24th Feb 2012

gaaaaaahgkjhgakjg asked: Do you know anything about black hole evaporation and what causes that to occur?

For a black hole to evaporate, it must lose more mass and energy than it gains. It begins when the black hole stops spinning. At this point, the black hole starts to lose energy from its interior, instead of from the space outside the horizon where spinning black holes lose energy.

As Stephen Hawking calculated back in the 70’s, when taking into account quantum mechanics, black holes are seen to emit blackbody radiation. In other words, black holes behave as though they have a constant temperature, and this temperature is inversely proportional to its mass. So as the size of the black hole shrinks, its temperature will increase, which in turn causes the black hole to produce more radiation. 

The key to this radiation is particle-antiparticle pairing. In this scenario, the gravitational energy of the black hole produces a particle and its antiparticle just outside the event horizon. What then happens is that the two particles either recombine and release energy in the form of radiation or one of the particles falls back into the event horizon while the other particle escapes into space. Since the black hole put in energy to create the two particles, in the latter case, the particle that escapes into space has carried away some of the black hole’s mass. With the continuation of this process, the evaporation of the black hole starts to increase rapidly as it shrinks in size until it ends in an explosion of elementary particles.

For stellar-mass and supermassive black holes, this effect is negligible. But for primordial black holes, since their lifetimes are quite long, could be in the process of this black hole evaporation.

This post has 3 notes
  1. supercuddlypuppies said: why do they have to be non-rotating?
  2. christinetheastrophysicist posted this