The Stochastic Casimir Effect

We model the one-dimensional `classical' vacuum by a system of annihilating Brownian motions on $\mathbb{R}$ with pairwise immigration. A pair of reflecting or absorbing walls placed in such a vacuum at separation $L$ experiences an attractive force which decays exponentially with $L$. This phenomenon can be regarded as a purely classical Casimir effect for a system of interacting Brownian motions.