Eikonal Theory for Transverse Photons and Massive Particles of Zero Spin

Abstract

A theory that agrees with another in all predictions within the latters domain of validity is sometimes called a covering theory. Thus, the microscopic theory of classical electrodynamics based on the Maxwell–Lorentz equations is the covering theory of macroscopic Maxwell electrodynamics which in itself is the covering theory of geometrical optics. The last-mentioned branch of optics deals with phenomena for which the finiteness of the wavelength of light can be neglected. In this approximation, the optical laws may be formulated in the language of geometry, and the basic quantity here is the eikonal, $S(\vec{r};\omega )$.