Black Hole Thermodynamics

Jacob Bekenstein and Stephen Hawking established that black holes obey the laws of thermodynamics. The surface area of the event horizon corresponds to entropy, which can only increase, never decrease. The surface gravity corresponds to temperature. These parallels are not loose analogies; they are exact physical relationships.

The Bekenstein-Hawking entropy of a black hole is proportional to its surface area. Even a single stellar-mass black hole carries far more entropy than all the ordinary matter in the observable universe combined — a hint that black holes hold vastly more information than their simple exterior suggests.