For the first time, scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at Earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein's 1915 General Theory of Relativity and opens an unprecedented new window to the cosmos. Physicists have concluded that the detected gravitational waves were produced during the final fraction of a second from the merger of two black holes to produce a single, more massive spinning black hole. The gravitational wave-producing collision of two black holes had been predicted but never observed.