  In the Letter [1] (also [2]) there is a claim that the generalised second law
of thermodynamics (entropy increase) for black holes provides some limits on
the rate of variation of the fundamental constants of nature (electric charge
e, speed of light c, etc.). We have come to a different conclusion. The results
in [1,2] are based on assumption that mass of a black hole does not change
without radiation and accreation. We present arguments showing that this
assumption is incorrect and give an estimate of the black hole mass variation
due to alpha=e^2/\hbar c variation using entropy (and quantum energy level)
conservation in an adiabatic process. No model-independent limits on the
variation of the fundamental constants are derived from the second law of
thermodynamics.
