Naked singularities, and Hawking

  • Thread starter 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 blackhole and continually inject material into it with high angular momentum, eventually you would have a naked singularity (since you'd eventually get an extremal blackhole). 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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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.
 
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George Jones
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JustinLevy said:
But it seems to me that if you take a static blackhole and continually inject material into it with high angular momentum, eventually you would have a naked singularity (since you'd eventually get an extremal blackhole). 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.
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.
 
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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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