The Smeared Null Energy Condition

Freivogel, Ben; Krommydas, Dimitrios

doi:10.1007/jhep12(2018)067

Cited by 22 publications

(36 citation statements)

References 53 publications

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“…Hence, in the same way that the absence 54 It would be interesting to see to what extent can positive energy theorems in gravity be reformulated using quantum versions of energy conditions such as the ANEC [130]. See [131] for a proposal of such an energy condition in the gravitational context (although we do not know if this is strong enough to prove a positive energy theorem). If one finds a quantum energy condition leading to a PET, then we would demand that the corresponding quantum inequality is violated in a non-supersymmetric setup, which would be a restriction on the set of QFT's that can arise as low energy limits of quantum gravity (a Swampland constraint).…”

Section: Jhep12(2020)032mentioning

confidence: 99%

Nothing is certain in string compactifications

García-Etxebarria

Montero

Sousa

et al. 2020

J. High Energ. Phys.

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A bubble of nothing is a spacetime instability where a compact dimension collapses. After nucleation, it expands at the speed of light, leaving “nothing” behind. We argue that the topological and dynamical mechanisms which could protect a compactification against decay to nothing seem to be absent in string compactifications once supersymmetry is broken. The topological obstruction lies in a bordism group and, surprisingly, it can disappear even for a SUSY-compatible spin structure. As a proof of principle, we construct an explicit bubble of nothing for a T3 with completely periodic (SUSY-compatible) spin structure in an Einstein dilaton Gauss-Bonnet theory, which arises in the low-energy limit of certain heterotic and type II flux compactifications. Without the topological protection, supersymmetric compactifications are purely stabilized by a Coleman-deLuccia mechanism, which relies on a certain local energy condition. This is violated in our example by the nonsupersymmetric GB term. In the presence of fluxes this energy condition gets modified and its violation might be related to the Weak Gravity Conjecture.We expect that our techniques can be used to construct a plethora of new bubbles of nothing in any setup where the low-energy bordism group vanishes, including type II compactifications on CY3, AdS flux compactifications on 5-manifolds, and M-theory on 7-manifolds. This lends further evidence to the conjecture that any non-supersymmetric vacuum of quantum gravity is ultimately unstable.

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Section: Jhep12(2020)032mentioning

confidence: 99%

Nothing is certain in string compactifications

García-Etxebarria

Montero

Sousa

et al. 2020

J. High Energ. Phys.

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“…The counterexample can be circumvented if a momentum cut-off is imposed, and it was recently shown in Ref. [45] that a conjectured null QEI with a UV momentum cutoff [46] is sufficient to prove a null geodesic singularity theorem using methods from [15]. However, the QEI involved remains to be proven and any curvature corrections estimated.…”

Section: Discussionmentioning

confidence: 99%

A semiclassical singularity theorem

Fewster,

Kontou

2021

Preprint

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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 singularity theorems have been derived under weakened energy conditions, none is directly derived from quantum field theory. Here, we employ a quantum energy inequality satisfied by the quantized minimally coupled linear scalar field to derive a singularity theorem valid in semiclassical gravity. By considering a toy cosmological model, we show that our result predicts timelike geodesic incompleteness on plausible timescales with reasonable conditions at a spacelike Cauchy surface.

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“…To overcome the problem encountered by Fewster and Roman, Freivogel and Krommydas proposed the smeared null energy condition (SNEC) 10 . The main concept behind it is that in quantum filed theory there often exists an ultraviolet cutoff UV .…”

Section: The Smeared Null Energy Conditionmentioning

confidence: 99%

A singularity theorem for evaporating black holes

Kontou¹,

Freivogel²,

Krommydas³

2021

Preprint

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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 condition (SNEC), a proposed bound on the weighted average of the null energy along a finite portion of a null geodesic. Using SNEC as an assumption we proceed to prove a singularity theorem. This theorem extends the Penrose singularity theorem to semiclassical gravity and has interesting applications to evaporating black holes.

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The Smeared Null Energy Condition

Cited by 22 publications

References 53 publications

Nothing is certain in string compactifications

Nothing is certain in string compactifications

A semiclassical singularity theorem

A singularity theorem for evaporating black holes

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