Mohajan, Haradhan (2013): Scope of Raychaudhuri equation in cosmological gravitational focusing and spacetime singularities. Published in: Peak Journal of Physical and Environmental Science Research , Vol. 1, No. 7 (26 December 2013): pp. 106114.

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Abstract
Indian scientist Amal Kumar Raychaudhuri established ‘Raychaudhuri equation’ in 1955 to describe gravitational focusing properties in cosmology. This equation is extensively used in general relativity, quantum field theory, string theory and the theory of relativistic membranes. This paper investigates the issue of the final fate of a gravitationally collapsing massive star and the associated cosmic censorship problems and spacetime singularities therein with the help of Raychaudhuri equation. It is conjecture that the universe is emerged from a big bang singularity where all the known laws of physics break down. On the other hand, when the star is heavier than a few solar masses, it could undergo an endless gravitational collapse without achieving any equilibrium state. This happens when the star has exhausted its internal nuclear fuel which provides the outwards pressure against the inwards pulling gravitational forces. Then for a wide range of initial data, a spacetime singularity must develop. It is conjecture that such a singularity of gravitational collapse from a regular initial surface must always be hidden behind the event horizon of gravity; this is called the cosmic censorship hypothesis. Thus cosmic censorship implies that the final outcome of gravitational collapse of a massive star must necessarily be a black hole which covers the resulting spacetime singularity. So, causal message from the singularity cannot reach the external observer at infinity. Raychaudhuri equation plays a pioneer role in cosmology to describe the gravitational focusing and spacetime singularities.
Item Type:  MPRA Paper 

Original Title:  Scope of Raychaudhuri equation in cosmological gravitational focusing and spacetime singularities 
English Title:  Scope of Raychaudhuri equation in cosmological gravitational focusing and spacetime singularities 
Language:  English 
Keywords:  Cosmic censorship, Einstein equation, gravitational focusing, Raychaudhuri equation, singularities. 
Subjects:  C  Mathematical and Quantitative Methods > C0  General > C02  Mathematical Methods 
Item ID:  52544 
Depositing User:  Haradhan Kumar Mohajan 
Date Deposited:  30 Dec 2013 05:54 
Last Modified:  26 Sep 2019 12:35 
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URI:  https://mpra.ub.unimuenchen.de/id/eprint/52544 