Can someone explain the 2022 nobel physics winner’s experiments and what they prove more simply?
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Quantum mechanics is a well established theory, but predicts many weird effects. One of these is that particles can become “entangled”which means that they share some properties. Then these particles can move apart, but the entanglement is retained. If we measure the property of one we will know instantly the property of the other. So far so simple, but the key thing is that the particles don’t have the property in common, and we just look at it. They exist in a superposition, meaning it could go either way. Then the act of measurement “collapses the wavefunction” meaning that the measured particle randomly “chooses” which option it has. That information is then passed instantly to the other particle, violating our understanding of how information can only travel at the speed of light.
One way to avoid this contradiction is to invoke “hidden local variables”. Basically we say that maybe the two particles do actually agree on which way they will go ahead of time, and that information is stored in the hidden variables. This is great at avoiding the contradiction (preserving “local realism”), but isn’t actually predicted by the scientific theory.
Someone called John Stewart Bell pointed out that under certain conditions a pair of entangled particles would behave differently under standard quantum mechanics vs if hidden variables are real. This allows an experiment to be set up to test which theory is actually real.
One of the winners, Clauser, was the first to do such an experiment, but the setup had flaws called “loopholes”. Another winner, Aspect, closed some of them. It has taken 50 years to be confident we have closed all the loopholes and that local hidden variables don’t exist.
So the result is to confirm that this aspect of quantum mechanics really is as weird as it seems, that entangled particles really do “communicate” faster than the speed of light. The way that the experiments were set up varies widely, so it’s a bit hard to explain all of them. Basically you measure a bunch of entangled particles and see how the random distribution turns out.
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