Abstract
We review the formulation of the problem of the electromagnetic
self-interaction of a relativistic charged particle in the
framework of the manifestly covariant classical mechanics of
Stueckelberg, Horwitz, and Piron. The gauge fields of this theory,
in general, cause the mass of the particle to change. We show
that the nonlinear Lorentz force equation for the
self-interaction resulting from the expansion of Green's function
has chaotic solutions. We study the autonomous equation for the
off-shell particle mass here, for which the effective charged
particle mass achieves a macroscopic average value determined by
what appears to be a strange attractor.