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  • 1605 (1).02080v2

    Rights statement: This is an author-created, un-copyedited version of an article accepted for publication/published in Journal of Cosmology and Astroparticle Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi:10.1088/1475-7516/2017/01/017

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Defocusing of null rays in infinite derivative gravity

Research output: Contribution to journalJournal article

Published
Article number017
<mark>Journal publication date</mark>10/01/2017
<mark>Journal</mark>Journal of Cosmology and Astroparticle Physics
Issue number1
Volume2017
Number of pages12
Publication statusPublished
Original languageEnglish

Abstract

Einstein's General theory of relativity permits spacetime singularities, where null geodesic congruences focus in the presence of matter, which satisfies an appropriate energy condition. In this paper, we provide a minimal defocusing condition for null congruences without assuming any Ansatz-dependent background solution. The two important criteria are: (1) an additional scalar degree of freedom, besides the massless graviton must be introduced into the spacetime; and (2) an infinite derivative theory of gravity is required in order to avoid tachyons or ghosts in the graviton propagator. In this regard, our analysis strengthens earlier arguments for constructing non-singular bouncing cosmologies within an infinite derivative theory of gravity, without assuming any Ansatz to solve the full equations of motion.

Bibliographic note

This is an author-created, un-copyedited version of an article accepted for publication/published in Journal of Cosmology and Astroparticle Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi:10.1088/1475-7516/2017/01/017