Homogeneous and isotropic universe. Homogeneity and isotropy in cosmology is a formal, active area of study, and it has many highly-credible experts. Current work being reviewed includes that of scholars such as Andrei Linde of Stanford with his 2014 report, Inflationary Cosmology after Planck 2013 (84-pages). Also there is the September 2016 article by Xingang Chen and Hossein Namjoo of the Institute for Theory and Computation (Harvard-Smithsonian Center for Astrophysics) and Mohammad Yi Wang of the Hong Kong University of Science and Technology,  A Direct Probe of the Evolutionary History of the Primordial Universe.

Of course, Wikipedia provides substantial introductory materials for each, homogeneity and isotropy.

Our work may extend the basic assumptions of Einstein’s special theory of relativity.

Your recommendations for additional references are welcomed and encouraged.