Watch an animation of a black hole shooting jets of particles through a "collapsing star at nearly the speed of light" and ...

The universe has a speed limit, and it's the speed of light. Nothing can travel faster than light — not even our best spacecraft — according to the laws of physics. So, what is the speed of light?

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 ...

Breakthroughs, discoveries, and DIY tips sent six days a week. Terms of Service and Privacy Policy. Back in 2018, astronomers examining the ruins of two collided ...

In 1676, by studying the motion of Jupiter's moon Io, Danish astronomer Ole Rømer calculated that light travels at a finite speed. Two years later, building on data gathered by Rømer, Dutch ...

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 ...

Light is the fastest-moving thing in the universe. So what would happen if the speed of light were much, much slower? In a vacuum, the speed of light is about 186,000 miles per second (300,000 ...

Light is faster than anything else in the known universe, though its speed can change depending on what it's passing through. When you purchase through links on our site, we may earn an affiliate ...