This thread is following up on some comments being made in another thread by ttn and others, including myself. The basic questions are: i) Is QM inherently non-local? ii) If yes, when did this result become clear? These questions are offshoots of discussions of EPR and Bell. For most readers, posts to this thread will probably end up seeming to be a debate over fine points that may not matter. Or maybe they do matter... ----------- ttn has argued that QM is inherently non-local, and feels that result was known shortly after EPR. ttn is also, to some degree at least, a member of the Bohmian mechanics (BM) school although I do not purport to convey ttn's position. On the other hand, I have a more orthodox position on QM that is frequently associated with the Copenhagen interpretation (QM-CI). As such, I do not tend to go much further than the formalism. Of couse, I like to speculate as much as anyone. Regarding i) above: I do not believe QM is non-local, assuming certain definitions of locality. As has been pointed out previously: "According to quantum theory, action at a space-like separated region does not change the probability of an outcome of a local measurement." (The fact that anything "non-local" has occurred is never evident until such time as the space-like separated measurement results are brought together.) I would not characterize the above defintion of locality as universally accepted, although it is certainly popular enough. In fact, the very conclusions you arrive at are usually dependent on your definition of locality. On the other hand: if you want to explain the "perfect" correlations when you perform Bell tests at 0 degrees between the Alice and Bob polarizers, non-local effects seem to be a pretty good explanation too. Regarding ii) above: ttn has argued that the non-locality of QM was evident after EPR, in fact was a conclusion of EPR. I argue that it absolutely was not a conclusion of EPR. It is *possible* that some might deduce that from some readings of EPR. But it was never stated as such in the paper itself. ttn has also offered up a quote from Einstein's later writing in support of this position. However, I would like to point out the following. Einstein assumed locality was a fact. Since he assumed the predictions of QM were otherwise correct, he felt QM was incomplete and local reality would win in the end. Such a viewpoint would REQUIRE Einstein to believe that an test of the EPR paradox would show that the predictions of QM were wrong. I.e. there would certainly be no perfect correlations! But guess what!! That would mean that if the Aspect tests were performed without ever knowing about the Bell inequality, and instead simply as a resolution of the EPR paradox... that local reality would have been refuted. If that is true: WHAT DO YOU NEED BELL FOR? The fact is, Einstein would have been shocked at such results. But others would still have argued that local reality was not excluded. It took Bell to rule out ALL local realistic theories. But the caveat to that is that Bell still does not prove that QM is non-local. You must look elsewhere to draw this conclusion.