THE SPEED OF LIGHT
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Light travelling through a vacuum moves at 299,792,458 metres (983,571,056 feet) per second – a universal constant known in equations as ‘c’, or the speed of light. According to Einstein’s theory of special relativity, nothing in the universe can travel faster than light. The theory states that as matter approaches the speed of light, that matter’s mass becomes infinite. That means the speed of light functions as a speed limit on the whole universe.
The speed of light is so immutable that it’s used to define international standard measurements like the metre. Through some crafty equations, it also helps define the kilogram and the Kelvin. But despite the speed of light’s reputation as a universal constant, scientists and science-fiction writers alike spend time contemplating faster-than-light travel. So far, no one’s been able to figure out how to travel at such speed. But that hasn’t slowed our collective hurtle towards new stories, new inventions and new realms of physics
A light year is the distance light can travel in one year – about 10 trillion kilometres (6 trillion miles). It’s one way astronomers and physicists measure immense distances across our universe. Light travels from the Moon to our eyes in about one second, which means the
