Naked singularities, and Hawking

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    Hawking Singularities
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Discussion Overview

The discussion centers around the concept of naked singularities and the implications of Hawking's views on their existence, particularly in relation to the cosmic censorship conjecture. Participants explore theoretical scenarios involving black holes, angular momentum, and the potential for singularities to be exposed. The conversation touches on various interpretations and implications within the context of black hole physics and mathematical relativity.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants suggest that injecting high angular momentum material into a static black hole could lead to the formation of a naked singularity, questioning the limits of black hole spin.
  • Others clarify that Hawking's bet with Thorne was primarily about information loss in black holes, not directly about naked singularities.
  • One participant mentions that while it may be theoretically possible to spin a black hole to extremal limits, practical constraints exist that prevent it from exceeding certain thresholds.
  • A reference to Brian Greene's work is made, discussing how Calabi-Yau shapes might shield against naked singularities and the transitions between black holes and elementary particles.
  • Participants reference the cosmic censorship conjecture as a significant unproven idea in the context of naked singularities.

Areas of Agreement / Disagreement

Participants express differing views on the conditions under which naked singularities might form, with some arguing for their possibility under certain conditions while others emphasize the constraints posed by existing theories. The discussion remains unresolved regarding the implications of Hawking's conjectures and the nature of singularities.

Contextual Notes

There are limitations in the assumptions made about black hole dynamics and the definitions of angular momentum and mass in the context of black hole physics. The discussion also highlights the complexity of the cosmic censorship conjecture and its implications for theoretical models.

JustinLevy
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I've read that Hawking believes the Universe somehow prevents naked singularities, and made a bet about it with Kip Thorne.

But it seems to me that if you take a static black hole and continually inject material into it with high angular momentum, eventually you would have a naked singularity (since you'd eventually get an extremal black hole). This seems very general to me. Actually, since the momentum of a particle is unbounded, technically you should be able to do this with just a single particle, correct?

Clearly the answer can't be that simple.
What am I missing?
 
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JustinLevy said:
I've read that Hawking believes the Universe somehow prevents naked singularities, and made a bet about it with Kip Thorne.

No. Hawking's bet with Thorne (and John Preskill) was concerned with the idea of information loss in black holes.

The idea that the universe prevents the formation of naked singularities refers to any of the various forms of the cosmic censorship conjecture, possibly the single most important unproven conjecture in mathematical relativity.
 
JustinLevy said:
But it seems to me that if you take a static black hole and continually inject material into it with high angular momentum, eventually you would have a naked singularity (since you'd eventually get an extremal black hole). This seems very general to me. Actually, since the momentum of a particle is unbounded, technically you should be able to do this with just a single particle, correct?

I think there are some general arguments that you can spin a black hole up to a = M in principle, but not beyond. As matter is injected into the black hole to increase a, M also increases, and the maximum value for a/M is 1. Thorne showed that, in practice, a black hole can be spun up to only a = 0.998M.
shoehorn said:
No. Hawking's bet with Thorne (and John Preskill) was concerned with the idea of information loss in black holes.

Hawking also bet Preskill about the existence of naked singularities; see

http://www.theory.caltech.edu/~preskill/bets.html.
 
In THE ELEGANT UNIVERSE (1999) Brian Greene in chapter 13, Black Holes: A string/M theory Perspective, has a great discussion on naked/hidden singularities and how Calabi Yau shapes, perhaps the fundamental description of additional dimensions in our universe, can shield us from them. It turns out there are many ways space tearing transitions can occur, many ways Calabi Yau shapes can continuously transform, and how certain physical configurations appear as either black holes or elementary particles...yes, it appears a massive black hole can transition to a massles particle following a three dimensional sphere collapse to a pinched point...corresponding to a black hole!

Wikipedia at http://en.wikipedia.org/wiki/Conifold_transition has a brief mathematical discussion. In the discussion here, "smooth transitions" I believe means "continuous" shielding/hiding underlying singularities. As usual while Wikipedia may be technically correct, it's descriptions are all too often rather opaque without other sources.
 

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