Experimental Results on Gravity at Short Distances

A number of today's most fundamental physical mysteries have gravity at their core. Why is dark energy, known to us through its repulsive gravitational effect, so small or non-zero? Why is gravity's energy scale so drastically different from that of the other fundamental forces? Are there hidden extra dimensions? Small-scale precision gravity experiments are an elegant means of searching for clues about and answers to these questions. I present results from the E\"ot-Wash group at the University of Washington. We conducted three torsion-balance experiments to test the gravitational inverse-square law from separations of 9.53mm down to 55$\mu$m. Our results constrain new gravity-strength yukawa-type interactions to have a length scale $\lambda\le56\mu$m at 95\% confidence.