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 ...

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 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 ...

Researchers at the University of Southampton in England have produced optical fibers that can transfer data at 99.7% of the universe's speed limit: The speed of light. The researchers have used these ...

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 ...