Republication of: Relativistic cosmology

This is a republication of a paper by G.F.R. Ellis first published in Proceedings of the International School of Physics: General Relativity and Cosmology, 1971, in which he formulated the framework for relativistic cosmology with an arbitrary background geometry. The article has been selected for publication in the Golden Oldies series of General Relativity and Gravitation. The paper is accompanied by a Golden Oldie Editorial comprising an editorial note written by Bill Stoeger and Ellis’ brief autobiography. Original paper: G. F. R. Ellis: Relativistic cosmology, In: Sachs, R.K. (ed.) Proceedings of the International School of Physics “Enrico Fermi”, Course 47: General relativity and cosmology, pp. 104–182. Academic Press, New York and London (1971). Reprinted with the kind permission of Elsevier Ltd, the current owner of the Academic Press copyright, and of the author.     

Republication of: Relativistic cosmology

This is a reprinting of the paper by Howard Percy Robertson, first published in 1933 in Rev. Mod. Phys., that is a very authoritative summary of relativistic cosmology at the stage at which it was up to 1933. The paper has been selected by the Editors of General Relativity and Gravitation for re-publication in the Golden Oldies series of the journal. This republication is accompanied by an editorial note written by George Ellis, and by Robertson’s biography, compiled by Andrzej Krasinski from printed sources.     

Relativistic kinetics and cosmology. I

A study is made of the problem of describing the cosmological expansion of a plasma in the framework of Chernikov's relativistic kinetic theory. It is shown that from the point of view of relativistic kinetics there are two stages in the evolution of the Universe in which thermodynamic equilibrium of the plasma is attained asymptotically: 1) the earliest ultrarelativistic stage, and 2) the nonrelativistic stage of the expansion, when the radiation is decoupled from the matter. It is shown that the relativistic kinetics of the plasma expansion at the time of decoupling of the radiation from the matter leads to transfer of energy from the photon component of the plasma to the electron component.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 42–47, August, 1980.     

Nonsingularity of Flat Robertson–Walker Models in the Special Relativistic Approach to Einstein's Equations

Recently the neglected issue of the causal structure in the flat space-time approach to Einstein's theory of gravity has been substantially resolved. Consistency requires that the flat metric's null cone be respected by the null cone of the effective curved metric. While consistency is not automatic, thoughtful use of the naive gauge freedom resolves the problem. After briefly recapitulating how consistent causality is achieved, we consider the flat Robertson–Walker Big Bang model. The Big Bang singularity in the spatially flat Robertson–Walker cosmological model is banished to past infinity in Minkowski space-time. A modified notion of singularity is proposed to fit the special relativistic approach, so that the Big Bang becomes nonsingular.