Detection of non-Newtonian gravity

An experiment was performed to test Newton's inverse square of law gravitation. The test compared accurately measured gravity values along a 600-m tower with upward continued gravity estimates calculated from ground measurements using algorithms based on Newtonian potential theory. Gravity measurements with an internal consistency of better than 20 μGal (1 μGal = 10-8 m/s2) were made on the tower at intervals of about 90 m using a single LaCoste-Romberg model G gravimeter. Field measurements of gravity (using the same instrument) and corresponding geodetic positions were performed at 77 points within a radius of 5 km from the tower. These and other gravimetric data within a radius of about 220 km were used to perform the upward continuation using two independent computational techniques. One is least squares collocation, which is based on a statistical interpretation of the local gravity field, and the other determines a local harmonic expansion on the field from the given data