A singularity is, roughly speaking, a region of extremely high density into which matter or light is attracted. While Steven Hawking has proposed that physical singularities can occur only inside Black holes where they cannot be seen, physicists Kip Thorne and John Preskill believe observable ("naked") singularity can exist. Hawking therefore made a bet with Throne and Preskill in 1991. After supercomputer simulations by M. Choptuik showed how a naked singularity could exist, Hawking was forced to concede the bet ("on a technicality," according to Hawking ) on Feb. 5, 1997. In concession, Hawking presented his colleagues with "adequate raiments to shield their nakedness from the vulgar view."

Christodoulou (1994, 1999) showed that naked singularities occur in the gravitational collapse of a scalar field.

Singularity Theorem