摘要
We study the entropy of an -site Kac ring in a non-equilibrium state. As the system dynamically evolves towards equilibrium and eventually to the initial state exhibiting Poincar茅 recurrence, we see that the entropy saturates over a period of time which is large for large . At about the time of order , the system starts to return to its initial state. We show that there is indeed a perfect 鈥渞ecurrence of statistical fluctuations鈥? which we are able to explore, as Kac鈥檚 ring possesses a finite recurrence time. Entropy is shown here to be a periodic function of the Poincar茅 recurrence time.