The controversial piston in the thermodynamic limit

We consider the evolution of a system composed of N non-interacting point particles of mass m in a container divided into two regions by a movable adiabatic wall (adiabatic piston). In this talk we discuss the thermodynamic limit where the area A of the container, the number N of particles, and the mass M of the piston go to infinity keeping A/M and N/M fixed. We show that in this limit the motion of the piston is deterministic. Introducing simplifying assumptions we discuss the approach to equilibrium and we illustrate the results with numerical simulations. The comparison with the case of a system with finite (A,N,M) will be presented.