How fast does light travel? Scientists have known for a long time that light always travels at the same speed: 299,792,458 metres per second.
The speed of light is the fastest speed that all energy, matter and information in the universe can travel.
The speed of light is very important in science. Because it is always the same – it is a known constant – it defines many things, including the length of a metre.
Using the speed of light scientists calculate many things. The speed of light is part of Einstein’s famous theory of relativity, E=mc2.
That is why there was such a shock within the scientific community this week when it was announced that a group of scientists has been recording some particles going faster than the speed of light.