Do black holes send ripples of gravity through space?
Einstein’s theory of gravity predicts that black holes can send ripples of gravity through the fabric of space itself. NASA’s LISA space mission, planned for launch within a decade, should be able to detect these waves of gravity – acting as a kind of cosmic “seismograph.” High on the cosmic Richter scale of quakes should be the collision of two black holes, or of a black hole with another star. LISA’s ability to detect colliding black holes is only the first step in its voyage of discovery. Gravity waves are a completely new tool with which to explore the universe. Gravity-wave astronomy complements traditional astronomy, and can reveal events in the universe that could not be explored using light and conventional telescopes. Can we see a black hole being formed? About once a day, there is a dazzling flash in the sky. It is not a flash of visible light, but a flash of gamma rays, a high-energy form of light even more powerful than X-rays. These flashes, called gamma-ray bursts, come f
