A New Method for Testing Newton's Gravitational Law

Abstract

We report on a new experimental method for determining the gravitational force of a laboratory test mass on a Fabry-Perot microwave resonator. The resonator consists of two Fabry-Perot mirrors suspended as pendulums. Changes of 2 × 10-11 m in the pendulum separation can be resolved as a shift of the resonance frequency of the resonator. The limit corresponds to an acceleration of 7 × 10-11 ms-2 of one mirror with respect to the other. In a first experiment we have measured the gravitational acceleration generated by a 125 kg test mass as a function of distance in the range 10 cm to 15 cm and tested Newton's gravitational law with an accuracy of 0,6%. No deviation is found and the gravitational constant G is determined with an accuracy of 1%.