  Boltzmann's struggle with a derivation of the Second Law of Thermodynamics is
sketched. So is his first derivation of the connection between entropy and
probability in 1877. Planck's derivation and quantum mechanical modifications
of Boltzmann's connection between entropy probability are given next. Then
Einstein's objections to a purely probabilistic rather than a dynamical
interpretation of entropy are discussed. Finally, the dynamical basis of the
Sinai-Ruelle-Bowen distribution for very chaotic systems is sketched and
appears to be an example of Einstein's dynamical interpretation of entropy.
