Editing Cosmic censorship hypothesis (section)

== Weak and strong cosmic censorship hypothesis ==

The weak and the strong cosmic censorship hypotheses are two conjectures concerned with the global geometry of spacetimes.

The '''weak cosmic censorship hypothesis''' asserts there can be no singularity visible from future [[null infinity]]. In other words, singularities need to be hidden from an observer at infinity by the event horizon of a [[black hole]]. Mathematically, the conjecture states that, for generic initial data, the [[causal structure]] is such that the maximal [[Cauchy surface|Cauchy development]] possesses a complete future null infinity.

The '''strong cosmic censorship hypothesis''' asserts that, generically, general relativity is a deterministic theory, in the same sense that classical mechanics is a deterministic theory. In other words, the classical fate of all observers should be predictable from the initial data. Mathematically, the conjecture states that the maximal Cauchy development of generic compact or asymptotically flat initial data is locally inextendible as a regular [[Lorentzian manifold]]. Taken in its strongest sense, the conjecture suggests locally inextendibility of the maximal Cauchy development as a continuous Lorentzian manifold [very Strong Cosmic Censorship]. This strongest version was disproven in 2018 by Mihalis Dafermos and Jonathan Luk for the [[Cauchy horizon]] of an [[Kerr metric|uncharged, rotating black hole]].<ref>{{cite magazine|last=Hartnett|first=Kevin|date=17 May 2018|title=Mathematicians Disprove Conjecture Made to Save Black Holes|url=https://www.quantamagazine.org/mathematicians-disprove-conjecture-made-to-save-black-holes-20180517/|magazine=[[Quanta Magazine]]|access-date=29 March 2020}}</ref> 

The two conjectures are mathematically independent, as there exist spacetimes for which weak cosmic censorship is valid but strong cosmic censorship is violated and, conversely, there exist spacetimes for which weak cosmic censorship is violated but strong cosmic censorship is valid.