John Stewart Bell Quotes (1928-1990)

“Bohr was inconsistent, unclear, willfully obscure and right. Einstein was consistent, clear, down-to-earth and wrong.”

“The concept of 'measurement' becomes so fuzzy on reflection that it is quite surprising to have it appearing in physical theory at the most fundamental level... does not any analysis of measurement require concepts more fundamental than measurement? And should not the fundamental theory be about these more fundamental concepts?”

“The theorem tells you that maybe there must be something happening faster than light, although it pains me even to say that much. The theorem certainly implies that Einstein's concept of space and time, neatly divided up into separate regions by light velocity, is not tenable. But then, to say that there's something going faster than light is to say more than I know.”

“Thus the formal proof of von Neumann does not justify his informal conclusion: 'It is therefore not, as is often assumed, a question of reinterpretation of quantum mechanics - the present system of quantum mechanics would have to be objectively false in order that another description of the elementary process than the statistical one be possible.' It was not the objective measurable predictions of quantum mechanics which ruled out hidden variables. It was the arbitrary assumption of a particular (and impossible) relation between the results of incompatible measurements either of which might be made on a given occasion but only one of which can in fact be made.”

“Theoretical physicists live in a classical world, looking out into a quantum-mechanical world. The latter we describe only subjectively, in terms of procedures and results in our classical domain.”

“To know the quantum mechanical state of a system implies, in general, only statistical restrictions on the results of measurements. It seems interesting to ask if this statistical element be thought of as arising, as in classical statistical mechanics, because the states in question are averages over better defined states for which individually the results would be quite determined. These hypothetical 'dispersion free' states would be specified not only by the quantum mechanical state vector but also by additional 'hidden variables' - 'hidden' because if states with prescribed values of these variables could actually be prepared, quantum mechanics would be observably inadequate.”

“The physicists didn't want to be bothered with the idea that maybe quantum theory is only provisional. A horn of plenty had been spilled before them, and every physicist could find something to apply quantum mechanics to. They were pleased to think that this great mathematician had shown it was so. Yet the Von Neumann proof, if you actually come to grips with it, falls apart in your hands! There is nothing to it. It's not just flawed, it's silly. If you look at the assumptions made, it does not hold up for a moment. It's the work of a mathematician, and he makes assumptions that have a mathematical symmetry to them. When you translate them into terms of physical disposition, they're nonsense. You may quote me on that: The proof of Von Neumann is not merely false but foolish!”

“There is a way to escape the inference of superluminal speeds and spooky action at a distance. But it involves absolute determinism in the universe, the complete absence of free will. Suppose the world is super-deterministic, with not just inanimate nature running on behind-the-scenes clockwork, but with our behavior, including our belief that we are free to choose to do one experiment rather than another, absolutely predetermined, including the ‘decision’ by the experimenter to carry out one set of measurements rather than another, the difficulty disappears. There is no need for a faster-than-light signal to tell particle A what measurement has been carried out on particle B, because the universe, including particle A, already ‘knows’ what that measurement, and its outcome, will be.”

“There is a way to escape the inference of superluminal speeds and spooky action at a distance. But it involves absolute determinism in the universe, the complete absence of free will. Suppose the world is super-deterministic, with not just inanimate nature running on behind-the-scenes clockwork, but with our behavior, including our belief that we are free to choose to do one experiment rather than another, absolutely predetermined, including the ‘decision’ by the experimenter to carry out one set of measurements rather than another, the difficulty disappears. There is no need for a faster-than-light signal to tell particle A what measurement has been carried out on particle B, because the universe, including particle A, already ‘knows’ what that measurement, and its outcome, will be.”

“The Copenhagen interpretation is a very ambiguous term. Some people use it just to mean the sort of practical quantum mechanics that you can do — like you can ride a bicycle without really knowing what you're doing. It's the rules for using quantum mechanics and the experience that we have in using it. […] Then there's another side to the Copenhagen interpretation, which is a philosophy of the whole thing. It tries to be very deep and tell you that these ambiguities, which you worry about, are somehow irreducible. It says that ambiguities are in the nature of things. We, the observers, are also part of nature. It's impossible for us to have any sharp conception of what is going on. because we, the observers, are involved. And so there is this philosophy, which was designed to reconcile people to the muddle; You shouldn't strive for clarity— that's naive.”

“We must thank John Bell for having shown us that philosophical questions about the nature of reality could be translated into problems for physicists, where naive experimentalists can contribute.”

“I had never met Bell, nor heard him lecture, but in my reading of his scientific papers I have developed a great admiration for him and his work. I have especially admired his attempts to dismantle the orthodox Copenhagen interpretation of quantum theory, written with such tremendous style and obvious enjoyment. Although in this book I have tried to present a balanced account - arguing one way and then another - I hope that I have done justice to Bell's superbly constructed criticisms. The debate over the meaning of quantum theory will certainly be poorer without him.”

“I told Wheeler that I had had a number of conversations with Bell about quantum theory. "He’s a wonderful fellow," Wheeler noted. "Did he say to you," Wheeler asked, laughing, "‘I’d rather be clear and wrong, than foggy and right’?" I told Wheeler that Bell had not used exactly those words, but that it certainly sounded like him. I also told Wheeler that from the time that Bell began to study the quantum theory, he had conceptual problems with it, and that I had asked Bell if, at that time, he thought that the theory might simply be wrong—to which Bell had answered, "I hesitated to think it might be wrong, but I knew that it was rotten." At this, Wheeler burst into a marvelous peal of laughter. The idea of the young Bell rebelling against the "rottenness" of the quantum theory struck Wheeler as incredibly funny.”

“In my opinion, John Bell performed an extremely important role then, and also later, in generally supporting - thereby making respectable - the apparently "fringe" activities of such people as Karolyhazy, Bohm, [Philip M.] Pearle, Ghirardi, and many others (including myself) in suggesting schemes that go beyond standard quantum mechanics, in the intended direction of realism. No physicist could doubt the scientific credentials of John Bell. The fact that he was prepared to go out of his way to support research of this kind gave it a previously unaccustomed status.”

“It was John Bell who investigated quantum theory in the greatest depth and established what the theory can tell us about the fundamental nature of the physical world. Moreover, by stimulating experimental tests of the deepest and most profound aspects of quantum theory, Bell's work led to the possibility of exploring seemingly philosophical questions, such as the nature of reality, directly through experiments. And this was just Bell's "hobby".”

“John S. Bell (1928–1990, right) and I at CERN in Bell’s office 10 years after the neutrino experiment. We were the quasi-official theorists of that experiment. We did not do very well, all things considered, because of inexperience and ignorance. After the experiment, in 1963, we both went to SLAC, where I wrote my computer program Schoonschip and he developed his famous inequalities. We also discussed other things, even wrote a paper together that was never published. He considered his work on the fundaments of quantum mechanics as a hobby, mainly to be done in the evening, at home. He told me that he intended to do away definitely with this nonsense of hidden variables, and so he did. Later he drifted more and more into this subject, and as I consider it as some sort of foolishness not good for anything having to do with the real world, I once asked him: “Why are you doing this? Does it make the slightest difference in the calculations such as I am doing?” To which he answered: “You are right, but are you not interested and curious about the interpretation?” He was right too, up to a point. While his work became very important, as it could be verified by experiment, often in this branch of physics the discussions are on the level of finding out how many angels can dance on the point of a needle. But even so: there are interesting things there.”