ABSTRACT
A characteristic and important feature of electrodynamics in a medium is that it provides for the possible emission of radiation by a uniformly moving charge. The theory of radiation in a medium can be treated most logically within the framework of the general electrodynamics of continuous media, which is also known as "macroscopic electrodynamics". The use of quantum concepts or, more exactly, quantum nomenclature, proves quite convenient for solving a wide variety of problems in the theory of radiation in a medium. The electrodynamics of continuous media is associated with this problem because in the presence of a sufficiently strong electromagnetic field the vacuum behaves under certain conditions like a birefringent medium. For instance, a weak electromagnetic wave propagating perpendicular to a constant and uniform magnetic field has different refractive indices, depending on whether the wave is polarized perpendicular or parallel to the field.
