On the Assignment of Entropy to Black Holes

Abstract

The range of validity of the usual identification of the black hole entropy with the area of the horizon is considered from a general point of view. The situation is then revised in the light of an example in which the actual presence of the event horizon on a given hypersurface depends on a quantum event which occurs in the future of the given hypersurface. This situation indicates that there is something fundamental that is missing in our current ideas about the nature of a theory of quantum gravity, or, alternatively, that there is something fundamental that we do not understand about entropy in general, or at least in its association with black holes.