Balázs Gyenis (LSE): “A proof of tendency towards equilibrium”

Abstract: When two gases mix their temperatures equalize. In the talk we take a look at a simple proof that aims to demonstrate this phenomena from historical, philosophical, and pedagogical perspectives. We argue that the proof can be viewed as a charitable reconstruction of Maxwell’s own 1860 argument, and if so, then Maxwell preceded Boltzmann’s first attempt to give a mechanical explanation of tendency towards equilibrium with at least 6 years. Albeit the proof makes a problematic probabilistic independence assumption – and, according to a recent criticism, also a problematic physical assumption in case the masses of the molecules are different -, in this regard it does not fare worse than other later attempts. On the other hand the probabilistic independence assumption of the proof is geometrically intuitive and even invites some speculation about the physical basis of irreversibility. The proof is also simpler than many later attempts and could reasonably be included in a course on classical mechanics.

Balázs Gyenis is an LSE Fellow. He specialises in the philosophy of physics.