Experimental examination of the inverse-square law of gravitation

Abstract

A ''source-independent'' null experiment for the inverse-square law of gravitation could be performed with a three-axis gravity gradiometer as a null detector of (del)²phi, the Laplacian of gravitational potential. With a gradient sensitivity of 10^-11 s^-2Hzsup(-1/2) and an integration time of 10⁶ s, one could resolve the force law to one part in 10⁵ in the range between 10² m and 10⁴ m, employing a mountain or a rock as the gravitating source. In a laboratory experiment one could obtain a resolution of the force law to better than one part in 10³ in the range between 1 m and 10 m using a rotating dumbbell of a reasonable size as a source.