Testing Gravitational Interactions Below 50 Microns

Attempts to unify the Standard Model and General Relativity often include features that violate the Weak Equivalence Principle (WEP) and/or the gravitational Inverse-Square Law (ISL). A violation of these would question our fundamental understanding of gravity. To further understand nature, undergraduate researchers and faculty at Cal Poly Humboldt are using an experiment to measure gravitational interactions below 50 microns. The experiment uses a torsion pendulum with equal masses of two different materials arranged as a composition dipole. The twist of the torsion pendulum is measured as an attractor mass in a parallel-plate configuration is oscillated nearby. This creates a time dependent torque on the pendulum. The magnitude and size of this torque may provide evidence for deviations in the WEP or ISL at this untested scale. The focus of the experiment at present is to apply adjustments to further isolate experimental results from environmental influences from the surroundings, and to optimize hardware for future data collection.