# Physics & Astronomy Colloquium
3:30 PM, Friday, October 1, 2010
Room 155, Chem-Phys Building
** Dr. Holger Mueller **
Department of Physics
University of California, Berkeley
* Gravitational Redshift, Equivalence Principle, and Matter Waves *
The gravitational redshift was the first consequence of General Relativity
described by Einstein, and its measurement continues to be fundamental to
our confidence in the theory. Clock comparison tests have reached an
accuracy of 7 parts in 10^{5}, while matter wave tests, in which redshift
anomalies modify material particles' Compton frequencies, have reached 7
parts in 10^{9}. The Standard Model Extension (SME) can be developed into a
comprehensive model for violations of the Einstein Equivalence Principle
which maintains conservation laws of the Standard Model. Here, we use SME to
show that modern redshift experiments can bound anomalies that are presently
poorly constrained and outside the reach of tests of the universality of
free fall. We identify the similarities and differences between matter wave
and clock comparison tests. Moreover, we propose the Geodesic Explorer, an
atom interferometer performing a redshift measurement in a sounding rocket,
the Space Station, or a freely flying satellite. Operation in microgravity
converts the redshift measurement into a null measurement while the velocity
along the gravitational potential gradient v provides a signal enhancement
by v^{2}/c^{2},
which can be 10^{6} times greater than in the lab. Such a test would
provide bounds on post-post Newtonian effects of General Relativity that
could be 1 billion times better than current laboratory bounds, and 10,000
times better than current astrophysics bounds.
Refreshments will be served in CP 179 at 3:15 PM |