Empirical and theoretical evidence for gravitational polarization of matter

Abstract

Empirical evidence indicating modification of gravity inside matter is summarized. It is argued that four independent sets of facts point in the same direction: a weakening of gravity inside matter. Direct evidence comes from measurements of gravity as function of depth in mines and bore holes (Airy experiments). Indirect evidence comes from discrepancies between the theoretical Standard Solar Model (SSM) and the observed neutrino flux, the observed seismic oscillations of the Sun, and geological evidence about the climate on the early Earth.The possible modifications of standard general relativity that might be compatible with the above and all other known facts are considered. It is argued that the solution to the problem is a term proportional to the scalar curvature R appearing in the matter Lagrangian leading to appearance of the Einstein tensor as part of the matter energy-momentum tensor. There is in fact strong theoretical reasons to have such terms corresponding to a gravitational "polarization" of matter and there does not seem to be any reason why they could not be large enough to give modifications already at the Newtonian level.