Supressing black hole evaporation?

  • #1
Suekdccia
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TL;DR Summary
Are there any ways to supress the evaporation of a black hole via Hawking radiation?
A very massive charged black hole could reach a near-extremal state in the right conditions supressing the rate of emission of Hawking radiation (https://physics.stackexchange.com/questions/490524/evaporation-of-large-charged-black-holes)

Meanwhile, the radiation emitted by a black hole can be confined through various mechanisms like massive fields, magnetic fields, anti-de Sitter boundaries or nonlinear interactions (arxiv.org/abs/1501.06570). This confined radiation could return to the black hole. Applied to Hawking radation this would mean that the black hole would not lose its mass to this emission

Could these mechanisms (jointly with Hawking radiation emission supression by a nearly-extremal black hole) help to supress the evaporation of a black hole?
 
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  • #2
Suekdccia said:
Could these mechanisms (jointly with Hawking radiation emission supression by a nearly-extremal black hole) help to supress the evaporation of a black hole?
Who knows? These are all theoretical speculations. None of them have any prospect of being experimentally tested any time soon. It's an open area of research. That means we don't know the correct answers to the questions we are asking.
 
  • #3
How about putting spherical mirror around the black hole?
 
  • #4
Demystifier said:
How about putting spherical mirror around the black hole?
Or, for that matter, having the hole exist in a universe with a CMBR whose temperature is greater than the hole's Hawking temperature. Which is the case in our current universe.

However, these kinds of simple, mundane options don't seem to be what the references given in the OP are talking about.
 
  • #6
PeterDonis said:
Or, for that matter, having the hole exist in a universe with a CMBR whose temperature is greater than the hole's Hawking temperature. Which is the case in our current universe.

However, these kinds of simple, mundane options don't seem to be what the references given in the OP are talking about.
The article mentions more down-to-earth mechanisms such as strong magnetic fields. So, couldn't such processes supress black holes' evaporation?
 
  • #7
Suekdccia said:
The article mentions more down-to-earth mechanisms such as strong magnetic fields. So, couldn't such processes supress black holes' evaporation?
See my response in post #2.
 
  • #8
I'm not sure what the question actually is. It seems you've already listed several ways in which you can "suppress" black hole evaporation. Are you just asking for some kind of exhaustive list of such options?
 
  • #9
PeterDonis said:
See my response in post #2.
But with that philosophy in mind, we would have to reject any discussion about Hawking radiation in this forum 🤷🏻
 
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  • #10
OlderWannabeNewton said:
I'm not sure what the question actually is. It seems you've already listed several ways in which you can "suppress" black hole evaporation. Are you just asking for some kind of exhaustive list of such options?
My question would be:

Is there any way that would be based on known physics (that is, one way that would not be overly speculative or that requires anything outside the current knowledge about black holes) that could possibly trap all the radiation of a black hole so that it would not be evaporated? (And I gave some examples to see if any of these could do this)
 
  • #11
Suekdccia said:
But with that philosophy in mind, we would have to reject any discussion about Hawking radiation in this forum 🤷🏻
Well, discussion of Hawking radiation really belongs in the Beyond the Standard Models forum--which is where I have just moved this thread.

Suekdccia said:
Is there any way that would be based on known physics
There can't be because Hawking radiation itself is not "known physics", since we do not have a "known" theory of quantum gravity.
 
  • #12
Suekdccia said:
My question would be:

Is there any way that would be based on known physics (that is, one way that would not be overly speculative or that requires anything outside the current knowledge about black holes) that could possibly trap all the radiation of a black hole so that it would not be evaporated? (And I gave some examples to see if any of these could do this)

What do you mean by "known" physics? Putting a black hole in AdS to prevent it from evaporating is "known" physics in that it's just semi-classical gravity (GR + QFT) in AdS. There's nothing speculative about this. But it's purely theoretical, we don't have any way of experimentally testing this.
 
  • #13
OlderWannabeNewton said:
it's just semi-classical gravity (GR + QFT)
More precisely, it's quantum field theory in curved spacetime. That said:

OlderWannabeNewton said:
it's purely theoretical, we don't have any way of experimentally testing this
Which means it isn't "known physics". It's theoretical speculation. It's not "known physics" unless and until it's actually been experimentally tested and confirmed.
 
  • #14
Is analogue Hawking radiation, namely radiation of phonons in systems with sonic horizon, "known" physics?
 
  • #15
Demystifier said:
Is analogue Hawking radiation, namely radiation of phonons in systems with sonic horizon, "known" physics?
Yes, but those aren't actual black holes and the radiation isn't actual Hawking radiation. I know proponents claim that the analogy is useful, but I'm skeptical, since we only have experimental evidence on one side of the analogy.
 
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  • #16
I think the real question here from an engineering perspective is, what type of power consumption is required to essentially re-route the hawking radiation of a black hole while also maintaining a "safe" distance/velocity in free fall around the event horizon to successfully conduct such an operation.

Beyond the math of whether it's possible, you have to think about the math that makes it possible. If the energy required to create the constraints of hawking radiation outweigh any benefits, than Occom's razor comes into play.

Purely for the math however, If you imagine a star at the minimum of threshold to become a black hole, about 20 solar masses, you end up, theoretically with a stellar black hole with about 3 solar masses.
My sub par math puts the power emitted by Hawking radiation for a black hole with a mass of about 3 solar masses at approximately 1.1×10−301.1×10−30 watts, which is tiny.

So maybe an array of satellites at the right distance with adequate shielding could potentially provide a large enough field to capture/redirect hawking radiation.

However these are all hypotheticals as there are too many variables left out of the speculations we're making and not enough physical evidence to provide reasonable conjecture to the reality of what's happening near a black hole.

Still fun to think about though.
 

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