In a distant galaxy, long ago, a pair of black holes, each about thirty times more massive than our sun, began to orbit one another. Over the next several hundred million years, gravitational waves generated by their motion caused them to spiral together, slowly at first but gathering speed as they came closer and closer, until they were whirling about one another at the same rate as the blades in a kitchen blender. They eventually slammed together at about a third of the speed of light, emitting a last burst of gravitational waves before settling down to the sedate life of an ‘ordinary’ black hole.
Read more about Music of the Spheres