Measurements of Gravitational Attractions at small Accelerations

Gravitational interactions were studied by measuring the influence of small external field masses on a microwave resonator. It consisted of two spherical mirrors, which acted as independent pendulums individually suspended by strings. Two identical field masses were moved along the axis of the resonator symmetrically and periodically between a near and a far position. Their gravitational interaction altered the distance between the mirrors, changing the resonance frequency, which was measured and found consistent with Newton’s law of gravity. The acceleration of a single mirror caused by the two field masses at the closest position varied from 5.4⋅10−12 ms−2 to 259⋅10−12 ms−2.