Classical Gravitational Interactions and Gravitational Lorentz Force
  In quantum gauge theory of gravity, the gravitational field is represented by gravitational gauge field. The field strength of gravitational gauge field has both gravitational electric component and gravitational magnetic component. In classical level, gauge theory of gravity gives out classical Newtonian gravitational interactions in a relativistic form. Besides, it gives out gravitational Lorentz force which is the gravitational force on a moving object in gravitational magnetic field. The direction of gravitational Lorentz force does not along that of classical gravitational Newtonian force. Effects of gravitational Lorentz force should be detectable, and these effects can be used to discriminate gravitational magnetic field from ordinary electromagnetic magnetic field. 
Ning Wu