Richard Matzner will investigate several interconnected fields having to do with theories of gravity and tests of those theories using manmade satellites. He will combine computer and analytical simulations to determine the utility of Earth satellites like LAGEOS or the proposed LAGEOS III in determining the post-Newtonian behavior of gravitational theories. Numerical studies will investigate cosmological and astrophysical phenomena, including cosmic strings, (the study of which requires large computational and graphics support) and cosmic inflation. The behavior of radiation (neutrinos) as a cooling medium in neutron stars with application to supernova evolution will be studied. Prediction of the behavior of the cosmic background radiation in inhomogeneous cosmologies will be carried out, as will theoretical studies of the nuclear abundances predicted in hot big bang cosmologies. Other theoretical work will include more study of inflation in cosmology, studies of gravitational wave propagation in cosmology and also near black holes, and different approaches (Regge calculus and computational field theory) to the study of gravitating systems.