The forces between surfaces of mobile, orientable dipoles. The method of reflection coefficients

Abstract
The interaction free energy between two planar bodies interacting across a uniform dielectric, expressed as a sum over allowed electrodynamic modes, is interpreted in terms of reflection coefficients. It is proved that, within the approximations implied by this modal approach, the force between identical bodies interacting across a uniform dielectric is always attractive. Explicit electrostatic results for interacting dipolar surfaces are obtained and these are applicable to the measured long range attractive forces between polar lipid bilayers.