 In particular, a remarkable parallel between the laws of black holes and the laws of thermodynamics indicates that gravity and thermodynamics may be linked in a fundamental (and previously unimagined) way. This linkage strongly suggests, among many things, that our fundamental ideas of entropy and the nature of the Second Law of thermodynamics must be reconsidered, and that the standard form of quantum evolution itself may need to be modified. While these suggestions are speculative, they nevertheless touch on deep issues in the foundations of physics. Indeed, because the central subject matter of all these diverse areas of research lies beyond the reach of current experimentation and observation, they are all speculative in a way unusual even in theoretical physics. In their investigation, therefore, physical questions of a technically sophisticated nature are inextricable from subtle philosophical considerations spanning ontology, epistemology, and methodology, again in a way unusual even in theoretical physics. 