2014/01/31 by John D. Barrow · 13 citations
Mathematics · Physics and Astronomy · #Anisotropy #Black Holes and Theoretical Physics #Cosmological constant #Cosmology #Cosmology and Gravitation Theories #Dark energy #Dimension (graph theory) #Galaxies: Formation, Evolution, Phenomena #Geometry #Homogeneity (statistics) #Homogeneous #Lambda #Mathematical physics #Mathematics #Metric expansion of space #Physics #Pure mathematics #Quantum mechanics #Scalar (mathematics) #Scalar field #Statistical physics #Theoretical physics #astro-ph.CO #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.89.064022
published in Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields 89(6) (American Physical Society) · 12 pages, no figs, typos corrected, extra discussion in Sec. V and in refs
arxiv created 2014/02/14 · openalex publication_date 2014/03/10 · arxiv updated 2015/06/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We enumerate the 4(1+F)+2S independent arbitrary functions of space required to describe a general relativistic cosmology containing an arbitrary number of noninteracting fluid (F) and scalar fields (S). Results are also given for arbitrary space dimension and for higher-order gravity theories, where the number increases to 16+4F+2S. Both counts are subject to assumptions about whether the dark energy is a cosmological constant. A more detailed analysis is provided when global homogeneity is assumed and the functions become constants. This situation is also studied in the case where the flat and open universes have compact spatial topologies. This changes the relative generalities significantly and places new constraints on the types of expansion anisotropy that are permitted. The most general compact homogeneous universes containing Friedmann models are spatially flat and described by 8+4F+2S constants. Comparisons are made with the simple six-parameter lambda-CDM model and physical interpretations provided for the parameters needed to describe the most general cosmological models.