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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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  • $\begingroup$ 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. $\endgroup$ – zibadawa timmy Nov 18 '14 at 2:21
  • $\begingroup$ @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. $\endgroup$ – Ben Crowell Nov 18 '14 at 3:00
  • $\begingroup$ See the end of this answer physics.stackexchange.com/a/6575/55483 $\endgroup$ – zibadawa timmy Nov 18 '14 at 3:09
  • $\begingroup$ 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. $\endgroup$ – MBN Nov 18 '14 at 8:53
  • $\begingroup$ @zibadawatimmy: Jerry Schirmer is correct. You're interpreting his statement incorrectly. $\endgroup$ – Ben Crowell Nov 18 '14 at 16:02

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