eli5 how do we know nothing is faster than light?

Question

eli5 how do we know nothing is faster than light?

In: 452

Answer 1

A long time ago, scientists discovered that massless things (incl. light) always move at the exact same speed, regardless of how fast the source or measurement system is moving.

A very smart guy named Einstein used this fact to do some math. He found that accelerating anything up to the speed of light, takes infinite energy. Which is impossible. Even more importantly, he found that getting mass to go faster takes an imaginary amount of mass. Which is even more impossible.

And things without mass go at exactly the speed of light – no slower, no faster.

Either way, Einstein’s math makes one thing very clear: nothing can go faster than light.

And this math that Einstein did, predicted a bunch of other things. Things scientists can test. Scientists like running tests, so they did (and still do) a lot of them.

And all those tests, match Einstein’s predictions exactly.

So scientists have only one option – accept that Einstein was right.