By golly, after all this time, I think I got it. You have to first start with the understanding that the spin of an entangled particle is indeterminate until you observe it. It’s not just that you don’t know the spin, it effectively doesn’t exist until you observe. The spin (and whether it is +1 or -1) is in the same state of complete uncertainty as is the health of Dr. Schrodinger’s poor cat. Just as the cat is neither alive nor dead, until you look, the spin is neither +1 or -1 until you look.
So when you do decide to look you don’t just see what the spin is for the first time, the spin is determined for the first time. What we know about entangled particles is that whatever we observe it to be, that its pair will be the opposite, no matter how far away that pair might be. So if I observe “my” electron and it is +1 I also know that its entangled brother is -1 no matter how far away it may be. Good for me.
Likewise an observer of the entangled brother, simultaneously seeing it is -1 knows “my” electron +1. But since neither electron was +1 or -1 until someone looked there is nothing to be gleaned here in the way of information.
Back on my end I want to send a message to my friend with the -1 electron. So I compel my electron to change to -1 hoping that will change my friend’s to +1. However, that does not happen because “forcing” a determined state on my electron breaks the entanglement. Since entanglement is dependent on uncertainty my elimination of uncertainty “spoiled” the entanglement. The mere act of trying to send a single message breaks my “quantum telegraph.”
To use the coin analogy in Ethan’s article, let’s take two entangled coins. If one flips heads, the other will end up tails, and vice versa. Thus, if I flip a coin, look at it, and see it is heads, I know the other coin flipped far away by my friend ended up tails.
Because of uncertainty both our coin flips were still random. Until we (or at least one of us) look we don’t know what that result will be. So I look and see my coin is heads, telling me my friend has the tails coin (and vice versa).
But if I flip my coin and cheat to make it come up heads, then the entanglement between them is broken and what my friend’s coin comes up as is not connected to what my coin will come up as.
Do I basically got it?