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?

There is a speed limit in the universe. While many great science fiction stories require this limit to be broken, right now, we are stuck at not going any faster than the speed of light. It is exactly ...

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 ...