Maxwell's equations with continuously distributed currents clarify the nature of energy and momentum transfer in electromagnetic interactions

Abstract

Transfer of energy and momentum by electromagnetic fields is among the most fundamental processes in the universe that is unequivocally described by microscopic Maxwell's equations. Here we show that commonly used models of harmonic or point-like currents necessitate the assumption of passive, non-influencing measurement devices (detectors) thereby systematically affecting the interpretation and quantification of the measured signals. Instead, by using mathematically complete definition of continuously distributed currents, we reveal that the measured signals are attributed to the intensity of the emitter-detector interactions, while the inherent energy and momentum radiated out by the emitter in a vacuum are zero. This systematic treatment provides physically broader insights into generation of electromagnetic fields and the associated transfer of energy and momentum, thereby opening new perspectives for the measurements and interpretations of electromagnetic interactions that underpin diverse physical phenomena.