If I'm not mistaken, doesn't the velocity of propagation of electromagnetic radiation (light) depend on the "medium" ? (quotes as its self propagating and needs no medium as such) Thus indices of refraction result... (my glasses work on this principle...)
Didn't a Canadian lab recently produce a Bose-Einstien condensate in which the measured rate of propagation of electromagnetic radiation (light) was at the incredibly low value of 33m/s?
I see interpreting a change in alpha as somehwat of a tautology, as Plank's constant was determined empirically by the interaction of electromagnetic radiation with electrons; Heisenberg comes to mind...
I find astronomers and cosmologists make huge leaps of faith that as an empiricist I have a hard time accepting.