Short-Range Tests of Gravitational Physics

Due to the incompatibility of the Standard Model and General Relativity, tests of gravity remain at the forefront of experimental physics research. At Humboldt State University, undergraduates and faculty are developing an experiment that will test gravitational interactions below the 50-micron distance scale. The experiment will measure the twist of a torsion pendulum as an attractor mass is oscillated nearby in a parallel-plate configuration, providing a time varying torque on the pendulum. The size and distance dependence of the torque variation will provide means to determine deviations from accepted models of gravity on untested distance scales. To observe the twist of the pendulum inside the vacuum chamber, an optical system with nano-radian precision is required. Improvements made to the optical autocollimator system that now achieves the required sensitivity, as well as recent data taken with this updated system are discussed. In addition, an overview of an adapted Michelson interferometer is being developed as an entirely new optical system. This system will potentially offer a dramatic increase in the ability to measure small changes in the angle of the torsion pendulum