Casimir forces in granular and other non equilibrium systems

Abstract

In this paper we present a method to calculate Casimir Forces for non equilibrium systems with long range correlations. The origin of the force are the fluctuating fields, and the modification that the external, macroscopic objects induce in the spectrum of the fluctuations. The method is first illustrated with a simple model: a reaction-diffusion non-equilibrium system with an structure factor that possesses a characteristic length. The second part of the paper deals with a granular fluid where correlations are long ranged at all scales. In the first case the hydrodynamic fluctuations are confined by two plates, while in the second one the confinement comes from two immobile large and heavy particles. In both cases Casimir forces are calculated, and their properties analyzed.