  Retarded potentials of a point-charge are considered, and new ones presented,
including potentials of a point-charge moving at the speed of light. The
Lienard-Wiechert potential (together with the usual retardation condition) is
only one of many retarded four-potentials that satisfy the homogeneous wave
equation and the Lorenz Gauge condition in free space. This analysis is in the
context of Special Relativity and classical electrodynamics.
