How can one detect the rotation of the Earth "around the Moon"? Part 2: Ultra-slow fall

Abstract

The paper proposes an alternative to the Foucault pendulum for detecting various movements of rotation of the Earth. Calculations suggest that if the duration of a "free" fall becomes longer the eastward deflection will be amplified in proportion with the increased duration. Instead of 20 micrometers for a one-meter fall, one can expect deflections more than 1,000 times larger when the fall lasts a few minutes. The method proposed in this paper consists in using the buoyancy of a (non viscous) liquid in order to work in reduced gravity. Not surprisingly, as in many astronomical observations, the main challenge is to minimize the level of "noise". Possible sources of noise are discussed and remedies are proposed. In principle, the experiment should be done in superfluid helium. However, a preliminary experiment done in water gave encouraging results in spite of a fairly high level of noise. In forthcoming experiments the main objective will be to identify and eliminate the main sources of noise. This experiment differs from the Foucault pendulum by its greater flexibility. By adequately selecting the major parameters, e.g. duration of the fall, viscosity of the fluid, size of the falling body, one can change the deflection target. It is hoped that the present paper will encourage new experiments in this direction.