It's really a classical dial, or something. Of course, the correct answer to this is "Brilliant point! See me after class.
Of course the three qubit mermin contextuality argument is probably the simplest. I'm looking forward to the 3-turkey paradox! Or, heck, maybe I should just read Mermin's argument Keeping those C-numbers out of it seems like a nice move. Although I think it needs a bit of work to be publishable, have you considered Am.
Feynman wrote an unusual little book titled QED, the Strange Theory of Light and Matter if I remember the title right that makes a pretty good attempt at it I'm sorry, but I hope that very few people read this, because you have written an explanation that confuses things more than it clarifies them. You start with a long example of what is very clearly and explicitly a hidden variable situation. Your reader's state of knowledge of what is in the boxes may be statistical in nature, but, what is in the box is in fact a turkey, or else it is in fact a duck. There's a hidden variable that you don't know, but it actually is a chicken, or it's a duck, whether you know it or not.
Having now spent a page or two getting your readers to visualize hidden-variables clearly and explicitly, there's pretty much no possible way to move to quantum mechanics, since quantum mechanics is not a hidden variable theory. Unless possibly by saying "Now, to understand quantum mechanics, simply forget everything I just told you.
More explicitly, in terms of your analogy, the possiblity that you could ever explain quantum mechanics vanishes when you get to this statement: "When we open a box we never see a half-turkey half-duck. Once you've told the reader that a superposition states "simply do not exist", you've essentially frozen them in the classical world. They can, and do, exist, and understanding that they exist is, more than any other point, the key to understanding quantum mechanics.
There's much truth in what Geoffrey A. Landis wrote. What I want to know is whether in generalized Bell inequalities, elliptically polarized turducken disproves reality, as well as locality.
I completely and totally disagree and believe that teaching students that wave functions are "real" is one of the biggest disservices ever rendered on physics students. Indeed I would claim it stopped my field, quantum computing, from every even being contemplated by at least twenty years.
Superpositions do not exist except on the pieces of paper we write down to describe a quantum system. Teaching students to believe that there is a wave function which is no different from the electromagnetic field instills into them all sorts of bad misconceptions. And point of fact, there does exist a local hidden variable theory for a single qubit contextual, of course. Of course I'm sure I won't win you over: you sound like an old school physicist : But if I can't win you over then maybe at least I could point you to something interesting to read which might make you yell at me less:.
You're right that Dave's description doesn't rule out hidden variables, and therefore fails to illustrate noncontextuality.
But -- is contextuality the most important thing about QM? It's certainly one of the most deep and puzzling things about QM, and every student should realize at some point that QM is not compatible with hidden variables. A much more deadly fallacy, to me, is your conflation of "superpositions exist" with which I agree! Rob Spekkens has done some interesting work, making a list of phenomena in quantum information theory that can and cannot resp. It turns out that the vast majority of them can; they depend only on roughly speaking information-disturbance relations.
It's quite hard to come up with a task that specifically requires contextuality. I also think that contextuality is hard to explain unless you've already spent some time thinking about hidden variables. So, if I only had 10 minutes to explain quantum, I'd probably skip contextuality. On the other hand, if I had another 10 minutes, I'd cover it, using I don't think I am -- the problem is that the word "exist" is ill-defined in this context . Dave is, I think, restricting "existence" to measurable properties like "is it a turkey? Already, "exist" is getting ambiguous.
It gets worse with quantum mechanics. The hidden variable issue was deepened by Bell's Inequality and Aspect's experiment, and then deepened again, as I hinted, with the elliptical polarization theory that undercuts Bell but threatened "realism" in QM. Robin Blume-Kohout brings in the difficult questions of the metaphysics of Mathematics, the metaphysics of Physics, and Wigner's paper on the "the unreasonable efficacy of mathematics in explaining the physical world.
I February Richard Hamming , who was neither a physicist nor a philosopher of mathematics but an applied mathematician and a founder of computer science, reflects on and extends Wigner's Unreasonable Effectiveness, mulling over four "partial explanations" for it. A different response, advocated by Physicist Max Tegmark , is that physics is so successfully described by mathematics because the physical world is completely mathematical, isomorphic to a mathematical structure, and that we are simply uncovering this bit by bit.
In this interpretation, the various approximations that constitute our current physics theories are successful because simple mathematical structures can provide good approximations of certain aspects of more complex mathematical structures. In other words, our successful theories are not mathematics approximating physics, but mathematics approximating mathematics. But, of course, in other parts of the Multiverse I agree with him.
In yet others, I am him. But do I exist somewhere as a superposition of me and him? Of me and you? I apologize here that It's hard to discuss QM without implicitly falling into an interpretation, because the language varies depending on the interpretation used, although the underlying mathematics is the same. I'll do my best to use interpretation-free language, but don't count on it Basically, when you make a measurement look inside the box, in your example , the probability of the measurement giving a result R is the projection of the initial state into the eigenstates defined by the measurement operator; but once you have made the measurement, the probability of the system being in that state is unity.
Right so far? So by definition, of course that's not what you will ever see.
And this is of course true in the case of a box containing a turkey or a duck. If you don't like K0 mesons, the trivial in fact, nearly classical case is a polarized photon. Light that is polarized at a 45 degree angle is a linear superposition of X and Y polarization. Does this mean diagonally polarized photons can't exist? Certainly not. Most certainly superposition states do exist and by this I mean in the real, physical sense, not the abstract philosophical sense.
I agree with almost everything you said in the long paragraph -- put concisely, the measurement protocol determines the set of things you could possibly see when you open the box. For photon polarization, we can easily design protocols that measure in one basis or in its conjugate. However, I'm not comfortable with two phrases: 1.
From quarks to computing, this fascinating introduction covers every element of the quantum world in clear and accessible language. Drawing on a wealth of. Editorial Reviews. Review. "Few appreciate how deeply quantum physics affects so many.
My discomfort with the second statement stems from the fact that I think this is quantum mechanics -- i. If we could, we wouldn't see the monster Dave described I used the phrase 'something in between' because English just doesn't have any simple, accurate words for superposition states of macroscopic objects. But you are quite right.
As Robin pointed out, one point which my little story didn't try to convey was that of contextuality. For qubits, unless you allow generalized measurements, not only is there a hidden variable theory, but there is a noncontextual hidden variable theory. But this fails when you go to higher dimensional quantum systems or allow generalized measurements.
The Kochen-Specker theorem says, in quite a real sense, that if you think about superpositions as "existing" independent of the context of the measurement, you will get yourself into trouble. Thus, in a real sense haha , I think that emphasizing that superpositions "exist" is a dangerous game which, only for qubits, doesn't get you into dangerous territory.
Cleese, M. Palin, E. Idle, G.
Chapman, T. Jones, T. Gilliam, C. Cleveland, J.
In this article, we summarize what we believe are the six best quantum physics books for beginners. All in all this book deserves our highest recommendations for beginners. You submitted the following rating and review. Mar 12, Kory rated it really liked it. View 1 comment.
Blog Phys. Fifth Writer: Sir, I don't know how to say this but I got to be perfectly frank. I really and truly believe this story of yours is the greatest story in motion-picture history. Larry: If there's one thing I can't stand, it's a yes-man! Get out!
Larry: There you are, you see, he spoke his mind. He said my idea was lousy. It just so happens my idea isn't lousy so get out you goddam pinko subversive, get out! Larry: I hope you three gentlemen aren't going to be indecisive!