Finding the Singularity of a Black Hole: Cosmic Censorship Conjecture

Abstract

According to the singularity theorem, a curvature singularity can be formed in a gravitational collapse under the null energy condition. Eventually, the singularity possesses sufficient mass density for the horizon to appear, and the compact object thereby evolves into a black hole. Hence, on the basis of general relativity, the singularity must be located at the center of the black hole. Our curiosity begins here: can we see the singularity? To answer this question, the cosmic censorship conjecture comes into play. That conjecture, which was originally proposed by Penrose, has two versions. The weak version states that a static observer located outside the black hole cannot see the singularity. Furthermore, the strong version states that no observers can see the singularity. Studies regarding the cosmic censorship conjecture are still ongoing, and evidently, its validation requires a deep understanding of the theory of gravity, including general relativity. Herein, we review the progress of studies associated with the weak and the strong cosmic censorship conjectures. Furthermore, we briefly describe the Penrose process for extracting energy from a black hole.