Comments by "Lepi Doptera" (@lepidoptera9337) on "The Problem with Quantum Measurement" video.

  1. That is exactly what an MRI machine does. "The measurement problem" is a naive confusion by theorists with little to no physical intuition. Because of angular momentum conservation a spin up here means that somewhere something needs to have a spin down. The only question is "where that something is".
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  2. A measurement doesn't measure the wave function. At most an infinite number of measurements would measure the magnitude of the projection of the wave function squared.
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  3.  @crimm2465  That's because decoherence is not the correct explanation. Both of you are tapping in the dark. ;-)
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  4. Yes, that was complete bullshit and I didn't even read it. ;-)
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  5. You can find his book online. It basically already treats an early form of decoherence way before anybody else caught on. Not that decoherence buys you anything. The actually correct explanation is also in von Neumann's book, though. Pay extra attention to chapter six.
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  6. Yes, that was complete bullshit and I didn't even read it. ;-)
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  7. No.
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  8. Nope.
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  9.  @orisphera  There is no randomness in quantum mechanics, only uncertainty. The theory describes what we can't know. It doesn't describe what the world knows about itself.
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  10.  @orisphera  Neither Bohmian mechanics nor hidden variables are physics. Quantum field theory is. QFT doesn't even have a need for measurements.
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  11. The problem here is that there is no problem. There are only people who don't understand physics. ;-)
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  12. Here, let me give you some attention. You are begging so nicely. ;-)
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  13. There is nothing particularly difficult going on here. Both gentlemen were wrong in different ways. Today we classify quantum mechanics as the unitary representation theory of the Poincare group. As soon as you can unpack that sentence you will understand absolutely everything about quantum mechanics and it will become completely trivial to you.
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  14. No, that's not how it works. ;-)
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  15. If you are listening to her you will never understand. She is simply talking nonsense here. It is theoretically extremely well understood what a measurement is. It is, BY DEFINITION, an irreversible energy transfer. The only problem here are theorists who are stuck at the kindergarten level of theory in which everything is reversible all the time. You can find such theorists in classical mechanics (they are only doing Hamiltonian mechanics on systems with finite phase space volumes) and in quantum mechanics (these are the ones who are talking about the "measurement problem"). Relativity provides a trivial solution to all of this and this was known since, at least, 1932.
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  16.  @galegreyson4196  I was an experimental high energy physicist. I have done trillions of quantum measurements while I was active. Not once was there a problem, either in the lab or in the theory. The theory even spells out explicitly for us what needs to happen to have a measurement outcome. It is very strange how many theorists seem to be completely blind to that element. That is the real mystery here... why otherwise reasonably smart people have such deep misconceptions about a nearly trivial topic. They can handle much more complicated stuff with ease, but when it comes to seeing the obvious they are blanking. ;-)
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  17.  @linusmlgtips2123  Awh, you are so cute when your failed education is feeling sorry for itself. ;-)
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  18. A measurement is an irreversible energy transfer. You are welcome. ;-)
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  19. We don't have a measurement problem in either case. All measurements are simply irreversible energy transfers. We are teaching this in undergrad thermodynamics and statistical mechanics but some of the theorists aren't paying any attention because they don't think that they need to understand this rather trivial fact. And for the most part they are correct. They don't... except when it comes to the interpretation of quantum mechanics, for which it is fundamental.
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  20. @ A clock is that which sits on your bedroom night stand: it's a system with a local energy source (weights, a spring, a battery, connection to the power grid) that disperses this energy as evenly as possible towards infinity. Clocks and time measurement are, apart from technological difficulties with the "as evenly as possible" part, about as trivial physical systems as they come.
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  21. @ We teach clocks in kindergarten. You were clearly not paying any attention. ;-)
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  22. It's not even correct. ;-)
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  23. One can't measure the wave function. The end.
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  24. No, it's due to the uncertain nature of quantum mechanics.
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  25. The wave function is not a physical entity. The only updates happen on paper.
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  26.  @dottedrhino  I have never seen another world other than on paper. Good luck finding one! Maybe Indiana Jones can help?
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  27. It is very disappointing that she is stuck at the level of non-relativistic QM. She of all people should know better what is going on.
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  28. So you are basically saying that your ignorance of the difference between ensemble and individual experiment creates god? Well, that's about as good as any other god creating ignorance claim, I guess.
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  29. Ah, another false dichotomy rears its ugly head.
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  30.  @rustyosgood5667  But it is... unless you are having groundhog day in your universe?
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  31.  @rustyosgood5667  Depends. There were cut scenes, so they probably shortened the final movie by one, if not two iterations. But who's counting, right?
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  32. That's not what the wave function does. The wave function describes the averages of an infinite ensemble of identical quantum systems. It says absolutely nothing about an individual system. There are only a few actual physical observables: energy, momentum, angular momentum and charges. What von Neumann calls "observables" or "measurements" in his book are histograms over these quantities. They have nothing to do with actual physics. Think of them as generalized Fourier transformations of the primary data.
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