出典:Wikipedia
出典:『Wikipedia』 (2009/06/29 21:11 UTC 版)
The Hoop Conjecture, proposed by Kip Thorne in 1972, states that an imploding object forms a black hole when, and only when, a circular hoop with a specific critical circumference could be placed around the object and rotated. The critical circumference is given by 2 times Pi times the Schwarzschild radius corresponding to the object's mass.