Point-source idealization in classical field theories. II. Mechanical energy losses from electromagnetic radiation reaction

This paper compares the mechanical energy losses due to electromagnetic radiation reaction on a two-particle, slow-motion system, as calculated from (1) the method of matched asymptotic expansions and (2) the Lorentz-Dirac equation, which assumes point sources. The matching derivation of the preceding paper avoided the assumption of a delta-function source by using Reissner-Nordstroem matching zones. Despite the differing mathematical assumptions of the two methods, their results are in agreement with each other and with the electromagnetic-field energy losses calculated by the evaluation flux integrals. Our purpose is eventually to analyze Rosenblum's use of point sources as a possible cause of disagreement between the analogous calculations of gravitational radiation reaction on a slow-motion system of two bodies. We begin with the simpler electromagnetic problem