Effect of Earth's Rotation on Trajectories of Free-Fall Bodies in Equivalence Principle Experiment**The project supported in part by National Natural Science Foundation of China under Grant Nos. 19835040, 10175070, and 10047004 as well as by NKBRSF (G19990754)

Abstract

Owing to Earth's rotation a free-fall body would move in an elliptical orbit rather than along a straight line forward to the center of the Earth. In this paper on the basis of the theory for spin-spin coupling between macroscopic rotating bodies we study violation of the equivalence principle from long-distance free-fall experiments by means of a rotating ball and a non-rotating shell. For the free-fall time of 40 s, the difference between the orbits of the two free-fall bodies is of the order of 10−9 cm which could be detected by an SQUID magnetometer because such a magnetometer can be used to measure displacements as small as 10−13 cm.