It's an analogy. The weirdness of QM comes from the following, slightly more complicated, situation. You have two cards, a red one and a blue one. You also h

It's an analogy. The weirdness of QM comes from the following, slightly more complicated, situation. You have two cards, a red one and a blue one. You also have two envelopes. Without looking at anything, you put one card in each envelope. You label them, and send one each to Alice and Bob. Now, we know for sure that when Alice opens her envelope and looks at the card, we immediately know which card Bob has. There is no information being exchanged, so Alice knows what card Bob has immediately when she opens her envelope. The weirdness of QM comes from looking at the intermediate states. i.e. the states before Alice opens her envelope. There are (waving wands) ways to tell what the intermediate states could be, by varying certain (QM) magical properties of the experiment. The weirdness of QM is this. Every single idea you have about the intermediate state is wrong. What do I mean by that? You could say there are "hidden variables". i.e. one envelope "really has" a red card in it, and the other envelope "really has" a blue card in it. This interpretation is wrong. Every experiment shows that the envelopes are in a "superposition" of states. That is, the envelopes don't contain either a red card or a blue card. They carry... something... that is maybe red and maybe blue. That seems strange, but OK. What happens when Alice opens her envelope? When Alice opens her envelope, the card which is "maybe blue, maybe red" suddenly becomes either 100% blue, or 100% red. The weird part is the next step. When Alice opens her envelope, Bob's card immediately becomes the opposite color. This happens no matter how far away Bob is from Alice. So is information traveling faster than the speed of light? No. We knew Alice's card was red or blue, so Bob's card must have been blue or red. Lo and behold, Bob's card turns out to be one of those colors. And yes, Bob's card really is in an indeterminate state prior to Alice opening her envelope. And once Alice opens her envelope, Bob's card really is 100% either red or blue. The confusion comes from what is really happening behind the scenes. i.e. What is the real explanation? The current QM research shows that the answer is "Uh... right... we're not actually sure." Somehow the two cards are connected (QM people say "entangled"), because when you look at one, the other immediately "decides" (?) what color it is. But there's no information being passed between the cards. There's nothing exchanged between the cards. Yet somehow Bob's card "knows" that Alice has looked at her card. This is profoundly strange and confusing. No one has any idea what's going on. Physicists have many theories, but it's difficult to either prove or disprove most of them. That takes time, money, expertise, etc. So we're left with "QM is strange". As Richard Feynman said, "QM is not only stranger than you can imagine, it's stranger than you can possibly imagine."