hey there MTW mention that the mass energy of the Earth moon system is less than the mass energy that the system would have if the 2 objects were at infinite separation. MTW say that it is due to gravitational forces. Please correct me if I'm wrong : The fact that the moon follows a geodesic of the Earth's gravitational field, means that the Earth is exerting a force on the moon which means Earth is losing energy due to that. The gyroscope precession also is due to the rotation of the Earth and the dragging of the spacetime => means the gravitational force is responsible for that. As long as Earth has mass, it bends spacetime => it will always have a gravitational field force . Can we extract a 'free' energy from that ? Thanks, A lone navigator in the MTW jungle.