Tower Gravity Experiment: Evidence for Non-Newtonian Gravity

We tested Newton's inverse-square law of gravitation 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\ifmmode\pm\else\textpm\fi{}35)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}8}$ ${\mathrm{ms}}^{\ensuremath{-}2}$ 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.