Einstein’s gravitational waves rest on a genuinely radical idea.
After decades of anticipation, we have directly detected gravitational waves—ripples in spacetime traveling at the speed of light through the universe. Scientists at LIGO (the Laser Interferometic Gravitational-wave Observatory) have announced that they have measured waves coming from the inspiral of two massive black holes, providing a spectacular confirmation of Albert Einstein’s general theory of relativity, whose hundredth anniversary was celebrated just last year.
Finding gravitational waves indicates that Einstein was (once again) right, and opens a new window onto energetic events occurring around the universe. But there’s a deeper lesson, as well: a reminder of the central importance of locality, an idea that underlies much of modern physics.