[nemothekid]

Maybe this is a basic question - but what I don’t understand is why this is called “spooky” action.

My intuition is you have two particles, and you don’t know what concrete states they are in, but you know all possible states (that may be represented as some sort of system of equations).

By observing a single particle you unlock a variable in that system of equations and can therefore solve the whole thing. To me it would be more straightforward to say the concrete state of the particle is simply unknown until it is observed. The concept of superposition seems like an overly complex description for this phenomenon.

I understand my view is wrong, but I don’t understand how I’m wrong

[tabtab]

Here's a layman's explanation of why "hidden local variables" theory doesn't match experiments:

https://www.wired.com/2014/01/bells-theorem/

In other words, modeling particle pairs as having matching static hidden "meta data" in them doesn't work. They do act as if there is instantaneous communication between the particles, but in a limited way that prevents us from using them for instant communication. Quantum mechanics is a weird tease, having magical properties that always serve up loopholes when we try to leverage the magic for real-world benefits. The quantum universe seems built by insurance lawyers who are masters at screwing consumers with fine-print when they go to make a claim.

[EliRivers]

I observe my particle here, and in doing so its state is decided.

The state of the entangled particle over there, a light year away (for example) is also decided. Instantly. Faster than the speed of light. Nothing travelled from here to there. No particle, no photon, nothing. How does over there "know" that I did something over here?

Sure feels kind of spooky.

To me it would be more straightforward to say the concrete state of the particle is simply unknown until it is observed.

It's not just unknown. It's undecided. It has no concrete state. It's not that it IS a one or a zero and you just don't know it. It's not yet been decided whether it's a one or a zero, but as soon as the decision is made for one of the entangled particles, the decision is also made for the other one, a light year away. Instantly. Spooky.

[rrss]

What you are describing is a hidden variable theory - i.e. there is some concrete state of the particles, but it is hidden.

John Bell demonstrated that in order for a hidden variable theory to make predictions in agreement with quantum mechanics, it must have nonlocal interactions, which means any workable hidden variable theory must also be pretty spooky.

https://en.wikipedia.org/wiki/Bell's_theorem