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quantafyre

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- Thread starter quantafyre
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In summary, according to the author, Hawking radiation is generated when a virtual particle pair is "split" at the exact edge of an event horizon. This occurs when one of the particle pair escapes to "normal" spacetime, while the other is pulled down into the hole. When this occurs, it is logical to assume that the black hole actually gains a very small amount of matter (the doomed companion of the free particle). However, as I understand it, Hawking radiation actually occurs when a portion of a "thing" or condition actually yields part of its being or totality. With Hawking radiation, this is not actually happening, since the Black hole/singularity is not giving anything of its "self" but is actually gaining (the sad

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quantafyre

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Bill_K

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Quoting from Birrell and Davies, "The average wavelength of the emitted quanta is ~M, i.e comparable with the size of the hole. As it is not possible to localize a particle to within one wavelength, it is therefore meaningless to trace the origin of the particles to any particular region near the horizon." ...As I understand it, Hawking radiation occurs when a virtual particle pair is 'split' at the exact edge of an event horizon.

"Virtual particle pairs with wavelength λ separate temporarily to a distance ~ λ. For λ ~ M, strong tidal forces operate to prevent reannihilation. One particle escapes to infinity with positive energy to contribute to the Hawking flux, while its corresponding antiparticle enters the black hole trapped by the deep gravitational potential well on a timelike path of negative energy relative to infinity."How can we speak of the black hole evaporating when in fact it is 'gaining' matter during Hawking radiation?

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quantafyre

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Bill_K

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tom.stoer

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Nevertheless Hawking's interpretation became standard.

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quantafyre said:

To say what Bill said in a slightly different way, the only thing that matters is that WHICHEVER of the virtual pair falls into the EH, it has negative energy.

Also, as I understand it from posts on this forum, there is some confusion around the actual operation of Hawking radiation and at least one post here said that Hawking himself said that the "virtual particle pair" is just a conceptual device to describe something that is a bit more complex than that.

EDIT: apparently it's another one of those cases where the math doesn't really translate well into English.

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PeterDonis

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phinds said:Hawking himself said that the "virtual particle pair" is just a conceptual device to describe something that is a bit more complex than that.

The Usenet Physics FAQ entry takes a similar position:

http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/hawking.html

It says that nobody has ever worked out a local description of how Hawking radiation is generated that corresponds to the "virtual particle pair" description, and describes in a bit more detail how the actual computations are done.

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tom.stoer

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I have to find a paper which does not use virtual particles but at least tunneling.

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atyy

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tom.stoer said:It's rather difficult: afaics Hawking's interpretation (particle-antiparticle pairs, virtual particles) cannot be derived from his (brilliant) calculation. There is no particle-antiparticle pair, and there is no one-loop integral, therefore no virtual particles (in the sense of the formalism).

So you wouldn't object if one just said "real" particle creation instead of "virtual" particle?

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tom.stoer

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I recommend to study Hawking's original paper:

http://www.itp.uni-hannover.de/~giulini/papers/BlackHoleSeminar/Hawking_CMP_1975.pdf

The idea is very simpe, the math is not very complicated. The main problem is that math and its interpretation start to deviate already in this paper! That's why I don't like Hawking's popular books; he doesn't care much for exactness when he starts to spin a yarn.

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Bill_K

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Tom, I hope you weren't expecting a Feynman diagram. The point is that particles are present in the vacuum state, and some of them head outward to future null infinity, while others head inward and cross the black hole's horizon. There's no suggestion that they were created pairwise at a definite location.It's rather difficult: afaics Hawking's interpretation (particle-antiparticle pairs, virtual particles) cannot be derived from his (brilliant) calculation. There is no particle-antiparticle pair, and there is no one-loop integral, therefore no virtual particles (in the sense of the formalism).

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Naty1

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Descriptions I have seen:

posted above:

it is not possible to localize a particle to within one wavelength,

virtual particle separation,

tunnelingand another from Leonard Susskind: pieces of long strings break off from the stretched horizon due to quantum fluctuations...and appear as real particles... from his book THE BLACK HOLE WAR.

posted above:

it is not possible to localize a particle to within one wavelength,

virtual particle separation,

tunnelingand another from Leonard Susskind: pieces of long strings break off from the stretched horizon due to quantum fluctuations...and appear as real particles... from his book THE BLACK HOLE WAR.

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tom.stoer

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Of course I don't expect Feynman diagrams; all what I am saying is that Hawking's interpretation of his own calculation is missleading.Bill_K said:Tom, I hope you weren't expecting a Feynman diagram. The point is that particles are present in the vacuum state, and some of them head outward to future null infinity, while others head inward and cross the black hole's horizon. There's no suggestion that they were created pairwise at a definite location.

Hawking radiation is a theoretical concept proposed by physicist Stephen Hawking in the 1970s. It is a type of radiation that is emitted by black holes due to quantum effects near the event horizon. According to this theory, black holes are not completely black, but instead emit radiation and eventually evaporate over time.

Hawking radiation is created when pairs of virtual particles (particles that pop in and out of existence in empty space) are separated by the intense gravitational pull of a black hole. One particle then gets pulled into the black hole, while the other escapes as radiation. This process results in a gradual decrease in the mass of the black hole, leading to eventual evaporation.

Currently, Hawking radiation has not been directly observed, as it is extremely weak and difficult to detect. However, scientists are using specialized instruments and techniques to try and capture evidence of this phenomenon.

According to Hawking's theory, all black holes will eventually evaporate over an extremely long period of time. However, the time it takes for a black hole to completely evaporate depends on its initial mass. Smaller black holes will evaporate much faster than larger ones.

Hawking radiation has significant implications for our understanding of black holes and the laws of physics. It suggests that even black holes, which were previously thought to be completely devoid of any physical processes, are subject to quantum effects. It also raises questions about the ultimate fate of black holes and the conservation of information within them.

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