A paradox in quantum gravity concerning the fate of information, such as the contents of an encyclopedia, that is dropped into a black hole which then evaporates by the Hawking process: is the information lost? Although Stephen Hawking originally argued that this is the case, such an outcome violates the fundamental principles of quantum mechanics. The issue has not yet been definitively resolved, but indications from superstring theory suggest that the information is not lost and that quantum mechanics is not violated. Hawking later came to support this view.