Q:

If black holes curve spacetime infinitely such as even light cannot get out, how come they are subject to Hawking's radiations? If they radiate anything, wouldn't the curved spacetime bring the radiations back to it and in the end the black hole wouldn't radiate anything outside its event horizon? What are the proofs that Hawking is right?

- Anonymous

- Anonymous

A:

This is a tricky problem. The standard general relativity solutions to the black hole problem do not allow this to happen. However, quantum mechanics is not taken into account and upon closer examination the virtual production of particle anti-particle pairs can allow one of the pair to escape with a net loss of energy of the black hole. If this loss is not compensated by accretion then the black whole will eventually evaporate.

As far as I know, there is no experimental evidence one way or the other. I presume you have already explored the Wiki-site

LeeH

To add a couple of points- the curvature at the event horizon itself would not be infinite. The event horizon is not a singularity. A point which is related to your question, although not directly answering it, is that actual black holes do not quite fully form from the collapse of stars because the collapse of the last bit of stuff needed to create the horizon takes infinitely long. You get instead a shell of almost collapsed stuff just barely outside where the event horizon would be. Its evaporation is very slow, but if quantum mechanics is right it's not infinitely slow.

Mike W.

As far as I know, there is no experimental evidence one way or the other. I presume you have already explored the Wiki-site

LeeH

To add a couple of points- the curvature at the event horizon itself would not be infinite. The event horizon is not a singularity. A point which is related to your question, although not directly answering it, is that actual black holes do not quite fully form from the collapse of stars because the collapse of the last bit of stuff needed to create the horizon takes infinitely long. You get instead a shell of almost collapsed stuff just barely outside where the event horizon would be. Its evaporation is very slow, but if quantum mechanics is right it's not infinitely slow.

Mike W.

*(published on 12/12/2010)*