Evaporating Black Holes

[Dark matter]

Recently, me and my friend had a conversation about Black Holes and why they evaporate. I have read about Black Hole evaporation and know some; however, the books that I have read do not completely explain evaporation and how it works. If you have any information, feel free to share.

[Klaynos]

The way it's always been explained to me:

 

You get particle anti-particle on the edge of bh, one on the outside one on the inside, occationally the outer one if it's an anti-particle will annihilate with a particle and there is a chance that one of the photons given off by this will be away from the bh, therefore the bh will have lost that bit of energy/mass...

[Zephir]

... the books that I have read do not completely explain evaporation and how it works.....

Currently, the Hawking mechanism is believed to be the only source of black hole evaporation. I don't believe so, but it's not difficult to explain the Hawking radiation from many perspectives.

 

 

You can use the optical refraction model, for example. By this model the event horizon is sort of total refraction phenomena due the immense vacuum density gradients in its neighbourhood ("curved spacetime"). Therefore every energy wave is reflected by this gradient like the light wave reflects itself from internal surface of water droplet. But this surface is permanently "scratched" by Brownian motion of vacuum particles (the "quantum noise"), which allows the subtle portion of radiation to escape from black hole. Note, that the decreasing radius of black hole decreases the effectiveness of total reflection phenomena as well, which should mean, the tiny black hole will explode fast (if we neglect the surface tension phenomena, which can stabilize such object - this is still opened question for me).

 

 

Anyway, if the size of black hole increases, the surface density gradient near of event horizon decreases (it changes itself into fuzzball), which allows to escape even the axions and neutrino from black hole. After certain size limit, the surface gradient will not effective in total reflection anymore and the black hole will change itself into giant brightly shinning star, so called the quasar, which evaporates itself, until it reaches the thermodynamical equillibrium. Due the gravity brightening of rotating black holes the polar jets are formed in this stage of BH evaporation - we can see, such object doesn't differ from other giant stars so far.

[Mr Skeptic]

As I understand it, black hole evaporation is due to virtual particle pairs (mostly photons) appearing just outside the event horizon. If one of these is sucked into the black hole, it cannot annihilate with its pair, and also that the pair has gained enough energy to become real at the expense of the gravitational potential energy of the black hole. So the black hole has lost some energy to things outside its event horizon.

[Dark matter]

And then this continues until the black hole loses all of its Gravitational potential energy?

 

The way it's always been explained to me:

 

You get particle anti-particle on the edge of bh, one on the outside one on the inside, occationally the outer one if it's an anti-particle will annihilate with a particle and there is a chance that one of the photons given off by this will be away from the bh, therefore the bh will have lost that bit of energy/mass...

 

So then this process happens over and over and over again until the black hole loses its energy..?

[Mr Skeptic]

And then this continues until the black hole loses all of its Gravitational potential energy?

 

 

 

So then this process happens over and over and over again until the black hole loses its energy..?

 

Yes. And apparently it happens faster the smaller the black hole is (cause the distortion in spacetime is sharper or something).

[djeinstine]

Yes. And apparently it happens faster the smaller the black hole is (cause the distortion in spacetime is sharper or something).

 

I know this is a tough questions but what happens to theoretical micro black holes then =x

[Klaynos]

they evaporate VERY quickly.