Hawking's area theorem

Hawking's area theorem

A result of general relativity theory proved by Stephen Hawking in papers published in 1971 and 1972, stating that in any process the area of a black hole can only increase. This increase in area is analogous to the increase in entropy in the second law of thermodynamics. The analogy led Jacob Bekenstein to postulate that a black hole has an entropy associated with its area.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006