Many-body correlations in the problems of electrodynamics of fluids

This paper presents a review of the theory of the many-body correlation phenomena in fluids, in which the collective character of the fluctuations is caused by the long-range interaction of electrodynamic origin. The procedure of the statistical mechanical averaging of the microscopic electrodynamic equations is developed for a classical system of the interacting polarizable molecules with a subsequent account of the molecular correlations. As a result an effective expansion for the refractive index is obtained. The dependence of the refractive index on the thermodynamic parameters near the critical point is investigated using the scaling-law asymptotics for the many-body correlation functions. A molecular theory of the multiple light scattering is suggested. A method of evaluation of the many-body any-order scattering intensity in the critical region is described. Using a resummation procedure, similar to that developed for the light propagation problem, the correlation function expansion is obtained for a classical system of charged and neutral particles, correlations due to the short-range forces are taken into account. The expansion gives series in terms of the effective “dressed” electrostatic potential containing no long-range Coulomb divergencies, nor short-range ones.