What is the name of the paradox regarding information loss in black holes?

The paradox regarding information loss in black holes is called the black hole information paradox. It arises from an apparent conflict between general relativity and quantum mechanics.

Stephen Hawking’s work on black-hole radiation suggested that black holes can slowly lose energy and eventually evaporate. If the outgoing Hawking radiation carries no detailed record of the matter that formed the black hole, the information describing that original matter would disappear. Quantum mechanics, however, normally requires information to be preserved through reversible, unitary evolution.

The issue became a major research problem in theoretical physics. Hawking initially argued that information was lost, but in 2004 he accepted the opposing view and conceded a famous bet with John Preskill. The paradox remains an active area of quantum-gravity research, even though many physicists now expect information to be preserved.