Sayan Kar
Articles written in Pramana – Journal of Physics
Volume 53 Issue 6 December 1999 pp 919-919
Volume 63 Issue 4 October 2004 pp 859-864
Quantifying energy condition violations in traversable wormholes
Sayan Kar Naresh Dadhich Matt Visser
The ‘theoretical’ existence of traversable Lorentzian wormholes in the classical, macroscopic world is plagued by the violation of the well-known energy conditions of general relativity. In this brief article we show: (i) how the extent of violation can be quantified using certain volume integrals and (ii) whether this ‘amount of violation’ can be minimised for some specific cut-and-paste geometric constructions. Examples and possibilities are also outlined.
Volume 69 Issue 1 July 2007 pp 49-76
The Raychaudhuri equations: A brief review
We present a brief review on the Raychaudhuri equations. Beginning with a summary of the essential features of the original article by Raychaudhuri and subsequent work of numerous authors, we move on to a discussion of the equations in the context of alternate non-Riemannian spacetimes as well as other theories of gravity, with a special mention on the equations in spacetimes with torsion (Einstein–Cartan–Sciama–Kibble theory). Finally, we give an overview of some recent applications of these equations in general relativity, quantum field theory, string theory and the theory of relativisitic membranes. We conclude with a summary and provide our own perspectives on directions of future research.
Volume 97, 2023
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