5 ms·

Wave function collapse is an additional mechanism. If you remove the wave function collapse, you get many worlds.

by mort96 4y ago

Jensson 4y ago
But we observe a random phenomena and call that wave function collapses, we don't observe many worlds. Many worlds is outside of observation, it is an additional feature of the universe that isn't based on any observations.
- mort96 4y ago
  I mean you're right of course, if this was easily experimentally testable we would've done so already. So we're left to choose between two theories: one in which the rules for macro systems and quantum systems are completely different and quantum systems collapse into a state consistent with the rules for macro systems when they interact with a macro system -- and one where there is only the one set of rules and no collapse. That doesn't mean you should choose to believe one or the other, but it means that one model requires fewer mechanisms than the other. At least that's my understanding.
  - Jensson 4y ago
    > one in which the rules for macro systems and quantum systems are completely different and quantum systems collapse into a state consistent with the rules for macro systems when they interact with a macro system That is wrong, quantum state collapse just makes the quantum wave take the shape of another quantum wave, nothing in it requires it to be related to macro state nonsense like pointwise particles etc. If that is the reason you don't like wavefunction collapse then you just misunderstood quantum mechanics basics, all wave function collapse is is that it is a rule for how quantum waves can transform, there is nothing about it that connects it to our macro world view. > and one where there is only the one set of rules and no collapse. MWI still has wave function collapse, the "we observe random part of the universe" part is the wave function collapse, that remains unexplained, why do we only see a random subset? You can't explain that. Many worlds make it harder to see that this part is unexplained, that makes it strictly worse as an interpretation in my opinion.
    - mort96 4y ago
      I was assuming you were arguing for something like the copenhagen interpretation. It now sounds like you're not, but I don't understand what interpretation you're referring to where the wave function takes the shape of another wave function. Do you mean that there is one universal wave function, but the "collapse" is one where the universal wave function discontinuously changes to reflect a probability distribution where (say) a particle's position has much less uncertainty? What is this interpretation called? Anyways, that's still an additional mechanism. > MWI still has wave function collapse, the "we observe random part of the universe" part is the wave function collapse, that remains unexplained, why do we only see a random subset? You can't explain that. That's not wave function collapse. The wave function just keeps evolving as normal. I don't know enough about this to explain how the MWI maps on to our subjective experiences, I could probably find some links but I'm sure you're as good at that as I am. I'm not arguing that MWI is a better interpretation here, just that it has fewer mechanisms.
      - Jensson 4y ago
        > I was assuming you were arguing for something like the copenhagen interpretation. It sounds like you're not, but I don't understand what interpretation you're referring to where the wave function takes the shape of another wave function. Do you mean that there is one universal wave function, but the "collapse" is one where the universal wave function discontinuously changes to reflect a probability distribution where (say) a particle's position has much less uncertainty? What is this interpretation called? Wave function collapse is an observed phenomena, this has no interpretation at all, its just taking what we observe and say "this is what we observe". I'm not sure why you call out "wave function collapse" as something strange or alien to quantum mechanics, it is one of the core parts. In the basic quantum mechanic course every physics student takes nowhere do they say "quantum waves collapses to pointwise particle states", they say "quantum waves collapses to eigenstates of quantum waves". So, wave function collapse is just what we call the observed phenomena that when we measure a quantum wave it takes the shape of one of the eigenstates of the measurement. That is all it is, and that is true regardless if you have a MWI or a Copenhagen, or like me a "quantum waves behave weirdly during some interactions" interpretations of quantum mechanics. And I think my interpretation makes the least assumptions, we have quantum waves, and during some interactions they collapse to one of its eigenstates of that interaction. That is the purest form of quantum mechanics, no need to do more than that. Edit: And trying to argue about more interpretations than that is like trying to invent some divine interpretation of Newtons laws of motions etc. Those are just descriptions of how things behaves.
  - kgwgk 4y ago
    > one in which the rules for macro systems and quantum systems are completely different and quantum systems collapse into a state consistent with the rules for macro systems when they interact with a macro system -- and one where there is only the one set of rules and no collapse ... and no clear relation with the states that we observe as it includes no rules defining macro systems?
    - ummonk 4y ago
      The size at which the outside world starts leaking into the system (and vice versa) in short timespans is pretty well defined both theoretically and experimentally, especially because quantum decoherence is a major annoyance to address in quantum computing.
      - kgwgk 4y ago
        There is no outside world in the "universal wavefunction" theories.
        ummonk 4y ago
        Huh? The universal wavefunction doesn't preclude you from modeling isolated systems with their own independent wavefunction. I.e. Psi(world) = Psi(system)*Psi(outside world). The extent to which you can model a system as truly isolated depends on its size and quality of quantum isolation. This can be calculated theoretically as well as measured empirically.
        kgwgk 4y ago
        If the universal wave function Psi(everything-in-this-universe-and-beyond) can be factorized as Psi(system)*Psi(everything else) then the state of the system is precisely defined. Isn’t the universal wavefunction supossed to be able to accomodate distinct realities where that system may be in different states?
        ummonk 4y ago
- d0mine 4y ago
  We don't observe almost all real number either. We observe some rational numbers. All these infinite number of unobservable real numbers is just waste /s
- akvadrako 4y ago
  The many worlds are not an additional feature of MWI compared to other interpretations. They all have them in the math. In pilot wave theories they are just claimed to not be real, yet they affect things. In objective collapse theories they disappear when measured.

Wave function collapse is an additional mechanism. If you remove the wave function collapse, you get many worlds.

by mort96 4y ago

Wave function collapse is an additional mechanism. If you remove the wave function collapse, you get many worlds.

But we observe a random phenomena and call that wave function collapses, we don't observe many worlds. Many worlds is outside of observation, it is an additional feature of the universe that isn't based on any observations.

mort96 4y ago
I mean you're right of course, if this was easily experimentally testable we would've done so already. So we're left to choose between two theories: one in which the rules for macro systems and quantum systems are completely different and quantum systems collapse into a state consistent with the rules for macro systems when they interact with a macro system -- and one where there is only the one set of rules and no collapse. That doesn't mean you should choose to believe one or the other, but it means that one model requires fewer mechanisms than the other. At least that's my understanding.
- Jensson 4y ago
  > one in which the rules for macro systems and quantum systems are completely different and quantum systems collapse into a state consistent with the rules for macro systems when they interact with a macro system That is wrong, quantum state collapse just makes the quantum wave take the shape of another quantum wave, nothing in it requires it to be related to macro state nonsense like pointwise particles etc. If that is the reason you don't like wavefunction collapse then you just misunderstood quantum mechanics basics, all wave function collapse is is that it is a rule for how quantum waves can transform, there is nothing about it that connects it to our macro world view. > and one where there is only the one set of rules and no collapse. MWI still has wave function collapse, the "we observe random part of the universe" part is the wave function collapse, that remains unexplained, why do we only see a random subset? You can't explain that. Many worlds make it harder to see that this part is unexplained, that makes it strictly worse as an interpretation in my opinion.
  - mort96 4y ago
    I was assuming you were arguing for something like the copenhagen interpretation. It now sounds like you're not, but I don't understand what interpretation you're referring to where the wave function takes the shape of another wave function. Do you mean that there is one universal wave function, but the "collapse" is one where the universal wave function discontinuously changes to reflect a probability distribution where (say) a particle's position has much less uncertainty? What is this interpretation called? Anyways, that's still an additional mechanism. > MWI still has wave function collapse, the "we observe random part of the universe" part is the wave function collapse, that remains unexplained, why do we only see a random subset? You can't explain that. That's not wave function collapse. The wave function just keeps evolving as normal. I don't know enough about this to explain how the MWI maps on to our subjective experiences, I could probably find some links but I'm sure you're as good at that as I am. I'm not arguing that MWI is a better interpretation here, just that it has fewer mechanisms.
    - Jensson 4y ago
      > I was assuming you were arguing for something like the copenhagen interpretation. It sounds like you're not, but I don't understand what interpretation you're referring to where the wave function takes the shape of another wave function. Do you mean that there is one universal wave function, but the "collapse" is one where the universal wave function discontinuously changes to reflect a probability distribution where (say) a particle's position has much less uncertainty? What is this interpretation called? Wave function collapse is an observed phenomena, this has no interpretation at all, its just taking what we observe and say "this is what we observe". I'm not sure why you call out "wave function collapse" as something strange or alien to quantum mechanics, it is one of the core parts. In the basic quantum mechanic course every physics student takes nowhere do they say "quantum waves collapses to pointwise particle states", they say "quantum waves collapses to eigenstates of quantum waves". So, wave function collapse is just what we call the observed phenomena that when we measure a quantum wave it takes the shape of one of the eigenstates of the measurement. That is all it is, and that is true regardless if you have a MWI or a Copenhagen, or like me a "quantum waves behave weirdly during some interactions" interpretations of quantum mechanics. And I think my interpretation makes the least assumptions, we have quantum waves, and during some interactions they collapse to one of its eigenstates of that interaction. That is the purest form of quantum mechanics, no need to do more than that. Edit: And trying to argue about more interpretations than that is like trying to invent some divine interpretation of Newtons laws of motions etc. Those are just descriptions of how things behaves.
- kgwgk 4y ago
  > one in which the rules for macro systems and quantum systems are completely different and quantum systems collapse into a state consistent with the rules for macro systems when they interact with a macro system -- and one where there is only the one set of rules and no collapse ... and no clear relation with the states that we observe as it includes no rules defining macro systems?
  - ummonk 4y ago
    The size at which the outside world starts leaking into the system (and vice versa) in short timespans is pretty well defined both theoretically and experimentally, especially because quantum decoherence is a major annoyance to address in quantum computing.
    - kgwgk 4y ago
      There is no outside world in the "universal wavefunction" theories.
      - ummonk 4y ago
        Huh? The universal wavefunction doesn't preclude you from modeling isolated systems with their own independent wavefunction. I.e. Psi(world) = Psi(system)*Psi(outside world). The extent to which you can model a system as truly isolated depends on its size and quality of quantum isolation. This can be calculated theoretically as well as measured empirically.
        kgwgk 4y ago
        If the universal wave function Psi(everything-in-this-universe-and-beyond) can be factorized as Psi(system)*Psi(everything else) then the state of the system is precisely defined. Isn’t the universal wavefunction supossed to be able to accomodate distinct realities where that system may be in different states?
        ummonk 4y ago
d0mine 4y ago
We don't observe almost all real number either. We observe some rational numbers. All these infinite number of unobservable real numbers is just waste /s
akvadrako 4y ago
The many worlds are not an additional feature of MWI compared to other interpretations. They all have them in the math. In pilot wave theories they are just claimed to not be real, yet they affect things. In objective collapse theories they disappear when measured.