Why Don't Black Holes Absorb Hawking Radiation?

[Swapnil]

If black hole is so powerful, why doesn't it suck in Hawking radiation as well. I mean, it is just an electromagnetic radiation like light, right?

 

[LURCH]

Yes, it is just ordinary radiation (EM). However, the nature of the model that proposes the existence of this phenominon is that the radiation is generated just outside the event horizon of the black hole, at precisely the distance form which the escape of EM radiation becomes possible. Therefore, it escapes the area of the black hole and travels outward inhto space.

 

[pibomb]

To my knowledge, Hawking radiation are escaping virtual particles. When vacuum fluctuations appear near a black hole, sometimes, one particle will be near enough to the Event horizon and will fall in, while the other (just far enough away from the event horizon) could escape. This phenomenon is associated with the geometry of the virtual particles' "appearance" and the orientation they appear in when next to a black hole.

 

[cesiumfrog]

...one particle will [...] fall in, while the other [escapes]

If a particle-antiparticle pair were created from fluctuations in the external electromagnetic field, even if the antiparticle falls in it should only increase the contained mass-energy. Can someone elaborate on the explanation?

 

[George Jones]

If a particle-antiparticle pair were created from fluctuations in the external electromagnetic field, even if the antiparticle falls in it should only increase the contained mass-energy. Can someone elaborate on the explanation?

I wrote a bit about this in https://www.physicsforums.com/showpost.php?p=620350&postcount=4", and, more importantly I also gave a good link.

 

[hellfire]

I wrote a bit about this in https://www.physicsforums.com/showpost.php?p=620350&postcount=4", and, more importantly I also gave a good link.

How does this explanation deal with the infinite time dilation for infalling objects observed by a remote observer?

 

[wxrocks]

I love how Hawking explains how he came up with the idea -- Going to bed and he realized BHs have edges! I can't say I think the same way when I am that tired.

 

[Wallace]

Infinite time dilation only occurs at the event horizon. Since Hawking radiation originates just outside of the horizon it does not experience infinite time dilation. If it did it would be unable to escape the black hole and wouldn't be called 'radiation'.

 

[George Jones]

How does this explanation deal with the infinite time dilation for infalling objects observed by a remote observer?

This explanation doesn't serve as a replacement for an actual calculation.

This notwithstanding, you have raised a very good point, and I'm not sure that the dust for this issue has completely settled.

I think various schemes have been put forward for why this is not a problem. Try looking for "transplanckian": using google; on the arxiv.

 

[Chronos]

Hawking radiation arises from the pure statistics of virtual particles popping in and out of existence at the event horizon. At least a few of them inevitably escape the maelstrom. This a very subtle way through which black holes obey the laws of thermodynamics - there is no free lunch. Black holes are nearly, but not quite immortal.

 

[hellfire]

Hawking radiation arises from the pure statistics of virtual particles popping in and out of existence at the event horizon. At least a few of them inevitably escape the maelstrom.

I wonder if it is really possible to compute Hawking radiation in that way. For example, how do you calculate the rate of created / annihilated virtual particles per unit volume and time? From what I know about QFT you can compute probabilities, for example for the transition <0|0>. Calculating this you will only see what virtual processes contribute to this transition, but not the number density of them.

 

[Chronos]

I have a biological analogy in mind - an amnionic membrane. A cell manages to preserve salinity by selectively permitting sodium ions to pass. The boundary layer of a black hole [event horizon] mimics this behavior.

 

[Sariaht]

Hawking radiation arises from the pure statistics of virtual particles popping in and out of existence at the event horizon. At least a few of them inevitably escape the maelstrom. This a very subtle way through which black holes obey the laws of thermodynamics - there is no free lunch. Black holes are nearly, but not quite immortal.

Let's say that a particlepair formed in "empty space", and that one of the particles was sucked in. What you are actually trying to say is that the particles obviously only passing by our roomtime, gets almost total room vector instead of whatever vector it had before, the thesis is that if the particles are lined, the outer particle might catch up with the inner particle, and if they collide, the photons they emit can escape the black hole. But since charged particles don't need room vektors to be able to emit energy, but a non roomly vektor that cut our room axis, that won't happen. But if you were talking about very small particles that through Heisenbergs relations happened to escape the black hole, because with the roomvektor it achieved in almost being sucked in, can excape through Heisenbergs relations, then it is impossible for the particle to stay in our universe for a longer time, since it can only get total roomvektor, if it is on the radius, and if it is on the radius, it cannot escape.

That is my oppinion, and I am entitled to express a such.

 

[Labguy]

Let's say that a particlepair formed in "empty space", and that one of the particles was sucked in. What you are actually trying to say is that the particles obviously only passing by our roomtime, gets almost total room vector instead of whatever vector it had before, the thesis is that if the particles are lined, the outer particle might catch up with the inner particle, and if they collide, the photons they emit can escape the black hole. But since charged particles don't need room vektors to be able to emit energy, but a non roomly vektor that cut our room axis, that won't happen. But if you were talking about very small particles that through Heisenbergs relations happened to escape the black hole, because with the roomvektor it achieved in almost being sucked in, can excape through Heisenbergs relations, then it is impossible for the particle to stay in our universe for a longer time, since it can only get total roomvektor, if it is on the radius, and if it is on the radius, it cannot escape.

That is my oppinion, and I am entitled to express a such.

I have posted this before but it fits well here too.

Chronos is correct about the mass-energy production of a black hole (BH) by way of Hawking radiation (HR). That is limited strictly to the "lifetimes" and energy release of a non-accreting black hole. Of course, a black hole with other matter being accreted will gain mass as long as the accretion rate exceeds the Hawking evaporation rate.

So, forget about a black hole sucking in matter of any kind and place it alone in a relatively empty region of space, at least empty enough to not draw in any nearby matter. This is where we can talk about the effects of Hawking radiation alone. The energy at the event horizon is as Chronos explained. This energy will produce virtual-particle (VP) pairs (from vacuum fluctuations outside the EH) and not just electrons/positrons as most often mentioned. The VP pair is produced by "borrowed" energy and must annihilate in ~10-30 atoseconds to “return” the energy. The Heisenberg uncertainty principle allows for two things. (1) It allows the VP pair to exist on borrowed energy for a finite, but very short, period of time, and (2) it allows the VP pair to be of any energy amount as long as, again, any "borrowed" energy is returned. Therefore, the VP pair is not limited to just electrons and positrons, it can also be quarks, protons, neutrons, and certain mesons regardless of energy required to produce the pair.

So, the virtual particle with negative energy falls into the BH and the other becomes a "real" particle with real mass. If it escapes into space (sometimes both will fall in), then the mass of whatever the escaping particle was will exactly match the mass-loss of the BH. Real mass is delivered into space as real particles. The BH loses that much mass, so the first two laws of thermodynamics are still happy, nothing has been violated.

so how does a small BH become so hot and evaporate so fast? Well, the "standard" HR process just mentioned was about one, single VP pair. In a large BH idling along this might be the case here and there around the EH. But, a smaller BH with more gravitational energy per square^anything will be producing VP pairs, of many different particle types, at a great pace. Now we have a swarm of real particles buzzing all around the EH at a very high density. Some will combine into more complex particles, but most will just escape or, to produce the intense energies mentioned, many particle-antiparticle pairs will meet and annihilate into pure energy. If the density is high enough and the particles massive enough, you will see the gamma-ray production so often mentioned, again, especially from small, short-lived BH's. Of course, it is actually the entire EM spectrum of photons that are produced but the gamma rays get the most attention.

 

[Sariaht]

So the time dimension is simply in a black hole, spatial, since particles cannot move in the speed of light along the time line. As soon as a particle is exposed of total acceleration, all dimensions are equally spatial, but the Heisenberg relations still remains and thereby a particle at the event radius can move backwards in time and thereby temporarily repulse the black hole and leave it. But since gravity is a force that is not dependent of vectors, since a black hole have none, but rather time distance, and therefor it is probable that the cosmological constant attract these days, and that masses attract each other because of their time distance. So the only way mass can really disappear in the black hole (except colliding along the time line one particle at a time depending on where they are along it) is if the Heisenberg relations makes time move backwards, or if time in empty space moves forward.

That is my oppinion, and I am entitled to express a such.

 

[Neelesh]

We can also say that how gamma rays emited ewen if light cannot escape from black hole? we can answer simpily Saying that gamma rays travel perpendicular to space time continummnot on it as light does.