Tunnelling and dynamical violation of the null energy condition

Abstract

The null energy condition is considered the most fundamental of the energy conditions, on which several key results, such as the singularity theorems, are based. The Casimir effect is one of the rare equilibrium mechanisms by which it is breached without invoking modified gravity or nonminimal couplings to exotic matter. In this work we propose an independent dynamical mechanism by which it is violated, with the only ingredients being standard (but nonperturbative) quantum field theory and a minimally coupled scalar field in a double-well potential. As for the Casimir effect, we explain why the averaged null energy condition is not violated by this mechanism. Nevertheless, the transient behavior could have profound impacts in early universe cosmology.