A regular old black hole is creepy enough, as these time-bending regions of space allow nothing to escape from their grasp. The only thing scarier than a supermassive black hole is a bunch of black holes screaming across the galaxy at nine-hundred million miles per hour. If you were to try and imagine what something called the Bootes void might look like, you may have to take yourself off for a quick cold shower. Dark Flow is the name scientists have given to the mysterious force which they have detected beyond the borders of our visible universe.
Source: Strange Mysteries