Since the time of Cavendish, torsion pendulums have been used for precision tests of the fundamental laws of physics. Modern torsion pendulums have such fantastic precision that we can constrain theoretical predictions more often associated with high energy particle physics and cosmology, which I will briefly review. In addition, our experiments can be used to search for exotic particles, some of which could be the mysterious dark matter. For instance, the axion is a promising dark matter candidate that has unique properties that may be accessible with our technique. I will present a new dedicated torsion pendulum experiment that looks for a macroscopic parity and time violating force mediated by virtual axions. For an axion mass greater than 1.3 meV we have improved the limit on this force by more than 13 orders of magnitude. In addition, we have demonstrated that one can operate a torsion pendulum in a strong magnetic field, and thus, have opened another path to look for very heavy axions.
Coffee and cookies before the presentation at 3:15 pm, and refreshments after the presentation will both be served in Room 128.