[Toutouxc]

The way I understand it, this is exactly the simplified (and incorrect) explanation.

Say SOMEONE ELSE puts the marbles in two envelopes and sends them to you and your friend in Australia. (it's someone else because we don't actually create the entangled particles, we just "get" them)

The marbles being red and blue (or both red or both blue, depending on what you're measuring) from the beginning would be a LOCAL hidden variable. It's local because it's been predetermined at the moment of creation and the marbles carry the property on themselves and it's hidden because you don't know how/why the person putting the marbles in those envelopes decided those colors and you can't see them until you open the envelope (measure the particle).

This way if you don't open your envelope, your friend's envelope contains a marble that's 50/50 red or blue and the color will be the predetermined one no matter what you do with your marble at home. So whatever decides the marble's color has nothing to do with your marble, it's local to the friend's one.

The actual measurements work differently. It's been experimentally proven many times that at the moment you look at your marble, the other marble's 50/50 probability of being red and blue shifts substantially to, for example 75/25. And that's without it having any way of knowing that you've seen your marble. So there are hidden variables that we don't understand, but they're not local. They somehow affect both marbles.

In real life there aren't only two colors and the probabilities aren't those nice numbers, but you get the principle.

[wnoise]

> The actual measurements work differently. It's been experimentally proven many times that at the moment you look at your marble, the other marble's 50/50 probability of being red and blue shifts substantially to, for example 75/25. And that's without it having any way of knowing that you've seen your marble. So there are hidden variables that we don't understand, but they're not local. They somehow affect both marbles.

This is completely incorrect, to the point where what you were trying to correct was actually more accurate, though incomplete.

The usual setup is that for any given axis, each person always measures 50:50. Measuring your own doesn't change the odds of the other.

Knowing the _results_ of your own does. For the same axis, the correlation is exact. For axes with an angle theta between them, we get a correlation of R ~ cos(theta/2).

The upshot is that there is no underlying (classical) probability distribution that can give rise to this that can explain things for all measurement axes. This is sometimes glossed as "correlation without correlata".

[Toutouxc]

I was trying to make the original marbles in envelopes comparison work a little better (the "holy f*ck this doesn't make sense" aspect), not to actually explain the phenomenon. I hope no one got confused. There's plenty of better sources and smarter people to get the accurate explanation from.

[Jemaclus]

> The actual measurements work differently. It's been experimentally proven many times that at the moment you look at your marble, the other marble's 50/50 probability of being red and blue shifts substantially to, for example 75/25. And that's without it having any way of knowing that you've seen your marble. So there are hidden variables that we don't understand, but they're not local. They somehow affect both marbles.

The rest of your explanation was super easy to grok (thank you!) but this part I can't wrap my head around. If the balls can be red or blue, and it's 50/50 before, how would the probability go to 75/25? I would expect it to either stay at 50/50 (no change) or to 100% (because the other ball is known).

Can you elaborate on this part? This is really fascinating.

[jayd16]

This explanation seems like it can't be correct and must be a simplification as well. If this was measurable in a way that's described here you'd be able to transmit information.

I always imagined the two "marbles" as possibly being two similar but differing clocks instead. The clocks will align more or less often depending on how similarly they're set and how fast each run. With this analogy you can come up with any distribution that fits your fancy.

Its probably a silly analogy but it lets me cling my notions of no spooky action.

[smusamashah]

So me and my friend are continuously getting those envelopes. I am opening all the envelops one after another and found that they are distributed 50/50 to red/blue.

Same if my friend is opening the envelops.

Now for all the opened envelops if I have got 10 red balls. Now if my friend open the paired envelops, he will probably get 7 blue and 3 red.

My observation of the balls had an effect on his side and shifted probabilities on his side.

If that's what you mean, what does observation or measuring even mean? How do the balls know the envelop has been opened.

[nojokes]

Can you explain how is this shift in probability measured?

[GoblinSlayer]

The experiment is repeated many times, statistics is computed over results, and gives probabilities and correlation.

[tsian2]

How much work has been put into ensuring that the observed samples aren't biased?

[iudqnolq]

What do you think? Is mainstream physics about to go "oh shit, we didn't take into account that we might be biased. Thank you random person on the internet for pointing this out".