Your experience of time is relative because it depends on motion – more specifically, your speed and acceleration.

People like George FitzGerald and Hendrik Lorentz, working in the 19th century, derived something spectacular: that when you got close to the speed of light, the Universe you observed appeared to ...

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 ...

All matter moves through space-time at the universal constant— the speed of light— but this speed is shared between motion in space and the flow of time. Objects don’t speed up beyond light ...

Light is fast. At 186,282 miles per second, it's the fastest thing there is, but even our quickest universal constant is slowed to a crawl by the vastness of space.

But the speed of light itself never changes through the vacuum of space. This idea was revolutionary when Einstein proposed it, with many professional physicists (wrongfully) resisting it for decades.

The spaceship is going super fast—like half the speed of light (0.5 c). You can see the light in the light clock moving at just c, since everyone sees light at that speed.

The fastest things ever made by humans are spacecraft, and the fastest spacecraft reached 330,000 mph – only 0.05% the speed of light. But there are ways to go faster.

Here's what the speed of light looks like. (Image credit: The Slow Mo Guys/YouTube) Amazingly, 100 billion frames per second is only a fraction of what the CalTech camera is capable of capturing.

The cube and the sphere were deformed to mimic length contraction — the cube, simulated to be moving at 80% of the speed of light, was actually a cuboid with an aspect ratio of 0.6, while the ...