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For black holes, we have no-hair theorems that say, under certain assumptions about the matter fields, that they are uniquely characterized by just a few parameters. Are there any such theorem for naked singularities? For example, the Kerr–Newman metric has a naked singularity for certain values of the charge and spin, so we would have a two-parameter family of naked singularities. But it seems that this family isn't all-inclusive, since we can have things like Penrose-Hawking "thunderbolts"...?[Penrose 1999]

Penrose, "The Question of Cosmic Censorship," J. Astrophys. Astr. (1999) 20, 233–248; http://www.ias.ac.in/jarch/jaa/20/233-248.pdf

related: Entropy of a naked singularity

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  • Electrons can be viewed as naked singularities in the right GR formulation, so they'd have to be at least as hairy as an electron. – zibadawa timmy Nov 18 '14 at 02:21
  • @zibadawatimmy: I don't think that's right. There are fundamental reasons why subatomic particles can't be GR-style singularities. If electrons were naked singularities, we would have fundamental problems in physics, and we would observe electrons to have very different properties than they actually have. –  Nov 18 '14 at 03:00
  • See the end of this answer http://physics.stackexchange.com/a/6575/55483 – zibadawa timmy Nov 18 '14 at 03:09
  • I might be wrong, but I think that the no hair theorems are proved assuming some form of cosmic censorship. So it seems that any such theorem about naked singularities would have to be proven in a very different way if such statements hold. It may be that there isn't any such description of naked singularities. – MBN Nov 18 '14 at 08:53
  • @zibadawatimmy: Jerry Schirmer is correct. You're interpreting his statement incorrectly. –  Nov 18 '14 at 16:02
  • @BenCrowell I can definitely accept that possibility. Is there a quick explanation of my mistake? – zibadawa timmy Nov 18 '14 at 16:05
  • @zibadawatimmy: He's saying that if you take the Kerr–Newman metric and put in the mass and charge of an electron, you get a naked singularity. That doesn't mean that an electron is a naked singularity. –  Nov 19 '14 at 02:21
  • @MBN: I could be wrong, but I think the assumptions of the black-hole no-hair theorems are stationarity, electrovac, and a horizon (which implies asymptotic flatness). I don't think any of these indirectly implies cosmic censorship. I'm basing this on http://relativity.livingreviews.org/Articles/lrr-1998-6/fulltext.html –  Nov 19 '14 at 15:26
  • @BenCrowell: You are probably right. – MBN Nov 20 '14 at 08:00

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