Electromagnetic Scoot

TL;DR

This paper demonstrates that classical electromagnetic scattering causes a shift in the system's mechanical mass moment, analogous to relativistic effects, due to non-radiative exchange between particles and fields.

Contribution

It extends the concept of center of mass shift from relativistic gravity to classical electromagnetism, deriving formulas for energy and momentum exchange during scattering.

Findings

Mechanical mass moment shifts during scattering.

Electromagnetic field stores and exchanges mass moment.

No radiation loss, purely field-particle exchange.

Abstract

Recent work on scattering of massive bodies in general relativity has revealed that the mechanical center of mass of the system (or, more precisely, its relativistic mass moment) undergoes a shift during the scattering process. We show that the same phenomenon occurs in classical scattering of charged particles in flat spacetime and study the effect in detail. Working to leading order in the interaction, we derive formulas for the initial and final values of the mechanical and electromagnetic energy, momentum, angular momentum, and mass moment. We demonstrate that the change in mechanical mass moment is balanced by an opposite change in the mass moment stored in the electromagnetic field. This is a non-radiative exchange between particles and field, analogous to exchange of kinetic and potential energy. A simple mechanical analogy is a person scooting forward on the floor, who exchanges mass moment with the floor. We therefore say that electromagnetic scattering results in an electromagnetic scoot.