1995/11/15 by David Taylor, David R Taylor, Roy Maartens
Physics and Astronomy · #Advanced Differential Geometry Research #Anisotropy #Astrophysics #Black Holes and Theoretical Physics #Classical mechanics #Cosmic microwave background #Cosmology #Cosmology and Gravitation Theories #Dark energy #Decoupling (probability) #Flatness problem #Friedmann–Lemaître–Robertson–Walker metric #General relativity #Gravitation #Graviton #Massless particle #Mathematical physics #Metric expansion of space #Physics #Quantum mechanics #Spacetime #Theoretical physics #Universe #gr-qc
paper · pdf · doi:10.1007/bf02153319
published as Gen.Rel.Grav. 27 (1995) 1309 · 14 pages LaTeX, no figures; to appear in General Relativity and Gravitation
arxiv created 1995/11/15 · openalex publication_date 1995/12/01 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
In the R+αR2 gravity theory, we show that if freely propagating massless particles have an almost isotropic distribution, then the spacetime is almost Friedmann-Robertson-Walker (FRW). This extends the result proved recently in general relativity (α=0), which is applicable to the microwave background after photon decoupling. The higher-order result is in principle applicable to a massless species that decouples in the early universe, such as a relic graviton background. Any future observations that show small anisotropies in such a background would imply that the geometry of the early universe were almost FRW.