Quantum Entanglement & Spooky Action at a Distance

I can't recommend Veritasium and CGP Grey enough. They are amazing YouTube Channels! Check out this video where Veritasium explains Quantum Entanglement. [VIDEO] It amazes me how he explains something so difficult in less than 10 minutes!

Check out [VIDEO] It's my favorite video for explaining how we know that the state is not determined until it has been measured. It's not just a decision we thought up on paper. It is real and well proven.

If quantum-entangled particles exist (they do) you can use them to coordinate in a way that's impossible within a "hidden variable" model of the universe. You can dig into this by searching for "bell's inequality" or "bell test experiments", there are a few different experiments that have been done many, many times. There's a pretty good Veritasium video that explains one such experiment in non-physicist terms: [VIDEO]

[VIDEO] is a good overview that I really like for Bell's inequality. Worth a watch if you have the time.

I don't think that explanation is clear. It takes a bit more work to get something which proves the experimental difference. One of the better explanations I've seen is regarding measuring spin with three state detectors: [VIDEO] This would give specific probabilities to certain outcomes (not just 50/50) IF there were a local hidden variable. (Note: the word local is important there. It means information encoded and carried by or with the particles themselves.)

If you watch for more than 4 minutes, this 9 minute video explains how Bell proved that the particles can't have been given opposite "ball colors" at the time they became entangled. [VIDEO] It's quite clever how he proved it, and that it's actually possible to rule out "information that we're just not aware of".

> it's both simply because it hasn't been measured ... Meaning it's either one or the other A common misconception about quantum superposition is that the particle "has" some state, and we only use superposition to model that we "dont know". This is called the hidden-variable theory ( [LINK] ). It's been proven that this hidden variable theory can't be true because of [LINK] . This is completely non-intuitive. See this video for a laymen's explanation: [LINK] (you may also need to watch the prev. video about the EPR paradox [LINK] ). Edit: actually, this is a much better video [VIDEO] - less technical and more visual.

Your example is akin to the Hidden variable theory (in the example the hidden variable will be the fact the two letters are copies). Bell's inequality tests have ruled out the hidden variable theory. Veritasium has a good video explaining Bell's inequality - [VIDEO]