Proving almost-homogeneity of the universe: An almost Ehlers-Geren-Sachs theorem

W. R. Stoeger, R Maartens, G. F. R. Ellis

Research output: Contribution to journalArticlepeer-review

Abstract

We show that if all fundamental observers measure the cosmic microwave background radiation to be almost isotropic in an expanding universe region, then that universe is locally almost spatially homogeneous and isotropic in that region. This shows the stability of the important exact result of this type of previously proved by Ehlers, Geren, & Sachs (EGS) and formalizes the way in which almost-isentropy of the background radiation gives evidence that the universe is almost a Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime. This is the needed foundation for all recent analyses, based on the Sachs-Wolfe effect, of how background radiation anisotropies relate to growing density inhomogeneities in an almost-FLRW expanding universe.
Original languageEnglish
Pages (from-to)1-5
Number of pages5
JournalThe Astrophysical Journal
Volume443
Issue number1
DOIs
Publication statusPublished - 10 Apr 1995

Keywords

  • COSMIC MICROWAVE BACKGROUND
  • COSMOLOGY, THEORY

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