Colloquium

It is well established that the long range van der Waals or thermal Casimir interaction between two semi-infinite dielectrics separated by a distance $H$ is screened by an intervening electrolyte. I will how this interaction is modified when an electric field of strength $E$ is applied parallel to the dielectric boundaries, leading to a non-equilibrium steady state with a current. The presence of the field induces a long range thermal repulsive interaction, scaling just like the thermal Casimir interaction between dielectrics without the intervening electrolyte, i.e. as $1/H^3$. The results are derived using stochastic density functional theory and I will give some background details on the method and some of its other applications in the theory of electrolytes.