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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
    Commented Nov 18, 2014 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. $\endgroup$
    – user4552
    Commented Nov 18, 2014 at 3:00
  • $\begingroup$ See the end of this answer physics.stackexchange.com/a/6575/55483 $\endgroup$
    – zibadawa timmy
    Commented Nov 18, 2014 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
    Commented Nov 18, 2014 at 8:53
  • $\begingroup$ @zibadawatimmy: Jerry Schirmer is correct. You're interpreting his statement incorrectly. $\endgroup$
    – user4552
    Commented Nov 18, 2014 at 16:02

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When considering naked singularities, the situation is more complex. The lack of an event horizon means that there is no natural boundary condition to impose the same level of uniqueness as seen in black holes.

Specific solutions in general relativity, suggest that naked singularities could exhibit more complex structures than black holes, potentially possessing additional "hair" or distinguishing features.

No-hair theorem for naked singularities is also connected to the Cosmic Censorship Hypothesis. This hypothesis suggests that, under realistic physical conditions, singularities formed during gravitational collapse are typically hidden behind event horizons, forming black holes rather than naked singularities. If this hypothesis holds true, naked singularities would not naturally occur, which could explain the lack of a developed no-hair theorem for these objects.

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