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Have We Been Interpreting Quantum Mechanics Wrong This Whole Time?
- dsugarman 12y agoI am not a quantum physicist, can anyone explain what implications (if any) a deterministic model of quantum mechanics would have on the potential of quantum computing?
- one-more-minute 12y agoI think the idea of this interpretation is specifically not to have any implications outside of what we already know. They should be equivalent in the sense that you can derive one from the other. It's like making Newtonian mechanical predictions based on F=ma vs. energy arguments, or analysing computation using a Turing machine vs. lambda calculus. The theory can't fundamentally change but you can use a different conceptual framework to get the same results (and some may be much easier to work with / more intuitive than others).
- inclemnet 12y agoI don't think it would have any implications, unless it predicted new behaviour above and beyond what the mathematics already described. This kind of debate is all about philosophical interpretation, the actual mathematics of QM are extremely well understood, and a different understanding of what 'really happens' (be it waves, many worlds, random collapse or whatever) would not affect how we already know quantum computers can work.
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- nsxwolf 12y agoNo. Yes.
- calhoun137 12y agoI would characterize these fluid dynamics experiments as "very cute", but nothing more. One of the sad things about physics these days is that it has become more like religion in a bad way. I first heard about Bohmenian mechanics, which this article is about, 8 years ago. I never believed in it, and always thought it was silly. I say "believe" because at this point it really is a question of faith. It was amusing to me to read this article, it makes all the same points I used to argue against but in a very clever and well written way. What the Bohmeanian mechanics people used to say was the only reason they couldn't respond to this or that problem with the theory was "not enough people were working on it". From the article: "Some researchers said that [Bohmean Mechanics] has trouble dealing with identical particles, and that it becomes unwieldy when describing multiparticle interactions. They also claimed that it combines less elegantly with special relativity. But other specialists in quantum mechanics disagreed or said the approach is simply under-researched."
- jessaustin 12y agoI say "believe" because at this point it really is a question of faith. Science. We're doing it wrong.
- theophrastus 12y agoThere is no need for "belief". There is only support by predictions validated, or skepticism borne of predictions disproved. The important work should discover predictions which distinguish these two models of the interactions of the very small and then put them to the test. Anyone who remains satisfied with self consistent mathematics alone is, as you say, approaching "religion", (unless it's a thesis in pure mathematics [smile]).
- pmoriarty 12y agoVirtually all science relies deeply on belief and trust. Show me the scientist who has replicated every experiment in the scientific texts and journals they read. They don't exist. At some point, you have to trust the system, trust other scientists, trust what you're reading, and believe that the system works. Sure, in principle you might be able to verify any experiment (given enough time and resources, which no one has), but in practice you can't even get close.
- tjradcliffe 12y agoThe difficulty with these semi-classical interpretations of quantum phenomena is that they tend to work nicely for a few very simple cases and fall to bits when things get more complex. Bohm's quantum potential works almost perfectly for single electron atoms, in which the quantum potential simply holds the electron still, but falls apart for multi-electron atoms, which require a higher dimensional space for the quantum potential to live. Although Bell did defend pilot wave theory--which is taught in every introductory QM course and covered in every introductory QM text--he himself did not see it as anything more than an inspiration for a more complete interpretation, which would necessarily be non-local in accordance with the theorem that bears his name. My own belief is that pilot waves cannot account for quantum statistics, and therefore cannot account for the heat capacity of solids: http://www.tjradcliffe.com/?p=470 http://www.tjradcliffe.com/?p=470 There is a claim that pilot wave theory somehow deals with this, but the argument is focused on the decay of radioactive particles rather than thermodynamics, which seems to be odd, because the thermodynamic argument is the fundamental one: the heat capacity of solids is an unequivocal way of counting available states, and if hidden variables (such as the "true" positions and momenta of the piloted particles) exist then they break the symmetry under exchange that gives rise to the statistics we observe, and create additional states that would... hmmm... OK, having thought about it for a bit I'm no longer entirely convinced it's impossible that pilot waves might preserve the symmetry while also preserving identity. It would require that exchanging the labels on the pilot waves precisely compensate for the labels on the particles. Would that be enough? I'm going to have to think more about this before forming a more firmly held opinion on it.
- anigbrowl 12y agoIt's hard to think about this given that the Copenhagen school has had decades of effort lavished on it, while De Broglie's concepts seem to have had very little development. I've always been a little interested in them because I like underdogs, but have assumed as a lay person that the Copenhagen approach was correct. The oil drop experiment is certainly thought-provoking.
- lmm 12y agoThe most obvious, naive extrapolation of ordinary quantum mechanics (that is, assume the experimenter is an ordinary quantum system behaving in the ordinary way) comes out as the many-worlds interpretation. There are arguments for others, but many-worlds should be your "default".
- msravi 12y agoAny sufficiently complex system that has a sufficiently large number of known/unknown parameters whose interactions are unknown/partially known/not measurable appears random. For example, while the path of a piece of paper as it drops to the ground can be modeled exactly based on several parameters such as gravity, air currents (and its parameters), etc. the number of parameters are so large and their interactions so complex, that the only useful approach is to model it statistically. The same goes for the weather. Or the economy. Or the stock market. It appears that the current quantum mechanical view of the world is simply an acknowledgement of this complexity and the associated unknowns. While it presents a statistical "model" that works for our purposes, it must be acknowledged as a model and not confused with reality. The push for figuring out what drives the statistics needs to continue beyond the building of a model.
- amluto 12y ago> It appears that the current quantum mechanical view of the world is simply an acknowledgement of this complexity and the associated unknowns. While it presents a statistical "model" that works for our purposes, it must be acknowledged as a model and not confused with reality. The push for figuring out what drives the statistics needs to continue beyond the building of a model. This is not a accurate representation of quantum mechanics. If you were to write down a classical description of the state of all the particles in a piece of paper and the state of all the particles that they might interact with over the course of a few seconds, and you solved the equations for what happens, you would get an exact description of the result. This description would be wrong if you look closely enough because classical mechanism doesn't correctly describe the universe we live in. If you did the same thing with a quantum description of the initial state of the paper, you would also get an exact description of the result. That description would be very strange -- if try to deduce what you would see if you looked at the piece of paper (remember, you're just a bunch more particles interacting with that paper), you learn the bizarre answer that you would seem to have some chance of seeing the paper in one configuration and some chance of seeing the paper in a different configuration. But there's no respect in which quantum mechanics is an acknowledgement of some kind of complexity that is beyond our computational ability to describe exactly. To the contrary, quantum mechanics is our attempt to describe things exactly, and it works amazingly well. It's certainly true that a full quantum description of all but the smallest systems is far beyond our ability to compute directly. That's when we switch to statistical mechanics or similar techniques to try to deal with the complexity in a manageable way. To the pedants: if you're trying to model a piece of paper with quantum mechanics, then you'll have to approximate the very small-scale high-energy bits, because we don't know the laws of physics at those scales. But there is so far no compelling reason to believe that those laws will not fit perfectly in the framework of quantum mechanics once we figure them out.
- emhs 12y agoSomehow, even though Collapse is insane if you think about it hard enough, and even though Pilot-waves are semi-classical and seem to be adding an additional complication that may not be necessary, both of these seem to be more popular among physicists than Many-Worlds. Somehow, even though superposition is observed and observable, even though the scale on which we can observe it is climbing steadily larger, people keep assuming that it either dissipates sometime before our scale, or that it's an illusion produced by some sort of semi-classical, overcomplicated reinterpretation. The original idea—that the wave function is the whole deal—works just fine if you accept that we can be in superposition too. If you simply accept that the entire classical concept might be an illusion, and work up from the wave function, there's no reason to shoehorn in an idea like Collapse or Pilot-Wave. Yes, Copenhagen is wrong. Yes, Collapse is patently absurd. Yes, assuming that there is exactly one, stochastic, probabilistic reality makes no sense. But that doesn't mean we need to add something complicated like an underlying superfluid that supports all of spacetime. This smells like Aether. Why does no one talk about Many-Worlds?
- jaekwon 12y agoBecause it's an oxymoron? If the "worlds" interact, then it's actually one world. If they don't interact, then it doesn't matter. It's like dynamic programming. It's just one way to look at the problem. It doesn't really exclude any of the other solutions.
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- millstone 12y agoMany Worlds is a far, far more popular interpretation than Bohm[1]. The strong objection to Many Worlds is not that macroscopic objects cannot be in superposition. There are many objections [2], but the principal one is the difficulty of deriving the Born Rule. This is a deep objection. The Born rule predicts of the result of quantum measurements in QM, and it's not clear how to get those results out of MWI. The Born Rule in MWI is inserted ad-hoc afterwards, or arises via some weird "world-counting" formalism that doesn't naturally connect to probabilities. So MWI has more the flavor of a visualization, not a theory that aims at making predictions. When you say "collapse is wrong," it depends on what is being collapsed. Sure, inserting some special "wavefunction collapse dynamics" separate from ordinary evolution is a pretty rough approach. But when the wavefunction is understood as encoding probabilities, then it's not something physical, and its collapse is no more mysterious than the probability of the Giants winning the World Series "collapsing" to 100% once the final game was played. [1]: http://arxiv.org/abs/1301.1069 http://arxiv.org/abs/1301.1069 [2]: http://www.mat.univie.ac.at/~neum/physfaq/topics/manyworlds http://www.mat.univie.ac.at/~neum/physfaq/topics/manyworlds has some [3]: http://arxiv.org/abs/gr-qc/9703089 http://arxiv.org/abs/gr-qc/9703089
- Animats 12y agoIf this leads to an experimentally verifiable prediction different from the current view of quantum mechanics, it's a very big deal. Otherwise, it's not.
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- amluto 12y agoI think that these oil droplet experiments are incredibly neat, but I'm surprised by the conclusions about the universe that people try to draw from them. There are fascinating lab experiments related to black holes [1]. Researchers have figured out how to build things in the lab that obey some laws that are mathematically very similar to those that we think that black holes obey. These black hole analogues end up doing similar things to what we expect real black holes to do. Nonetheless, no one seems to see those experiments and conclude that "Wow! Our universe must contain black holes that emit Hawking radiation!". These oil droplet experiments do something quite similar. They create an environment that is reasonably well described by the same equations as pilot waves, and, since those equations are known to make the same predictions as quantum mechanics, the oil droplets do the things that we would imagine quantum particles to do. This may be beautiful, but just as the existence of black hole analogues in the laboratory does not imply that black holes are real, the existence of pilot-wave-following oil droplets does not imply that pilot waves are better than quantum mechanics. [1] http://www.nature.com/nphys/journal/v10/n11/full/nphys3104.html http://www.nature.com/nphys/journal/v10/n11/full/nphys3104.h...
- eli_gottlieb 12y agoPretty much everyone actually thinks black holes are real. IANAP.
- jwuphysics 12y agoPretty much everyone actually thinks black holes are real. I am a physicist.
- yzzxy 12y agoI think he was referring to Hawking radiation - which is far more controversial in physics circles and a major WTF idea for non-physicists - and other theoretical black-hole behavior, not existence of black holes themselves.
- simonh 12y agoYes of course, but not because we can create approximate analogues of them in the laboratory.
- lisper 12y agoThe "smoking gun" quote: "Yet an experimental test of droplet entanglement remains a distant goal." And it will remain a distant goal forever. Per Bell's theorem, entanglement is inherently non-local. Bohmian pilot waves are also non-local, so they can reproduce all the results of QM, but no purely classical model can.
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- mkempe 12y agoHere are Yves Couder's 2011 slides with more details, graphs, photos, and references. [1] I have a general question for those who are expert in physics, or who have a hobbyist interest: have you read Louis de Broglie's "Ondes et mouvement" (1926)? it's only 133 pages in the original French edition. Or his 1924 PhD thesis? [2] [1] http://www.physics.utoronto.ca/~colloq/Talk2011_Couder/Couder.pdf http://www.physics.utoronto.ca/~colloq/Talk2011_Couder/Coude... [2] https://tel.archives-ouvertes.fr/tel-00006807/document https://tel.archives-ouvertes.fr/tel-00006807/document
- ThomPete 12y agoI think the whole problem of interpreting quantum mechanics and classical physics is that from what we can see it's counter intuitive and anti-narrative i.e. it cannot be expressed philosophically/via language in any meaningful way. Mathematically it makes sense, experimentally it makes sense, it is as proven as classical physics are proven yet the two contradict each other. Perhaps it is as the old zen-buddhist saying go. Wisdom lies in paradox.
- boardstretcher 12y agoTitle is confusing. Correct me if I'm wrong, but Quantum Mechanics is the interpretation of the very small, so the title is essentially 'Have we been interpreting the interpretation wrong this whole time?'
- inclemnet 12y agoQuantum mechanics in this sense refers to the (very well researched and understood) mathematical theory. This theory permits multiple philosophical explanations of what is 'really happening' to give the mathematical results that we confirm to be correct in experiments. Any debate about the interpretation of quantum mechanics refers to to this question of what really happens, not to any details of what QM actually predicts will happen. That is, until/unless experiments are devised to separate these philosophical explanations, but nothing much has happened on this front for decades.
- boardstretcher 12y agoGreat explanation. Thanks for clearing that up so succinctly.
- officialjunk 12y agohere's there original research: http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.108.264503 http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.108... an article about this gets published about once a year. here's the first one i encountered: http://physicsworld.com/cws/article/news/2012/jul/09/bouncing-droplets-simulate-zeeman-effect http://physicsworld.com/cws/article/news/2012/jul/09/bouncin...
- espitia 12y agoAlthough I read the article, I really don't understand much the theories and technicality of it. What has fascinated me for a while is the slit experiment. What I tie this to is the Law of Attraction. Say that the subconsciousness is the connection from ourselves to the universe (via meditation for example), what if this is the way for us, through our thoughts, to "observe" what is going to happen (in other words, what we want to happen) and therefore the universe "brings" it to us simply because we observed it? Thanks to having some sort of logic I can believe in, I use the law of attraction and it has proven to always bring me what I want in life so far :)
- inclemnet 12y agoIt's vastly more plausible that your brain is good at seeing patterns where none exist than that you have psychic powers.
- jaekwon 12y agoPilot wave resonance/nonresonance from the two receivers of a Bell's inequality experiment may affect the behavior at the source leading to a kind of Monty Hall problem observed as QM. Are we certainly capable of firing a singular entangled photon on command at the press of a button regardless of the orientation of the receivers, or does the firing ability of the source emitter seem to falter with orthogonality at the end receivers? Of course this could be complicated by a mechanism at the source that ensures a single pair to be emitted. Imagine a mechanism that ensures that only one pair is produced, but it is produced eventually, like a for-loop with a break statement. And maybe the only way to conduct the Bell's Inequality experiment meaningfully is with such a throttling mechanism, which would mask the answer to the question above. Though there might be hints in the amount of time required to generate that singular pair, as if the for-loop had to run more iterations before it was produced, detected only with sensitive timing instruments like with side-channel timing attacks in cryptographic black boxes.