What exactly is Hawking radiation?
Stephen Hawking showed in the early 1970s that black holes are not completely black. They have a slight tint of gray, if you will. That means black holes do not just suck everything in—or accrete, as they call it scientifically—but in fact they must radiate some energy out. This process is known as Hawking radiation. The intensity of Hawking radiation is determined by the temperature of the black hole. The higher it is, the more intense the radiation is, just like a hot bar of metal emits much more heat than a cold one. Now it turns out that the temperature of the black hole is inversely proportional to its mass. The more massive a black hole, the cooler it is. Thus small black holes are very hot and radiate a lot, while large, astronomical black holes are extremely cold and barely radiate at all. The black holes found in the universe are so cold that it takes forever for them to evaporate, many orders of magnitude longer than the age of the universe. By contrast, black holes at the LH
