I am studying the history of Quantum Mechanics and was reading about particle entanglement. What I would like to know is how did Einstein see that particle Entanglement meant that particles would be affected by spooky action at a distance. I guess that spooky action at a distance may also be associated to mean a form of connectedness. I would like to understand what led him to this conclusion? Put another way what is it in the formulations of QM that suggested that this particular phenomenon would occur? I am an avid reader of physics books and magazines so please feel free to give as much detail as you like.