2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/87426Representing the relativistic physical fields as sections of the Clifford Bundle (or of the Spin-Clifford Bundle) of Minkowski spacetime we show that all the relativistic wave equations satisfied by these fields possess solutions traveling with arbitrary speeds $0 \leq v < \infty$. By giving rigorous mathematical definitions of reference frames and of the Principle of Relativity (PR) we prove that physical realizations of the $v > 1$ solutions of, e.g., the Maxwell equations imply in a breakdown of the PR, but in no contradiction at all with known physical facts.46 pages, Latex2e article style with option rose.sty to reproduce the published version; no figuresClassical PhysicsMathematical Physicstext