Gravitational waves—ripples in space-time caused by violent cosmic events—travel at the speed of light in every direction, eventually fading out like ripples in water. But some events are so destructive and extreme that they create disturbances in spacetime more like powerful waves than small ripples, with enough energy to reach our own detectors here on Earth.  Today, the LIGO Collaboration announced the detection of the most colossal black hole merger known to date, the final product of which ...