Gravity's ghost

In theory, at least, gravitational waves do exist. Scientists tell us we are constantly bathed in gravitational radiation, which is generated when stars explode or collide, and a portion of their mass becomes energy that ripples out like a disturbance on the surface of a serene pond. But unfortunately no gravitational wave has ever been directly detected, even though the search has lasted more than forty years. That's why, when a sudden burst of energy was detected recently by the giant laser Interferometer Gravitational Observatory, scientists were both cautious and optimistic. Could this be…