DISPERSION INVARIANT AND ENERGY-MOMENTUM TENSOR IN MACROSCOPIC ELECTRODYNAMICS

Eigenvalue problem is introduced for macroscopic Maxwell's equations describing waves in medium similar to waveguide. The parameter lambda is derived for energy-momentum tensor by means of derivative: partial lambda/partial k(i), where k(i) is the wave vector. Dispersion invariant is shown to be a normalized action for the electromagnetic field in a medium. An example is considered for the wave guide with isotropic medium having space and time dispersion. Operation with lambda-parameter technique is demonstrated. Advantages are discussed for the given approach on calculation of energy-momentum tensor in more complex problems.