 The “obvious fact” that the temperature of a black hole can be, at best, only absolute zero was shown to be illusory when Hawking (1974, 1975) demonstrated that black holes are not completely black after all. His analysis of the behavior of quantum fields in black-hole spacetimes revealed that black holes will emit radiation with a characteristically thermal spectrum: a black hole generates heat at a temperature that is inversely proportional to its mass and directly proportional to its surface gravity. It glows like a lump of smoldering coal even though light should not be able to escape from it! The temperature of this Hawking radiation is extremely low for stellar- and galactic-scale black holes, but for very, very small black holes the temperatures would be high. (The Hawking temperature of the black hole at the center of the Milky Way, Sagittarius A*, having a mass of approximately 4 million solar masses, is approximately 10-14 Kelvin; for a black hole to be room temperature, it would have to have a mass of about 1018 kg—about 1000 times the mass of Mt. Everest—and so be about 10-7 m across, the size of a virus.) This means that a very, very small black hole should rapidly evaporate away, as all of its mass-energy is emitted in high-temperature Hawking radiation. Thus, when quantum effects are taken into account, black holes will not satisfy the Area Theorem, the second of the classical laws of black hole, as their areas shrink while they evaporate. (Hayward et al. 2009 discuss the status of deriving a “local” flux of Hawking radiation for quasi-local black holes; Nielsen 2009 discusses this along with the status of attempts to prove the laws of black holes for quasi-local black holes.) 