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Observation is more important than model; if we take the model too seriously, we can be led astray. It's much like extending a metaphor too far. We observe dou
by simpaticoder 2y ago
Observation is more important than model; if we take the model too seriously, we can be led astray. It's much like extending a metaphor too far.
We observe double-slit diffraction and model it with the wave-function. This doesn't preclude other models, and some of those models will be more intuitive than others. The model we use may only give us a slice of insight. We can model a roll of the dice with a function with 6 strong peaks and consider the state of the dice in superposition. The fact that the model is a continuous real function is an artifact of the model, a weakness not a strength. We are modeling a system who's concrete state is unknown between measurements (the dice is fundamentally "blurred"), and we keep expecting more from the model than it wants to give.
Programmers may have better models, actually. The world is a tree where the structure of a node births a certain number of discrete children at a certain probability, one to be determined "real" by some event (measurement), but it says little about "reality". The work of the scientist is to enumerate the children and their probabilities for ever more complex parent nodes. The foundations of quantum mechanics may be advanced by new experiments, but not, I think, by staring at the models hoping for inspiration.
- nimish 2y agoFinally! Too much of physics is obsessed with the map and not the territory. This is how you get the tortured reasoning that views measurement and observation as somehow different. Even einstein struggled.
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- GeekyBear 2y agoDoesn't the difference between measurement and observation stem from an extension of the double slit experiment discussed in thus artucle? It you place a detector on one of the two slits in the prior experiment, (so that you measure which slit each individual photon goes through) the interference pattern disappears. If you leave the detector in place, but don't record the data that was measured, the interference pattern is back.
- alserio 2y agoI'm not a physicist, but that doesn't really sound right. Might I ask you a reference or an explanation?
- GeekyBear 2y agoI believe I first read about it in the book, Gödel, Escher, Bach.
- irjustin 2y agoIt is correct. There's SO MUCH weirdness surrounding the double slit. https://en.wikipedia.org/wiki/Double-slit_experiment#Variations_of_the_experiment https://en.wikipedia.org/wiki/Double-slit_experiment#Variati...
- o11c 2y agoHm, it says the observer-at-the-slit experiment hasn't been performed because it would absorb the photons. But it also says the experiment can be done with larger particles, so that shouldn't be a problem ...
- kevinventullo 2y agoDo you have a reference for that last paragraph?
- lukev 2y agoI have heard similar things but this is THE most deeply weird result and I’ve never heard a good explanation for the setup. A lot of people pose it as a question of pure information: do you record the data or not? But what does that mean? The “detector” isn’t physically linked to anything else? Or we fully physically record the data and we look at it in one case vs deliberately not looking in the other? Or what if we construct a scenario where it is “recorded” but encrypted with keys we don’t have? People are very quick to ascribe highly unintuitive, nearly mystical capabilities with respect to “information” to the experiment but exactly where in the setup they define “information” to begin to exist is unclear, although it should be plain to anyone who actually understands the math and experimental setup.
- whatshisface 2y agoThat is true for classical probability, but the idea that unknown quantities are determining the outcomes in quantum mechanics has been disproven in the event of the speed of light being a true limit on communication speed. This is known as, "Bell's theorem."
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- codethief 2y agoDe Broglie and Bohm would like to have a word…
- exe34 2y agoAnd that word would be....?
- codethief 2y agoDe Broglie–Bohm theory is a hidden-variable theory but does not allow for FTL communication.
- davorak 2y agoMy understanding is that it is not that simple, pilot-wave theories, are not the traditional hidden-variable theories. While some setups look very simple in pilot-wave compared to say the schrodinger equation, other setups are as unintuitive in pilot-wave as schrodinger equation is in some. My lightly held conclusion is if it really was a full and more straight forward solution it would dominate the conversation more than it does now. This option was formed reading some primary sources but mostly reviews and comparisons of QM theories. Unlike other methodologies I have never working through a full QM example problem in pilot-wave theory.
- codethief 2y agoI'm not sure what the point is you're trying to make. OP claimed > the idea that unknown quantities are determining the outcomes in quantum mechanics has been disproven in the event of the speed of light being a true limit on communication speed. and I provided an immediate counterexample. Yes, Bell's Theorem and its exact assumptions are not entirely straightforward but let's please stop propagating those falsehoods that die-hard proponents of the Copenhagen interpretation commonly propagate.
- jfengel 2y agoThe models of quantum mechanics have already withstood experiments to a dozen decimal places. You aren't going to find departures just by banging around in your garage; you just can't generate enough precision. The only way forward at this point is to start with the model and design experiments focusing on some specific element that strikes you as promising. Unless you're staring at the model you're just guessing, and it's practically impossible that you're going to guess right.
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- simpaticoder 2y ago>You aren't going to find departures just by banging around in your garage This kind of rhetoric saddens me. Someone says "design an experiment" and you jump to the least charitable conclusion. That people do this is perhaps understandable, but to do it and not get pushback leads to it happening more and more, to the detriment of civil conversation. No, the experiment I had in mind would take place near the Schwarzchild radius of a black hole. This would require an enormous effort, and (civilizational) luck to defy the expectations set by the Drake equation/Fermi paradox. It's something to look forward to, even if not in our lifetimes!
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- exe34 2y ago> No, the experiment I had in mind would take place near the Schwarzchild radius of a black hole I think the GP was thinking of more practical experiments, not science fiction.
- SiempreViernes 2y agoI mean you did just suggest that classical QM can be supplanted by your heavily underspecified finite(?)-state model for which you provide essentially no details, you must admit that's pretty crank-y behaviour.
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- GoblinSlayer 2y agoA model is supposed to be accurate. When it's inaccurate, you should understand where and how it's inaccurate and not just become agnostic.
- simpaticoder 2y agoThe trouble with QM is with it's interpretations, not with the accuracy of it's predictions. The latter informs interest in the former. QM works, but the models imply that nature is neither "local" - e.g. entanglement experiments undermine hidden-variables, nor "real" - e.g. a particle does not have a momentum (or position) until you measure it. These physical properties are not just hidden, they are undefined. These implications fly in the face of basic macroscale intuitions about what "physical reality" means, which makes it interesting. Inconsistency is a signal that we have discoveries yet to make. Note that "Many worlds people" think there is no inconsistency - my sketch of a model is fully consistent with that interpretation, if you wish, by simply assign a new universe to every child node in which the node is reached.
- GoblinSlayer 2y agoWhat you say doesn't quite correspond to quantum physics as it's known. Quantum physics is quantitative and precise, so it's difficult to say there's something undefined there. It doesn't suggest nonlocality, absence of hidden variables means only absence of hidden variables. It doesn't suggest antirealism, if only due to precision, you can say it doesn't work how you want, but at worst this makes it unintuitive. Conversely Dirac formalism works as if quantum state exists in itself in precise form, which has a good compatibility with basic macroscale intuitions about what "physical reality" means.
- rini17 2y agoBut quantum physics can't predict exactly where the individual dots on the detector will be, only their distribution. That does not sound totally quantitative and precise and defined. You would not accept such predictions for macroscopic objects :)
- nick3443 2y agoYour 6-sided dice example sort of brings some focus to his argument of 'its not a real wave it's a math wave ". The result of a 6-sided dice roll exists more in our minds as "math dice" because for most people, if you rolled and it fell in a sewer, lost etc, you wouldn't consider the roll complete until you grabbed a different dice and rolled it. More attached to the person rolling it and the resulting 'what does the number affect'.
- scythe 2y ago>The fact that the model is a continuous real function is an artifact of the model, a weakness not a strength. The wave function is the square root of a probability distribution. The wavefunction is a continuous real function of position because position is modeled as a continuous real variable. The idea of the wavefunction as a function of position is generally supported by the fact that it can be used to predict the measurement results of diffraction experiments like the double-slit experiment, but also practically the whole field of X-ray diffraction. There is not just one experimental result that is explained by wavefunctions. There are widely used measurement techniques whose outcomes are calculated according to the quantum properties of matter — like X-ray diffraction and Raman scattering — which are widely considered to be extremely reliable. There is a good reason to explain the model of reality expressed by the equations as clearly as possible, because we want people to be able to use the equations. Plenty of people (though certainly not all) expect quantum mechanics to be eventually modified to have a consistent theory of gravity. But physicists have experience with this. Special relativity and classical quantum mechanics were both more complex than Newtonian (classical) mechanics, and quantum field theory is more complicated than either. General relativity is substantially more involved than special relativity. It is likely that further extensions will continue to get worse. The model of reality taught by Newtonian (classical) mechanics is also still widely discussed and used in introductory physics courses and many areas of physics (such as fluid dynamics) and engineering. This model also discusses position on the real line. Even though classical mechanics had to be modified, the use of Cartesian coordinates and real numbers turned out to be durable. Usually the finitists will formally "rescue" countability by suggesting that the world could exist on the computable numbers, which are countable and invariant under computable rotations. But the computable numbers are a very unsatisfying model of reality, and have a lot of the same "weirdness" as the real numbers. Therefore they suggest that some other model must exist without giving a lot of specifics. Why this should be somehow helpful and not injurious to the pedagogy of physics is not clear.
- cryptonector 2y ago> The foundations of quantum mechanics may be advanced by new experiments, but not, I think, by staring at the models hoping for inspiration. To come up with new experiments that might shed light it certainly helps to spend time exploring the models to come up with new predictions that they might make. Sure, one can also come up with new experiments based only on existing observations, but it's most interesting when we can make predictions, as testing those advances some theories and crushes others.
- calebm 2y ago"The Tao that can be told is not the eternal Tao."