How much null-energy-condition breaking can the Universe endure?
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Theoretical cosmology on null energy condition violation.
It derives theoretical constraints on cosmological models.
Theoretical cosmology bounds on NEC violation; object is physics, not research practice.
Abstract
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 early times. However, it is expected that there should still be a limit in semiclasssical gravity to how much `negative energy' can accumulate over time and in space as a result of quantum effects. In the course of formulating quantum-motivated energy conditions, the smeared null energy condition has emerged as a recent proposal. This condition conjectures the existence of a semilocal bound on negative energy along null geodesics, which is expected to hold in semiclassical gravity. In this work, we show how the smeared null energy condition translates into theoretical constraints on NEC-violating cosmologies. Specifically, we derive the implied bounds on dark energy equation-of-state parameters and an inequality between the duration of a bouncing phase and the growth rate of the Hubble parameter at the bounce. In the case of dark energy, we identify the parameter space over which the smeared null energy condition is consistent with the recent constraints from the Dark Energy Spectroscopic Instrument (DESI).
Stored with the screening record, where it is evidence for the labels above.
The record
- Venue
- Physical review. D/Physical review. D.
- Topic
- Reservoir Engineering and Simulation Methods
- Field
- Engineering
- Canadian institutions
- Perimeter InstituteUniversity of Waterloo
- Funders
- Institut Périmètre de physique théoriqueNatural Sciences and Engineering Research Council of CanadaGovernment of CanadaMinistry of Colleges and UniversitiesInnovation, Science and Economic Development Canada
- Keywords
- UniverseTheoretical physicsPhysicsAstronomyComputer science
- Has abstract in OpenAlex
- yes