Black Hole

All that has been said so far involves black holes as described by the general theory of relativity. However, in the realm of the very small, quantum mechanics has proved to be the proper theory to describe the physical world. To date, no one has successfully combined general relativity with quantum mechanics to produce a fully consistent theory of quantum gravity; however, in 1974, British physicist Stephen Hawking (1942–) suggested that quantum principles showed that a black hole should radiate energy like a perfect radiator having a temperature inversely proportional to its mass. This radiation—termed Hawking radiation—does not come about by the conventional departure of photons from the black hole's surface—which is impossible—but as a result of certain effects predicted by quantum physics. While the amount of radiation for any astrophysical black hole is very small (e.g., the radiation temperature for a black hole with the mass of the Sun would be 10^-7K), the suggestion that loss of energy from a black hole was possible at all was revolutionary. It suggested a link between quantum theory and general relativity, and has spawned a host of new ideas expanding the relationship between the two theories. It is the ability of a black hole to lose mass via Hawking radiation (i.e., to evaporate) that prevents microscopic black holes, such as those that physicists hope to produce at CERN, from swallowing up the earth. These black holes evaporate faster than they can grow.