I’m not surprised that you’re not surprised :D EPR’s paper introducing the superluminal entanglement thought experiment was published in 1935, and they basically said what you did—that clearly quantum mechanics was incomplete, and there was some way that the spins had decided which was which beforehand.
Bell’s theorem, which uses a significantly more complicated situation to demonstrate why that’s not possible, was published in 1964. So it took an entire field about 30 years to see why entanglement should be surprising!
Also, if you want more “surprising” aspects of entanglement, I think superdense coding is a nice example. Basically, sharing an entangled qubit does let you send information, but only after you also send one more qubit in an ordinary way. This is very not possible with hidden variables.
I’m not surprised that you’re not surprised :D EPR’s paper introducing the superluminal entanglement thought experiment was published in 1935, and they basically said what you did—that clearly quantum mechanics was incomplete, and there was some way that the spins had decided which was which beforehand.
Bell’s theorem, which uses a significantly more complicated situation to demonstrate why that’s not possible, was published in 1964. So it took an entire field about 30 years to see why entanglement should be surprising!
Also, if you want more “surprising” aspects of entanglement, I think superdense coding is a nice example. Basically, sharing an entangled qubit does let you send information, but only after you also send one more qubit in an ordinary way. This is very not possible with hidden variables.