Black holes may not constrain varying constants

TL;DR

This paper challenges previous claims by demonstrating that black hole thermodynamics does not constrain whether the fine structure constant lpha has changed due to variations in the speed of light or electric charge, when considering the full thermal environment.

Contribution

It shows that black hole thermodynamics is compatible with an increase in lpha regardless of whether it results from changes in c, e, or both, contradicting earlier conclusions.

Findings

Black hole thermodynamics does not favor decreasing c or increasing e exclusively.

Considering the full thermal environment alters previous constraints on fundamental constant variations.

The fine structure constant lpha can vary without conflicting with black hole thermodynamics.

Abstract

New and rather controversial observations hint that the fine structure constant \alpha may have been smaller in the early universe, suggesting that some of the fundamental ``constants'' of physics may be dynamical. In a recent paper, Davies, Davis, and Lineweaver have argued that black hole thermodynamics favors theories in which the speed of light c decreases with time, and disfavors those in which the fundamental electric charge e increases. We show that when one considers the full thermal environment of a black hole, no such conclusion can be drawn: thermodynamics is consistent with an increase in \alpha whether it comes from a decrease in c, an increase in e, or a combination of the two.