The speed of light remains one of physics’ firmest assumptions, but scientists still test whether it ever shifts under extreme conditions. A new review draws together decades of observations, ...

Astronomers have found what is currently the fastest known star in the Milky Way, a faint star racing through the extreme ...

Einstein’s claim that the speed of light is constant has survived more than a century of scrutiny—but scientists are still daring to test it. Some theories of quantum gravity suggest light might ...

On one hand, the speed of light is just a number: 299,792,458 meters per second. And on the other, it’s one of the most important constants that appears in nature and defines the relationship of ...

Add Yahoo as a preferred source to see more of our stories on Google. A new review tightens limits on whether light changes speed in deep space, sharpening one of physics' most important tests.