5 ms·

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 whic

by 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.
    - mort96 4y ago
      Yes, the collapse of the wave function is ... when the wave function collapses from representing a superposition of multiple states to representing one state ("collapses to eigenstates of quantum waves"). It. Does. Not. Happen. With. MWI. The single universal wave function always just keeps evolving according to the normal rules.
      - Jensson 4y ago
        In MWI the event where we stop observing some of its state is the collapse, it didn't disappear, you just made it harder to understand. So MWI doesn't make things clearer, it hides the complexity of quantum mechanics, you might like it better when you no longer see the complexity, but to me I want it front and center so that I don't miss it. Edit: Or to make it clearer that it isn't magic, the event where some parts of the wave function suddenly stops interacting with the other parts of the wave function, that is a wave function collapse, and yes it does happen in MWI, you can't just change the laws of quantum mechanics so it has to work that way.
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

by mort96 4y ago

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.
  - mort96 4y ago
    Yes, the collapse of the wave function is ... when the wave function collapses from representing a superposition of multiple states to representing one state ("collapses to eigenstates of quantum waves"). It. Does. Not. Happen. With. MWI. The single universal wave function always just keeps evolving according to the normal rules.
    - Jensson 4y ago
      In MWI the event where we stop observing some of its state is the collapse, it didn't disappear, you just made it harder to understand. So MWI doesn't make things clearer, it hides the complexity of quantum mechanics, you might like it better when you no longer see the complexity, but to me I want it front and center so that I don't miss it. Edit: Or to make it clearer that it isn't magic, the event where some parts of the wave function suddenly stops interacting with the other parts of the wave function, that is a wave function collapse, and yes it does happen in MWI, you can't just change the laws of quantum mechanics so it has to work that way.

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