Our equations of motion are simultaneously satisfactory and unsatisfactory: they yield the
equations of motion for an isolated object with a great deal of internal structure (time-dependent
multipoles with the emission of gravitational and electromagnetic radiation) in the form of
Newton’s second law. In addition, they contain a definition of angular momentum with an angular
momentum flux. The dipole part of the angular momentum flux agrees with classical E&M theory.
Unfortunately, there appears to be no way to study or describe interacting particles in this
However, there are some areas where these ideas might be tested, though the effects would be very
small. For example, earlier we saw that there was a contribution to the Bondi mass (an addition to the
Reissner–Nordström mass) from the quadrupole moment,
There were predicted contributions to both the momentum and angular momentum flux from the
gravitational and electromagnetic quadrupole radiation as well as new terms in the definition of the angular
momentum, e.g., charge/magnetic-dipole coupling term
There are other unfamiliar terms that can be thought of as predictions of this theoretical construct. How to
possibly measure them is not at all clear.