Laboratory experiments to test relativistic gravity

Abstract

Advancing technology will soon make possible a new class of gravitation experiments: pure laboratory experiments with laboratory sources of non-Newtonian gravity and laboratory detectors. This paper proposes seven such experiments; and for each one it describes, briefly, the dominant sources of noise and the technology required. Three experiments would utilize a high-$Q$ torque balance as the detector. They include (i) an "Amp\`ere-type" experiment to measure the gravitational spin-spin coupling of two rotating bodies, (ii) a search for time changes of the gravitation constant, and (iii) a measurement of the gravity produced by magnetic stresses and energy. Three experiments would utilize a high-$Q$ dielectric crystal as the detector. They include (i) a "Faraday-type" experiment to measure the "electric-type" gravity produced by a time-changing flux of "magnetic-type" gravity, (ii) a search for "preferred-frame" and "preferred-orientation" effects in gravitational coupling, and (iii) a measurement of the gravitational field produced by protons moving in a storage ring at nearly the speed of light. One experiment would use a high-$Q$ toroidal microwave cavity as detector to search for the dragging of inertial frames by a rotating body.