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Notte Europea dei Ricercatori 2023

In occasione della Notte Europea dei Ricercatori 2022, l’INAF-Osservatorio Astrofisico di Catania ha organizzato varie attività per il pubblico che si svolgeranno tra il 28 e il 30 settembre.

Gravitational entropy proposals adaptable to structure formation in Cosmology

Sede A. Riccò Via Santa Sofia 78, Catania

I would like to summarize and present cosmological applications of two proposals of Gravitational entropy, which are distinct from the standard holographic approach and from the entropy of the sources. One is the proposal by Clifton-Ellis and Tabakol (CET) based on the Bel-Robinson tensor, the other by Hosoya and Buchert (HB), based on the Leibler-Kullbach functional of Information Theory. By applying these proposals to inhomogenous dust solutions of Einstein’s equations (LTB and Szekeres models), we have shown in various published articles that both proposals are equivalent in their predictions, but CET is local and HB is non-local. Both yield entropy production in spacetime regions that can be characterized by generation and growth of structure (either overdensities or voids). The CET proposal provides an interesting interpretation of the cosmological constant as an asymptotic gravitational temperature that characterizes a finite entropy saturation value.