5 ms·

Correct if I'm wrong, but I think that Many Worlds Interpetation does not explain a thing. It's like religion - one can think it's possible, other - impossible.

by Ingaz 14y ago

Correct if I'm wrong, but I think that Many Worlds Interpetation does not explain a thing. It's like religion - one can think it's possible, other - impossible. But it can't be proved or disproved

nessus42 14y ago
I'm pretty sure that, in theory, all the major interpretations of QM are experimentally distinguishable from each other. The feasibility of ever being able to perform some of these experiments, however, is rather questionable. Two exceptions to this are (1) that the Many Worlds Interpretation is experimentally indistinguishable from the Bohm Interpretation, unless you want to commit suicide many times with a quantum revolver; and (2) the Copenhagen Interpretation doesn't define what a "measurement" is, so scientifically determining whether it's correct or not is impossible. None of this implies that any of this is "like religion".
- pfedor 14y ago
  Be specific. What experiment do you have in mind that could distinguish between interpretations? Note that if the "experiment" involves dying to see what's on the other side then it doesn't exactly make it seem less like a religion.
  - nessus42 14y ago
    You might as well say that the Bohm interpretation is "like religion" then, rather than saying that the MWI is. If your assertion is that we might never know which is true, the Many Worlds Interpretation or the Bohm Interpretation, then you might be right. But, if it comes down to these two, most scientists are going to go with the Many Worlds Interpretation by Occam's razor. There are many other theories that we reject by Occam's razor that we can't disprove, and yet we don't typically consider these rejections to be a matter of "religion".
    - pfedor 14y ago
      You might as well say that the Bohm interpretation is "like religion" then, rather than saying that the MWI is. I might except MWI clearly has more True Believers. If your assertion is that we might never know which is true My assertion is that since all interpretations lead to the same exact predictions for every imaginable experiment, it doesn't make sense to say that in any meaningful way one interpretation is true and the others aren't. You might as well be arguing whether the electromagnetic field is weaved by tiny angels out of their hair or not. The Copenhagen interpretation is the closest to "no interpretation" in that it's the most direct way of translating the math into actual predictions. Quoting the guy who said you shouldn't multiply entities without necessity, to justify the introduction of infinitely many parallel worlds, is an interesting rhetorical maneuver.
      - nessus42 14y ago
        > My assertion is that since all interpretations lead to the same exact predictions for every imaginable experiment This is not the case. Other than MWI and Bohm, the major interpretations (not including Copenhagen) make different predictions that are, in theory, distinguishable. It's just that it is completely infeasible to perform the experiments at this time. Maybe in 100 years or in 1,000 years, we'll have the technology to perform these experiments. When the time comes that we can perform these experiments, one of the possible outcomes is that we narrow it down to MWI/Bohm. Once that happens, however, we will have no way to scientifically determine which of the two is the correct interpretation, except to the degree that we trust our intuitions about Ockham's razor. But that is certainly not going to let us know the answer for sure. > The Copenhagen interpretation is the closest to "no interpretation" in that it's the most direct way of translating the math into actual predictions. If we ever want to actually do experiments to determine under precisely which situation the probability wave collapses, then we have to do better than the Copenhagen Interpretation, since it doesn't define what a "measurement" is. Without such a definition, there's no way to test whether it is correct or not. > Quoting the guy who said you shouldn't multiply entities without necessity, to justify the introduction of infinitely many parallel worlds, is an interesting rhetorical maneuver. It's not a "rhetorical maneuver". I'll just refer you to the Stanford Encyclopedia of Philosophy for more info: It seems that the majority of the opponents of the MWI reject it because, for them, introducing a very large number of worlds that we do not see is an extreme violation of Ockham's principle: "Entities are not to be multiplied beyond necessity". However, in judging physical theories one could reasonably argue that one should not multiply physical laws beyond necessity either (such a verion of Ockham's Razor has been applied in the past), and in this respect the MWI is the most economical theory. Indeed, it has all the laws of the standard quantum theory, but without the collapse postulate, the most problematic of physical laws. The MWI is also more economic than Bohmian mechanics which has in addition the ontology of the particle trajectories and the laws which give their evolution. Tipler 1986 (p. 208) has presented an effective analogy with the criticism of Copernican theory on the grounds of Ockham's razor.
  - Symmetry 14y ago
    Well, all the theories of quantum mechanics that rely on waveform collapse all predict that waveform collapse happens, while those that don't don't. Observing that larger and larger objects still have tinier and tinier but still existent quantum effects is evidence against collapse. And if you can demonstrate quantum effects in people, then you've pretty much ruled out the Copenhagen and von Neumann interpretations. Those experiments are inconceivably difficult with our current level of technology, though.
    - pfedor 14y ago
      So you're saying, if Quantum Mechanics turns out to correctly describe larger and larger systems--in other words, unless we discover some new physics which makes QM break at a certain scale--then your pet interpretation will turn out to be true?
      - Symmetry 14y ago
        No, I'm saying that if Schrödinger's equation describes larger and larger systems that means that Quantum Mechanics is Schrödinger's equation rather than being Schrödinger's equation plus waveform collapse. Maybe you could try reading through the Interpretations of Quantum Mechanics Wikipedia page[1] to get a better sense of the issues being talked about here? Whether or not waveforms collapse at a certain scale is precisely the most important issue of disagreement here, and it actually is subject to experiment in theory. And experiment could probably even distinguish between the various families of waveform collapse too. Not that this will distinguish between all interpretations, but it would at least cut the possible number in half. Remember, waveform collapse or "some new physics which makes QM break at a certain scale" was actually the assumption of the people who started quantum physics, and the default assumption of popular writing including the article we're discussing. It wasn't until much later that Everett proposed that it might be an unnecessary hypothesis like Maxwell's aether. [1]http://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics http://en.wikipedia.org/wiki/Interpretations_of_quantum_mech...

by Ingaz 14y ago

Correct if I'm wrong, but I think that Many Worlds Interpetation does not explain a thing. It's like religion - one can think it's possible, other - impossible. But it can't be proved or disproved

nessus42 14y ago

I'm pretty sure that, in theory, all the major interpretations of QM are experimentally distinguishable from each other. The feasibility of ever being able to perform some of these experiments, however, is rather questionable. Two exceptions to this are (1) that the Many Worlds Interpretation is experimentally indistinguishable from the Bohm Interpretation, unless you want to commit suicide many times with a quantum revolver; and (2) the Copenhagen Interpretation doesn't define what a "measurement" is, so scientifically determining whether it's correct or not is impossible. None of this implies that any of this is "like religion".

pfedor 14y ago
Be specific. What experiment do you have in mind that could distinguish between interpretations? Note that if the "experiment" involves dying to see what's on the other side then it doesn't exactly make it seem less like a religion.
- nessus42 14y ago
  You might as well say that the Bohm interpretation is "like religion" then, rather than saying that the MWI is. If your assertion is that we might never know which is true, the Many Worlds Interpretation or the Bohm Interpretation, then you might be right. But, if it comes down to these two, most scientists are going to go with the Many Worlds Interpretation by Occam's razor. There are many other theories that we reject by Occam's razor that we can't disprove, and yet we don't typically consider these rejections to be a matter of "religion".
  - pfedor 14y ago
    You might as well say that the Bohm interpretation is "like religion" then, rather than saying that the MWI is. I might except MWI clearly has more True Believers. If your assertion is that we might never know which is true My assertion is that since all interpretations lead to the same exact predictions for every imaginable experiment, it doesn't make sense to say that in any meaningful way one interpretation is true and the others aren't. You might as well be arguing whether the electromagnetic field is weaved by tiny angels out of their hair or not. The Copenhagen interpretation is the closest to "no interpretation" in that it's the most direct way of translating the math into actual predictions. Quoting the guy who said you shouldn't multiply entities without necessity, to justify the introduction of infinitely many parallel worlds, is an interesting rhetorical maneuver.
    - nessus42 14y ago
      > My assertion is that since all interpretations lead to the same exact predictions for every imaginable experiment This is not the case. Other than MWI and Bohm, the major interpretations (not including Copenhagen) make different predictions that are, in theory, distinguishable. It's just that it is completely infeasible to perform the experiments at this time. Maybe in 100 years or in 1,000 years, we'll have the technology to perform these experiments. When the time comes that we can perform these experiments, one of the possible outcomes is that we narrow it down to MWI/Bohm. Once that happens, however, we will have no way to scientifically determine which of the two is the correct interpretation, except to the degree that we trust our intuitions about Ockham's razor. But that is certainly not going to let us know the answer for sure. > The Copenhagen interpretation is the closest to "no interpretation" in that it's the most direct way of translating the math into actual predictions. If we ever want to actually do experiments to determine under precisely which situation the probability wave collapses, then we have to do better than the Copenhagen Interpretation, since it doesn't define what a "measurement" is. Without such a definition, there's no way to test whether it is correct or not. > Quoting the guy who said you shouldn't multiply entities without necessity, to justify the introduction of infinitely many parallel worlds, is an interesting rhetorical maneuver. It's not a "rhetorical maneuver". I'll just refer you to the Stanford Encyclopedia of Philosophy for more info: It seems that the majority of the opponents of the MWI reject it because, for them, introducing a very large number of worlds that we do not see is an extreme violation of Ockham's principle: "Entities are not to be multiplied beyond necessity". However, in judging physical theories one could reasonably argue that one should not multiply physical laws beyond necessity either (such a verion of Ockham's Razor has been applied in the past), and in this respect the MWI is the most economical theory. Indeed, it has all the laws of the standard quantum theory, but without the collapse postulate, the most problematic of physical laws. The MWI is also more economic than Bohmian mechanics which has in addition the ontology of the particle trajectories and the laws which give their evolution. Tipler 1986 (p. 208) has presented an effective analogy with the criticism of Copernican theory on the grounds of Ockham's razor.
- Symmetry 14y ago
  Well, all the theories of quantum mechanics that rely on waveform collapse all predict that waveform collapse happens, while those that don't don't. Observing that larger and larger objects still have tinier and tinier but still existent quantum effects is evidence against collapse. And if you can demonstrate quantum effects in people, then you've pretty much ruled out the Copenhagen and von Neumann interpretations. Those experiments are inconceivably difficult with our current level of technology, though.
  - pfedor 14y ago
    So you're saying, if Quantum Mechanics turns out to correctly describe larger and larger systems--in other words, unless we discover some new physics which makes QM break at a certain scale--then your pet interpretation will turn out to be true?
    - Symmetry 14y ago
      No, I'm saying that if Schrödinger's equation describes larger and larger systems that means that Quantum Mechanics is Schrödinger's equation rather than being Schrödinger's equation plus waveform collapse. Maybe you could try reading through the Interpretations of Quantum Mechanics Wikipedia page[1] to get a better sense of the issues being talked about here? Whether or not waveforms collapse at a certain scale is precisely the most important issue of disagreement here, and it actually is subject to experiment in theory. And experiment could probably even distinguish between the various families of waveform collapse too. Not that this will distinguish between all interpretations, but it would at least cut the possible number in half. Remember, waveform collapse or "some new physics which makes QM break at a certain scale" was actually the assumption of the people who started quantum physics, and the default assumption of popular writing including the article we're discussing. It wasn't until much later that Everett proposed that it might be an unnecessary hypothesis like Maxwell's aether. [1]http://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics http://en.wikipedia.org/wiki/Interpretations_of_quantum_mech...