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Center for Nonlinear Studies |
Boltzmann's microscopic prescription for computing the entropy of a macroscopic system in a specified macrostate explains how the observed time asymmetric behavior of isolated macroscopic systems arises from the time symmetric dynamics of their microscopic constituents: classical or quantum. It also generalizes Clausius' second law to macroscopic systems not in local thermal equilibrium and thus imposes constraints on laws describing their time evolution. This will be illustrated by an extension of Boltzmann's H-theorem for dilute gases to dense fluids. I will also discuss stochastically driven open systems.