On the Maxwell constant c as a generalized universal velocity

On the basis of the absoluteness of the vacuum light velocity and of the Lorentz transformations, the concept of a “measurable spatial velocity along the time axis” of a given observer can be introduced in a natural way, on the same footing of the “usual” velocities in the observer’s local three-space; full equivalence is thus established among all the coordinate directions, in the spirit of Relativity. As a natural issue of this procedure, the observer can describe the overall spatial motion of a given observable, namely in both the three-dimentional space and in the one-dimentional time, in terms of a spacelike “world-velocity” four-vector, the physically measurable modulus of which turns out to be equal to the Maxwell constant c, for all observables and according to all observers. This opens up a unified scenario for all kinds of particles: the absoluteness of the Maxwell constant c as a generalized world-velocity characterizes all the physical entities, and is not restricted to lightlike particles alone. PACS 03.30.+p, 04.20.-q, 04.20.Cv