Tower gravity experiment: evidence for non-Newtonian gravity

Newton's inverse-square law of gravitation is tested by comparing gravity measured on a 600-m tower with gravity calculated from ground measurements. A significant departure from the law was detected, approaching (-500 + or - 35) x 10 to the -8th m/sq S at the top of the tower, and suggestive of a rapidly attenuating non-Newtonian attractive force. These results are marginally consistent with a one-term Yukawa-type attractive force, but they are fully consistent with two Yukawa-type forces, attractive and repulsive, and then also with Airy and Cavendish experiments. (Author)