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?

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 ...

How do we know the speed of light – and why does it have a speed limit at all? Leah Crane explores the history of one of the ...

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 ...

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 ...

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 glow from faster-than-light particles gives us a unique way to explore the universe. Nothing can travel faster than light — in a vacuum. But when light slows down, sometimes matter can blaze past ...

Simply put, if I were to shine a beam of light between two plates that were close enough to exhibit the attraction of the Casimir effect, would the speed of light as it travels parallel to the plates ...