Hawking radiation is a very, very slow process. A black hole with the mass of the Sun, for example, would take many trillions of years—far longer than the current age of the universe—before its Hawking radiation had any significant effect on its size or mass. Given enough time, though, the energy that leaks through a black hole’s event horizon becomes appreciable. Since matter and energy can directly convert from one to another, the black hole’s mass will decrease a corresponding amount.

According to theoretical calculations, a black hole having the mass of Mount Everest—which, by the way, would have an event horizon smaller than an atomic nucleus—would take about ten to twenty billion years to lose all its energy, and thus matter, back into the universe because of Hawking radiation. In the final instant, when the last bit of matter is lost, the black hole will vanish in a violent explosion that may release a huge blast of high-energy gamma rays. Perhaps astronomers may someday observe just such a phenomenon and confirm the idea of Hawking radiation as a scientific theory.