The extended Lorentz force
  The Lorentz force equations provide a partial description of the geodesic motion of a charged particle on a four-manifold. Under the hypothesis that Maxwell's equations express symmetry properties of the Ricci tensor, the full electromagnetic connection is determined. From this connection, the fourth equation of the geodesic is derived. The validity of this fourth equation can be determined by studying the decay of charged particles in an electric field. Time will accelerate or decelerate relative to the proper time of a charged particle moving in an electric field. Unstable charged particles moving in opposite directions parallel to an electric field should exhibit different decay rates. 
Michael A. Graber