3 ms·

Feynman said that quote in 1965, and it may have been true when he said it. The Many-Worlds Interpretation was technically invented before then (1957), but was

Feynman said that quote in 1965, and it may have been true when he said it. The Many-Worlds Interpretation was technically invented before then (1957), but was a fringe theory and not disseminated much prior to the 1980s. I don't think you could get away with saying the same quote today.

mikeash 9y ago
Implying that many-worlds is the key to unlocking true understanding of QM? What's the basis for that?
- Simon_says 9y ago
  Yea, that's exactly what I'm implying. As for the basis for it -- I'm not sure how to put it. Every other interpretation is deeply confused, but MWI gives a deterministic, algorithmic, and non-mysterious explanation. MWI may or may not be correct, but an adherent definitely would not say they "don't understand" QM.
  - mikeash 9y ago
    I thought the various competing interpretations of QM were all exactly equivalent when it came time to actually crank through the math in an algorithmic fashion.
    - Simon_says 9y ago
      Not exactly equivalent. The Copenhagen Interpretation has a pretty big theoretical hole in that the condition for when a wavefunction collapse occurs is not defined within the theory itself. Supposedly collapse occurs during a "measurement". Well, what's a measurement? Your measuring apparatus are all made up of matter that supposed to be following the same fundamental physical laws. I think you'd be hard pressed to write a computer program that takes as input a description of all the particles and their wavefunctions and compute when a measurement occurs. In practice, scientists doing calculations under the Copenhagen Interpretation will choose the points in time to perform a collapse so that the calculations match experimental results. This is what I mean when I say that Copenhagen is non-algorithmic. That's a forgivable mistake if you invent your theory before the idea of an algorithm is formalized (as was CI), but today it's not a forgivable mistake. If you decide to fix the problem with Copenhagen Interpretation by explicitly defining that a measurement is when X happens for some X, then you've allowed for an experiment whose results can differentiate between Copenhagen and Many Worlds. MWI says that different parts of the wave function can affect each other no matter how distant, though the effect size decreases exponentially with distance. So set up an experiment so that X occurs and then be able to measure interference from distant parts of the wavefunction that are either present (in MWI) or not present (in CI). That distinguishes the interpretations via experiment.
      - mikeash 9y ago
        Thanks. I must have gotten mixed up with the equivalence of some of these interpretations, and the lack of actual experiments to distinguish the others.
        Simon_says 9y ago
        The mix up is not your fault. I see it routinely written that the interpretations don't make any difference to predictions, and I never see anyone talk about or acknowledge the issues I just raised. I feel like I'm taking crazy pills.

mikeash 9y ago

Implying that many-worlds is the key to unlocking true understanding of QM? What's the basis for that?

Simon_says 9y ago
Yea, that's exactly what I'm implying. As for the basis for it -- I'm not sure how to put it. Every other interpretation is deeply confused, but MWI gives a deterministic, algorithmic, and non-mysterious explanation. MWI may or may not be correct, but an adherent definitely would not say they "don't understand" QM.
- mikeash 9y ago
  I thought the various competing interpretations of QM were all exactly equivalent when it came time to actually crank through the math in an algorithmic fashion.
  - Simon_says 9y ago
    Not exactly equivalent. The Copenhagen Interpretation has a pretty big theoretical hole in that the condition for when a wavefunction collapse occurs is not defined within the theory itself. Supposedly collapse occurs during a "measurement". Well, what's a measurement? Your measuring apparatus are all made up of matter that supposed to be following the same fundamental physical laws. I think you'd be hard pressed to write a computer program that takes as input a description of all the particles and their wavefunctions and compute when a measurement occurs. In practice, scientists doing calculations under the Copenhagen Interpretation will choose the points in time to perform a collapse so that the calculations match experimental results. This is what I mean when I say that Copenhagen is non-algorithmic. That's a forgivable mistake if you invent your theory before the idea of an algorithm is formalized (as was CI), but today it's not a forgivable mistake. If you decide to fix the problem with Copenhagen Interpretation by explicitly defining that a measurement is when X happens for some X, then you've allowed for an experiment whose results can differentiate between Copenhagen and Many Worlds. MWI says that different parts of the wave function can affect each other no matter how distant, though the effect size decreases exponentially with distance. So set up an experiment so that X occurs and then be able to measure interference from distant parts of the wavefunction that are either present (in MWI) or not present (in CI). That distinguishes the interpretations via experiment.
    - mikeash 9y ago
      Thanks. I must have gotten mixed up with the equivalence of some of these interpretations, and the lack of actual experiments to distinguish the others.
      - Simon_says 9y ago
        The mix up is not your fault. I see it routinely written that the interpretations don't make any difference to predictions, and I never see anyone talk about or acknowledge the issues I just raised. I feel like I'm taking crazy pills.