Sub-millimeter tests of the gravitational inverse-square law

Thesis (Ph. D.)--University of Washington, 2001The Newtonian Law of Universal Gravitation states that the strength of the gravitational force between point test bodies falls as the inverse-square of the distance between them. Recently, novel new theoretical scenario, inspired by string or M theory, predict possible violations of this inverse-square behavior with test mass separations below 1 mm.Motivated by these theories, we tested the gravitational inverse-square law at separations ranging down to 138 mum using 10-fold symmetric torsion pendulums and rotating 10-fold symmetric attractors. We improved previous constraints on inverse square law violations by up to a factor of 104 and saw no deviations from Newtonian physics. These measurements describe the first direct observation of the gravitational interaction with test mass separations below 0.5 mm.We performed two similar experiments denoted by 'I' and 'II' throughout the text. This dissertation includes thorough descriptions of the apparatus, analysis procedures, and results of these experiments