No Quantum Nonlocal Effects

This is an elementary fact about quantum mechanics.

Dr. Bee explains:

Most importantly, if you do something to one of the pair of entangled particles, 4:46 that does nothing to the other. Say you turn the spin of the particle on the right upside-down 4:53 even though you don’t know what it is. Then the spin of the other particle doesn’t change at all. 4:59 No, it doesn’t. You wouldn’t believe how often I see even physicists get this wrong. I just 5:05 the other day heard a talk from someone who works on quantum computing for heaven’s sake 5:10 who said that if you manipulate one of a pair of entangled particles then that will non-locally 5:16 affect the other. It will not. It’s just that if you make a measurement on one of the particles, 5:23 then that will tell you something about the other. Because they’re correlated. ...

The person who 5:50 makes a measurement on one end can’t tell that a measurement was even done on the other end. 5:56 So: Entanglement is real, we know that. Whether spooky action is real is still a matter of debate, 6:04 but you can’t send information faster than light with either.

She is correct. No one has ever found any nonlocal quantum effects. Just correlations.

It should not be complicated. The same happens classically.

What she says about "spooky action" is a little confusing, so here is her explanation.

2:36 Strange or not, Bohr said that when we measure a particle, 2:40 this superposition “collapses” and suddenly the particle is in only one place. It’s this collapse 2:47 that Einstein referred to as spooky action. Because it would indeed be faster than light. 2:53 The moment you find the particle in one place, you instantaneously know it can’t be elsewhere. 3:00 Einstein disagreed with Bohr. Einstein thought that quantum particles are really only in one 3:06 place and that the sudden update of the wave-function just means that you 3:10 have learned the particle isn’t elsewhere. And his main argument, here it comes, was that by 3:17 claiming the collapse is a physical process, Bohr was introducing a “spooky action at a distance”. 3:26 Even if this spooky action existed though, it couldn’t transfer information. Just because you 3:32 find out what’s going on elsewhere doesn’t mean you sent information there.

When you find a classical particle, you immediately know it cannot be elsewhere. If that is spooky, then classical mechanics is spooky. Regardless, no information or anything else goes faster than light.

Usually she branches into a plug for superdeterminism. Mercifully, she did not this time.