| Proposed theories that unify gravity and quantum mechanics often require Newton's gravitational inverse-square law to fail below some length scale. Additionally, some theorists have proposed the discovery of Dark Energy may imply altered gravitational dynamics at short length scales. These facts motivated our previous and continued efforts to test gravity at the smallest achievable distances. This dissertation describes an improved test of gravity using a torsion pendulum and attractor designed with 120-fold azimuthal symmetry. We tested the inverse-square law at separations down to 60 microns and have excluded gravity-strength Yukawa interactions with length scale > 42 microns at the 95% confidence level. However, our data preferred the inclusion of a Yukawa potential at longer length scales, in a region of parameter space previously excluded by experiment, indicating some yet unresolved systematic issues. This dissertation provides a complete description of the experiment and gives guidance for improved future measurement. |
