Cosmic Censure

In Astrophysical, the cosmic principle of censure ( CCH for cosmic censorship principle ) is a Conjecture in connection with the nature of the Singularité S in the Espace-temps.

The singularities which appear in the solutions of the equation of Einstein are typically hidden behind a horizon of the events of a Black hole, and cannot thus be seen remainder of the space time. A singularity which is not hidden is called “naked singularity”. The weak principle of the cosmic censure said that there does not exist in the universe of naked singularities other only the Big Bang itself.

Introduction

Since the physical behavior of the singularities is unknown, so naked singularities can be seen remainder of the Espace-temps, the Causalité can be violated, and physics to lose its capacity of prediction. The problem cannot be avoided, since according to a Théorème developed by the English physicists Stephen Hawking and Roger Penrose, the singularities are inevitable under reasonable physical conditions. In the absence of naked singularities, the universe is deterministic, and it is possible to predict the evolution of the universe by knowing its conditions at only one time. A violation of the cosmic principle of censure would imply a violation of the determinism, because it is impossible to predict the behavior of the space time in the causal future of a naked singularity.

This principle was formulated in 1969 per Roger Penrose, and he is not formulated in a completely formal way. In other words, he is formulated more like one research program, in order to find a formulation formal which is physically correct, and whose veracity can be tested by observations.

Problems

There exists a certain number of problems to the formulation of this principle:

It is not difficult to build a space time which has naked singularities, but which are “physically unreasonable”. The typical example of such a space time being space time sometimes called “superextrême” of Reissner-Nordström, where $M<|Q|$ , and which contains a singularity in the center ( $r=0$ ) which is not surrounded by a horizon (it is thus not a black hole).
It is formally possible that an observer inside the horizon of the events can see the singularity. It is for example the case inside the horizon of a black hole of Reissner-Nordström, though the interior solution at the external horizon of this black hole is unstable and thus that the relevance of this solution is dubious (see Black hole of Reissner-Nordström). The version of the principle of censure which excludes this case is called cosmic principle extremely of censure.

The cosmic principle extremely of censure

See too

Internal bonds

External bonds

The old Study Bureau (conceded by Stephen Hawking in 1997)
The new Study Bureau

References

Earman, John: Bangs, Crunches, Whimpers, and Shrieks: Singularities and Acausalities in Relativistic Spacetimes (1995), see especially chapter 2
Penrose, Roger: " The Question off Cosmic Censorship" , Chapter 5 in Black Holes and Relativistic Stars , Robert Wald (editor), (1994)
Penrose, Roger: " Singularities and time-asymmetry" , Chapter 12 in General Relativity: Year Einstein Centenary Survey (Hawking and Israel, editors), (1979), see especially section 12.3.2, pp. 617-629
Shapiro, S.L., and Teukolsky, S.A.: " Formation off Naked Singularities: The Violation off Cosmic Censorship" , Physical Review Letters 66 , 994-997 (1991)
Wald, Robert, General Relativity , 299-308 (1984)

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