Among the most powerful but as yet undetected events in the universe are the mergers of supermassive black holes. These billion-solar-mass monsters, residing in the centers of large galaxies, can glom together during galactic collisions after a spiraling dance, as shown here. The colorful bands represent propagating gravitational fields, while the gray spheres indicate the black holes' event horizons, the boundary from within which not even light can escape.

Albert Einstein's general theory of relativity predicts that black hole mergers should send out intense blasts of gravitational waves, ripples in space-time. Scientists are learning how to detect and recognize those waves by studying supercomputer models run at two NASA campuses, the Ames Research Center at Moffett Field, California, and the Goddard Space Flight Center in Greenbelt, Maryland. The simulations reveal that the recoil from the combining of black holes could shoot the resulting merged supermassive black hole right out of its galaxy.