Shooting the Moon: Probing Fundamental Gravity in the Solar System Tom Murphy, Assistant Professor of Physics, University of California, San Diego

The fundamental incompatibility of quantum mechanics with general relativity together with our well-quantified ignorance of large-scale gravity (dark energy, dark matter) strongly suggests that we intensify our tests of gravity.  APOLLO (the Apache Point Observatory Lunar Laser-ranging Operation) is a new project that will bring about order-of-magnitude improvements in testing several fundamental aspects of gravity.  Using a 3.5 meter telescope to bounce laser pulses off of the retroreflector arrays left on the moon by the Apollo astronauts, APOLLO will be capable of millimeter range-precision.  By determining the exact shape of the lunar orbit, it will be possible to test the equivalence principle, the time-rate-of-change of the gravitational constant, gravitomagnetism, and geodetic precession to at least ten times better precision than currently tested.  In addition, APOLLO will be sensitive to departures from the inverse-square law of gravity and can potentially probe the effects of extra dimensions to which only gravity has access.