10 research outputs found
Wave propagation in linear electrodynamics
The Fresnel equation governing the propagation of electromagnetic waves for
the most general linear constitutive law is derived. The wave normals are found
to lie, in general, on a fourth order surface. When the constitutive
coefficients satisfy the so-called reciprocity or closure relation, one can
define a duality operator on the space of the two-forms. We prove that the
closure relation is a sufficient condition for the reduction of the fourth
order surface to the familiar second order light cone structure. We finally
study whether this condition is also necessary.Comment: 13 pages. Phys. Rev. D, to appea