Geophysical evidence for non-newtonian gravity

Abstract

Measurements of the variation of gravity with depth in mines and boreholes permit the densities of intervening rock strata to be inferred. In the few cases in which reliable absolute values of density have been independently determined, the calculations can be used to check the value of the newtonian gravitational constant, G. Such large-scale measurements of G are important because the validity of the inverse square law of gravity at short range is being questioned. We have made such a series of measurements and have found four other data sets in the literature that suffice for the estimation of G. We also report here a statistical analysis of 1,100 km² of overlapping sea floor and sea surface gravity data from the Gulf of Mexico (made available by Exxon). All these estimates of G give values that are higher than the conventional, laboratory-determined one. While the possibilities of systematic errors in these data sets preclude a definite conclusion that Newton's law of gravity fails at short range, the strong circumstantial evidence suggests that well controlled large-scale experiments on the inverse square law are urgently required.