There Is Something Faster Than Light

In 1935, Einstein [music] came up with a thought experiment that showed quantum mechanics breaks one of the most sacred principles [music] in physics, that nothing can go faster than the speed of light. Physicists assumed he was wrong. [music] They thought that at 56, Einstein was an old man past his prime and just unable to accept the new theory of physics because it [music] was too radical. But 30 years later, one man stumbled across Einstein's forgotten paper when he realized something.

The prediction could actually be tested. When scientists ran the experiment, they were shocked. Quantum physics really does break the universal [music] speed limit. We're obliged to invoke something like actions going faster than light from one place to another.

>> This is a video about one of the spookiest [music] and most misunderstood experiments in all of physics. And it [music] might even be the strongest evidence we have that we live in many worlds. If the sun were to disappear all of a sudden, how long would it take until we noticed and were released out into space? Newton's theory says that gravity acts instantly across any distance.

So, if there's a change in gravity, we should feel it immediately. But Newton himself was disturbed by this. That one body may act upon another at a distance is to me so great an absurdity that I believe no man who has a competent faculty of thinking can ever fall into it. But in 1905, Einstein realized [music] action at a distance isn't just absurd.

It leads to outright paradoxes. Einstein had discovered that observers moving at different speeds can disagree about when events happened. Let's say you see two things happen at the same time. An observer speeding past would see it differently.

To them, one of these happened first, and both points of view are equally valid. But in the case of gravity, this leads to disaster. Say you see the sun disappearing and earth flying off at the same time as Newton predicted. Then the other observer sees something impossible.

They see the earth flying off first even while the sun is still there. And it should of course be pulling the earth in. So to them it looks like cause and effect are reversed. The only way out of this paradox is to reject the assumption we started with.

So gravity ...