Black Hole Singularity: Discussing Quantum Theories

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Main Question or Discussion Point

Hi,
I'm new on here and this is my first post, so forgive me if I don't master the threads instantly :) - right, now that's out of way:

I want to open a discussion on the singularity in Black Holes, namely in regards to the well known issue of Special Realitivity breaking down at the singularity and attempts to address the problem of infinity. An infinitely dense and energetic singularity would violate quantum principles (see article linked below the following paragraph).

Recent Quantum research and theory in the fields of Quantum Loop Gravity (QLG) and Quantum Loop Cosmology (QLC) are beginning to study the Quantum aspects of Black Holes. This research really is quite recent, so data and modelling is still to mature fully. However, the following article gives a great overview of these fields and references much of the recent research in these fields on this topic (references all point to credible, peer reviewed journals):

http://www.scholarpedia.org/article/Astrophysical_and_cosmological_signatures_of_Loop_Quantum_Gravity#Black_holes_in_loop_quantum_gravity

See section 3 of the above for Black Holes specifically.

In essence, quantum effects and forces could prevent a singularity in Black Holes, and instead, could 'bounce' matter/energy in an opposite effect in the form of White Holes. White holes are predicted in Relativity. Simple overview of White Holes in the article link below, although I recommend the article above for more detailed scientific observation and many reference papers to examine the current research.

https://www.space.com/40422-are-white-holes-dark-matter.html

My aim is to not have this thread becoming a debate between standard and quantum models of Black Holes. Quite contrary, it would be great to use this to gain more insight into current research on Quantum Theory in Black Holes and Relativistic effects such as Hawking Evaporation (discussed in the research highlighted in the above article), as well as trying to marry Quantum Mechanics with Relativity.

Please feel free to contribute with any more insight, It's a fascinating time for both classical and quantum physics :)

Thanks,

Stu
 
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Answers and Replies

  • #2
PeterDonis
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quantum effects and forces could prevent a singularity in Black Holes, and instead, could 'bounce' matter/energy in an opposite effect in the form of White Holes. White holes are predicted in Relativity.
Not in any practical sense. They are valid mathematical solutions of the Einstein Field Equation, but there is no physically realistic way to have them come into existence.

The (hypothetical--none of this has been checked experimentally and won't be any time soon) quantum effects you are referring to do not turn a black hole into a white hole. A white hole has a horizon--it's just a horizon that nothing can fall into, instead of a horizon that nothing can come out of. (The absence of any physically realistic way of creating such a horizon is a key reason why there is no physically realistic way for a white hole to come into existence.) The hypothetical quantum effects you refer to would prevent any horizon from ever forming; everything that fell into the "black hole" region (which is now not really a black hole but a temporarily trapped region) would eventually come out, though it might be drastically altered in between.

I recommend the paper above
Just to be clear, the link you gave is not to a paper; it's to an article on scholarpedia, not a peer-reviewed scientific publication. It does give many good references to peer-reviewed scientific publications, but it isn't one itself.
 
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Hi Peter,

Thanks for your reply and insight on this matter.

In the research that has been done, there is modelling that the original event horizon would not change, and would become the equivalent horizon for the white hole, if the matter were to be eventually ejected by Quantum effects.

I'm by no means arguing this is fact, far from it, and I appreciate any input like yours on the topic. I am, however, intrigued by the fact Special Relativity breaks down when a Singularity is considered.

I'd love to know if there are any other current solutions to this? I'm genuinely intrigued by the nature of black holes and potential quantum considerations, but am no means subscribing to any idea, especially considering quantum research in the area is still in its infancy.

This paper has more information on the potential involvement of quantum gravity:

https://journals.aps.org/prd/abstract/10.1103/PhysRevD.92.104020

EDIT: Free Arxiv link provided kindly by Peter:

https://arxiv.org/abs/1407.0989

Thanks,

Stu
 
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Hi Peter,

Thanks for your reply and insight on this matter.

In the research that has been done, there is modelling that the original event horizon would not change, and would become the equivalent horizon for the white hole, if the matter were to be eventually ejected by Quantum effects.

I'm by no means arguing this is fact, far from it, and I appreciate any input like yours on the topic. I am, however, intrigued by the fact Special Relativity breaks down when a Singularity is considered.

I'd love to know if there are any other current solutions to this? I'm genuinely intrigued by the nature of black holes and potential quantum considerations, but am no means subscribing to any idea, especially considering quantum in the area is still in its infancy.

This paper has more information on the potential involvement of quantum gravity:

https://journals.aps.org/prd/abstract/10.1103/PhysRevD.92.104020

Thanks,

Stu
I've also amended the original post to state that it is an article, not a paper.

My apologies for that,

Stu
 
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PeterDonis
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In the research that has been done, there is modelling that the original event horizon would not change, and would become the equivalent horizon for the white hole, if the matter were to be eventually ejected by Quantum effects.
Please give a reference. I've never seen a model like this in any peer-reviewed paper, but of course I haven't read every single one in the literature.
 
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PeterDonis
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I'll take a look.
Ok, on a quick skim, the terms "black hole" and "white hole" are not really correct when describing the spacetime geometry this paper is proposing. There is no true event horizon anywhere, either future (black hole) or past (white hole). Instead, there is a region within a certain distance of the "center" at ##r = 0## that, for a certain period of time, contains "trapped surfaces", i.e., surfaces that locally things fall into but don't come out of, or locally things come out of but don't fall into. But this is just local to that region of spacetime; a true black hole or white hole horizon is global.
 
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Never mind, I see you have. But the link you gave is behind a paywall. The arxiv preprint is here:

https://arxiv.org/abs/1407.0989

I'll take a look.
Would love to know your thoughts, thanks.

And I should've posted Arxiv first time round. You'll have to forgive my rookie errors on this site.

Thnaks,

Stuart
 
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Ok, on a quick skim, the terms "black hole" and "white hole" are not really correct when describing the spacetime geometry they are proposing. There is no true event horizon anywhere, either future (black hole) or past (white hole). Instead, there is a region within a certain distance of the "center" at ##r = 0## that, for a certain period of time, contains "trapped surfaces", i.e., surfaces that locally things fall into but don't come out of, or locally things come out of but don't fall into. But this is just local to that region of spacetime; a true black hole or white hole horizon is global.
Hi Peter,

Thanks for taking a look and providing great insight. I am not as knowledgeable as you, far from it and this is the sort of reply I was looking for.

I will keep researching to see what quantum observations have produced in terms of Black Hole theory.

Thank you for your input and reply. I'll post anything else that may be of interest in these replies.

Thanks,

Stuart
 
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There is no true event horizon anywhere, either future (black hole) or past (white hole). Instead, there is a region within a certain distance of the "center" at r=0r=0r = 0 that, for a certain period of time, contains "trapped surfaces", i.e., surfaces that locally things fall into but don't come out of, or locally things come out of but don't fall into. But this is just local to that region of spacetime; a true black hole or white hole horizon is global.
Hi again Peter,

I'd recommend, if you have the time or interest, of course, looking at that paper.

I've attached a sshot relating to the point quoted above:

Screenshot_20181015_000944.jpg

It seems they have a potential solution to the issue you've raised, as well as many equations relating to the quantum effects they are discussing.

My research is only really just beginning in this area, so I have a lot to look into myself, and that was a driving factor for creating this thread.

Hope it's of interest.

Thanks,

Stuart
 

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  • #11
PeterDonis
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It seems they have a potential solution to the issue you've raised
What you quoted is not a "solution" to an "issue" I raised. It's confirmation that my statements about their model were correct. The absence of an event horizon in their model is not an "issue" at all. It's just a fact about their model which makes the terms "black hole" and "white hole", as those terms are standardly defined in physics (i.e., to be based on the presence of true event horizons), not correct when describing their model. Their use of those terms in their paper is not standard usage. But that doesn't affect the physics of their model; it's just terminology.
 
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What you quoted is not a "solution" to an "issue" I raised. It's confirmation that my statements about their model were correct. The absence of an event horizon in their model is not an "issue" at all. It's just a fact about their model which makes the terms "black hole" and "white hole", as those terms are standardly defined in physics (i.e., to be based on the presence of true event horizons), not correct when describing their model. Their use of those terms in their paper is not standard usage. But that doesn't affect the physics of their model; it's just terminology.
Okay fair enough,

I guess I didn't word that reply appropriately, didn't mean to offend, and I'm happy to be educated where I may lack knowledge (for example with correct terminology for phenomena).

In any case it's an interesting model and I'm intrigued in how quantum effects can be factored into black hole theory.

Thanks for your input on this, it all helps with understanding the strengths/limitations of current research in this area.

Stu
 

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