In one minute

Eleni-Alexandra Kontou and Ko Sanders review the status of energy conditions in general relativity and quantum field theory, with history, technical results, applications and some new derivations. Pointwise energy conditions began as reasonable limits on matter and became assumptions in proofs of singularity theorems and of the non-existence of wormholes and similar exotic phenomena. Yet quantum fields, and even some simple classical fields, systematically violate every pointwise energy condition. Weaker statements, quantum energy inequalities and averaged energy conditions, hold more widely and may still prove some earlier results. One of them, the achronal averaged null energy condition, is expected to hold universally for gravitating matter, even in semiclassical or quantum gravity.

Energy conditions in general relativity and quantum field theory