Erik said: > It is difficult to explain briefly. The best I can do is to say that > the traditional approach, and Feynman's approach, concentrate on > things like reversible heat engines, whereas _Thermal Physics_ starts > from considering the quantum states available to a system and develops > partition functions and statistics to determine how systems behave.
So the former focuses more on thermodynamics (which deals in quantities like pressures, volumes, energies, entropies and free energies that characterise macrostates) and the latter more on statistical mechanics (which looks on a deeper level to consider the statistics of microstates). I think that one of the triumphs of physics was to show how macroscopic thermodynamics arises out of the detailed classical or quantum mechanics of the microscopic contituents of the system when we use statistics to handle our ignorance of the exact state. Rich GCU Brief Summary
