Tom Murphy
I am an associate professor in the physics department at UCSD, and a member of CASS, the Center for Astrophysics and Space Sciences. I am working on an ultra-precise test of General Relativity using the technique of lunar laser ranging.
The APOLLO project (Apache Point
Observatory Lunar Laser-ranging Operation) is a joint endeavor between
UCSD, the University of Washington (with Eric Adelberger), and Harvard
University (with
Christopher Stubbs) that utilizes the 3.5 meter telescope at Apache Point in southern New Mexico to
bounce a laser pulse off the retro-reflector arrays left on the lunar
surface by the Apollo astronauts. By precisely measuring the shape of the
lunar orbit (to millimeter precision!), one can put any theory of gravity
to a hard test—assessing whether gravity pulls on gravity the
same way it pulls on "ordinary" matter (strong equivalence
principle), whether the strength of gravity changes as the universe
expands, etc. See the APOLLO Page
for more information.