Field Momentum, Inertial Momentum and Gravitational Momentum of a System of Bodies in the Post-Newtonian Approximation

摘要

It is shown that in the post-newtonian approximation the gravitational momentum of a system of point particles is equal to the sum of field momentum and inertial momentum only in two classes of coordinate systems. This equality may be treated as a natural condition on a coordinate system in which the generally covariant Einstein equations are to be solved.