Advances in Astrophysics
The Electromagnetic Energy-Momentum Tensor in Expanding Universes
Download PDF (452.7 KB) PP. 198 - 203 Pub. Date: August 1, 2018
Author(s)
- Hans-J. Fahr*
Argelander Institut für Astronomie, Universität Bonn Auf dem Hügel 71, 53121 Bonn, Germany - Michael Heyl
Deutsches Zentrum für Luft und Raumfahrt (DLR) Königswinterer Str. 522 - 524, 53227 Bonn, Germany
Abstract
In two previous papers the authors have investigated the characteristics of freely propagating
cosmic photons in expanding homogenous flat universes from particle and wave points
of view, respectively. The result was that the energy density of these freely propagating photons
scales with 1/S3 instead with the generally accepted and redshift-related 1/S4, with S being the
cosmic scale factor. This is a surprising result at first glance but finally very understandable if
energy conservation has to be required also for cosmic photons without creating a conflict with
observations. In this paper we treat freely propagating cosmic photons with a totally different
approach, namely with the electromagnetic energy-momentum tensor (from now on abbreviated
with EMT). The implementation of the EMT, when correctly interpreted for freely propagating
photons, into Einstein’s field equations then automatically leads to the same 1/S3-scaling law for
the energy density of cosmic photons, herewith confirming the results found earlier for the particle
and wave view. We conclude that the observed cosmological redshift of photons (energy density
/ 1/S4) is compatible with the law of energy conservation, i.e energy density / 1/S3 if interpreted
on a new physical basis.
Keywords
Cosmic microwave background, electromagnetic energy-momentum tensor, theory
References
[1] H.J. Fahr and M. Heyl, "How are Cosmic Photons Redshifted?", AdAp, vol. 2, no. 1, pp. 1-7, 2017
[2] H.J. Fahr and M. Heyl, "How are Cosmic Photons Redshifted?", AdAp, in press, 2018
[3] H.F.M Goenner, Einführung in die Spezielle und Allgemeine Relativit?tstheorie. Spektrum Akademischer Verlag, Heidelberg, 1996
[4] R. Becker and F. Sauter, Theorie der Elektrizit?t, Band 1. Teubner Verlagsgesellschaft, Stuttgart, 1962
[5] R.C. Tolman, Relativity, Thermodynamics and Cosmology. Dover Publications, New York, 1987
[6] L.D. Landau and E.M. Lifschitz, Lehrbuch der Theoretischen Physik, Band 4. Akademie Verlag, Berlin, 1986