Entanglement is a fucked up concept that I’m just starting to grasp.

Parametric down sampling, say, causes particles to split, and then certain states of the resultant particles must respect conservation.

So if the source particle had no spin, but the resultant particles must have spin, one will have minus half spin and the other will have plus half spin. Equals zero, which was the total spin of the source particle. Same deal with charges.

But they are not resolved until this wishy-washy “measurement” thing comes into the picture