SINCE ANCIENT TIMES describing the behavior of macroscopic matter in terms of dynamic principles that govern its microscopic constituents has fascinated physicists. Foundations of the modern understanding were laid by Ludwig Boltzmann in the latter part of the 19th century. From physical arguments concerning the probable number of binary collisions (the Stosszahlansatz based on the principle of molecular chaos), Boltzmann deduced a “kinetic” equation satisfied by the probability distribution function.