WFU Physics Colloquium

Black hole thermodynamics gained prominence in the early seventies with the discovery by Hawking that black holes are not really "black" in the sense that they emit radiation with a perfect black body spectrum. Hawking found the temperature measured at infinity to be proportional to the surface gravity of the horizon, and all of black hole thermodynamics along with a statistical mechanical description was subsequently described at spatial infinity. Problems quickly arose with this formulation as it was discovered the canonical ensemble was unstable. The program was revived when York re-formulated the problem using finite boundaries as any physically reasonable problem should be handled, and soon thereafter used "quasilocal" quantities in the description of black hole thermodynamics. A new and purely geometrical quasilocal definition of the gravitational energy naturally emerged, which also described the thermodynamical internal energy of a system containing a black hole. Applications to static black hole configurations are described as well as results pertaining to the much more difficult rotating black holes.