Mazur replies

Quantum mechanics of a test particle interacting with a spinning string (torsion vortex) is the quantum mechanics of the celebrated Aharonov-Bohm effect. The angular momentum per unit length J characterizing the spinning string corresponds to the magnetic flux Φ of the Aharonov-Bom fluxon and the gravitational mass-energy E of an incoming particle corresponds to the electric charge q. The characteristic periodicity of the gravitational Aharonov-Bohm scattering cross-section in the product of $GEJ$ has suggested a new quantization of mass-energy relation. We encounter a new physical situation where the gravitational mass-energy is quantized and the quantization condition contains both the Newton constant G and the Planck constant h.