Does black-hole evaporation imply that physics is non-unitary, and if so, what must the laws of physics look like? An Essay

Abstract

Stephen Hawking's discovery of black hole evaporation had the remarkable consequence that information is destroyed by a black hole, which can only be accommodated by modifying the laws of quantum mechanics. Different attempts to evade the information loss paradox were subsequently suggested, apparently without a satisfactory resolution of the paradox. On the other hand, the attempting to include non-unitarity into quantum mechanics might lead to laws predicting observable consequences such as nonlocality or violation of energy-momentum conservation; but it may be possibly to circumvent these obstacles. Recent developments seem to require a different view on quantum gravity and suggest that ideas about locality in physics and Hawking's semi-classical approximation are misleading. An accurate description may show unitary evolution and no information loss after all.