How to Avoid the Ambiguity in Applying the Copernican Principle for Cosmic Topology: Take the Observational Approach
arXiv:astro-ph/0101191 · doi:10.1016/S0273-1177(02)00728-7
Abstract
It is often stated that homogeneity and isotropy of the Universe are assumptions of the almost Friedmann-Lema^itre (FL) model (the hot big bang model), inspired from the Copernican Principle. However, only local homogeneity and isotropy are required by the model: multiply connected almost FL models are locally homogeneous and isotropic, but they can be globally anisotropic and/or globally inhomogeneous. Toy models are used here to show how global anisotropy and/or global inhomogeneity of an almost FL model could be shown directly in observations. This approach may avoid having to make any assumptions regarding global anisotropy and inhomogeneity.
9 pages, 6 figures, accepted for Advances in Space Research