Time asymmetry in a dynamical model of the one-dimensional ideal gas

We present a simple dynamical model of the one-dimensional ideal gas and show how it can be used to introduce a number of fundamental ideas in statistical mechanics. We use the model to illustrate the role of initial conditions in explaining time asymmetry and show that although the dynamical model is time-reversal invariant, the macroscopic behavior of the gas can be time-asymmetric if the initial conditions are chosen properly. (c) 2008 American Association of Physics Teachers.