black hole evaporation
- 04-21-2004, 03:13 PM
- 04-21-2004, 04:44 PM
Not 100% certain, I will have to check but this is what i remember:
Black holes emit radiation, termed Hawking radiation. As the mass of a black hole decreases a higher volume of hawking radiation is emitted and this results in an increase in the rate ot the black hole "evaporation".
you probably already knew this though.
- 04-21-2004, 05:01 PM
Hawking radiation occurs when two virtual particles appear and one of them gets drawn into the black hole and the other escapes into space. I am curious why the black hole shrinks by absorbing a virtual particle. The black hole shouldnt shrink because 'one got away' due to the fact that the virtual particles appeared independantly of the black hole and should not effect it's size leading to it's evaporation.
04-21-2004, 05:03 PM
size, i am curious about this phenomena. any ideas of the mechanisms? or is this just one of the secrets awaiting in the elusive theory of quantum gravity?Originally Posted by size
04-21-2004, 05:49 PM
That would be about 30 pages long and would require a lot of math (I am not sure that I could even do a tenser chart anymore) here is the short version without the theoretical background.
We live in a sea of virtual particles. These are a result of the wave/particle duelality that is one of the underlying principles of quantum mechanics. Basically particles simiatously travel all points to a target, or to put it another way have a defined probability of being in any one place or time (time has a different meaning in quantum mechanics, an electron traveling faster then light (backwards in time, this is permitted due to the uncertainty principle witch states that you can not know both the position and speed of a particle at the same time with any accuracy. Sense you can at time predict a particles position with high accuracy it is possible for it to “escape” the paradox by briefly going faster then light.) Will behave like a positron going forward in time. This it is possible for positron to meet the future electron (when the positron slows down) and annihilate each other leaving the original election to continue. Reactions like this and other give rise to the virtual particle fields.). Though complex reactions in space-time and the quantum wave factors the virtual particle fields are created. These are quite real; in fact the fields on magnets are a good example.
The other factor here is energy. Quantum mechanics allows for particles to come into existence by borrowing energy from the quantum vacuum. (This is a term used to describe empty space; witch is not so empty really. I am really simplifying things here because this is getting long. As it turns out even space-time is not smooth here, rather the quantum fluctuations become increasing violent as you look at smaller and smaller reaches. On the order of the plank scale it is described as “foam”. ) Mother nature is stingy however and any energy that is borrowed must be paid back. Not only must the energy be paid back but also the greater the amount the sooner it must be paid back. That is why the virtual pair elections almost always annihilate each other, to release the energy back. But there is no rule on ware that energy has to come from
Witch finally brings us to your question (**** this is long.) Lets look at the electron reaction again but this time the first election is in orbit just above the surface of the event horizon. The election is suddenly in a well-defined position witch cause it speed to become unknowable. The election exceeds the speed of light causing it to behave like a position going forward in time. But sense the election has also gone back in time and slowed down it is now an election again. Now lets look at the situation here. From the impartial observers standpoint there are now 3 particles instead of one, the first electron, the positron, and the election that came from the future. Only one of these can remain a real particle. However this time something new happens. The curvature of the space-time around the event horizon is strong enough to rip one of the particles away, lets say the positron. Now there is no way for the particle pair to annihilate each other. So the remaining 2 elections are free, real particles. The quantum singularity has to cough up the energy to be returned to the quantum vacuum. The energy is taken from the gravity well. Or to put it another way the quantum singularity has just swallowed a chunk of negative energy and suffers a reduction in mass to account for it. You can look at it either way, six in one hand half dozen in the other.
Hope this answers your question.
04-21-2004, 05:51 PM
yah bro they do shrink over time. that was the whole point of his discovery of them obaying the 2nd law.Originally Posted by canadian champ
04-21-2004, 10:13 PM
Wow I learned something new today! Will I ever use it in life? Most definitly hell NO!
just curious but why was this question even asked?
04-21-2004, 10:55 PM
Originally Posted by Skye
No no no no. This is all wrong. The correct answer is: who gives a ****? j/k
04-21-2004, 11:36 PM
04-22-2004, 01:04 AM
That was a well written explanation and saved me the time of looking it up.
I just always try to remember that an inverse relationship exists between Hawking radiation and the mass of a black hole.
04-22-2004, 03:37 AM
04-22-2004, 08:47 AM
Because the second electron is the actual radiation in this example. The first electron was already there and second election and the positron were the virtual particle pair arising from the quantum vacuum. Sense in this example the positron is the "hole" that the singularity consumes the remaining virtual particle is the one that becomes real and is seen as the radiation from the event horizon.Originally Posted by MMC77
I used leptons in this case for simplicity sake but the more common reactions are usually with the messenger particle and occasionally hardons. There are many ways that one can look at this and give different descriptions of what happens.
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