What makes it so that quantum mechanics doesn’t break locality in entanglement yet hidden variable theories will?
In Bell‘s inequality said that hidden variables theories need to break locality in order to match experiment result. But why on the other hand quantum mechanics are able to preserve locality?
On the internet I found out two explanation on why quantum mechanics doesn't break locality in entanglement:
Since you can't choose what a particle collapsed into, technically you didn't transferred information faster than light
You didn't exchange information faster than light because you are only exchanging information when two observers came together and compare the result, which the process isn't faster than light
So first of all, which is correct? And why can't hidden variables theories use the same explanation?
Also, quantum mechanics noted that if you observers one particle, it'll immediately collapse the other. So does it mean that the signal of "hey I'm observed so go collapse" not consider as part of communicating faster than light? I mean gravitational waves travels only at the speed of light. So if you consider collapse as destroying the structure of the wave in the wave function, it shouldn't be able to immediately collapse the other particle, isn't it?