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Particles 2018, 1(1), 230-237;

Effective Null Raychaudhuri Equation

INFN Bologna, Via Irnerio 46, I-40126 Bologna, Italy
Received: 24 September 2018 / Revised: 17 October 2018 / Accepted: 19 October 2018 / Published: 23 October 2018
PDF [235 KB, uploaded 23 October 2018]


The effects on Raychaudhuri’s equation of an intrinsically-discrete or particle nature of spacetime are investigated. This is done through the consideration of null congruences emerging from, or converging to, a generic point of spacetime, i.e., in geometric circumstances somehow prototypical of singularity issues. We do this from an effective point of view, that is through a (continuous) description of spacetime modified to embody the existence of an intrinsic discreteness on the small scale, this adding to previous results for non-null congruences. Various expressions for the effective rate of change of expansion are derived. They in particular provide finite values for the limiting effective expansion and its rate of variation when approaching the focal point. Further, this results in a non-vanishing of the limiting cross-sectional area itself of the congruence. View Full-Text
Keywords: quantum gravity; Raychaudhuri equation; effective metric quantum gravity; Raychaudhuri equation; effective metric
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Pesci, A. Effective Null Raychaudhuri Equation. Particles 2018, 1, 230-237.

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