If the Sun were to spontaneously cease emitting light, we wouldn't know about it for about 8 minutes and 20 seconds. The light that's arriving here on Earth, right at this very moment, was emitted ...

Two black holes, each with accretion disks, are illustrated here just before they collide. The inspiral and merger of binary black holes provided humanity with our first direct measurement of ...

In Newtonian physics, gravity was thought to be instantaneous. But in Albert Einstein’s general theory of relativity, the speed of light, c, is the fastest possible speed for any interaction that ...