I have a few questions about something I read in the http://pancake.uchicago.edu/~carroll/hawkingdublin.txt of Stephen Hawking's talk at GR17. He says that it has been claimed that the information paradox can be resolved by a duality between supergravity in anti de sitter (AdS) space and a conformal field theory (CFT) on the boundary of AdS space. (Apparently his own work is only an attempt to explain how the information gets out of a black hole). The argument goes that since the CFT is unitary, supergravity must be information preserving. These are my questions: 1. If we know that the spacetime is AdS space, doesn't that imply that there is no matter anywhere, and therefore no black holes and no problem with information falling into black holes? 2. Can you really prove that supergravity is information preserving by considering only one solution of the "super-Einstein" equation? (I suspect that the answer to this question will answer the first as well). 3. What is the boundary of AdS space? (I never understood how a space that extends to infinity in every direction can have a boundary).