Understanding Black Hole Singularity

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Discussion Overview

The discussion centers on the nature of black hole singularities, exploring whether they truly exist and the implications of their presence or absence. Participants examine concepts from general relativity and quantum mechanics, debating the formation of singularities, event horizons, and the properties of matter within black holes.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants question the existence of singularities, arguing that they are unproven and may not form under certain conditions.
  • Others assert that mathematical proofs by Penrose and Hawking indicate that singularities must form when matter collapses within the event horizon.
  • A viewpoint suggests that singularities are mathematical artifacts resulting from the limitations of general relativity, which does not account for quantum mechanics.
  • Some participants propose alternative models, such as the idea of a central massive particle with properties similar to fermions, rather than a singularity.
  • There is a discussion about the relationship between mass density and the formation of event horizons, with some arguing that an event horizon can exist without a singularity.
  • Concerns are raised about the implications of quantum effects on the classical understanding of black holes and singularities.
  • Some participants express skepticism about the quantization of mass and its relevance to black hole properties.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the existence of singularities within black holes, with multiple competing views presented throughout the discussion. The debate remains unresolved, with differing opinions on the implications of general relativity and quantum mechanics.

Contextual Notes

Limitations include the dependence on classical theories of general relativity and the unresolved nature of quantum gravity, which may affect the understanding of singularities and event horizons.

  • #31
qraal said:
And what is goin to force that mass of particles to get so small?

I'm under the impression that collapse is inevitable once inside 2M because the matter now exists in space-like spacetime (i.e. r is temporal) and regardless of the forces involved, no stable radius is possible and matter will keep collapsing until r=0 or spacetime ceases to exist (which is suppose to be the case at Planck scale) or time-like spacetime is reinstated as in the case of rotating or charged black holes.
 
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  • #32

Any model with a radius less than the Planck radius no longer obeys General Relativity and according to cosmologists, virtual particle turbulent Quantum Foam is encountered, and there is no evidence that Planck scale dimensions are capable of being exceeded without completely replacing General Relativity with Quantum Gravity. Also, the Planck radius is a stable radius.

Also, there may be other degeneracy conditions based upon degenerate quark matter and Quantum Gravity and other conservation laws that may exist inside a black hole to prevent the collapse to Planck and sub-Planck scales.

According to Loop Quantum Cosmology which is based upon Loop Quantum Gravity, all wave packets that reach a classical singularity as 'a crunch', 'bounce off'. The result is a state that oscillates between bouncing off the core singularity as 'a bounce' and rebounding back to the event horizon as 'a bang'. I have included a link to a video and references from Wikipedia that demonstrates this:
"[URL
[PLAIN]http://relativity.livingreviews.org/Articles/lrr-2005-11/tn_bouncestill.png
[/Color]
Reference:
http://en.wikipedia.org/wiki/Loop_quantum_gravity"
http://en.wikipedia.org/wiki/Loop_quantum_cosmology"
http://en.wikipedia.org/wiki/Quantum_foam"
http://en.wikipedia.org/wiki/Big_Crunch"
http://en.wikipedia.org/wiki/Big_Bounce"
http://en.wikipedia.org/wiki/Big_Bang"
http://en.wikipedia.org/wiki/Oscillatory_universe"
http://www.humnet.ucla.edu/humnet/phil/faculty/Smeenk/Bojowald_LQC.pdf"
http://relativity.livingreviews.org/Articles/lrr-2005-11/articlesu50.html"
 
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  • #33
While a radius (or reduced circumference) can be deemed a stable radius for matter that has collapsed to Planck density/pressure, r=0 would still apply to the outer edge of this radius as this would be the end of spacetime (though some kind of bounce would probably stop this occurring, the collapsed matter oscillating close to Planck properties), the volume of matter with Planck density/pressure contained within the radius would be without dimension, as with these properties, the energies that distinguish matter and space are supposed to combine. I'm tempted to say that the Planck matter would be supersymmetric but this would be speculating. It's also fair to say that no matter how little, spin would have some effect on the final collapse of the singularity which may go some way of stopping the matter from reaching absolute Plank properties, and as stated, high energy virtual particles would probably play some part also.

The following paper is a good overview of the different types of singularity-

http://www.unc.edu/~mgood/research/Singularity.pdf

The following papers are a bit maths heavy but insightful-

Singularities and Quantum Gravity
Authors: Martin Bojowald
http://arxiv.org/abs/gr-qc/0702144

Loop quantum gravity and black hole singularity
Authors: Leonardo Modesto
http://arxiv.org/abs/hep-th/0701239

On the black hole singularity issue in loop quantum gravity
Authors: A. DeBenedictis
http://arxiv.org/abs/0907.0826

The following isn't in a user friendly format but is also insightful-

Quantum Foam and de Sitter-like universe
Authors: P. A. Zizzi
http://arxiv.org/abs/hep-th/9808180

There's also the matter of the weak singularity at the inner horizon of rotating or charged BH's which if applies may render GR mute before even reaching the centre of the black hole.
 
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  • #34
We already know GR is mute before the singularity.
 
  • #35
Why so many physicists for years accepted GR beyond the Planck wall?
 
  • #36
universe11 said:
Why so many physicists for years accepted GR beyond the Planck wall?

Can you cite a paper where GR is used at sub-Planck scales?
[/Color]
 

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