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The dynamics of bouncing universes is characterized by violating certain coordinate invariant restrictions on the total energy-momentum tensor, customarily referred to as energy conditions. Although there could be epochs where the null…

High Energy Physics - Theory · Physics 2017-11-22 Massimo Giovannini

We present a consistent effective theory that violates the null energy condition (NEC) without developing any instabilities or other pathological features. The model is the ghost condensate with the global shift symmetry softly broken by a…

High Energy Physics - Theory · Physics 2009-11-11 Paolo Creminelli , Markus A. Luty , Alberto Nicolis , Leonardo Senatore

As Einstein's gravity is a non-renormalizable theory, it can be a good description of physics only at the scales of energy or spacetime curvature below the Planck mass. Moreover, it requires the presence of an infinite tower of…

General Relativity and Quantum Cosmology · Physics 2025-08-22 Ziyue Zhu , Alexey S. Koshelev , Yang Liu , Anna Tokareva

In discussions of Bousso's Covariant Entropy Bound, the Null Energy Condition is always assumed, as a sufficient {\em but not necessary} condition which helps to ensure that the entropy on any lightsheet shall necessarily be finite. The…

High Energy Physics - Theory · Physics 2010-12-23 Brett McInnes

It has been suggested that the cosmological constant is a variable dynamical quantity. A class of solution has been presented for the spherically symmetric space time describing wormholes by assuming the erstwhile cosmological constant…

General Relativity and Quantum Cosmology · Physics 2008-11-26 F. Rahaman , M. Kalam , M. Sarker , A. Ghosh , B. Raychaudhuri

We explore consequences of the Averaged Null Energy Condition (ANEC) for scaling dimensions $\Delta$ of operators in four-dimensional $\mathcal{N}=1$ superconformal field theories. We show that in many cases the ANEC bounds are stronger…

High Energy Physics - Theory · Physics 2020-02-19 Andrea Manenti , Andreas Stergiou , Alessandro Vichi

We consider spherically-symmetric black holes in semiclassical gravity. For a collapsing radiating thin shell we derive a sufficient condition on the exterior geometry that ensures that a black hole is not formed. This is also a sufficient…

General Relativity and Quantum Cosmology · Physics 2019-06-04 Valentina Baccetti , Robert B. Mann , Daniel R. Terno

The classical energy conditions are known to not be fundamental physics -- they are typically violated by semiclassical quantum effects. Consequently, some effort has gone into finding possible semiclassical replacements for the classical…

General Relativity and Quantum Cosmology · Physics 2013-09-25 Prado Martin-Moruno , Matt Visser

Quantum null energy condition (QNEC) is usually stated as a bound on the expectation value of null components of the stress energy tensor at a point in terms of second null shape variations of the entanglement entropy at the same point. It…

High Energy Physics - Theory · Physics 2023-10-17 Pratik Roy

Although wormholes can be treated as topological objects in spacetime and from a global point-of-view, a precise definition of what a wormhole throat is and where it can be located can be developed and treated entirely in terms of local…

General Relativity and Quantum Cosmology · Physics 2007-05-23 David Hochberg , Matt Visser

The null energy condition (NEC) is a cornerstone of general relativity, and its violation could leave observable imprints in the cosmic gravitational wave spectrum. Theoretical models suggest that NEC violations during inflation can amplify…

General Relativity and Quantum Cosmology · Physics 2025-03-28 Zu-Cheng Chen , Lang Liu

Traversable wormhole solutions in General Relativity require exotic matter sources that violate the null energy condition (NEC), and such behavior maybe avoided in modified gravity. In this study, we analyze the energy conditions for…

General Relativity and Quantum Cosmology · Physics 2023-01-25 Anshuman Baruah , Parangam Goswami , Atri Deshamukhya

One of the fundamental questions of theoretical cosmology is whether the universe can undergo a non-singular bounce, i.e., smoothly transit from a period of contraction to a period of expansion through violation of the null energy condition…

General Relativity and Quantum Cosmology · Physics 2020-11-26 Anna Ijjas , Paul J. Steinhardt

Quantum inequalities bound the extent to which weighted time averages of the renormalized energy density of a quantum field can be negative. They have mostly been proved in flat spacetime, but we need curved-spacetime inequalities to…

General Relativity and Quantum Cosmology · Physics 2015-05-13 Eleni-Alexandra Kontou , Ken D. Olum

The classical Penrose inequality, a relation between the ADM mass and the area of any cross section of the black hole event horizon, was introduced as a test of the weak cosmic censorship conjecture: if it fails, the trapped surface is not…

General Relativity and Quantum Cosmology · Physics 2025-11-27 Eduardo Hafemann , Eleni-Alexandra Kontou

The inflationary paradigm has transformed our understanding of the early universe; yet most inflationary models are considered geodesically past-incomplete, suggesting a beginning of time or a primordial Big Bang singularity. The…

High Energy Physics - Theory · Physics 2026-03-25 Damien A. Easson , Joseph E. Lesnefsky

We develop a symmetric traversable wormhole model, integrating Einstein's gravitational coupling phantom field and a nonlinear electromagnetic field. This work indicates the emergence of negative ADM mass within a specific parameter range,…

General Relativity and Quantum Cosmology · Physics 2023-12-08 Chen-Hao Hao , Long-Xing Huang , Xin Su , Yong-Qiang Wang

We identify a new critical parameter in Choptuik's gravitational collapse: the angle at which null energy condition (NEC) saturation lines intersect at the center of the critical spacetime. These NEC lines coincide with regions of vanishing…

General Relativity and Quantum Cosmology · Physics 2024-11-15 Christian Ecker , Florian Ecker , Daniel Grumiller

The Quantum Null Energy Condition (QNEC) relates energy to the second variation of entropy in relativistic quantum field theory. We use the QNEC inequality to bound entanglement entropy in quenches. At early times the entanglement entropy…

High Energy Physics - Theory · Physics 2019-09-04 Márk Mezei , Julio Virrueta

We discuss a proposal on how gravitational collapse of a NEC (Null Energy Condition) violating spherically symmetric fluid distribution can avoid the formation of a zero proper volume singularity and eventually lead to a Lorentzian wormhole…

General Relativity and Quantum Cosmology · Physics 2021-08-11 Soumya Chakrabarti , Sayan Kar
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