2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/102406There is actually a mistake in this paper, but it is still a nice try worth a read. It is (not quite) proved that within the framework of Special Relativity, a force exerted on a \emph{classical particle} by a field must be of the form $\yv{E}+\yv{v}\times\yv{B}$, the Lorentz force form. The proof makes use of an action principle in which the action is the sum of a free particle part, and an interaction part.A subtle mistake was found. This paper is actually mistaken, but still a nice try worth a read :)Classical Physicstext