Giant Casimir effect in fluids in non-equilibrium steady states

TL;DR

This paper predicts a significantly larger Casimir force in non-equilibrium fluids with temperature gradients, due to long-range correlations, which could be experimentally observed.

Contribution

It introduces the concept of a giant Casimir effect in non-equilibrium fluids, linking it to long-range correlations and a divergent Burnett coefficient.

Findings

Non-equilibrium Casimir force is anomalously large.

Force is related to a divergent Burnett coefficient.

Force should be experimentally detectable.

Abstract

In this letter we consider the fluctuation induced force exerted between two plates separated by a distance $L$ in a fluid with a temperature gradient. We predict that, for a range of distances $L$, this non-equilibrium force is anomalously large compared to other Casimir forces. The physical reason is that correlations in a non-equilibrium fluid are generally of longer range than other correlations, even than those near an equilibrium critical point. This giant Casimir force is related to a divergent Burnett coefficient that characterizes an Onsager cross effect between the pressure and the temperature gradient. The predicted Casimir force should be detectable with currently available experimental techniques.