  We consider the interaction of gravity, as expressed by Einstein's Equations
of General Relativity, to other force fields. We describe some recent results,
discussing both the mathematics, and the physical interpretations. These
results concern both elementary particles, as well as cosmological models.
(This paper describes joint work variously done with with F. Finster, N.
Kamran, B. Temple, and S.-T. Yau.)
