General Relativity V

In the heart of a distant galaxy, two supermassive black holes are whirling around each other once every 18 months. They create tiny ripples in space itself, known as gravitational waves. These ripples cause the black holes to spiral even closer together. Eventually, they’ll merge, creating an outburst of gravitational waves that’ll make space ring like the peal of a church bell.
Scientists are already looking for outbursts from similar mergers, as well as other violent events. They’ve completed upgrades to large detectors in the United States and Europe. And they’re launching a small satellite that’ll test the technologies for a space-based detector in a couple of decades.
Gravitational waves are predicted by Albert Einstein’s theory of gravity, known as general relativity. The theory says that any moving object creates such ripples. The ripples are so tiny, though, that they haven’t been detected.
There’s plenty of evidence of gravitational waves. For example, scientists have mea