Hi Saibal,
You are entirely correct about that. Non-local models can indeed
reproduce QM. No surprise than that all the remaining approaches to
the unification of physical theories still fighting it out (string/M
theories,
loop quantum gravity, twistor theory) are non-loca,l unlike the old
QFTs.
That is not the case with 't Hooft's CA models, of course. But he has
later began to play with (deterministic) M-brane type ideas (since he
started teaching string theory) and those may hold better promise.
He is also no longer insisting on the pre-determinism loophole notion
(at least the last time I heard him this year). Maybe he realized that
made him sound a bit foolish...
His web site is always entertaining:
http://www.phys.uu.nl/~thooft/
Godfrey Kurtz
(New Brunswick, NJ)
-----Original Message-----
From: Saibal Mitra <smitra.domain.name.hidden>
To: kurtleegod.domain.name.hidden
Cc: everything-list.domain.name.hidden
Sent: Fri, 19 Aug 2005 18:06:23 +0200
Subject: Re: subjective reality
Hi Godfrey,
As you wrote in reply to others, local deterministic models seem to be
ruled
out. The class of all formally describable models is much larger than
that
of only the local deterministic models. So, although 't Hooft may be
proved
wrong (if loopholes like pre-determinism don't save him), non-local
models
can reproduce QM.
Saibal
----- Original Message -----
From: <kurtleegod.domain.name.hidden>
To: <smitra.domain.name.hidden>; <marchal.domain.name.hidden.ac.be>
Cc: <everything-list.domain.name.hidden>
Sent: Sunday, August 14, 2005 06:07 PM
Subject: Re: subjective reality
> Hi Saibal,
>
> Yes, trans-Plankian physics is likely to be quite different from our
> cis-plankian
> one. However I think the main reason 't Hooft claims the no-go
> theorems of
> quantum physics are "in small print" is because his "reading glasses"
> are no
> longer current :-), I am afraid. His arguments for the prevalence of
> simple
> deterministic models at this scaled have varied over the years (as
his
> little
> examples) and some of these are quite clever, I'll agree.
>
> However, as you very well point out, any transplankian theory worth
> looking
> into has to reproduce a recognizable picture of the cisplankian world
> we know
> and that means: quantum mechanics (non-locality and all) in some
> discernible limit (and General Relativity too in some other limit)
and
> all
> indications is that this cannot be done from deterministic models
> alone.
> 't Hooft has been working around this for the last 10 years or so and
> he doesn't have much to show for it. Considering that it took him
less
> than 2 years to come up with a renormalization prescription for
> non-abelian gauge
> theories in his youth I suspect "god's dice" are loaded against him
> this time.
>
> However he is always fascinating to read and hear. I saw him at
Harvard
> this winter for the Colemanfest and he had the most fabulous
> animations...
>
> Godfrey Kurtz
> (New Brunswick, NJ)
>
> -----Original Message-----
> From: Saibal Mitra <smitra.domain.name.hidden>
> To: kurtleegod.domain.name.hidden; marchal.domain.name.hidden.ac.be
> Cc: everything-list.domain.name.hidden
> Sent: Sat, 13 Aug 2005 01:34:19 +0200
> Subject: Re: subjective reality
>
> Hi Godfrey,
>
> 't Hooft's work is motivated by problems one encounters in Planck
scale
> physics. 't Hooft has argued that the no go theorems precluding
> deterministic models come with some ''small print''. Physicists
> working on
> ''conventional ways'' to unite gravity with QM are forced to make
such
> bold
> assumptions that one should now also question this ''small print''.
>
> As you wrote, 't Hooft has only looked at some limited type of
models.
> It
> seems to me that much more is possible. I have never tried to do any
> serious
> work in this area myself (I'm too busy with other things). I would
say
> that
> anything goes as long as you can explain the macroscopic world. One
> could
> imagine that a stochastic treatment of some deterministic theory
could
> yield
> the standard model, but now with the status of the quantum fields as
> fictitional ghosts. If photons and electrons etc. don't really
exists,
> then
> you can say that this is consistent with ''no local hidden
variables''.
>
> Saibal
>
>
>
> > Hi Saibal,
> >
> > You are correct that Gerard 't Hooft is one of the world exponents
in
> > QFTh.
> > But Quantum Field Theory is but one small piece of QM and one in
> which
> > non-local effects do not play a direct role (as of yet).
> Understandably
> > 't Hooft's forays into Quantum Mechanics have not, however, been
> > very insightful as he himself confesses (you can check his humorous
> > slides in the Kavli Institute symposium of last year on the Future
of
> > Physics).
> >
> > So far he has supplied mostly some interesting simple CA models
from
> > which one
> > can indeed extract something akin to superpositions but that in no
> way
> > bypasses
> > the basic facts of entanglement and non-local correlations.
> >
> > He may very well be the very last hold out for a deterministic (an
> thus
> > classically mechanistic) point-of-view but I would not count him
out
> > just yet. If any one around has the brain to deal with this its
him!
> > That much I will grant you...
> >
> > (Now I have met 't Hooft! 't Hooft was a neighbor of mine and I
tell
> > you: Bruno is no 't Hooft! ;- )
> >
> > Best regards
> >
> > Godfrey Kurtz
> > (New Brunswick, NJ)
> >
> > -----Original Message-----
> > From: Saibal Mitra <smitra.domain.name.hidden>
> > To: kurtleegod.domain.name.hidden; marchal.domain.name.hidden.ac.be
> > Cc: everything-list.domain.name.hidden
> > Sent: Fri, 12 Aug 2005 21:11:30 +0200
> > Subject: Re: subjective reality
> >
> > Godfrey Kurtz wrote
> >
> > > More specifically: I believe QM puts a big kabosh into any
> > non-quantum
> > > mechanistic view of the physical world. If you
> > > don't get that, than maybe you don't get a lot of other things,
> > Bruno.
> > > Sorry if this sounds contemptuous. It is meant
> > > to be.
> >
> >
> > There aren't many people with a better understanding of QFT than 't
> > Hooft.
> >
> >
> >
> > http://arxiv.org/abs/quant-ph/0409021
> >
> >
> > http://arxiv.org/abs/gr-qc/9903084
> >
> >
> > http://arxiv.org/abs/quant-ph/0212095
> >
> >
> > http://arxiv.org/abs/hep-th/0105105
> >
> >
> > http://arxiv.org/abs/hep-th/0104219
> >
> >
> > http://arxiv.org/abs/hep-th/0104080
> >
> >
> >
> >
> > Saibal
> >
> >
> >
> >
> >
>
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>
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Received on Fri Aug 19 2005 - 12:42:45 PDT