Testing Gravitational Interactions Below Fifty Microns*

Attempts at unifying the Standard Model with General Relativity predict faults that could violate both the Weak Equivalence Principle (WEP) and the Gravitational Inverse Square Law (ISL). For unification theories to be investigated further, we must increase our understanding of gravity on a fundamental level. Undergraduate researchers and faculty at Cal Poly Humboldt are performing precise gravitational tests with sensitivity to new effects at and below a distance of 50μm. This experiment uses a torsion pendulum symetrically composed of two materials of equal mass placed opposite an oscillating attractor mass. The magnitude of torque measured on the pendulum due to gravitational attraction at such a scale could lead to deviational observations from the WEP and ISL. Recently, researchers have been focusing on minimizing noise and possible sources of extraneous interference by testing for and characterizing factors such as magnetic interactions, leveling issues, and temperature effects to increase the experiment's efficacy.