  Spacetime Algebra (STA) provides unified, matrix-free spinor methods for
rotational dynamics in classical theory as well as quantum mechanics. That
makes it an ideal tool for studying particle models of zitterbewegung and using
them to study zitterbewegung in the Dirac theory. This paper develops a
self-contained dynamical model of the electron as a lightlike particle with
helical zitterbewegung and electromagnetic interactions. It attributes to the
electron an electric dipole moment oscillating with ultrahigh frequency, and
the possibility of observing this directly as a resonance in electron
channeling is analyzed in detail. A modification of the Dirac equation is
suggested to incorporate the oscillating dipole moment. That enables extension
of the Dirac equation to incorporate electroweak interactions in a new way.
