----- Oorspronkelijk bericht -----
Van: "Alan Forrester" <alan_forrester2.domain.name.hidden>
Aan: <Fabric-of-Reality.domain.name.hidden>
Verzonden: donderdag 18 juli 2002 11:22
Onderwerp: Re: Copenhagen interpretation
> --- Saibal Mitra <smitra.domain.name.hidden> wrote:
>
> > > How specifically do you explain EPR correlations under this theory?
> > How
> > do
> > > you get past the difficulty of reconciling your version of the CI with
> > > special and general relativity seeing as, as Hardy showed in a paper
in
> > > Physical Review Letters, any single universe interpretation fo QM must
> > be
> > > not only non-local, but also non-Lorentz-invariant?
> >
> > I still have to look at that paper, but I suspect that the non-local,
> > non-Lorentz-invariant behaviour refers to the behaviour of the
> > nonexistent
> > particles. That's no problem. Concerning EPR correlations, 't Hooft is a
> > bit
> > vague in his latest article. I think the whole issue of EPR correlations
> > is
> > irrelevant, again because of the nonexistence of particles.
> >
>
> It doesn't have anyhting to do with particles, simply with the values of
> observables, and correlations in these values. Relativistic quantum
theory
> cannot accomodate the existence of particles at all, but it still has
> EPR-type correlations. Regardless of whether particles exist or not, EPR
> correlations do exist and Bell's Theorem shows that it is impossible for
> any version of quantum theory in which observables are single-valued to
> explain them single-valuedness is all that is required, nothing else, look
> it up. So I would be very surprised if 't Hooft can explain them, unless
he
> has a disproof of Bell's Theorem, which seems unlikely.
Since 't Hooft's theory reduces to QM (in certain limits), there is no
problem here. Bell's theorem comes with some ``small print´´ that you have
ignored here. In fact you can never rule a deterministic universe out
experimentally. All you can do is rule certain types of deterministic univer
ses out.
A trivial counterexample can be constructed as follows. Just simulate the
Schrödinger equation on a classical computer. Simulate how Aspect performes
his experiment. Then observe that the computer can be described using the
laws of ordinary classical physics. The physics needed to describe the
computer is certainly Lorentz invariant and completely local. Yet the
virtual Aspect has just measured the violation of Bell's inequalities. Of
course, this example is very similar to the usual MWI picture. To save
computing time you could write a program that only computes what is
happening in one branch (selected by a random generator). Whatever you
program, the computer won't violate Lorentz invariance or locality.
> > >
> > > In short, the CI requires the complete destruction of the two most
> > > fundamental of the two most fundamental theories (it also destroys QM
> > > because the whole point is to eliminate the only interpretation of QM
> > that
> > > provides a satisfactory explanation fo QM phenomena, the MWI) of 20th
> > > century physics, what does it offer to off-set this overwhelming
> > > disadvantage?
> >
> > It offers the ultimate laws of physics. Note that the MWI doesn't
provide
> > an
> > explanation of QM phenomena at all, as MWI is itself QM (minus
collapse).
>
> A gross oversimplification. That would be like DeWitt's statement that QM
> provides its own interpretation, which is obviously wrong because of the
> dog's dinner that has been made (and continues to be made, by t'Hooft
among
> others) of interpreting QM.
>
> > In
> > 't Hooft's theory QM is derived from deeper principles.
>
> No, it isn't. In
> http://arxiv.org/abs/gr-qc/9903084
> t'Hooft claims that quantum computers would not work, quantum theory
> predicts that they would. Therefore in t'Hooft's model, the Schrodinger
> Equation is simply false, he provides no alternative, but just mumbles
that
> somehow it will all come right in the end.
He does provide an alternative. See the first part of the article. Ok., he
looks at extremely simple universes that can only be in a few states, but he
clearly demonstrates how you get to the Schrödinger equation.
>'t Hooft's supposed answer to
> this is that there is a preferred basis, and that the universe stays in
> this basis forever, but this is simply inconsitent with QM, preferred
bases
> are only ever local approximations to the structure of the multiverse, see
> for example,
>
> "Preferred basis in quantum theory and the problem of classicalization of
> the quantum Universe", A. O. Barvinsky and A. Yu. Kamenshchik, Phys. Rev.
D
> 52, 743-757 (1995)
>
>'t Hooft writes,
>
> '"Reality", as we perceive it, does not refer to the question of whether
an
> electron went through one slit or another.'
>
> That is because there is no explanation of single particle interference in
> which does not feature some physical thing, the wave function, passing
> through both slits. The MWI is true, the CI is false, the CI is so bad
> that even 't Hooft doesn't believe it, as shown by this remark.
>
> There are real, deep, fundamental problems related to QM, relativity and
> gravity that remain to be solved, it's a shame that talented people like
> 't Hooft choose to waste their time on the CI rather than admitting that
> classical physics is dead and gone forever and that it's time to take QM
> seriously.
Physicists have taken QM seriously for 80 years. Despite a quarter century
of effort we still don't have an acceptable theory of quantum gravity. The
possibility that QM is wrong should be taken serious. It's a shame that only
't Hooft is taking this possibility serious.
Saibal
Received on Sat Jul 20 2002 - 15:22:08 PDT