To the Problem of Electromagnetic Field Energy in the Medium with Temporal and Spatial Dispersion Outside the Transparency Domain

The problem of calculation of electromagnetic field energy outside the transparency domain is discussed. It is shown that charged particle contribution to the energy of electromagnetic perturbations in the general case can be described in terms of bilinear combination of the dielectric polarizability of the medium. The explicit form of such contribution is found. The relations obtained are used to generalize the Planck's law to the case of absorptive medium.