Eighth velocity of light

Abstract

In dispersive media the phase velocity, group velocity, energy velocity, signal velocity, relativistic velocity constant, and ratio-of-units velocity are usually not useful concepts for wave packets. The centrovelocity has been suggested as a measure which overcomes many of the objections to the first six. We describe yet another, based on the cross-correlation of the original and received wave packets, which is shown to be useful in time-of-flight measurements in weakly and strongly dispersive media; absorption and amplification are readily accommodated. Applications for specific examples of wave packets in magnetoplasmas are presented.