Best measurement of the gravitational constant/ best test yet of special relativity

The following press conference is scheduled for the American Physical Society (APS) April Meeting in Long Beach, California April 29-May 2, 2000.

Jens H. Gundlach of the University of Washington (206-543-4080) will report a long-awaited higher precision measurement of the gravitational constant, usually denoted by the letter G. It is almost 10 times the precision of previous measurements, and also offers the best determination yet of the Earth's mass. (For more information, see the lay language paper by Gundlach and colleagues at http://www.aps.org/meet/APR00/baps/vpr/layp11-03.html)

Einstein's theory of special relativity rests on two postulates: (1) that the laws of physics are the same for all reference systems moving at a constant velocity with respect to each other and (2) the speed of light through vacuum is a constant independent of the speed of the light source. Kenneth Brecher of Boston University (617-353-3423) uses the sharpness of arriving wave pulses from distant gamma-ray bursters to affirm the second postulate to within one part in 10^20 (paper B16.13). Presenting an overview of recent adjustments made to the fundamental physics constants (Paper W10.03), Peter Mohr of NIST (301-975-3217, [email protected]) will explain how conflicting experimental results have made the recommended value for G, the gravitational constant,10 times less precise than before. At the other extreme, he will describe how the Rydberg constant (which helps prescribe an atom's spectrum of wavelength values) is known 100 times more accurately than in 1986, thanks to breakthroughs in measuring visible light.

The press conference will be held in room 201A in the Long Beach Convention Center. Press conferences will be held in room 201B. Pressroom hours: Sat-Tues 8 AM to 5 PM. Pressroom phone numbers: 562-499-7780 and 81. Fax: 562-499-7784. The meeting website, including all the abstracts, is http://www.aps.org/meet/APR00/#general. See also the APS virtual pressroom at http://www.aps.org/meet/APR00/baps/vpr. Journalists intending to attend the meeting should send in their request for a press badge, if they haven't already done so, to Ben Stein at [email protected].