2ND POST-NEWTONIAN ORDER RENORMALIZATION OF 1ST POST-NEWTONIAN ORDER GRAVITY IN THE SOLAR-SYSTEM

The quantitatively most significant effect of second post-Newtonian order (1/c4) gravity in the solar system is its possible renormalization of the parameters which appear in first post-Newtonian order (1/c2) gravity. Because of inhomogeneities in the background cosmological matter density, parameterized post-Newtonian coefficients G, gamma, beta, ... which appear in first post-Newtonian order gravity may be renormalized at order 10(-5), depending on the higher order structure of the gravitational interaction. A compact body such as the Sun may acquire renormalized mass parameters M(gamma), M(beta), ..., which generally will differ from each other and from its inertial mass M(I) and/or gravitational mass M(G) by the order of the body's gravitational self-energy, again depending on the second post-Newtonian order structure of gravity but having magnitude of order 4 x 10(-6) in the case of the Sun. The relationships between these renormalization effects and the specific structure of the second post-Newtonian order metric field expansion is developed. The concept of ''extended Lorentz invariance '' is employed, in which the gravitational physics remains Lorentz-invariant after rescalings due to distant spectator matter. If this extended invariance is fulfilled, we find that a compact body's gamma-mass is determined by its inertial mass and gravitational mass. This prediction is testable with higher precision measurements of light deflections near the Sun. General relativity theory, which fully embodies the strong equivalence principle, predicts a complete absence of these renormalization effects; experiments which can measure or constrain these effects are therefore tests of the second post-Newtonian order structure of general relativity.