  Recent observations of the fine structure of spectral lines in the early
universe have been interpreted as a variation of the fine structure constant.
  From the assumed validity of Maxwell equations in general relativity and well
known experimental facts, it is proved that $e$ and $\hbar$ are absolute
constants. On the other hand, the speed of light need not be constant.

General Relativity and Quantum Cosmology;High Energy Physics - Theory;Quantum Physics