Black holes, whose very existence was first predicted by Einstein's theory of general relativity nearly a century ago, are the strangest objects in the universe. Thought to be produced when a super-giant star much larger than our Sun explodes in its final death throes, they are places where the normal rules of physics break down, where density becomes infinite, and where the force of gravity is so strong that even light can't escape, which is why they are called black holes. Their existence can never be seen even with the most powerful telescopes, but only inferred by the actions of their gravity on the space that surrounds them, such as when they swallow a star unfortunate enough to come within their grasp. They are also very difficult to find, which makes it all the more surprising that two were recently found at the same time, and residing in the same galaxy orbiting each other.
This auspicious discovery was made by the European Space Agency's (ESA) orbiting x-ray observatory XMM-Newton. The only reason the discovery was possible because of what is called a 'tidal disruption event' that occurred when one of the black holes swallowed a nearby star. This caused the massive eruption of x-rays and other cosmic particles that was detected by the satellite. The fact that the two black holes were found orbiting each other in the same galaxy is even more remarkable, and the only way scientists think this could have happened is if the two galaxies, each containing a black hole at its center, somehow merged, much as our galaxy and our nearest neighboring galaxy, Andromeda, are believed to be planning to merge billions of years from now. As astronomer Stefani Kormossa of the Max Planck Institute in Germany explained, by studying the data from this and similar events, astronomers hope to be able to determine the rate at which galaxies merge, which may provide clues to the ultimate fate of the universe.
As to what will happened to the two newly discovered black holes, they will probably continue to orbit each other for millions if not billions of years, gradually getting closer and closer until they finally merge, producing the most powerful explosion the universe has seen since the original Big Bang. Since the galaxy where the black holes are located is so far away, we shouldn't have much to worry about. In any event, we will probably be long gone before that happens.