To lokjh(?) guest: The stat mech itself does not depend on the microscopic dynamics of a system. If a system is classical, use Boltzman statistics, or quantum, then Bose or Fermi or other statistics. I bet no one can derive the concept of entropy from the fundamental particle theory. The 2nd law of thermodynamics cannot be understood microscopically, i.e. by reduction, withouth entropy defined by Boltzman not by Klausius(? I forgot). But, then what is entropy? If the string theorists could derive entropy from their equation, it would deserve to be called by "the theory of everything".