The current probabilistic interpretation of the quantum theory leads i — Quantum mechanics

"Quantum mechanics was, and continues to be, revolutionary, primarily because it demands the introduction of radically new concepts to better describe the world. In addition we have argued that conceptual quantum revolutions in turn enable technological quantum revolutions."

"If relativity is about the geometrical structure of space-time, what is quantum mechanics about? There are a surprising variety of answers to this question: that quantum mechanics is about energy being quantized in discrete lumps or quanta, or about particles being wavelike, or about the universe continually splitting into countless co-existing quasi-classical universes, with many copies of ourselves, and so on. A rather more mundane answer, with quite remarkable implications, has emerged over the past thirty years or so from the study of the difference between classical information and quantum information: quantum mechanics is about new sorts of probabilistic correlations in nature, so about the structure of information, insofar as a theory of information in the sense relevant to physics is essentially a theory of probabilistic correlations."

"We choose to examine a phenomenon [Double-slit experiment] which is impossible, absolutely impossible, to explain in any classical way, and which has in it the heart of quantum mechanics. In reality, it contains the only mystery. We cannot make the mystery go away by "explaining" how it works. We will just tell you how it works. In telling you how it works we will have told you about the basic peculiarities of all quantum mechanics."

"It is truly surprising how little difference all this makes. Most physicists use quantum mechanics every day in their working lives without needing to worry about the fundamental problem of its interpretation. Being sensible people with very little time to follow up all the ideas and data in their own specialties and not having to worry about this fundamental problem, they do not worry about it. A year or so ago, while Philip Candelas (of the physics department at Texas) and I were waiting for an elevator, our conversation turned to a young theorist who had been quite promising as a graduate student and who had then dropped out of sight. I asked Phil what had interfered with the ex-student’s research. Phil shook his head sadly and said, “He tried to understand quantum mechanics.” So irrelevant is the philosophy of quantum mechanics to its use, that one begins to suspect that all the deep questions about the meaning of measurement are really empty, forced on us by our language, a language that evolved in a world governed very nearly by classical physics. But I admit to some discomfort in working all my life in a theoretical framework that no one fully understands. And we really do need to understand quantum mechanics better in quantum cosmology, the application of quantum mechanics to the whole universe, where no outside observer is even imaginable. The universe is much too large now for quantum mechanics to make much difference, but according to the big-bang theory there was a time in the past when the particles were so close together that quantum effects must have been important. No one today knows even the rules for applying quantum mechanics in this context."

"This particular question of locality is still open, in my opinion. I think we have not found a way of digesting this situation. I think we have not found a way of digesting this situation. We have the formulas of quantum mechanics, and they work extremely well; but I have not digested them. There certainly remains something to be said, some illumination to be found."

"It will be difficult. But the difficulty really is psychological and exists in the perpetual torment that results from your saying to yourself, But how can it be like that? which is a reflection of uncontrolled but utterly vain desire to see it in terms of something familiar. I will not describe it in terms of an analogy with something familiar; I will simply describe it. There was a time when the newspapers said that only twelve men understood the theory of relativity. I do not believe there ever was such a time. There might have been a time when only one man did, because he was the only guy who caught on, before he wrote his paper. But after people read the paper a lot of people understood the theory of relativity in some way or other, certainly more than twelve. On the other hand, I think I can safely say that nobody understands quantum mechanics. So do not take the lecture too seriously, feeling that you really have to understand in terms of some model what I am going to describe, but just relax and enjoy it. I am going to tell you what nature behaves like. If you will simply admit that maybe she does behave like this, you will find her a delightful, entrancing thing. Do not keep saying to yourself, if you can possibly avoid it, But how can it be like that? because you will get down the drain, into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that."

"As long as you keep getting born, it’s okay to die sometimes."

"The smart way to keep people passive and obedient is to strictly limit the spectrum of acceptable opinion, but allow very lively debate within that spectrum - even encourage the more critical and dissident views. That gives people the sense that theres free thinking going on, while all the time the presuppositions of the system are being reinforced by the limits put on the range of the debate."

"History is a strange experience. The world is quite small now; but history is large and deep. Sometimes you can go much farther by sitting in your own home and reading a book of history, than by getting onto a ship or an airplane and traveling a thousand miles. When you go to Mexico City through space, you find it a sort of cross between modern Madrid and modern Chicago, with additions of its own; but if you go to Mexico City through history, back only 500 years, you will find it as distant as though it were on another planet: inhabited by cultivated barbarians, sensitive and cruel, highly organized and still in the Copper Age, a collection of startling, of unbelievable contrasts."

"As soon as a thought or word becomes a tool, one can dispense with actually ‘thinking’ it, that is, with going through the logical acts involved in verbal formulation of it. As has been pointed out, often and correctly, the advantage of mathematics—the model of all neo-positivistic thinking—lies in just this ‘intellectual economy.’ Complicated logical operations are carried out without actual performance of the intellectual acts upon which the mathematical and logical symbols are based. … Reason … becomes a fetish, a magic entity that is accepted rather than intellectually experienced."

"Our feminist culture at the present moment is completely dependent on capitalism. My grandmother was still scrubbing clothes on the back porch on a washboard!"

"A word of the faith that never balks, Here or henceforward it is all the same to me, I accept Time absolutely. It alone is without flaw, it alone rounds and completes all, That mystic baffling wonder alone completes all. (23)"