12 ms·

That's not your fault; most anybody who reads about quantum physics from most sources will be baffled by it because most authors are thoroughly confused themsel

That's not your fault; most anybody who reads about quantum physics from most sources will be baffled by it because most authors are thoroughly confused themselves. Look up the Many-Worlds Interpretation. I won't say it's the truth, but it's the most plausible theory available. The math is relatively straightforward, and it gives a deterministic and understandable explanation of what's going on. Denying Many-Worlds necessitates the invention of the philosophical equivalent of epicycles upon epicycles. I've learned that any article or paper that posits something strange going on without even mentioning Many-Worlds is simply not worth the ink it's written with.

ThomPete 11y ago
But doesn't many-world interpretation still require a leap of faith though?
- spacehome 11y ago
  No? At least not any more than any other theory in science. It's a mathematical model that makes predictions. When the predictions stop matching experiment, then we can throw it away.
  - ThomPete 11y ago
    Maybe I am wrong but as far as I understand thats not really the issue here. As far as I understand there are 3 types of competing interpretations all trying to deal with the local universe vs. the non-local one and trying to explain them in a way that make sense. 1) Logically consistent, allow us to make predictions but which requires a leap of faith (Many World interpretation) 2) Mathematically correct but does not allow us to make predictions (string theory) 3) Allow us to make predictions, doesn't require leap of faith but isn't logically consistent all the way (Copenhagen interpretation) There is also a couple of outsiders like the electrical universe and plasma universe which completely ignores the idea of quantum weirdness but as far as I understand they also require some leap of faith.
    - gizmo686 11y ago
      Copenhagen requires a leap of faith to accept wavefunction collapse.
      - deleted 11y ago
        [deleted]
  - guscost 11y ago
    The difference with an interpretation like MWI is that no experiment can disprove it, even in theory. The interpretation requires that the many worlds do not interact, and unless that changes, there is no way to observe anything contradictory to the interpretation that doesn't also contradict QM. Most other famous science theories are falsifiable (I would say it is a necessary condition to qualify as science).
    - pjscott 11y ago
      It's a mathematical model that makes observable predictions. It's easily falsifiable: just show that its predictions are false. Now, you could argue that there's no test to distinguish it from other interpretations of quantum mechanics, but that applies to them as well.
      - guscost 11y ago
        Which predictions of the MWI are observable? > It's a mathematical model that makes observable predictions. It sounds like you're talking about QM itself, not any interpretation.
        Moshe_Silnorin 11y ago
        QM, itself, predicts macroscopic decoherence. Many worlds is more a prediction of QM than an interpretation.
        guscost 11y ago
        Great way to present it, but we're still talking about a prediction that can't be tested, even in theory.
      - ThomPete 11y ago
        It makes mathematical predictions perhaps but thats not enough as far as I understand to claim that you can make predictions in any normal sense of that word. And therefore the Parent I was originally responding to at least from my understanding is claiming something thats not telling the whole story.
- marcosdumay 11y ago
  Only if you believe in it. It's the easiest to understand interpretation of QM, and completely equivalent to all others. So, why not use it?
  - danharaj 11y ago
    Because it gets rather complicated to formalize when you try to reconcile universe splitting with special relativity. There is an even simpler interpretation of quantum mechanics: the relational interpretation. It does not speak of any states and therefore no wavefunction collapse. 0 is ontologically better than infinity.
    - spacehome 11y ago
      > it gets rather complicated to formalize when you try to reconcile universe splitting with special relativity Why? And why is it more of a problem for MWI than other interpretations?
      - danharaj 11y ago
        When does a universe split? The relativity of simultaneity causes problems: one observer will have to interpret the universe as splitting in one way and then the other, while another will observe the opposite ordering. My personal favorite interpretation is the relational interpretation [1], where we just stop asking nonsensical questions about the universe. It does away with problematic notions that arise from our biases as human beings. [1] http://plato.stanford.edu/entries/qm-relational/ http://plato.stanford.edu/entries/qm-relational/
- Jach 11y ago
  No. Check out http://arxiv.org/abs/astro-ph/0302131 http://arxiv.org/abs/astro-ph/0302131
AgentME 11y ago
I learned a lot from and really enjoyed the Quantum Physics posts at Less Wrong: http://lesswrong.com/lw/r5/the_quantum_physics_sequence/ http://lesswrong.com/lw/r5/the_quantum_physics_sequence/ . The author starts out focusing on the Many-Worlds interpretation and later defends that point, apparently sharing your criticisms. Early on, the author has a lot to say against other teaching approaches that present Quantum Physics as fundamentally mysterious ("No one really understands it anyway, just use these equations") or leave out the Many-Worlds interpretation: >I am not going to tell you that quantum mechanics is weird, bizarre, confusing, or alien. QM is counterintuitive, but that is a problem with your intuitions, not a problem with quantum mechanics. [...] It is always best to think of reality as perfectly normal. >Dragging a modern-day student through all this [initially teaching the subject in the order it was discovered] may be a historically realistic approach to the subject matter, but it also ensures the historically realistic outcome of total bewilderment. Talking to aspiring young physicists about "wave/particle duality" is like starting chemistry students on the Four Elements. [...] The universe is not wavering between using particles and waves, unable to make up its mind. It's only human intuitions about QM that swap back and forth.
- spacehome 11y ago
  Yea, that's a good sequence for its philosophical views, though it's a little light on mathematics and calculations for my taste. It works well as a companion to a more rigorous work. I wish there were a rigorous textbook written from a Many-Worlds perspective.
jorgecurio 11y ago
explain why many world interpretation is deserving of so much predisposed legitimacy when no evidence of it exists and no way to properly measure it.
n4r9 11y ago
Many-Worlds has flaws comparable to many other leading interpretations, which is why it's not a large majority view among quantum information and foundations researchers. Explaining why the observable universe is Born-rule typical is a major issue for Many-Worlds. http://arxiv.org/pdf/gr-qc/9703089.pdf http://arxiv.org/pdf/gr-qc/9703089.pdf is a good discussion of this issue, which I don't think has yet had a satisfactory rebuttal. A more up to date version is at http://arxiv.org/abs/0905.0624 http://arxiv.org/abs/0905.0624 It's silly to insist that every article about quantum phenomena should refer to any particular interpretation of the mathematics.
- spacehome 11y ago
  I thought that explaining the Born rule is a problem for every interpretation.
  - n4r9 11y ago
    It is for many, but not all. Generally speaking, it's less of an issue for interpretations that give an epistemic role to the wavefunction. Perhaps an extreme example, but in the "QBist" interpretation the wavefunction and Born rule are merely a convenient calculus for the prediction of future interactions with the system. It's not the only way to encode this probabilistic information, but it's nice and compact. The issue is then not "why the Born rule?" but "why this particular set of probabilities over potential outcomes?". Then again, a lot of people find the very idea of epistemic interpretations of quantum theory distasteful, especially in light of the Bell, Kochen-Specker and PBR type inequalities.

ThomPete 11y ago

But doesn't many-world interpretation still require a leap of faith though?

spacehome 11y ago
No? At least not any more than any other theory in science. It's a mathematical model that makes predictions. When the predictions stop matching experiment, then we can throw it away.
- ThomPete 11y ago
  Maybe I am wrong but as far as I understand thats not really the issue here. As far as I understand there are 3 types of competing interpretations all trying to deal with the local universe vs. the non-local one and trying to explain them in a way that make sense. 1) Logically consistent, allow us to make predictions but which requires a leap of faith (Many World interpretation) 2) Mathematically correct but does not allow us to make predictions (string theory) 3) Allow us to make predictions, doesn't require leap of faith but isn't logically consistent all the way (Copenhagen interpretation) There is also a couple of outsiders like the electrical universe and plasma universe which completely ignores the idea of quantum weirdness but as far as I understand they also require some leap of faith.
  - gizmo686 11y ago
    Copenhagen requires a leap of faith to accept wavefunction collapse.
    - deleted 11y ago
      [deleted]
- guscost 11y ago
  The difference with an interpretation like MWI is that no experiment can disprove it, even in theory. The interpretation requires that the many worlds do not interact, and unless that changes, there is no way to observe anything contradictory to the interpretation that doesn't also contradict QM. Most other famous science theories are falsifiable (I would say it is a necessary condition to qualify as science).
  - pjscott 11y ago
    It's a mathematical model that makes observable predictions. It's easily falsifiable: just show that its predictions are false. Now, you could argue that there's no test to distinguish it from other interpretations of quantum mechanics, but that applies to them as well.
    - guscost 11y ago
      Which predictions of the MWI are observable? > It's a mathematical model that makes observable predictions. It sounds like you're talking about QM itself, not any interpretation.
      - Moshe_Silnorin 11y ago
        QM, itself, predicts macroscopic decoherence. Many worlds is more a prediction of QM than an interpretation.
        guscost 11y ago
        Great way to present it, but we're still talking about a prediction that can't be tested, even in theory.
    - ThomPete 11y ago
      It makes mathematical predictions perhaps but thats not enough as far as I understand to claim that you can make predictions in any normal sense of that word. And therefore the Parent I was originally responding to at least from my understanding is claiming something thats not telling the whole story.
marcosdumay 11y ago
Only if you believe in it. It's the easiest to understand interpretation of QM, and completely equivalent to all others. So, why not use it?
- danharaj 11y ago
  Because it gets rather complicated to formalize when you try to reconcile universe splitting with special relativity. There is an even simpler interpretation of quantum mechanics: the relational interpretation. It does not speak of any states and therefore no wavefunction collapse. 0 is ontologically better than infinity.
  - spacehome 11y ago
    > it gets rather complicated to formalize when you try to reconcile universe splitting with special relativity Why? And why is it more of a problem for MWI than other interpretations?
    - danharaj 11y ago
      When does a universe split? The relativity of simultaneity causes problems: one observer will have to interpret the universe as splitting in one way and then the other, while another will observe the opposite ordering. My personal favorite interpretation is the relational interpretation [1], where we just stop asking nonsensical questions about the universe. It does away with problematic notions that arise from our biases as human beings. [1] http://plato.stanford.edu/entries/qm-relational/ http://plato.stanford.edu/entries/qm-relational/
Jach 11y ago
No. Check out http://arxiv.org/abs/astro-ph/0302131 http://arxiv.org/abs/astro-ph/0302131

AgentME 11y ago

I learned a lot from and really enjoyed the Quantum Physics posts at Less Wrong: http://lesswrong.com/lw/r5/the_quantum_physics_sequence/ http://lesswrong.com/lw/r5/the_quantum_physics_sequence/ . The author starts out focusing on the Many-Worlds interpretation and later defends that point, apparently sharing your criticisms. Early on, the author has a lot to say against other teaching approaches that present Quantum Physics as fundamentally mysterious ("No one really understands it anyway, just use these equations") or leave out the Many-Worlds interpretation: >I am not going to tell you that quantum mechanics is weird, bizarre, confusing, or alien. QM is counterintuitive, but that is a problem with your intuitions, not a problem with quantum mechanics. [...] It is always best to think of reality as perfectly normal. >Dragging a modern-day student through all this [initially teaching the subject in the order it was discovered] may be a historically realistic approach to the subject matter, but it also ensures the historically realistic outcome of total bewilderment. Talking to aspiring young physicists about "wave/particle duality" is like starting chemistry students on the Four Elements. [...] The universe is not wavering between using particles and waves, unable to make up its mind. It's only human intuitions about QM that swap back and forth.

spacehome 11y ago
Yea, that's a good sequence for its philosophical views, though it's a little light on mathematics and calculations for my taste. It works well as a companion to a more rigorous work. I wish there were a rigorous textbook written from a Many-Worlds perspective.

jorgecurio 11y ago

explain why many world interpretation is deserving of so much predisposed legitimacy when no evidence of it exists and no way to properly measure it.

n4r9 11y ago

Many-Worlds has flaws comparable to many other leading interpretations, which is why it's not a large majority view among quantum information and foundations researchers. Explaining why the observable universe is Born-rule typical is a major issue for Many-Worlds. http://arxiv.org/pdf/gr-qc/9703089.pdf http://arxiv.org/pdf/gr-qc/9703089.pdf is a good discussion of this issue, which I don't think has yet had a satisfactory rebuttal. A more up to date version is at http://arxiv.org/abs/0905.0624 http://arxiv.org/abs/0905.0624 It's silly to insist that every article about quantum phenomena should refer to any particular interpretation of the mathematics.

spacehome 11y ago
I thought that explaining the Born rule is a problem for every interpretation.
- n4r9 11y ago
  It is for many, but not all. Generally speaking, it's less of an issue for interpretations that give an epistemic role to the wavefunction. Perhaps an extreme example, but in the "QBist" interpretation the wavefunction and Born rule are merely a convenient calculus for the prediction of future interactions with the system. It's not the only way to encode this probabilistic information, but it's nice and compact. The issue is then not "why the Born rule?" but "why this particular set of probabilities over potential outcomes?". Then again, a lot of people find the very idea of epistemic interpretations of quantum theory distasteful, especially in light of the Bell, Kochen-Specker and PBR type inequalities.