Nothing that has a physical existence travels faster than light. In a vacuum it travels at 300,000km (186,000 miles) per second. We tend to think that we are seeing things as they are, but that is not quite true. We are seeing them as they were at the moment that the light left them to travel to us. Of course, for most purposes, as light travels so quickly, this makes no difference at all. It is only when we are looking at the stars, which are unimaginably huge distances away that we really are seeing the distant past. Light from our Sun takes about eight minutes to reach the Earth, but it takes less than a tenth of a second to travel across the Atlantic.
When Albert Einstein first predicted that light travels the same speed everywhere in our Universe, he essentially stamped a speed limit on it: 300,000 kilometres per second (186,000 miles per second) – fast enough to circle the entire Earth eight times every second.
But that’s not the whole story. In fact, it’s just the beginning. Before Einstein, mass – the atoms that make up you, me, and everything we see – and energy were treated as separate entities. But in 1905, Einstein forever changed the way physicists view the Universe. Einstein’s special theory of relativity permanently tied mass and energy together in the simple yet fundamental equation E = mc2.
This little equation predicts that nothing with mass can move as fast as light, or faster. The closest humankind has ever come to reaching the speed of light is inside of powerful particle accelerators like the Large Hadron Collider and the Tevatron.
These colossal machines accelerate subatomic particles to more than 99.99 percent the speed of light, but as Physics Nobel laureate David Gross explains, these particles will never reach the cosmic speed limit. To do so would require an infinite amount of energy and, in the process, the object’s mass would become infinite, which is impossible. (The reason particles of light, called photons, travel at light speeds is because they have no mass.)
Since Einstein, physicists have found that certain entities can reach superluminal (that means “faster-than-light”) speeds and still follow the cosmic rules laid down by special relativity. While these do not disprove Einstein’s theory, they give us insight into the peculiar behavior of light and the quantum realm.
Picture Credit : Google