Friday, December 14, 2001, 16:00
WHGA Auditorium
Dr. U. Schmidt, Heidelberg
Abstract:
The universality of free fall is the most precisely tested manifestation
of
the Equivalence Principle. Whether or not gravitational self-energy
obeys
the Equivalence Principle cannot be tested in laboratory experiments,
because gravitational self-energy is negligibly small for any
laboratory-scale object. The lunar-ranging test of the Equivalence
Principle for gravitational self-energy (Strong Equivalence Principle)
is
ambiguous. We removed this ambiguity by pushing the contribution of the
composition-dependent acceleration of the Earth and the Moon towards the
sun down to the 10^{-13} level. Measurements were performed with an
improved
high precision, rotating torsion balance.
Motivated by higher-dimensional theories, we also use the torsion
balance
technique to test the gravitational inverse-square law at small
distances (
< 3mm). Recent data improve previous constraints on deviations from
Newtonian physics by up to a factor of 1000.