A Sub-Millimeter Parallel-Plate Test of Gravity

Thesis (Ph.D.)--University of Washington, 2015Newton's inverse-square law of gravitation is the oldest standing mathematical description of a fundamental interaction. Experimental tests of gravity's distance-dependence define a frontier between our understanding of gravity and many proposed forms of new physics. We performed a parallel-plate test of the gravitational inverse-square law at sub-millimeter distances. Using a tantalum/titanium torsion balance locked in electrostatic feedback, we performed a null search for deviations from uniformity of the gravitational field of a planar tantalum/aluminum mass. Key innovations include an interferometric isolating-foil position monitor, a completely reproducible analysis tool-chain, and a publicly-unblinded analysis. Using the traditional Yukawa parametrization, our results are consistent with Newton's inverse-square law at α=1 over distances from λ= 104 μm to 1320 μm with 95% confidence