependent and metric-based analyses. We present in this letter an averaging formalism for the scalar parts of Einstein's equations that is coordinate-independent and only functionally depends on a metric. This formalism is applicable to general 3+1 foliations of spacetime for an arbitrary fluid with tilted flow. We clarify the dependence on spacetime foliation and argue that this dependence is weak in cosmological settings. We also introduce a new set of averaged equations that feature a global cosmological time despite the generality of the setting, and we put the statistical nature of effective cosmologies into perspective.
Keywords
Cite
@article{arxiv.1805.10455,
title = {Cosmological backreaction and its dependence on spacetime foliation},
author = {Thomas Buchert and Pierre Mourier and Xavier Roy},
journal= {arXiv preprint arXiv:1805.10455},
year = {2018}
}
Comments
9 pages, Letter, matches published version in CQG