A SIMPLE-MODEL FOR THE APPROACH OF ENTROPY TO THERMODYNAMIC-EQUILIBRIUM

We consider a simple dynamical system in three different ways, demonst rating that dynamic entropy behaviour can be radically different depen ding on the perspective. Namely, the Boltzmann-Gibbs entropy of the en tire (invertible) system may be constant, increasing or decreasing as a function of time. However, by taking a trace of an invertible dynami cal system we may either obtain a system in which the entropy is conti nuously decreasing or an exact (non-invertible) factor may be obtained which shows a global evolution of entropy to a unique equilibrium.