The assumed universality of the equivalence principle suggests that a particle in a gravitational field has identical physics to one in an accelerated frame. Yet, energy considerations prohibit radiation from a static particle in a gravitational field while the accelerating counterpart emits. Solutions to the fundamental problems of radiation from charges in a gravitational field and consequences to the equivalence principle usually contrast the far-field and global nature of radiation with the local validity of the equivalence principle. Here, we suggest reliable physical solutions that recognizes the essential need for motional currents and the magnetic component for radiation to occur. Our discussion reiterates the need for a fresh careful look at universality of free fall (UFF) for charged particles in a gravitational field.
Some remarks on an old problem of radiation and gravity
