PROFESSOR MANU PARANJAPE

We propose an experiment to directly detect the consequence of the finite speed of propagation of changes in the gravitational field and to measure this speed. Our analysis is based on the idea that if one is able to detect the static gravitational field of a massive body in the laboratory, then moving that body induces changes in the gravitational field that propagate to the detector with a finite delay. We assume that the delay is equal to the distance between the body and the detector divided by the speed of propagation. Moving just one body in the presence of a detector simply introduces the corresponding changes in the gravitational field at the position of the detector at the appropriately advanced time. However with two or more bodies moving in the presence of the detector, it is easy to conceive of a situation where the changes in the gravitational field at the position of the detector will contribute constructively or destructively. Observing this interference should be possible would allow for the determination of the speed of propagation of the changes in the gravitational field.