Probing Fundamental Physics with Gravitational Experiments

University Of Washington, Seattle WA

Investigators

Abstract

This award allows the University of Washington Eot-Wash Group to develop ultra-sensitive torsion-balance instruments capable of detecting the ultra-weak forces suggested by modern ideas in theoretical physics, especially attempts to unify gravity with the other three fundamental forces. In particular, instruments will be developed that: 1) probe for ``large'' extra dimensions by testing Newton's inverse-square law down to length scales substantially smaller than the diameter of a human hair, 2) test Einstein's Weak Equivalence Principle with a sensitivity fifty times better than previously published results, 3) look for quantum gravity effects by testing Lorentz symmetry or charge-parity (CP) and charge-parity-time (CPT) violation, 4) search for the force produced by axion-like particles with masses around 1000 micro-eV, 5) operate at temperatures close to absolute zero to study factors that limit torsion-balance sensitivity. The Eot-Wash Group has consistently provided the most precise studies of the broadly interesting issues they investigate. This required technical innovations that have found applications in other areas such as ground and space-based gravitational-wave detection. The Group's results are used by elementary-particle, gravitational and cosmological theorists to constrain interesting new ideas, are widely disseminated through publications, review papers, colloquia, invited talks, lab tours and public lectures, and are featured in magazine and newspaper articles in this country and in Europe. The variety of scientific issues addressed by the Group and the many experimental challenges involved provide an excellent education in experimental physics for graduate students and postdoctoral fellows, as well as unusually attractive opportunities for undergraduate research projects.