Testing Gravitational Interactions Below Fifty 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 either would call into question our fundamental understanding of gravity. To further investigate this, undergraduate researchers and faculty at Cal Poly Humboldt are conducting precision measurements of gravitational interactions below 50 microns. This project employs a torsion pendulum configured as a composition dipole with equal masses of titanium and aluminum. The twist angle and frequency of the pendulum is measured as an attractor mass in a parallel-plate configuration oscillates within submillimeter separations. The magnitude of the time-dependent torque caused by these oscillations may provide evidence for deviations in the WEP or ISL at untested scales. The focus of the experiment at present is to apply adjustments to further isolate experimental results from environmental influences from the surroundings, analyze recent data, and to optimize the experiment for future data collection.