Redshifting of cosmological black bodies in BSBM varying-alpha theories

TL;DR

This paper investigates how black-body radiation behaves in theories where the electron charge and fine structure constant vary, showing that such variations do not alter the standard cosmological evolution of black-body radiation.

Contribution

It demonstrates that varying-alpha theories can be formulated as relativistic dielectrics and that these do not affect the cosmological evolution of black-body radiation.

Findings

No change in the temperature evolution of black-body radiation.

Black-body radiation propagates as in standard cosmology despite varying constants.

Theories can be interpreted as relativistic dielectrics without affecting cosmological predictions.

Abstract

We analyse the behaviour of black-body radiation in theories of electromagnetism which allow the electron charge and the fine structure constant to vary in space and time. We show that such theories can be expressed as relativistic generalizations of a conventional dielectric. By making the appropriate definition of the vector potential and associated gauge transformations, we can identify the equivalent of the electric and displacement fields, $\mathbf{E}$ and $\mathbf{D}$, as well as the magnetic $ \mathbf{B}$ and $\mathbf{H}$ fields. We study the impact of such dielectrics on the propagation of light in the so-called BSBM theory and conclude that no changes are created to the standard cosmological evolution of the temperature and energy-density of black-body radiation.