Submillimeter Test of the Gravitational Inverse-Square Law: A Search for “Large” Extra Dimensions

Motivated by higher-dimensional theories that predict new effects, we tested the gravitational $1/r^2$ law at separations ranging down to $218\mu \mathrm{m}$ using a 10-fold symmetric torsion pendulum and a rotating 10-fold symmetric attractor. We improved previous short-range constraints by up to a factor of 1000 and find no deviations from Newtonian physics.