Energy conditions and their cosmological implications

TL;DR

This paper discusses the foundational energy conditions in general relativity, their violations due to quantum and classical effects, and explores the profound cosmological and theoretical implications of such violations.

Contribution

It highlights the weakening of traditional energy conditions and examines their violations' potential to enable exotic phenomena like wormholes and warp drives.

Findings

Quantum effects violate energy conditions

Classical systems can also violate energy conditions

Violations imply possibilities of wormholes and time machines

Abstract

The energy conditions of general relativity permit one to deduce very powerful and general theorems about the behaviour of strong gravitational fields and cosmological geometries. However, the energy conditions these theorems are based on are beginning to look a lot less secure than they once seemed: (1) there are subtle quantum effects that violate all of the energy conditions, and more tellingly (2), there are also relatively benign looking classical systems that violate all the energy conditions. This opens up a Pandora's box of rather disquieting possibilities --- everything from negative asymptotic mass, to traversable wormholes, to warp drives, up to and including time machines.