Gravitational waves and where to find them

Advanced LIGO has just begun its search for gravitational waves. For thousands of years, astronomy was the province of visible light, that narrow band of colors the human eye can see. In the 20th century, astronomers pushed into other kinds of light, from radio waves to infrared light to gamma rays. Researchers built neutrino detectors and cosmic ray observatories to study the universe using particles instead. Most recently, another branch of lightless astronomy has been making strides: gravitat...