Title: "Observables in General Relativity: New Results"
The problem of determining observables in General Relativity is as old as GR itself. Only for some spacetimes with special asymptotic behavior or additional Killing symmetries have observables been constructed explicitly. Thus any insight on their generic properties should be welcome. In this talk some new results will be presented. They were found from a formal expression for the observables in terms of gauge choices and intrinsic coordinates, based on the original diffeomorphism symmetry of GR. This permits to derive some interesting properties of observables, such as their interpretation in terms of "evolving constants of motion" (C.Rovelli) or the emergence of Dirac-brackets from the algebra of observables. These results can be made explicit for mini-superspace models and will be exemplified in the talk by the case of homogeneous cosmological models.