VELOCITY OF GRAVITATIONAL WAVES

OBSERVATIONS by Weber1 indicate that waves may exist in the gravitational field in space. Wave motion in general requires transfer of energy between two modes of energy storage. The existence of gravitational waves in space thus requires a further system of energy storage coupled with that in the regular gravitational field. The field system for gravitational waves may be analogous to the system of magnetic and electric fields that accounts for electromagnetic waves. In the gravitational case, the analogue of the magnetic field is a spin-spin coupling force between rotating masses2. This force is expected to be very small in any experimental arrangement now possible in a physics laboratory on Earth because the gravitational coefficient η analogous to μ (magnetic permeability of space) for magnetic fields is equal to G/S2, where G is the universal gravitational constant and S is the velocity of propagation of gravitational forces in free space, which in general relativity theory is frequently assumed to be the velocity of light. © 1969 Nature Publishing Group.