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Yes, the collapse of the wave function is ... when the wave function collapses from representing a superposition of multiple states to representing one state ("

by 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.
- mort96 4y ago
  I did not say it made anything easier to understand. I did not say it made anything clearer. I did not say I like it better. Stop putting words into my mouth. I said it has fewer mechanism. Which it does. Because it does not have the wave function collapse mechanism.
  - Jensson 4y ago
    But the wave function collapse is there. Wave functions stops interacting with each other, that is a micro system phenomena, it requires nothing of our macro state magic, and we can observe it, it happens, and that is what we call "wave function collapse", and it happen in MWI.
    - mort96 4y ago
      In MWI, there is one single wave function. It is the single wave function which describes the state of "the multiverse". It is always in a superposition of eigenstates. It never collapses. That's literally the entire point of the MWI. If you refuse to understand that, you have some reading to do. I don't believe further discussion is fruitful.
      - Jensson 4y ago
        But that wave function still gets transformed similar ways as wave function collapses would. You can turn around a particle with wave function collapses, we have done that in reality, so no matter how you structure your MWI the wave function collapse is there. That giant waveform you are talking about thus has to react to wave function collapses, there is no way around it.
        mort96 4y ago
        > But that wave function still gets transformed similar ways as wave function collapses would. No it doesn't? After a wave function collapse, a particle's (or quantum system's) wave function is reduced from representing a superposition of eigenstates to representing one eigenstate. That does not happen in MWI. I don't understand why you find that so difficult to accept. If a particle is in a superposition, and an observer observes the particle, MWI says that the observer also enters a superposition with one eigenstate for each of the particle eigenstates, following the normal "rules" of interaction/entanglement since the observer is also a quantum system. There is no collapse.
        Jensson 4y ago
        > That does not happen in MWI So if I use a series of quantum collapses to move a particle a meter forward, a state it wasn't originally in, how would that work in MWI? To do that you just make a long series of "measurements", each perturbation so small that the chance is basically 100% since the chance is squared with the overlap, how did that particle get moved according to MWI? How do you explain that without wavefunction collapse?
- d_tr 4y ago
  There is no state collapse in the MWI. This is a very basic fact about it. The whole point is that what we experience as a "collapse" in a lab experiment is not really happening.

by mort96 4y ago

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.

mort96 4y ago
I did not say it made anything easier to understand. I did not say it made anything clearer. I did not say I like it better. Stop putting words into my mouth. I said it has fewer mechanism. Which it does. Because it does not have the wave function collapse mechanism.
- Jensson 4y ago
  But the wave function collapse is there. Wave functions stops interacting with each other, that is a micro system phenomena, it requires nothing of our macro state magic, and we can observe it, it happens, and that is what we call "wave function collapse", and it happen in MWI.
  - mort96 4y ago
    In MWI, there is one single wave function. It is the single wave function which describes the state of "the multiverse". It is always in a superposition of eigenstates. It never collapses. That's literally the entire point of the MWI. If you refuse to understand that, you have some reading to do. I don't believe further discussion is fruitful.
    - Jensson 4y ago
      But that wave function still gets transformed similar ways as wave function collapses would. You can turn around a particle with wave function collapses, we have done that in reality, so no matter how you structure your MWI the wave function collapse is there. That giant waveform you are talking about thus has to react to wave function collapses, there is no way around it.
      - mort96 4y ago
        > But that wave function still gets transformed similar ways as wave function collapses would. No it doesn't? After a wave function collapse, a particle's (or quantum system's) wave function is reduced from representing a superposition of eigenstates to representing one eigenstate. That does not happen in MWI. I don't understand why you find that so difficult to accept. If a particle is in a superposition, and an observer observes the particle, MWI says that the observer also enters a superposition with one eigenstate for each of the particle eigenstates, following the normal "rules" of interaction/entanglement since the observer is also a quantum system. There is no collapse.
        Jensson 4y ago
        > That does not happen in MWI So if I use a series of quantum collapses to move a particle a meter forward, a state it wasn't originally in, how would that work in MWI? To do that you just make a long series of "measurements", each perturbation so small that the chance is basically 100% since the chance is squared with the overlap, how did that particle get moved according to MWI? How do you explain that without wavefunction collapse?
d_tr 4y ago
There is no state collapse in the MWI. This is a very basic fact about it. The whole point is that what we experience as a "collapse" in a lab experiment is not really happening.