Cosmic Censorship Hypothesis - Problems With The Concept

Problems With The Concept

There are a number of difficulties in formalizing the hypothesis:

• There are technical difficulties with properly formalizing the notion of a singularity.
• It is not difficult to construct spacetimes which have naked singularities, but which are not "physically reasonable;" the canonical example of such a spacetime is perhaps the "superextremal" Reissner-Nordstrom solution, which contains a singularity at that is not surrounded by a horizon. A formal statement needs some set of hypotheses which exclude these situations.
• Caustics may occur in simple models of gravitational collapse, and can appear to lead to singularities. These have more to do with the simplified models of bulk matter used, and in any case have nothing to do with general relativity, and need to be excluded.
• Computer models of gravitational collapse have shown that naked singularities can arise, but these models rely on very special circumstances (such as spherical symmetry). These special circumstances need to be excluded by some hypothesis.

In 1991, John Preskill and Kip Thorne bet against Stephen Hawking that the hypothesis was false. Hawking conceded the bet in 1997, due to the discovery of the special situations just mentioned, which he characterized as "technicalities". Hawking later reformulated the bet to exclude those technicalities. The revised bet is still open, the prize being "clothing to cover the winner's nakedness".