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The classical singularity theorems of General Relativity rely on energy conditions that are easily violated by quantum fields. Here, we provide motivation for an energy condition obeyed in semiclassical gravity: the smeared null energy…

General Relativity and Quantum Cosmology · Physics 2021-10-25 Eleni-Alexandra Kontou , Ben Freivogel , Dimitrios Krommydas

The null energy condition (NEC), an important assumption of the Penrose singularity theorem, is violated by quantum fields. The natural generalization of the NEC in quantum field theory, the renormalized null energy averaged over a finite…

High Energy Physics - Theory · Physics 2021-11-11 Jackson R. Fliss , Ben Freivogel , Eleni-Alexandra Kontou

Quantum fields can notoriously violate the null energy condition (NEC). In a cosmological context, NEC violation can lead to, e.g., dark energy at late times with an equation-of-state parameter smaller than $-1$ and nonsingular bounces at…

General Relativity and Quantum Cosmology · Physics 2025-07-01 Elly Moghtaderi , Brayden R. Hull , Jerome Quintin , Ghazal Geshnizjani

The violation of the null energy condition (NEC) is essential for constructing nonsingular cosmological scenarios, such as Genesis cosmology, which avoids the initial singularity by initiating cosmic evolution from an asymptotically…

General Relativity and Quantum Cosmology · Physics 2026-03-19 Dong-Hui Yu , Mian Zhu , Yong Cai

A null line is a complete achronal null geodesic. It is proven that for any quantum fields minimally coupled to semiclassical Einstein gravity, the averaged null energy condition (ANEC) on null lines is a consequence of the generalized…

General Relativity and Quantum Cosmology · Physics 2010-04-06 Aron C. Wall

The averaged null energy condition (ANEC) requires that the integral over a complete null geodesic of the stress-energy tensor projected onto the geodesic tangent vector is never negative. This condition is sufficient to prove many…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Noah Graham , Ken D. Olum

The expected stress-energy tensor <T_{ab}> of quantum fields generically violates the local positive energy conditions of general relativity. However, <T_{ab}> may satisfy some nonlocal conditions such as the averaged null energy condition…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Eanna Flanagan , Robert Wald

We prove a singularity theorem in semiclassical gravity without assuming global hyperbolicity or the null energy/curvature condition; the former is replaced by the weaker causality conditions of stable causality and past reflectivity, and…

High Energy Physics - Theory · Physics 2026-05-08 Netta Engelhardt , Ivri Nagar

Hawking's black hole area theorem was proven using the null energy condition (NEC), a pointwise condition violated by quantum fields. The violation of the NEC is usually cited as the reason that black hole evaporation is allowed in the…

General Relativity and Quantum Cosmology · Physics 2023-03-14 Eleni-Alexandra Kontou , Veronica Sacchi

The Averaged Null Energy Condition (ANEC) states that the integral along a complete null geodesic of the projection of the stress-energy tensor onto the tangent vector to the geodesic cannot be negative. Exotic spacetimes, such as those…

General Relativity and Quantum Cosmology · Physics 2013-03-14 Eleni-Alexandra Kontou , Ken D. Olum

We establish analogues of the Hawking and Penrose singularity theorems based on (a) averaged energy conditions with exponential damping; (b) conditions on local stress-energy averages inspired by the Quantum Energy Inequalities satisfied by…

General Relativity and Quantum Cosmology · Physics 2013-02-01 Christopher J. Fewster , Gregory J. Galloway

We propose a new bound on the average null energy along a finite portion of a null geodesic. We believe our bound is valid on scales small compared to the radius of curvature in any quantum field theory that is consistently coupled to…

High Energy Physics - Theory · Physics 2021-04-20 Ben Freivogel , Dimitrios Krommydas

Quantum fields do not satisfy the pointwise energy conditions that are assumed in the original singularity theorems of Penrose and Hawking. Accordingly, semiclassical quantum gravity lies outside their scope. Although a number of…

General Relativity and Quantum Cosmology · Physics 2022-04-13 Christopher J. Fewster , Eleni-Alexandra Kontou

The present article lies at the interface between gravity, a highly nonlinear phenomenon, and quantum field theory. The nonlinear field equations of Einstein permit the theoretical existence of classical wormholes. One of the fundamental…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Kamal K. Nandi , Yuan-Zhong Zhang , Nail G. Migranov

In this paper the averaged weak (AWEC) and averaged null (ANEC) energy conditions, together with uncertainty principle-type restrictions on negative energy (``quantum inequalities''), are examined in the context of evaporating black hole…

General Relativity and Quantum Cosmology · Physics 2009-10-28 L. H. Ford , Thomas A. Roman

The Averaged Null Energy Condition (ANEC) states that the integral along a complete null geodesic of the projection of the stress-energy tensor onto the tangent vector to the geodesic cannot be negative. ANEC can be used to rule out…

General Relativity and Quantum Cosmology · Physics 2015-07-23 Eleni-Alexandra Kontou

The generalized second law can be used to prove a singularity theorem, by generalizing the notion of a trapped surface to quantum situations. Like Penrose's original singularity theorem, it implies that spacetime is null geodesically…

General Relativity and Quantum Cosmology · Physics 2016-12-07 Aron C. Wall

The Averaged Null Energy Condition (ANEC) requires that the average along a complete null geodesic of the projection of the stress-energy tensor onto the geodesic tangent vector can never be negative. It is sufficient to rule out many…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Christopher J. Fewster , Ken D. Olum , Michael J. Pfenning

In spherical symmetry, solutions of the semiclassical Einstein equations belong to one of two possible classes. Both classes contain solutions that -- depending on the dynamic behavior of the horizon -- describe evaporating physical black…

General Relativity and Quantum Cosmology · Physics 2022-03-10 Pravin K. Dahal , Sebastian Murk , Daniel R. Terno

Regular black holes have become a popular alternative to the singular mathematical black holes predicted by general relativity as they circumvent mathematical pathologies associated with the singularity while preserving crucial black hole…

General Relativity and Quantum Cosmology · Physics 2024-08-15 Ioannis Soranidis
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