Narrow Results

We obtain a new expression for the electromagnetic fluctuations outside a metal surface, in terms of its surface impedance, providing a generalization to real metals of Lifshitz theory of van der Waals interactions between dielectric solids. We use the new formulae to compute the radiative heat transfer between two metal surfaces, separated by an empty gap. It is shown that an experiment on heat transfer may provide a resolution of a long-standing controversy about the effect of thermal corrections on the Casimir force between real metal plates.

We examine recent prescriptions for estimating the thermal Casimir force between two metallic plates from the point of view of their consistency with the Bohr-van Leeuwen theorem of classical statistical physics. We find that prescriptions including the effect of ohmic dissipation satisfy the theorem, while prescriptions that neglect ohmic dissipation do not.