The speed of light is a fundamental constant, approximately 299,792,458 meters per second. It's the same for all observers and hasn't changed measurably over billions of years. Nothing can travel ...

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 ...

The internet is such a slowpoke. In principle, it should operate at nearly the speed of light, which is more than 670 million miles per hour. Instead, internet data moves 37 to 100 times slower than ...

Chris Impey receives funding from the National Science Foundation and the Hearst Foundation. Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, ...

The constancy of the speed of light is a pillar of modern physics, but questions persist about its absolute universality.

Nothing can move faster than the speed of light. When Einstein set forth his theory of relativity, this was his inviolable postulate: that there was an ultimate cosmic speed limit, and that only ...

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 ...