scholarly journals Space–time inhomogeneity, anisotropy and gravitational collapse

2012 ◽  
Vol 44 (10) ◽  
pp. 2503-2520 ◽  
Author(s):  
Ranjan Sharma ◽  
Ramesh Tikekar
Keyword(s):  
Gravitational Collapse ◽  
Space Time

NEGATIVE ENERGY DENSITY IN SPINNING MATTER SOURCES IN WORMHOLE SPACE–TIMES WITH TORSION

1998 ◽  
Vol 13 (38) ◽  
pp. 3069-3072
Author(s):  
L. C. GARCIA DE ANDRADE
Keyword(s):  
Energy Density ◽  
Spin Density ◽  
Gravitational Collapse ◽  
Negative Pressure ◽  
Negative Energy ◽  
Space Time ◽  
Negative Energy Density ◽  
Traversable Wormholes ◽  
Radial Tension

Negative energy densities in spinning matter sources of non-Riemannian ultrastatic traversable wormholes require the spin energy density to be higher than the negative pressure or the radial tension. Since the radial tension necessary to support wormholes is higher than the spin density in practice, it seems very unlikely that wormholes supported by torsion may exist in nature. This result corroborates earlier results by Soleng against the construction of the closed time-like curves (CTC) in space–time geometries with spin and torsion. It also agrees with earlier results by Kerlick according to which Einstein–Cartan (EC) gravity torsion sometimes enhance the gravitational collapse instead of avoiding it.

scholarly journals Meaningless Questions in Cosmology and Relativistic Astrophysics

1976 ◽  
Vol 31 (11) ◽  
pp. 1271-1276 ◽  
Author(s):  
M. Heller ◽  
M. Reinhardt
Keyword(s):  
Event Horizon ◽  
Gravitational Collapse ◽  
Space Time ◽  
Initial Singularity ◽  
Relativistic Astrophysics ◽  
General Classification ◽  
The Universe

Abstract After a general classification of meaningless questions in science we concentrate on empirically meaningless questions. Introducing the concepts of informationally connected, semiconnected and disconnected observers, a formalism for the analysis of the informational structure of space-time is developed. We discuss some problems of epistemological nature in cosmology and blade hole physics. A number of questions like "What was 'before' the initial singularity of the universe?" or "What is the fate of matter in gravitational collapse inside the event horizon?" turn out to be empirically meaningless. We also show that a "wormhole" does not violate causality for the set of informationally connected observers who do not enter it.

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.

scholarly journals Gravitational collapse in anti-de Sitter space–time

2003 ◽  
Vol 571 (3-4) ◽  
pp. 245-249 ◽  
Author(s):  
G.L. Alberghi ◽  
R. Casadio
Keyword(s):  
Gravitational Collapse ◽  
De Sitter Space ◽  
Space Time ◽  
De Sitter

The curvature effect on the gravitational collapse of interacting and non-interacting combination of dark matter and dark energy

2020 ◽  
Vol 35 (17) ◽  
pp. 2050078
Author(s):  
S. Z. Abbas ◽  
H. H. Shah ◽  
W. Chammam ◽  
H. Sun ◽  
Wasim Ul Haq ◽  
...  
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Gravitational Collapse ◽  
Space Time ◽  
Relativistic Astrophysics ◽  
Spherically Symmetric ◽  
Curvature Effect ◽  
De Formula ◽  
General Relativistic

The study of gravitational collapse is a very interesting phenomena in general relativistic astrophysics. Here, in this study we investigated the gravitational collapse of a spherically symmetric core of a star, constituted of dark matter (DM) ([Formula: see text]), in dark energy (DE) ([Formula: see text]) background. It was investigated that gravitational collapse of interacting and noninteracting combination of DM and DE yields BH formation. In this work, our main aim is to examine the effect of space–time curvature [Formula: see text] on the gravitational collapse of interacting and noninteracting combination of dark matter and DE. We achieve the visible influence of curvature on gravitational collapse analytically and interpret the results graphically.

DYNAMICAL SYMMETRY WITH GENERAL INITIAL AREA RADIUS IN QUASI-SPHERICAL GRAVITATIONAL COLLAPSE, AND ANISOTROPY AND INHOMOGENEITY OF SPACE–TIME

2008 ◽  
Vol 17 (01) ◽  
pp. 43-53
Author(s):  
TANWI BANDYOPADHYAY ◽  
ANUSUA BAVEJA ◽  
SUBENOY CHAKRABORTY
Keyword(s):  
Gravitational Collapse ◽  
Dynamical Symmetry ◽  
Space Time ◽  
Anisotropic Pressure ◽  
Final State ◽  
Initial Area

This paper deals with the role of anisotropy and inhomogeneity of space–time in quasi-spherical gravitational collapse. The effect of the initial area radius has been studied in characterizing the final state of collapse. Both dust and fluid with anisotropic pressure are considered as the collapsing matter. The results are presented in the form of propositions.

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