Irreversibility

The phenomenon of irreversibility is explained on the basis of an analysis by H. L. Frisch. The history of the debate over irreversibility is briefly discussed, including Boltzmann’s H-theorem, Zermelo's Wiederkehreinwand, Poincaré recurrences, Loschmidt's Umkehreinwand and Liouville’s theorem. The derivation of irreversible behavior for the ideal gas position distribution is carried out explicitly. Using this derivation, the Wiederkehreinwand and the Umkehreinwand are revisited and explained. The first thing we must establish is the meaning of the term ‘irreversibility’. This is not quite as trivial as it might seem. The irreversible behavior I will try to explain is that which is observed. Every day we see that time runs in only one direction in the real world,.