Varying alpha and black hole entropy

TL;DR

This paper discusses how, contrary to previous claims, the entropy of certain charged dilaton black holes remains unchanged under variations of the fine structure constant alpha, challenging the idea of entropy decrease in black holes.

Contribution

It demonstrates that for a class of charged dilaton black holes, entropy remains invariant under adiabatic changes in alpha, providing a counterexample to prior assertions.

Findings

Black hole entropy does not decrease with increasing alpha for certain dilaton black holes.

Entropy remains unchanged under adiabatic alpha variations.

Potential implications for black hole thermodynamics and fundamental constants.

Abstract

Recently it has been suggested that an increase in the fine structure constant alpha with time would decrease the entropy of a Reissner-Nordstrom black hole, thereby violating the second law of thermodynamics. In this note we point out that, at least for a certain class of charged dilaton black holes related to string theory, the entropy does not change under adiabatic variations of alpha and one might expect it to increase for non-adiabatic changes.