The fine structure constant and the speed of light

Abstract

Recently, Davies, Davis and Lineweaver have concluded that a possible detection of a cosmological variation in the fine structure constant, a = e[superscript 2] /ħc (where e is the electronic charge, ħ is the reduced Planck constant and c is the speed of light) implies that the speed of light decreases as the Universe expands. In examining the two competing reasons for the variation of this fundamental parameter – an increase in the electronic charge or a decrease in the speed of light – they argued against the former by considering the thermodynamics of charged black holes. However, their argument is based upon a misapplication of the principles of black hole thermodynamics. A possible variation in α does not mandate a changing speed of light.