This theorem assumes that the velocity of molecules in a system are uncorrelated, which is called Stosszahlansatz.
The "wind-tree" model developed by Ehrenfest was a pedagogical tool used to illustrate this theorem. This theorem assumes that the velocity of molecules in a system are uncorrelated, which is called Stosszahlansatz. The namesake function of this theorem is the integral over the velocity-space of the probability of the state times the natural log of the probability with respect to volume. One criticism of this theorem suggested that a system that has evolved from a non steady-state to a steady-state would (*) retrace its path back to the original state; that criticism was proposed by Loschmidt. For 10 points, identify this theorem from statistical mechanics, supplements the second law of thermodynamics and says that the time derivative for the entropy of an irreversible process has a lower bound of zero.
The "wind-tree" model developed by Ehrenfest was a pedagogical tool used to illustrate this theorem.
{Boltzmann H}-{theorem}