TWO weeks ago, a pair of scientists made the sensational announcement that they had measured the speed of gravity for the first time. But the claim has sparked a passionate debate among physicists over whether the researchers have measured anything other than the speed of light.
While Newton thought gravity acts instantaneously, Einstein’s theory of general relativity assumes that the force of gravity propagates at the speed of light. This means that if the Sun were suddenly plucked out of the Solar System, the Earth would stay in orbit for 8.3 minutes – the same time as it takes light…
