Spatial anisotropy in nonsymmetric gravitation theories.

We show that the energies of atomic states can depend strongly on an atom's orientation in space according to theories of gravity which couple the antisymmetric part of a nonsymmetric-tensor gravitational field to the electromagnetic field. Atomic-physics experiments designed to test the isotropy of space are directly sensitive to such orientation dependence. We derive a new constraint that these experiments impose on nonsymmetric theories and show how this constraint works with existing ones to establish that the magnitude of effects due to an antisymmetric-tensor component of the gravitational field must be more than 1000 times smaller than suggested in the recent literature on nonsymmetric theories.