The black hole information paradox

Hawking’s black hole information paradox arises when the formation and subsequent evaporation of a black hole is examined in the context of quantum theory. It pits quantum mechanical unitarity against locality in spacetime and highlights the incompatibility between the world view offered by general relativity and that of quantum physics. In a gravity theory with a gauge theory dual, the paradox must be resolved in favor of unitary evolution. The challenge is then to implement unitarity on the gravity side and a key issue, which is at the center of the recent debate on firewalls, is whether this requires giving up the equivalence principle.