  The aim of this paper is to investigate the fundamental problems of
retardation and radiation caused by non-uniformly moving point sources using
the theories of electrodynamics and elastodynamics. This paper investigates and
compares the retarded electromagnetic fields and the retarded elastodynamic
fields. For the non-uniform motion of a general point source, the
Li\'enard-Wiechert type potentials and the radiation and nonradiation fields
are derived for a point charge and for a point force.
