Journal Article

Black holes constrain varying constants

Davis, Tamara M., Davies, P. C. W., Lineweaver, Charles H.

2002

Overview

There is evidence to suggest that the fine-structure constant, alpha --a measure of the strength of the electromagnetic interaction between photons and electrons--is is slowly increasing over cosmological timescales. As alpha = e super(2)/ h-bar c (where e is the electronic charge, h-bar is Planck's constant and c is the speed of light), this would call into question which of these fundamental quantities are truly constant. Here we consider black-hole thermodynamics as a test of which constants might actually be variable, discounting those that could lead to a violation of the generalized second law of thermodynamics.