In this paper we study the origin of inertia in a curved spacetime,
particularly the spatially flat, open and closed Friedmann universes. This is
done using Sciama's law of inertial induction, which is based on Mach's
principle, and expresses the analogy between the retarded far fields of
electrodynamics and those of gravitation. After obtaining covariant expressions
for electromagnetic fields due to an accelerating point charge in Friedmann
models, we adopt Sciama's law to obtain the inertial force on an accelerating
mass m by integrating over the contributions from all the matter in the
universe. The resulting inertial force has the form F=−kma, where k<1
depends on the choice of the cosmological parameters such as ΩM,
ΩΛ, and ΩR and is also red-shift dependent.Comment: 10 page