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What is problematic about the many-worlds interpretation. Even without non-locality, it solves the non-determinism problem, which seems far more problematic to

What is problematic about the many-worlds interpretation. Even without non-locality, it solves the non-determinism problem, which seems far more problematic to me.

ploxiln 11y ago
Well, the only one of the many-worlds that actually matters is this particular one, right here. What can we say/predict about this exact one. The others don't matter to me in the slightest... EDIT: well that's not a great explanation of why I dislike the many-worlds hypothesis, let me try again. Like some other ideas, including the existence of God, it's not (yet?) falsifiable. Which doesn't make it false, of course. But it's a really extraordinary idea. It's not just many worlds, it's a fuck-ton. And what can we do with all of them? Are they for nothing? Does nothing that happens matter because it happened differently in a separate but equally real "world"? I guess, I can believe that "god plays dice with the universe", but I can not believe that "god makes infinite copies of the whole universe and tries all possible quantum outcomes".
- lisper 11y ago
  > it's a fuck-ton Or zero. (But it's definitely not one.) Personally I find the zero-worlds view to be the most intuitively satisfying: http://www.flownet.com/ron/QM.pdf http://www.flownet.com/ron/QM.pdf (Or the movie version: https://www.youtube.com/watch?v=dEaecUuEqfc https://www.youtube.com/watch?v=dEaecUuEqfc) David Mermin's Ithaca interpretation is essentially the same thing: http://arxiv.org/abs/quant-ph/9609013 http://arxiv.org/abs/quant-ph/9609013 The slogan is that "we are correlations without correlata".
- gizmo686 11y ago
  The interpretation we use does not have any effect on our ability to make predictions; the equations are the same. EDIT: response to parent edit Almost by definition interpretations are not falsifiable. The many world interpenetration is literally equivalent to the other interpretations, because they all describe how we understand the meaning of the same mathematical model; and it is that model that is making predictions. In my opinion (as a mathematician, not a physicist), the many worlds interpretation is the more natural way to read quantum theory. That is to say, if I were tasked to design a universe given quantum physics as the specification, my naive implementation would correspond to the many worlds interpretation. An equally valid interpretation is that we are a computer simulation, and quantum physics describes the rounding behavior of said simulation. As far as I am concerned the only point of having an interpretation is to help build an intuition for the models.
- lgas 11y ago
  Why not?
- orangecat 11y ago
  But it's a really extraordinary idea. It's not just many worlds, it's a fuck-ton. Another way of looking at it is that there's only one "world": the amplitude distribution over quantum configuration space. https://www.quora.com/How-does-observation-collapse-probabilities https://www.quora.com/How-does-observation-collapse-probabil... has a decent explanation/argument.
- sciolizer 11y ago
  Do you believe god exists and has a psychology? I'm trying to understand if you have trouble believing because you don't think god would create such a universe, or if you have trouble believing because such a universe is innately unbelievable. If the latter, then I would ask, "Do you believe the ocean is deep, even though you can only see the surface?"
  - ploxiln 11y ago
    The latter. I don't really understand the ocean metaphor, since humans have seen below the surface, quite a distance with remote-controlled submersibles.
    - sciolizer 11y ago
      Perhaps a better analogy would be, do you believe that matter exists beyond the observable universe? Because of the expansion of the universe, it is theoretically possible for me to get in a space ship and travel away from you at such a high speed that we would never be able to meet again, even if at some point we both decided to head back toward each other as fast as possible, and even if we were both immortal. Our light cones would no longer intersect. Probably you would assume that I continue to exist, despite that for all intents and purposes I cannot affect your life in anyway and therefore "don't" exist. Similarly if I crossed the event horizon of a black hole. I believe that a qubit is in superposition (i.e. exists in multiple miniature "universes"), because that theory produces results that are consistent with experiment. When the qubit's universes de-cohere with mine, such that for all intents and purposes I can now only ever observe the qubit in one particular state, why should I assume that the other universes have ceased to exist? Decoherence is a continuous process, just like traveling outside of a light cone, so why treat them any differently. It's rather arbitrary to say that increased distance in space preserves existence, while increased distance in phase space does not.
- Kutta 11y ago
  A usual reply is that physicists don't or shouldn't care about metrics of the size of the universe but rather the simplicity and symmetry of physics. After all, the universe might well be infinite without many worlds, and why do even we care about amounts of stuff? The library of Babel doesn't contain more information than any single book in it. Similarly, pointing to specific areas in a large universe may require adding details.
- fizx 11y ago
  > "god makes infinite copies of the whole universe and tries all possible quantum outcomes". MWI says that probability is conserved across the multiverse (unitarity of the global wavefunction)! The only reason we can "create universes" is because we're in the low-entropy time near the Big Bang. As we start getting closer to the heat death of the multiverse, then less "universes" are being created, because there's no room for them. In fact, given enough time, eventually some of the "universes" will actually join back together! If the multiverse is finite and closed (we don't know this), then sooner or later (like e^2^120 years later, according to a back-of-envelope calculation I saw) all of the universes will be lucky enough to join back up (Poincare recurrence), and we'll end up where we started. I like looking at MWI not as the creation of universes, but as the creation of perspectives on one universe. In any case, it obeys conservation laws.
ryandamm 11y ago
Well, for starters it requires an infinite number of universes, each with zero 'weight.' Secondly, it causes problems for materialist views of the universe. (I wrote a long term paper about this as an undergrad, but that was, like, 15 years ago and I don't have the cuneiform tablets anymore.) Briefly, there's no way to explain the statistical correlations between spin polarization states: if we measure the polarization of a photon in a basis that's only, say, 5 degrees offset from its known polarization, the statistical breakdown between the two resulting polarization states is something like 9:1; what if it's only a few arc-seconds off? Then the universe must divide more and more finely. You quickly realize the universe must be infinitely-divisible (because quantum collapse occurs so often, and each collapse anywhere in the universe must divide the universe, it can't even be discretized at, say, some Planck-like scale). That said, it does neatly solve local realism. But you have to believe in an immortal soul or something non-material -- I believe that has to be the 'weighting factor'. (Again, that was the uncomfortable conclusion of my paper, wish I could conjure more of it.)
- norea-armozel 11y ago
  I think that materialism is a dead concept anyways. It just doesn't seem to support itself under the weight of evidence in physics which seems to contradict it. So, either materialism goes or physicists are going to have a fun time with new experiments overturning old ones.
  - ryandamm 11y ago
    Wow, that's a strong statement. (Are we using the same definition of materialism?) I use it to mean that there are no outside forces describing the state of the universe beyond what's materially measurable/describable; in other words, probably we have no transmaterial soul. That's a strong assumption for anyone who's religious, but it's sort of gospel for atheists. That said, it's the many-worlds hypothesis doesn't square with a totally-naive interpretation of Bell's Inequality and materialism/atheism. So... are you saying that we have to admit there's a God/transmaterial soul / some other magical thing because we don't understand the implication of Bell's inequality? If so, that's a big jump, but I can't say it's wrong. Just that I don't take that leap along with you. You know, there are more things in heaven and earth, Horatio, than etc etc. For both of us.

What is problematic about the many-worlds interpretation. Even without non-locality, it solves the non-determinism problem, which seems far more problematic to me.

ploxiln 11y ago

Well, the only one of the many-worlds that actually matters is this particular one, right here. What can we say/predict about this exact one. The others don't matter to me in the slightest... EDIT: well that's not a great explanation of why I dislike the many-worlds hypothesis, let me try again. Like some other ideas, including the existence of God, it's not (yet?) falsifiable. Which doesn't make it false, of course. But it's a really extraordinary idea. It's not just many worlds, it's a fuck-ton. And what can we do with all of them? Are they for nothing? Does nothing that happens matter because it happened differently in a separate but equally real "world"? I guess, I can believe that "god plays dice with the universe", but I can not believe that "god makes infinite copies of the whole universe and tries all possible quantum outcomes".

lisper 11y ago
> it's a fuck-ton Or zero. (But it's definitely not one.) Personally I find the zero-worlds view to be the most intuitively satisfying: http://www.flownet.com/ron/QM.pdf http://www.flownet.com/ron/QM.pdf (Or the movie version: https://www.youtube.com/watch?v=dEaecUuEqfc https://www.youtube.com/watch?v=dEaecUuEqfc) David Mermin's Ithaca interpretation is essentially the same thing: http://arxiv.org/abs/quant-ph/9609013 http://arxiv.org/abs/quant-ph/9609013 The slogan is that "we are correlations without correlata".
gizmo686 11y ago
The interpretation we use does not have any effect on our ability to make predictions; the equations are the same. EDIT: response to parent edit Almost by definition interpretations are not falsifiable. The many world interpenetration is literally equivalent to the other interpretations, because they all describe how we understand the meaning of the same mathematical model; and it is that model that is making predictions. In my opinion (as a mathematician, not a physicist), the many worlds interpretation is the more natural way to read quantum theory. That is to say, if I were tasked to design a universe given quantum physics as the specification, my naive implementation would correspond to the many worlds interpretation. An equally valid interpretation is that we are a computer simulation, and quantum physics describes the rounding behavior of said simulation. As far as I am concerned the only point of having an interpretation is to help build an intuition for the models.
lgas 11y ago
Why not?
orangecat 11y ago
But it's a really extraordinary idea. It's not just many worlds, it's a fuck-ton. Another way of looking at it is that there's only one "world": the amplitude distribution over quantum configuration space. https://www.quora.com/How-does-observation-collapse-probabilities https://www.quora.com/How-does-observation-collapse-probabil... has a decent explanation/argument.
sciolizer 11y ago
Do you believe god exists and has a psychology? I'm trying to understand if you have trouble believing because you don't think god would create such a universe, or if you have trouble believing because such a universe is innately unbelievable. If the latter, then I would ask, "Do you believe the ocean is deep, even though you can only see the surface?"
- ploxiln 11y ago
  The latter. I don't really understand the ocean metaphor, since humans have seen below the surface, quite a distance with remote-controlled submersibles.
  - sciolizer 11y ago
    Perhaps a better analogy would be, do you believe that matter exists beyond the observable universe? Because of the expansion of the universe, it is theoretically possible for me to get in a space ship and travel away from you at such a high speed that we would never be able to meet again, even if at some point we both decided to head back toward each other as fast as possible, and even if we were both immortal. Our light cones would no longer intersect. Probably you would assume that I continue to exist, despite that for all intents and purposes I cannot affect your life in anyway and therefore "don't" exist. Similarly if I crossed the event horizon of a black hole. I believe that a qubit is in superposition (i.e. exists in multiple miniature "universes"), because that theory produces results that are consistent with experiment. When the qubit's universes de-cohere with mine, such that for all intents and purposes I can now only ever observe the qubit in one particular state, why should I assume that the other universes have ceased to exist? Decoherence is a continuous process, just like traveling outside of a light cone, so why treat them any differently. It's rather arbitrary to say that increased distance in space preserves existence, while increased distance in phase space does not.
Kutta 11y ago
A usual reply is that physicists don't or shouldn't care about metrics of the size of the universe but rather the simplicity and symmetry of physics. After all, the universe might well be infinite without many worlds, and why do even we care about amounts of stuff? The library of Babel doesn't contain more information than any single book in it. Similarly, pointing to specific areas in a large universe may require adding details.
fizx 11y ago
> "god makes infinite copies of the whole universe and tries all possible quantum outcomes". MWI says that probability is conserved across the multiverse (unitarity of the global wavefunction)! The only reason we can "create universes" is because we're in the low-entropy time near the Big Bang. As we start getting closer to the heat death of the multiverse, then less "universes" are being created, because there's no room for them. In fact, given enough time, eventually some of the "universes" will actually join back together! If the multiverse is finite and closed (we don't know this), then sooner or later (like e^2^120 years later, according to a back-of-envelope calculation I saw) all of the universes will be lucky enough to join back up (Poincare recurrence), and we'll end up where we started. I like looking at MWI not as the creation of universes, but as the creation of perspectives on one universe. In any case, it obeys conservation laws.

ryandamm 11y ago

Well, for starters it requires an infinite number of universes, each with zero 'weight.' Secondly, it causes problems for materialist views of the universe. (I wrote a long term paper about this as an undergrad, but that was, like, 15 years ago and I don't have the cuneiform tablets anymore.) Briefly, there's no way to explain the statistical correlations between spin polarization states: if we measure the polarization of a photon in a basis that's only, say, 5 degrees offset from its known polarization, the statistical breakdown between the two resulting polarization states is something like 9:1; what if it's only a few arc-seconds off? Then the universe must divide more and more finely. You quickly realize the universe must be infinitely-divisible (because quantum collapse occurs so often, and each collapse anywhere in the universe must divide the universe, it can't even be discretized at, say, some Planck-like scale). That said, it does neatly solve local realism. But you have to believe in an immortal soul or something non-material -- I believe that has to be the 'weighting factor'. (Again, that was the uncomfortable conclusion of my paper, wish I could conjure more of it.)

norea-armozel 11y ago
I think that materialism is a dead concept anyways. It just doesn't seem to support itself under the weight of evidence in physics which seems to contradict it. So, either materialism goes or physicists are going to have a fun time with new experiments overturning old ones.
- ryandamm 11y ago
  Wow, that's a strong statement. (Are we using the same definition of materialism?) I use it to mean that there are no outside forces describing the state of the universe beyond what's materially measurable/describable; in other words, probably we have no transmaterial soul. That's a strong assumption for anyone who's religious, but it's sort of gospel for atheists. That said, it's the many-worlds hypothesis doesn't square with a totally-naive interpretation of Bell's Inequality and materialism/atheism. So... are you saying that we have to admit there's a God/transmaterial soul / some other magical thing because we don't understand the implication of Bell's inequality? If so, that's a big jump, but I can't say it's wrong. Just that I don't take that leap along with you. You know, there are more things in heaven and earth, Horatio, than etc etc. For both of us.