5 ms·

Also, this is a marvel of a sentence: "Other than MWI and Bohm, the major interpretations (not including Copenhagen)" "Other than Android and Windows Mobile, a

by pfedor 14y ago

Also, this is a marvel of a sentence: "Other than MWI and Bohm, the major interpretations (not including Copenhagen)" "Other than Android and Windows Mobile, all major cell phone operating systems (not including iOS)" The long and short of it is, for purely philosophical reasons you don't like the notion of the state vector collapse. You freely admit that there is no way to experimentally distinguish between your favorite interpretation and the Copenhagen interpretation. You just declare that it's not even a contender, using arguments which have nothing to do even in principle with the outcome of any experiments. Saying that something is not precisely defined sounds to me totally like grasping at straws. Nothing's ever precisely defined in science, you could criticize any theory including Newton's mechanics by saying that it doesn't define precisely what a measurement is. Which never stopped anyone from measuring things and comparing the values they measured with what the theory predicted. You quote someone who made an analogy with Copernicus. The Copernican theory simplified the calculations right away, whereas with Quantum Mechanics, the calculations stay exactly the same no matter what story you feel like telling yourself so that you can take the outcome of these calculations and compare them with the real world. Let me make this clear that I'm not against MWI. I care about MWI exactly as much as about the Copenhagen interpretation (which is not very much.) I am however opposed to pretending that one of the two exactly equivalent ways of saying something is "more true" than another. Staying within Quantum Mechanics, there are two ways of writing the equations of motion: the Heisenberg picture and the Schroedinger picture. In the former the state vector is constant but the operators are a function of time, in the latter the operators are constant and the state vector evolves with time. The two formulations are equivalent, sometimes it is convenient use one or the other for a specific calculation and often you use a mix of both (so called interaction picture.) Nobody argues that say the Heisenberg picture is "really true" as opposed to the Schroedinger picture. If someone did, that would be inane, even if they invoked Copernicus and Occam (even though the analogy with Copernicus would be maybe better, since the calculations actually are different depending which picture you choose.)

nessus42 14y ago
> The long and short of it is, for purely philosophical reasons you don't like the notion of the state vector collapse. That's not the long and the short of it. I didn't say anything of the sort. You ramble on apparently oblivious that to the fact that different interpretations of QM can and do make different predictions about what causes wave-function collapse. E.g., GRW makes different predictions from Penrose's interpretation. Why you are oblivious to this fact, I cannot fathom, as I've mentioned this fact several times now. http://en.wikipedia.org/wiki/Ghirardi-Rimini-Weber_theory http://en.wikipedia.org/wiki/Penrose_interpretation In theory, someday we'll be able to design experiments that determine which one of these interpretations, if either, is correct. So, as you should be able to see, this is in no way comparable to different forms for equations that make identical predictions. As to the measurement problem http://en.wikipedia.org/wiki/Measurement_problem Newtonian mechanics has no such measurement problem, so it is you who are grasping at straws. If a QM Interpretation is going to be considered a complete theory, it has to answer certain questions. For instance, if were were to train cats to operate quantum measurement devices and to perform experiments for us, and we consequently determined that measurements performed by cats did not cause wave function collapse, would that confirm or deny the Copenhagen Interpretation? A. Neither, because the Copenhagen Interpretation doesn't define "measurement", and so we have no idea whether or not measurement by cats counts as "measurement". You don't like cats, substitute in nanoscale molecular robots instead.
- pfedor 14y ago
  I'm not familiar with GRW, Penrose's theory is obviously more than an interpretation, he postulates new physics which is experimentally testable. The MWI does nothing of the sort to they're not at all similar. Looks like you are trying to confuse the issue: to deny that QM interpretations are not experimentally testable, you bring into discussion a bunch of things which are not interpretations, but actual scientific theories, and call them "interpretations." You might as well argue that the ancient Greek religion was testable (you could climb Mount Olympus and see whether Zeus was there or not), therefore religions are testable, therefore the existence of God is a scientific fact. Regardless of wonderful qualities of the GRW theory and the Penrose interpretation, the fact stands that there is no experimental way, even in principle, to distinguish between MWI and Copenhagen. If you teach cats or mice or West Highland Terriers to perform quantum mechanical experiments, they will still not be able differentiate experimentally between MWI and Copenhagen. And you will not be able to determine whether measurements performed by cats cause wave function collapse, because you will have to observe the cat to ask him what he observed.
  - nessus42 14y ago
    > I'm not familiar with GRW, Penrose's theory is obviously more than an interpretation I have no desire to get into a debate on terminology. I've just been using the terminology that was taught to me in an entire semester-long class I took at MIT on QM and its various "interpretations". GRW was called an "interpretation", as was Penrose's. The term "interpretation" is also the term used on the Wikipedia page for "Penrose's Interpretation". > the fact stands that there is no experimental way, even in principle, to distinguish between MWI and Copenhagen. That is not a fact; your assertion is false: http://en.wikipedia.org/wiki/Many-worlds_interpretation#Comparative_properties_and_possible_experimental_tests See the text starting at "However, in 1985 David Deutsch published three related thought experiments which could test the theory vs the Copenhagen interpretation."
    - pfedor 14y ago
      You know what, this is interesting. I would love to be proven wrong. I searched for that paper but couldn't find it, nor any description of the experiment it proposes. I wrote an email to professor Deutsch asking him to send me a pdf copy. I will get back to you if/when he responds. I still kind of suspect that the paper will make some assumptions that will effectively mean "if <magic> then we could test the MWI in the following way: ...".

by pfedor 14y ago

nessus42 14y ago

> The long and short of it is, for purely philosophical reasons you don't like the notion of the state vector collapse. That's not the long and the short of it. I didn't say anything of the sort. You ramble on apparently oblivious that to the fact that different interpretations of QM can and do make different predictions about what causes wave-function collapse. E.g., GRW makes different predictions from Penrose's interpretation. Why you are oblivious to this fact, I cannot fathom, as I've mentioned this fact several times now. http://en.wikipedia.org/wiki/Ghirardi-Rimini-Weber_theory http://en.wikipedia.org/wiki/Penrose_interpretation In theory, someday we'll be able to design experiments that determine which one of these interpretations, if either, is correct. So, as you should be able to see, this is in no way comparable to different forms for equations that make identical predictions. As to the measurement problem http://en.wikipedia.org/wiki/Measurement_problem Newtonian mechanics has no such measurement problem, so it is you who are grasping at straws. If a QM Interpretation is going to be considered a complete theory, it has to answer certain questions. For instance, if were were to train cats to operate quantum measurement devices and to perform experiments for us, and we consequently determined that measurements performed by cats did not cause wave function collapse, would that confirm or deny the Copenhagen Interpretation? A. Neither, because the Copenhagen Interpretation doesn't define "measurement", and so we have no idea whether or not measurement by cats counts as "measurement". You don't like cats, substitute in nanoscale molecular robots instead.

pfedor 14y ago
I'm not familiar with GRW, Penrose's theory is obviously more than an interpretation, he postulates new physics which is experimentally testable. The MWI does nothing of the sort to they're not at all similar. Looks like you are trying to confuse the issue: to deny that QM interpretations are not experimentally testable, you bring into discussion a bunch of things which are not interpretations, but actual scientific theories, and call them "interpretations." You might as well argue that the ancient Greek religion was testable (you could climb Mount Olympus and see whether Zeus was there or not), therefore religions are testable, therefore the existence of God is a scientific fact. Regardless of wonderful qualities of the GRW theory and the Penrose interpretation, the fact stands that there is no experimental way, even in principle, to distinguish between MWI and Copenhagen. If you teach cats or mice or West Highland Terriers to perform quantum mechanical experiments, they will still not be able differentiate experimentally between MWI and Copenhagen. And you will not be able to determine whether measurements performed by cats cause wave function collapse, because you will have to observe the cat to ask him what he observed.
- nessus42 14y ago
  > I'm not familiar with GRW, Penrose's theory is obviously more than an interpretation I have no desire to get into a debate on terminology. I've just been using the terminology that was taught to me in an entire semester-long class I took at MIT on QM and its various "interpretations". GRW was called an "interpretation", as was Penrose's. The term "interpretation" is also the term used on the Wikipedia page for "Penrose's Interpretation". > the fact stands that there is no experimental way, even in principle, to distinguish between MWI and Copenhagen. That is not a fact; your assertion is false: http://en.wikipedia.org/wiki/Many-worlds_interpretation#Comparative_properties_and_possible_experimental_tests See the text starting at "However, in 1985 David Deutsch published three related thought experiments which could test the theory vs the Copenhagen interpretation."
  - pfedor 14y ago
    You know what, this is interesting. I would love to be proven wrong. I searched for that paper but couldn't find it, nor any description of the experiment it proposes. I wrote an email to professor Deutsch asking him to send me a pdf copy. I will get back to you if/when he responds. I still kind of suspect that the paper will make some assumptions that will effectively mean "if <magic> then we could test the MWI in the following way: ...".