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Re: QCs and the MWI

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  • Charles Goodwin
    ... From: ... after observation it collapses into one possibility. ... messy and incomprehensible, but necessary as a machine for
    Message 1 of 8 , Mar 31 5:16 PM
      ----- Original Message -----
      From: <alan_forrester@...>
      > Prediction is not the be-all and end-all of everything! You also have to think about explanation.
      > Let's consider QCs under the Copenhagen Interpretation (henceforth CI).
      > The CI, as far as I understand it, says that when we are not observing a quantum system it acts according to the SE, but that
      after observation it collapses into one possibility.
      > The CI treats our preconception that there is only one universe as unquestionable gospel and it treats quantum mechanics as being
      messy and incomprehensible, but necessary as a machine for grinding out the right answers to certain observational questions like
      "waht happens if I shine photons one at a time through a double slit set-up?"
      > QCs take advantage of distinctly quantum mechanical phenomena to do things that classical comptuers can't.
      > Since it's mode of operation is distictively quantum mechanical the CI says that its operation is utterly incomprehensible.
      > I fail to understand how anyone could find the CI version of how QCs work compelling.
      > Similar objections hold for the statistical, hidden variables and just about all the other interpretations.

      But if the MWI is purely an *interpretation* of QM - if it makes NO predictions which distinguish it from other interpretations -
      what's the point of it? If it can't be tested scientifically it must become (as Karl says, quoting Kant) one of those things of
      which we cannot speak and hence must remain silent.

      Charles
    • Charles Goodwin
      ... From: To: Sent: Sunday, April 01, 2001 11:43 AM Subject: QCs and the MWI ... Therefore we
      Message 2 of 8 , Mar 31 6:36 PM
        ----- Original Message -----
        From: <alan_forrester@...>
        To: <Fabric-of-Reality@yahoogroups.com>
        Sent: Sunday, April 01, 2001 11:43 AM
        Subject: QCs and the MWI


        > The MWI takes the implications of quantum theory, including QCs, seriously and then attempts to explain them.
        > So QCs constitute evidence for the MWI because the MWI can explain how they operate but the other interpretations can't.

        Therefore we should use the MWI because it has more explanatory power? But it doesn't make any new testable predictions....Or
        explain underlying mechanisms....sigh. That leaves us in the position of no interpretation being any better than any other. And we
        don't even know whether QCs will *work* anyway!!!

        Charles
      • David Deutsch
        ... You ve fallen for some very bad metaphysical theories. I think it s high time you read *The Fabric of Reality*, especially Chapter 2. See also my *Comment
        Message 3 of 8 , Apr 1, 2001
          Charles Goodwin <charles@...> wrote on 1/4/01 3:36 am:

          > Therefore we should use the MWI because it has more explanatory power? But it
          > doesn't make any new testable predictions....Or explain underlying
          > mechanisms....sigh. That leaves us in the position of no interpretation being
          > any better than any other.

          You've fallen for some very bad metaphysical theories. I think it's high
          time you read *The Fabric of Reality*, especially Chapter 2. See also my
          *Comment on Lockwood...* (available on my web site).

          -- David Deutsch
          http://www.qubit.org/people/david/David.html
        • Charles Goodwin
          Yes you re right. I can only say in my defence that I have to fit in my replies in between interruptions from my 2 year old son and therefore have to rattle
          Message 4 of 8 , Apr 1, 2001
            Yes you're right. I can only say in my defence that I have to fit in my replies in between interruptions from my 2 year old son and
            therefore have to rattle them off really quickly, and the comment you've quoted slipped through the net. Sorry, I will remember to
            engage my brain before typing in future!

            Charles

            ----- Original Message -----
            From: "David Deutsch" <david.deutsch@...>
            To: <Fabric-of-Reality@yahoogroups.com>
            Sent: Sunday, April 01, 2001 9:22 PM
            Subject: Re: QCs and the MWI


            > Charles Goodwin <charles@...> wrote on 1/4/01 3:36 am:
            >
            > > Therefore we should use the MWI because it has more explanatory power? But it
            > > doesn't make any new testable predictions....Or explain underlying
            > > mechanisms....sigh. That leaves us in the position of no interpretation being
            > > any better than any other.
            >
            > You've fallen for some very bad metaphysical theories. I think it's high
            > time you read *The Fabric of Reality*, especially Chapter 2. See also my
            > *Comment on Lockwood...* (available on my web site).
            >
            > -- David Deutsch
            > http://www.qubit.org/people/david/David.html
            >
            >
            >
            >
            >
            > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
            >
            >
          • Capital Office
            ... But it doesn t make any new testable predictions....Or explain underlying mechanisms....sigh. That leaves us in the position of no interpretation being
            Message 5 of 8 , Apr 1, 2001
              Charles Goodwin wrote:
              > Therefore we should use the MWI because it has more explanatory power?
              But it > doesn't make any new testable predictions....Or explain
              underlying > mechanisms....sigh. That leaves us in the position of no
              interpretation being > any better than any other.

              D.D was very clear in FoR that his 'theories' did not make predictions and
              (therefore) could never be tested or disproved. His ideas are only an
              'intepretation' or an 'explanation' of QM.

              Or in other words, the justification of MWI is fundamentally philosophical
              in nature, and not scientific. (In the more strict sense of the use of the
              word 'scientific'.)

              Actually, your criticism is perfectly valid for a purely scientific theory
              and has nothing to do with having "fallen for some very bad metaphysical
              theories" as D.D. would have you believe.

              On the other hand D.D. is right in claiming that your criticism is invalid,
              provided you accept the entire edifice he has constructed, and not just
              bits of it.

              Karl
            • Charles Goodwin
              I agree, as things stand. But I hope that at some point one interpretation or another will lead to a deeper theory which *does* have testable differences. (I
              Message 6 of 8 , Apr 1, 2001
                I agree, as things stand. But I hope that at some point one interpretation or another will lead to a
                deeper theory which *does* have testable differences. (I was hoping that QCs would fulfill that role
                but I now see they don't. Of course the most interesting outcome of QCs may be that they DON'T work,
                which will force *all* interpretations to be reevaluated....!)

                Charles

                > -----Original Message-----
                > From: Capital Office [mailto:development@...]
                > Sent: Monday, 2 April 2001 4:32 a.m.
                > To: Fabric-of-Reality@yahoogroups.com
                > Subject: Re: QCs and the MWI
                >
                >
                > Charles Goodwin wrote:
                > > Therefore we should use the MWI because it has more explanatory power?
                > But it > doesn't make any new testable predictions....Or explain
                > underlying > mechanisms....sigh. That leaves us in the position of no
                > interpretation being > any better than any other.
                >
                > D.D was very clear in FoR that his 'theories' did not make predictions and
                > (therefore) could never be tested or disproved. His ideas are only an
                > 'intepretation' or an 'explanation' of QM.
                >
                > Or in other words, the justification of MWI is fundamentally philosophical
                > in nature, and not scientific. (In the more strict sense of the use of the
                > word 'scientific'.)
                >
                > Actually, your criticism is perfectly valid for a purely scientific theory
                > and has nothing to do with having "fallen for some very bad metaphysical
                > theories" as D.D. would have you believe.
                >
                > On the other hand D.D. is right in claiming that your criticism is invalid,
                > provided you accept the entire edifice he has constructed, and not just
                > bits of it.
                >
                > Karl
                >
                >
                >
                >
                >
                > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                >
              • Capital Office
                Having re-read some of the recent posts on this thread I fear I may have helped create a confusion with regard to the scientific status of MWI. I would like to
                Message 7 of 8 , Apr 1, 2001
                  Having re-read some of the recent posts on this thread I fear I may have
                  helped create a confusion with regard to the scientific status of MWI.

                  I would like to point out that the criticism that MWI "does not make any
                  novel predictions and therefore cannot be tested" is not necessarily valid.

                  If you accept the argument that we already know everything there is to know
                  about QM; that is, that the descriptions of the behaviours of the phenomena
                  described by QM are complete, then it is hardly fair to expect MWI to be
                  able to produce novel predictions.

                  And even if MWI did produce novel predictions, other theorists might
                  possibly be able to re-interpret the meaning of the observation anyway. It
                  would not necessarily settle the issue in a decisive way.

                  On the other hand, the lack of a theory of quantum gravity suggests that
                  certain aspects of QM may be incomplete. This does not help the supporters
                  of MWI.

                  Anyway, the statement that MWI is *only* a philosophical description and
                  not a *proper* scientific theory is not really fair. Ultimately, however,
                  the issue will be decided by "doing science" and not talking philosophy!

                  Karl
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