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That is true for classical probability, but the idea that unknown quantities are determining the outcomes in quantum mechanics has been disproven in the event o

That 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."

deleted 2y ago
[deleted]
codethief 2y ago
De Broglie and Bohm would like to have a word…
- exe34 2y ago
  And that word would be....?
  - codethief 2y ago
    De Broglie–Bohm theory is a hidden-variable theory but does not allow for FTL communication.
    - davorak 2y ago
      My 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 ago
        I'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.
    - exe34 2y ago
      Thank you! I need to read more in that area.
      - programd 2y ago
        Let me throw in "Hydrodynamic Quantum Analogs" [1] as a fascinating review of how quantum effects emerge in experiments with bouncing oil drops on liquid. This is fully a pilot wave driven experiment and there has been a lot of academic work analyzing the system and trying to fit it into the de Broglie-Bohm formulations of quantum dynamics. To quote section 10.2: "The [experimental] system represents a classical realization of wave–particle duality as envisaged by de Broglie, wherein a real object has both wave and particle components." We've already got all those fields interacting in the real world, so I don't find it very far fetched that quantum mechanics emerges from their fully classically described interactions, probably expressed in some really gnarly 4D math. [1] https://thales.mit.edu/bush/wp-content/uploads/2021/04/BushOza-ROPP.pdf https://thales.mit.edu/bush/wp-content/uploads/2021/04/BushO...
      - codethief 2y ago
        Tim Maudlin's "Philosophy of Physics: Quantum Theory" makes for an excellent read! It addresses tons of questions which are rarely answered (let alone asked) in your run-of-the-mill university-level QM class.
TheOtherHobbes 2y ago
Bell's Theorem disproves local hidden variables. Reality can be interpreted as non-local. There has been no conclusive proof it isn't. c isn't a limit on the kind of non-locality that is required, because you can have a mechanism that appears to operate instantaneously - like wavefunction collapse in a huge region of space - but still doesn't allow useful FTL comms. Bell's Theorem has no problem with this. Some of the Bohmian takes on non-locality have been experimentally disproven, but not all of them. The Copenhagen POV is that particles do not necessarily exist between observations. Only probabilities exist between observations. So there has to be some accounting mechanism somewhere which manages the probabilities and makes sure that particle-events are encouraged to happen in certain places/times and discouraged in others, according to what we call the wavefunction. This mechanism is effectively metaphysical at the moment. It has real consequences and was originally derived by analogy from classical field theory, with a few twists. But it is clearly not the same kind of "object" as either a classical field or particle.
- mnky9800n 2y ago
  Why isn’t the accounting mechanism a quantum extension of the principle of least action?
- movpasd 2y ago
  There may be no conclusive proof, but it's a philosophically tough pill to swallow. Non-locality means things synchronise instantly across the universe, can go back in time in some reference frames, and yet reality _just so happens_ to censure these secret unobservable wave function components, trading quantum for classical probability so that it is impossible for us to observe the difference between a collapsed and uncollapsed state. Is this really tenable? Strip back the metaphysical baggage and consider the basic purpose of science. We want a theoretical machine that is supplied a description about what is happening now and gives you a description of what will happen in the future. The "state" of a system is just that description. A good _scientific_ theory's description of state is minimal: it has no redundancy, and it has no extraneous unobservables.

deleted 2y ago

[deleted]

codethief 2y ago

De Broglie and Bohm would like to have a word…

exe34 2y ago
And that word would be....?
- codethief 2y ago
  De Broglie–Bohm theory is a hidden-variable theory but does not allow for FTL communication.
  - davorak 2y ago
    My 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 ago
      I'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.
  - exe34 2y ago
    Thank you! I need to read more in that area.
    - programd 2y ago
      Let me throw in "Hydrodynamic Quantum Analogs" [1] as a fascinating review of how quantum effects emerge in experiments with bouncing oil drops on liquid. This is fully a pilot wave driven experiment and there has been a lot of academic work analyzing the system and trying to fit it into the de Broglie-Bohm formulations of quantum dynamics. To quote section 10.2: "The [experimental] system represents a classical realization of wave–particle duality as envisaged by de Broglie, wherein a real object has both wave and particle components." We've already got all those fields interacting in the real world, so I don't find it very far fetched that quantum mechanics emerges from their fully classically described interactions, probably expressed in some really gnarly 4D math. [1] https://thales.mit.edu/bush/wp-content/uploads/2021/04/BushOza-ROPP.pdf https://thales.mit.edu/bush/wp-content/uploads/2021/04/BushO...
    - codethief 2y ago
      Tim Maudlin's "Philosophy of Physics: Quantum Theory" makes for an excellent read! It addresses tons of questions which are rarely answered (let alone asked) in your run-of-the-mill university-level QM class.

TheOtherHobbes 2y ago

Bell's Theorem disproves local hidden variables. Reality can be interpreted as non-local. There has been no conclusive proof it isn't. c isn't a limit on the kind of non-locality that is required, because you can have a mechanism that appears to operate instantaneously - like wavefunction collapse in a huge region of space - but still doesn't allow useful FTL comms. Bell's Theorem has no problem with this. Some of the Bohmian takes on non-locality have been experimentally disproven, but not all of them. The Copenhagen POV is that particles do not necessarily exist between observations. Only probabilities exist between observations. So there has to be some accounting mechanism somewhere which manages the probabilities and makes sure that particle-events are encouraged to happen in certain places/times and discouraged in others, according to what we call the wavefunction. This mechanism is effectively metaphysical at the moment. It has real consequences and was originally derived by analogy from classical field theory, with a few twists. But it is clearly not the same kind of "object" as either a classical field or particle.

mnky9800n 2y ago
Why isn’t the accounting mechanism a quantum extension of the principle of least action?
movpasd 2y ago
There may be no conclusive proof, but it's a philosophically tough pill to swallow. Non-locality means things synchronise instantly across the universe, can go back in time in some reference frames, and yet reality _just so happens_ to censure these secret unobservable wave function components, trading quantum for classical probability so that it is impossible for us to observe the difference between a collapsed and uncollapsed state. Is this really tenable? Strip back the metaphysical baggage and consider the basic purpose of science. We want a theoretical machine that is supplied a description about what is happening now and gives you a description of what will happen in the future. The "state" of a system is just that description. A good _scientific_ theory's description of state is minimal: it has no redundancy, and it has no extraneous unobservables.