Splitting of the Maxwell Tensor. II. Sources

The sources of the bound tensor ${T_{\mathrm{I}}}^{\mu \nu }$ and the emitted tensor ${T_{\mathrm{II}}}^{\mu \nu }$ introduced by the author in his treatment of radiation reaction without advanced fields are investigated. It is found that both parts of the energy tensor have a $\delta$-function-type source on the world line of the charged particle. The strength of the source is, in each case, the rate of change of the corresponding four-momentum. This is in sharp contrast with the situation in the advanced-field approach where the radiation field is source free and one has emission but not emitter. A very simple derivation of the Lorentz-Dirac equation based on the above results is presented.