Stopped light: Towards plane-wave-free electrodynamics

A spatially infinite plane wave, as one of the possible solutions of Maxwell's equations, is a mathematically correct but physically empty image. It is pointed out that physically realised solutions in the form of nonplane waves are not strictly transverse waves outside a material medium and are characterised by three polarisation components, the superluminal phase and subluminal group velocities, the dispersion, the necessary presence of the fragments of a standing wave ('stopped light'), and the existence of a mass-like quantity, which can be defined as a finite observable (but not immanent) inertial and gravitational photon rest mass. This mass cannot be distinguished in a number of thought 'gedanken' experiments from the rest mass in a standard treatment.