Phase Transitions in Finite Systems

Paul Mainwood, Oxford

The most successful theories of phase transitions apply only to systems with an infinite number of degrees of freedom. Yet we apply them to finite macroscopic systems, typically justifying this move by claiming that the systems are large enough to be ``approximately infinite''. Recently, a number of worries have been raised about this practice in the philosophical literature. I attempt to separate these into independent problems, and to resolve the ones that matter.