An experimental test of the inverse square law of gravitation at range of 0.1 m

Abstract

Theories attempting to unify gravitation with other interactions of Nature assume that the gravitational force arises from the exchange of particles. Several authors have predicted deviations, depending on the Compton wavelength of the particle assumed in different theories, from the inverse square law at laboratory distances. The deviation reported by Long (Nature, Lond. 260, 417 (1976)) shows that the Compton wavelength should be shorter than 2.2 m and longer than 1.8 m. The null experiment of Spero et al. (Phys. Rev. Lett. 44, 1645 (1980)) conflicts with this conclusion unless the gravitational vacuum polarization mechanism suggested by Long (Nuovo Cim. B 55, 252 (1980)) operates. Improved Cavendish type experiments (experiments in which forces are measured by a torsion balance as first done by Henry Cavendish) have been performed at the Cavendish Laboratory, both in non-null and null experimental modes. The result of the non-null experiment conflicts with that of Long and his suggestion, but is consistent with that of the experiment of Spero et al. (1980). The result of the null experiment shows that the Compton wavelength of the exchanged particle must exceed 4.9 m.