Space, time and heat

Abstract

The local conservation law for energy in classical general relativity is subtle and has been extensively discussed. We propose a new physical interpretation for this law which naturally brings out a thermodynamic flavor of general relativity theory. Given a reference system, we are able to rewrite the local conservation law so that it separates into “work” and “heat” terms. This gives a striking geometric interpretation for “heat” in general relativity. The interpretation offered here assumes direct physical reality once quantum effects are considered. The ideas proposed here have implications at the intersection of gravity, thermodynamics and quantum theory.