How appropriate are the gravitational entropy proposals for traversable wormholes?

Chakraborty, Samarjit; Guha, Sarbari; Goswami, Rituparno

doi:10.1007/s10714-022-02934-3

Cited by 3 publications

(2 citation statements)

References 58 publications

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“…the Hawking-Bekenstein entropy of a BH [11], can be obtained from the GE. Such studies have also been conducted by the authors in [12][13][14] using the Weyl proposal due to Rudjord et al [7,8] and the CET proposal [15].…”

Section: Introductionmentioning

confidence: 99%

Arrow of time and gravitational entropy in collapse

Chakraborty,

Maharaj,

Guha

et al. 2024

Class. Quantum Grav.

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We investigate the status of the gravitational arrow of time in the case of a spherical collapse of a fluid that conducts heat and radiates energy. In particular, we examine the results obtained by W. B. Bonnor in his 1985 paper where he found that the gravitational arrow of time was opposite to the thermodynamic arrow of time. The measure of gravitational epoch function $P$ used by Bonnor was given by the ratio of the Weyl square to the Ricci square. In this paper, we have assumed the measure of gravitational entropy $P_{1}$ to be given by the ratio of the Weyl scalar to the Kretschmann scalar. Our analysis indicates that Bonnor's result seems to be validated, i.e., the gravitational arrow and the thermodynamic arrow of time point in opposite directions. This strengthens the opinion that the Weyl proposal of gravitational entropy applies only to the universe as a whole (provided that we exclude the white wholes).

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Section: Introductionmentioning

confidence: 99%

Arrow of time and gravitational entropy in collapse

Chakraborty,

Maharaj,

Guha

et al. 2024

Class. Quantum Grav.

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“…Chakraborty et al [20] applied the CET entropy for different anisotropic cosmologies (including the quasi-flat Szekeres class II model) by looking at the Penrose Weyl curvature hypothesis around the initial singularity and identifying for which models (and under which assumptions) the Weyl hypothesis is valid. Chakraborty et al [21] applied the entropy definition from Rudjord et al [10], as well as the CET proposal, to traversable wormholes (though they only considered the CET proposal for static spacetimes). Villalba et al [22] analyze the connections between the Newmann-Penrose scalars with the equation of state of asymptotically anti-de Sitter Reissner-Nördstrom black holes using CET's Bel-Robinson's square root thermodynamical description proposing conditions at the horizons in terms of pressures and energy densities as alternative thermodynamical definitions of these surfaces.…”

Section: Introductionmentioning

confidence: 99%

Gravitational entropy in Szekeres class I models

Pizaña¹,

Sussman²,

Hidalgo³

2022

Class. Quantum Grav.

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Developing a self-consistent notion of gravitational entropy in the context of cosmological structure formation has been so far an elusive task. Various theoretical proposals have been presented, initially based on Penrose’s Weyl Curvature Hypothesis, and variations of it. A more recent proposal by Clifton, Ellis, and Tavakol (CET) considered a novel approach by deﬁning such entropy from a Gibbs equation constructed from an effective stress-energy tensor that emerges from the ’square root’ algebraic decomposition of the Bel-Robinson tensor, the simplest divergence-less tensor related to the Weyl tensor. Since, so far all gravitational entropy proposals have been applied to highly restrictive and symmetric spacetimes, we probe in this paper the CET proposal for a class of much less idealized spactimes (the Szekeres class I models) capable of describing the joint evolution of arrays of arbitrary number of structures: overdensities and voids, all placed on selected spatial locations in an asymptotic ΛCDM backgound. By using suitable covariant variables and their ﬂuctuations, we ﬁnd the necessary and sufﬁcient conditions for a positive CET entropy production to be a negative sign of the product of the density and Hubble expansion ﬂuctuations. To examine the viability of this theoretical result we examine numerically the CET entropy production for two elongated over dense regions surrounding a central spheroidal void, all evolving jointly from initial linear perturbations at the last scattering era into present day Mpc-size CDM structures. We show that CET entropy production is positive for all times after last scattering at the precise spatial locations where structure growth occurs and where the exact density growing mode is dominant. The present paper provides the least idealized (and most physically robust) probe of a gravitational entropy proposal in the context of structure formation.

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Gravitational entropy of Hayward black hole

Iguchi

2023

Annals of Physics

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How appropriate are the gravitational entropy proposals for traversable wormholes?

Cited by 3 publications

References 58 publications

Arrow of time and gravitational entropy in collapse

Arrow of time and gravitational entropy in collapse

Gravitational entropy in Szekeres class I models

Gravitational entropy of Hayward black hole

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