Black Holes and Tachyon radiation...

[Zylstra]

Another ignorant question..

How does Hawking radiation 'escape' the black holes it's emitted from, when light can't? after being emitted, why is it not pulled back into the black hole in an endless cycle?

 

[scikidus]

Another ignorant question..

How does Hawking radiation 'escape' the black holes it's emitted from, when light can't? after being emitted, why is it not pulled back into the black hole in an endless cycle?

Here's how Hawking radiation is believed to work.

On the quantum scale, random perturbations can cause particles to pop into and out of existence in high-energy areas. A common event is for a photon and its antiparticle to appear together and very quickly annihilate each other. However, if these particles pop into existence on the event horizon, one may just inside the even hroizon while the other is just outside of it. If both particles are traveling at the speed of light, then one will fall into the black hole (it can't escape) and the other WILL escape, because it's not inside the event horizon. This leads to a net decrease in the energy, and therefore mass, of the black hole.

 

[Zylstra]

Thanks. My mistake was thinking it was emitted form the center of the black hole

 

[ExeFBM]

One issue I always had with Hawking radiation is, How often is it happening? There can't be a huge number of particles forming right at the critical point where one escapes and another is swallowed.

Given this only tiny amounts of matter will be lost by the black hole, but isn't the black hole constantly sucking up new matter anyway? Is the tiny erosion force of Hawking radiation really enough to overcome the influx of new matter? Or am I missing something?

 

[scikidus]

One issue I always had with Hawking radiation is, How often is it happening? There can't be a huge number of particles forming right at the critical point where one escapes and another is swallowed.

Given this only tiny amounts of matter will be lost by the black hole, but isn't the black hole constantly sucking up new matter anyway? Is the tiny erosion force of Hawking radiation really enough to overcome the influx of new matter? Or am I missing something?

The rate of loss is very small for big black holes, but it gets faster and faster for smaller and smaller black holes. Microscopic black holes evaporate almost instantly.

The evaporation time of a black hole is calculated as follows:

(stolen from Wikipedia)

Or, if you crunch those numbers down (as I just did for you), you get:

t = 4.26096653*10^(-18) * M^3

Also, more particles are forming than you might think: the event horizon of a black hole has a ton of energy.

 

[Zylstra]

Can these particles appear totally outside of the event horizon, or is it only at/past the EH that the conditions are met for its occurrence?

 

[scikidus]

Can these particles appear totally outside of the event horizon, or is it only at/past the EH that the conditions are met for its occurrence?

All that has to happen is that one particle must fall into the blac hole and one must not. If the two particles formed outside the event horizon, one might be travelling directly at the event horizon and the other away from it.

 

[Zylstra]

All that has to happen is that one particle must fall into the blac hole and one must not. If the two particles formed outside the event horizon, one might be travelling directly at the event horizon and the other away from it.

Allow me to clarify the question: the necessary energy and other conditions for these particles to come into being, they can occur outside of the event horizon?

 

[scikidus]

Yes, but it's more likely to occur closer to the event horizon than farther away. For instance, the accretion disk of a black hole can reach millions of degrees.