Revisiting Laws of Black Hole Mechanics and Violation of Null Energy Condition

Mohanpur,

doi:10.4236/jhepgc.2019.51004

Cited by 4 publications

(3 citation statements)

References 24 publications

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“…The wormhole solution is supported by materials that violate the energy condition and is called 'exotic matter'. Conditions of averaged and pointwise energy have been violated in the singularity theorem and theorems of classical black holes [24]. Violation of energy conditions has seen in some physical phenomena such as Casimir effect [25] and…”

Section: Introductionmentioning

confidence: 99%

Energy condition of wormhole and thin shell by assuming conformal symmetry in teleparallel-Rastall gravity

Nazavari,

Saaidi

2023

Phys. Scr.

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The static spherically symmetric wormhole solution for a non-isotropic perfectfluid energy-momentum tensor within the context of teleparallel-Rastallgravity is investigated. First, by imposing static and non-static conformalsymmetry on the static spherically symmetric space-time metric, we investigatedthe null energy condition at the throat of traversable wormholes andshowed that the null energy condition in the throat and its neighborhood isviolated. Secondly, with the aim of minimize the usage of exotic matter, wefound regions where the energy conditions are valid at the junction surface.We found that in the static case of conformal symmetry solution, the nullenergy condition (NEC), weak energy condition (WEC), and Strong energycondition (SEC) are valid for different λ0 parameters. Moreover, we obtainedthat for the non-static symmetric solution of conformal symmetry, the NECand WEC are satisfied for different sets of (k, ˜ λ0) parameters. Finally, wehave explored the stable regions by the parameter η2 ( square speed of sound)for different sets of (k, ˜ λ0) parameters.

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Section: Introductionmentioning

confidence: 99%

Energy condition of wormhole and thin shell by assuming conformal symmetry in teleparallel-Rastall gravity

Nazavari,

Saaidi

2023

Phys. Scr.

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“…The singularity theorems are proved using the earlier work of Raychaudhuri [4] in the causal structure of geodesic congruences, generalized in [5]. However, proofs of singularity theorems in BH strongly depend on the null energy condition (see [6][7][8]). The null energy condition essentially states that the energy-momentum tensor T µν of the matter satisfies the following condition T µν (x)n µ (x)n ν (x) ≥ 0, (I.1)…”

Section: Introductionmentioning

confidence: 99%

“…for any null vector n µ , satisfying g µν (x)n µ (x)n ν (x) = 0 where g µν is the metric tensor of the spacetime manifold. However, over the years, violations of the null energy condition (NEC) [6,[9][10][11][12] have been found in several physical situations. Later, it has been proposed that average null energy condition (ANEC) [13][14][15][16][17][18][19] is the minimum requirement for the study of BH and it holds for any spacetime, based on the work [20].…”

Section: Introductionmentioning

confidence: 99%

Classification of quantum states based on the null energy condition

Mandal

2021

Preprint

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Violation of the null energy condition plays an important role both in the general theory of relativity and quantum field theory in curved spacetimes. Over the years, it has been shown that the violation of the null energy condition leads to instability and violation of causality. In quantum field theory, violation of the energy condition also depends on the quantum states apart from the geometry of curved spacetime. Hence, the quantum effects play an important role in the violation of the null energy condition. We show that the set of all the coherent states does not violate the null energy condition. Further, we also show that under certain conditions, the null energy condition is violated either by a pure state or a mixed state. Furthermore, the dynamical violation of the null energy condition by the quantum states is also discussed here.

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Conformal and kinetic couplings as two Jordan frames of the same theory

Gal’tsov

2020

Eur. Phys. J. C

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Certain scalar-tensor (ST) theories with non-minimal coupling of the scalar field to curvature may admit an Einstein frame representation, where gravity is described by the Einstein–Hilbert action plus the scalar sector. Between them, some theories exactly coincide in their respective Einstein frames. If transformations between Jordan and Einstein frames are invertible, these theories can be associated with two Jordan frames of the unique theory. Such successive dualities can connect theories with non-derivative coupling, like $$R\phi ^2$$Rϕ2, with derivatively coupled theories, like Horndeski and DHOST. In absence of matter, these are equivalent, though looking very different. We show the existence of a successive duality between the $$R\phi ^2$$Rϕ2 theory and a recently found Palatini kinetically coupled theory, which both look in their Einstein frames as Einstein theory minimally coupled to scalar. Transforming singular exact solutions of the latter to Jordan frames, we compare desingularization properties of the above two theories which both violate the null energy condition. It is found that kinetically coupled theory has stronger desingularization features, exhibiting possibility of Genesis-type behavior of the homogeneous and isotropic cosmological solutions.

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Revisiting Laws of Black Hole Mechanics and Violation of Null Energy Condition

Cited by 4 publications

References 24 publications

Energy condition of wormhole and thin shell by assuming conformal symmetry in teleparallel-Rastall gravity

Energy condition of wormhole and thin shell by assuming conformal symmetry in teleparallel-Rastall gravity

Classification of quantum states based on the null energy condition

Conformal and kinetic couplings as two Jordan frames of the same theory

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