FRICTION FORCE WITH NON-INSTANTANEOUS INTERACTION BETWEEN MOVING HARMONIC-OSCILLATORS

The friction force acting between two weakly interacting, harmonic osc illators which move slowly with respect to each other, is considered. In a previous paper the case of instantaneous interaction was treated (J.S. Hoye and I. Brevik, Physica A 181 (1992) 413) and the expression for the force was obtained by use of a variety of methods in statisti cal mechanics. The present paper deals with the case of non-instantane ous interaction. It turns out that in order to obtain a complete descr iption one has to take into account the medium (e.g., a thermal vacuum field or crystal lattice) through which the interaction propagates. W e consider successively the cases where one, respectively two, oscilla tors are present in interaction with the medium. Our discussion has a bearing on the self-interaction problem in classical electrodynamics. As a check of the general formalism, the self-interaction on a dielect ric spherical particle moving in a thermal radiation field is evaluate d by considering the momentum transfer from absorbed radiation.