scholarly journals GENERALIZED STRONG CURVATURE SINGULARITIES AND WEAK COSMIC CENSORSHIP IN COSMOLOGICAL SPACETIMES

2006 ◽  
Vol 21 (19) ◽  
pp. 1501-1509 ◽  
Author(s):  
WIESŁAW RUDNICKI ◽  
ROBERT J. BUDZYŃSKI ◽  
WITOLD KONDRACKI
Keyword(s):  
Cosmic Censorship ◽  
Cosmological Models ◽  
Asymptotic Structure ◽  
Naked Singularities ◽  
Further Development ◽  
Strong Curvature ◽  
Curvature Type

This paper is a further development of the approach to weak cosmic censorship proposed by the authors in Ref. 5. We state and prove a modified version of that work's main result under significantly relaxed assumptions on the asymptotic structure of spacetime. The result, which imposes strong constraints on the occurrence of naked singularities of the strong curvature type, is in particular applicable to physically realistic cosmological models.

scholarly journals HIGHER DIMENSIONAL INHOMOGENEOUS DUST COLLAPSE AND COSMIC CENSORSHIP

2002 ◽  
Vol 17 (20) ◽  
pp. 2747-2747
Author(s):  
A. BEESHAM
Keyword(s):  
Black Holes ◽  
Cosmic Censorship ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Naked Singularities ◽  
Singularity Theorems ◽  
Sitter Spacetime ◽  
Higher Dimensional ◽  
Cosmic Censorship Hypothesis ◽  
Strong Curvature

The singularity theorems of general relativity predict that gravitational collapse finally ends up in a spacetime singularity1. The cosmic censorship hypothesis (CCH) states that such a singularity is covered by an event horizon2. Despite much effort, there is no rigorous formulation or proof of the CCH. In view of this, examples that appear to violate the CCH and lead to naked singularities, in which non-spacelike curves can emerge, rather than black holes, are important to shed more light on the issue. We have studied several collapse scenarios which can lead to both situations3. In the case of the Vaidya-de Sitter spacetime4, we have shown that the naked singularities that arise are of the strong curvature type. Both types of singularities can also arise in higher dimensional Vaidya and Tolman-Bondi spacetimes, but black holes are favoured in some sense by the higher dimensions. The charged Vaidya-de Sitter spacetime also exhibits both types of singularities5.

INHOMOGENEOUS DUST COLLAPSE WITH COSMOLOGICAL CONSTANT

2005 ◽  
Vol 14 (03n04) ◽  
pp. 707-715 ◽  
Author(s):  
S. G. GHOSH
Keyword(s):  
Cosmological Constant ◽  
Gravitational Collapse ◽  
Dust Cloud ◽  
Cosmic Censorship ◽  
Space Time ◽  
De Sitter ◽  
Naked Singularities ◽  
Asymptotic Flatness ◽  
Sitter Background ◽  
Strong Curvature

We investigate the occurrence of naked singularities in the gravitational collapse of an inhomogeneous dust cloud in an expanding de Sitter background — a piece of Tolman–Bondi–de Sitter space–time. It turns out that the collapse proceed in the same way as in the Minkowski background, i.e., the strong curvature naked singularities form and thus violate the cosmic censorship conjecture. Our result unambiguously support the fact that the asymptotic flatness of space–time is not a necessary ingredient for the development of naked singularities.

HIGHER DIMENSIONAL CHARGED NULL FLUID COLLAPSE AND COSMIC CENSORSHIP

2002 ◽  
Vol 11 (02) ◽  
pp. 237-244 ◽  
Author(s):  
S. G. GHOSH ◽  
R. V. SARAYKAR
Keyword(s):  
Black Holes ◽  
Energy Condition ◽  
Cosmic Censorship ◽  
Final Outcome ◽  
Spherically Symmetric ◽  
Curvature Singularity ◽  
Naked Singularities ◽  
Dimensional Spacetime ◽  
Higher Dimensional ◽  
Strong Curvature

We analyze here the spherically symmetric collapse of a charged null fluid in a higher dimensional spacetime. Both naked singularities and black holes are shown to be developing as final outcome of the collapse. A relationship between weak energy condition and occurrence of strong curvature singularity is pointed out.

scholarly journals GRAVITATIONAL COLLAPSE OF PERFECT FLUID IN SELF-SIMILAR HIGHER DIMENSIONAL SPACE–TIMES

2003 ◽  
Vol 12 (05) ◽  
pp. 913-924 ◽  
Author(s):  
S. G. GHOSH ◽  
D. W. DESHKAR
Keyword(s):  
Perfect Fluid ◽  
Gravitational Collapse ◽  
Dimensional Space ◽  
Energy Condition ◽  
Cosmic Censorship ◽  
Naked Singularities ◽  
Four Dimensions ◽  
Higher Dimensional ◽  
Self Similar ◽  
Strong Curvature

We investigate the occurrence and nature of naked singularities in the gravitational collapse of an adiabatic perfect fluid in self-similar higher dimensional space–times. It is shown that strong curvature naked singularities could occur if the weak energy condition holds. Its implication for cosmic censorship conjecture is discussed. Known results of analogous studies in four dimensions can be recovered.

scholarly journals COLLAPSING SHELLS OF RADIATION IN HIGHER DIMENSIONAL SPACE–TIME AND COSMIC CENSORSHIP CONJECTURE

2001 ◽  
Vol 16 (27) ◽  
pp. 4481-4488 ◽  
Author(s):  
S. G. GHOSH ◽  
R. V. SARAYKAR ◽  
A. BEESHAM
Keyword(s):  
Dimensional Space ◽  
Cosmic Censorship ◽  
Space Time ◽  
Naked Singularities ◽  
Higher Dimensional ◽  
Dimensional Space Time ◽  
Self Similar ◽  
Strong Curvature ◽  
Special Case ◽  
Cosmic Censorship Conjecture

Gravitational collapse of radiation shells in a non-self-similar higher dimensional spherically symmetric space–time is studied. Strong curvature naked singularities form a highly inhomogeneous collapse, violating the cosmic censorship conjecture. As a special case, self similar models can be constructed.

FIVE-DIMENSIONAL DUST COLLAPSE WITH COSMOLOGICAL CONSTANT

2007 ◽  
Vol 16 (01) ◽  
pp. 53-64 ◽  
Author(s):  
S. G. GHOSH ◽  
D. W. DESHKAR ◽  
N. N. SASTE
Keyword(s):  
Cosmological Constant ◽  
Causal Structure ◽  
Cosmic Censorship ◽  
De Sitter ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Positive Cosmological Constant ◽  
Naked Singularities ◽  
Spherical Collapse ◽  
Strong Curvature

We study the five-dimensional spherical collapse of an inhomogeneous dust in the presence of a positive cosmological constant. The general interior solutions, in the closed form, of the Einstein field equations, i.e. the 5D Tolman–Bondi–de Sitter, is obtained which in turn is matched to the exterior 5D Schwarzschild–de Sitter. It turns out that the collapse proceeds in the same way as in the Minkowski background, i.e. the strong curvature naked singularities form and thus violate the cosmic censorship conjecture. A brief discussion on the causal structure singularities and horizons is also given.

scholarly journals SPHERICALLY SYMMETRIC GRAVITATIONAL COLLAPSE OF A DUST CLOUD IN THIRD-ORDER LOVELOCK GRAVITY

2011 ◽  
Vol 20 (12) ◽  
pp. 2317-2335 ◽  
Author(s):  
KANG ZHOU ◽  
ZHAN-YING YANG ◽  
DE-CHENG ZOU ◽  
RUI-HONG YUE
Keyword(s):  
Gravitational Collapse ◽  
Dust Cloud ◽  
Cosmic Censorship ◽  
High Order ◽  
Spherically Symmetric ◽  
Lovelock Gravity ◽  
Third Order ◽  
Relativistic Case ◽  
Naked Singularities ◽  
Cosmic Censorship Hypothesis

We investigate the spherically symmetric gravitational collapse of an incoherent dust cloud by considering a LTB-type spacetime in third-order Lovelock Gravity without cosmological constant, and give three families of LTB-like solutions which separately corresponding to hyperbolic, parabolic and elliptic. Notice that the contribution of high-order curvature corrections have a profound influence on the nature of the singularity, and the global structure of spacetime changes drastically from the analogous general relativistic case. Interestingly, the presence of high order Lovelock terms leads to the formation of massive, naked and timelike singularities in the 7D spacetime, which is disallowed in general relativity. Moveover, we point out that the naked singularities in the 7D case may be gravitational weak therefore may not be a serious threat to the cosmic censorship hypothesis, while the naked singularities in the D ≥ 8 inhomogeneous collapse violate the cosmic censorship hypothesis seriously.

IS THE NAKED SINGULARITY INCOMPATIBLE TO QUANTUM GRAVITY?

2005 ◽  
Vol 20 (24) ◽  
pp. 1823-1829 ◽  
Author(s):  
LI XIANG ◽  
YOU-GEN SHEN
Keyword(s):  
Generalized Uncertainty Principle ◽  
Charged Particles ◽  
Naked Singularity ◽  
Cosmic Censorship ◽  
Second Law ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Naked Singularities ◽  
Sitter Spacetime ◽  
Cosmic Censorship Hypothesis

In this paper two consequences of the generalized uncertainty principle (GUP) are discussed in a heuristic manner. Both could be regarded as the evidences that prefer the cosmic censorship hypothesis (CCH). The first one is that the second law tends to decline the massless charged particles if the effects of the GUP on the thermodynamics of a de Sitter spacetime are considered. This weakens the threat to the horizon of an extreme charged black hole. The second one is that the uv/ir correspondence provides a constraint on the relation between the energy and the size of a system, which is incompatible to the naked singularities.

scholarly journals A Little Quantum Help for Cosmic Censorship and a Step Beyond All That

2013 ◽  
Vol 2013 ◽  
pp. 1-4
Author(s):  
Nikolaos Pappas
Keyword(s):  
General Relativity ◽  
Event Horizon ◽  
Crucial Role ◽  
Naked Singularity ◽  
Cosmic Censorship ◽  
Usual Sense ◽  
Naked Singularities ◽  
Open Question ◽  
Heisenberg's Uncertainty Principle ◽  
The Universe

The hypothesis of cosmic censorship (CCH) plays a crucial role in classical general relativity, namely, to ensure that naked singularities would never emerge, since it predicts that whenever a singularity is formed an event horizon would always develop around it as well, to prevent the former from interacting directly with the rest of the Universe. Should this not be so, naked singularities could eventually form, in which case phenomena beyond our understanding and ability to predict could occur, since at the vicinity of the singularity both predictability and determinism break down even at the classical (e.g., nonquantum) level. More than 40 years after it was proposed, the validity of the hypothesis remains an open question. We reconsider CCH in both its weak and strong versions, concerning point-like singularities, with respect to the provisions of Heisenberg’s uncertainty principle. We argue that the shielding of the singularities from observers at infinity by an event horizon is also quantum mechanically favored, but ultimately it seems more appropriate to accept that singularities never actually form in the usual sense; thus no naked singularity danger exists in the first place.

Sign in / Sign up

Export Citation Format

Share Document