  Some deterministic cellular automata have been observed to follow the pattern
of the second law of thermodynamics: starting from a partially disordered
state, the system evolves towards a state of equilibrium characterized by
maximal disorder. This chapter is an exposition of this phenomenon and of a
statistical scheme for its explanation. The formulation is in the same vein as
Boltzmann's ideas, but the simple combinatorial setup offers clarification and
hope for generic mathematically rigorous results. Probabilities represent
frequencies and subjective interpretations are avoided.
