Field energies and principles of equivalence

THE radial free fall motion of a charged body in a gravitational field is calculated here. A simple approach is presented, which includes the effects of the electrostatic and gravitational field energies of the falling body. The result shows that the acceleration is dependent on both mass and charge of the falling body and that both gravitational and electrostatic field energies gravitate repulsively, indicating that bodies of larger mass or larger charge will fall more slowly than bodies of lesser mass or smaller charge. Thus Einstein's principle of equivalence is not valid, as it requires that all physical systems experience the same acceleration of gravity. The approach also shows the difference between inertial and gravitational mass in a gravitational field. © 1978 Nature Publishing Group.