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From: Stephen Paul King <stephenk1.domain.name.hidden>

Date: Sun, 22 Feb 2004 23:45:20 -0500

Dear Russell,

Let me add that I do not think that it is sufficient to embed space-time

in Hilbert space, we also need some way of explaining how space-time

phenomena acts on the Hilbert space's vectors. The infamous "back-action"...

I have an idea but it is pure vapor at this point ...

Kindest regards,

Stephen

----- Original Message -----

From: "Stephen Paul King" <stephenk1.domain.name.hidden>

To: "Russell Standish" <R.Standish.domain.name.hidden>

Cc: <everything-list.domain.name.hidden>; <issues.domain.name.hidden.org>

Sent: Sunday, February 22, 2004 11:39 PM

Subject: Re: Is the universe computable?

*> Dear Russel,
*

*>
*

*> Does this "quantum theorist " have anything published on this that i
*

can

*> find online? I do need to do better than "can"! I need a "must"! ;-)
*

*>
*

*> Stephen
*

*>
*

*> ----- Original Message -----
*

*> From: "Russell Standish" <R.Standish.domain.name.hidden>
*

*> To: "Stephen Paul King" <stephenk1.domain.name.hidden>
*

*> Cc: "Russell Standish" <R.Standish.domain.name.hidden>;
*

*> <everything-list.domain.name.hidden>; <issues.domain.name.hidden.org>
*

*> Sent: Sunday, February 22, 2004 11:22 PM
*

*> Subject: Re: Is the universe computable?
*

*>
*

*> On Sun, Feb 22, 2004 at 10:33:37PM -0500, Stephen Paul King wrote:
*

*> > Dear Russel,
*

*> >
*

*> > The reference page is about the necessary resources for quantum
*

*> > computation in general. The "result" that "our space-time structure can
*

*> > emerge from a computation on a Hilbert space" is not complicated, we
*

just

*> > prove that the class of all possible evolutions of QM systems includes
*

QM

*> > computations.
*

*> > Then we take Deutsch's work showing how classical systems can be
*

*> > simulated by quantum computations and identify the subset(class) of
*

*> > simulations with the subset(class) of our experiences of "our world"
*

and

*> > figure out how to switch from a 3rd person to a 1st person
*

representation

*> > (something like what Bruno Marchal proposes) .
*

*>
*

*> Ahh, that little word "can". I was taking your previous statement as
*

*> stating something much more profound - that 4D space-time must emerge
*

*> from a Hilbert space computation. Still - perhaps it is possible. I
*

*> was at dinner a couple of weeks ago with a quantum theorist who
*

*> claimed exactly that, starting from a standard QED formulation, and
*

*> taking the h->0 limit. Alas, they tend not to teach QED at
*

*> undergraduate level, so my ability to evaluate this claim is
*

*> impoverished.
*

*>
*

*> > The hard part is taking the idea that Hilbert space is a
*

*> representation
*

*> > of something that has ontological reality - not just a mental construct.
*

*> >
*

*>
*

*> Its not so hard. If we accept ensembles of descriptions as having the
*

*> ultimate ontological reality (similar, if not equivalent, to Bruno's
*

*> arithmetic realism), then Hilbert spaces emerge as the highest measure
*

*> structure under fairly mild assumptions about the nature of
*

*> consciousness. (detailed in my "Why Occam's Razor paper).
*

*>
*

*> > Kindest regards,
*

*> >
*

*> >
*

*> > Stephen
*

*> >
*

*> > ----- Original Message -----
*

*> > From: "Russell Standish" <R.Standish.domain.name.hidden>
*

*> > To: "Stephen Paul King" <stephenk1.domain.name.hidden>
*

*> > Cc: <everything-list.domain.name.hidden>; <issues.domain.name.hidden.org>
*

*> > Sent: Sunday, February 22, 2004 6:04 PM
*

*> > Subject: Re: Is the universe computable?
*

*> >
*

*> > On Wed, Jan 21, 2004 at 11:46:17AM -0500, Stephen Paul King wrote:
*

*> > >
*

*> > > Again, that does not work because we can not take space-time (ala
*

*> GR)
*

*> > to
*

*> > > be "big enough" to allow us to fit QM into it. On the other hand, it
*

has

*> > > been shown that a QM system, considered as a quantum computational
*

*> system,
*

*> > > can simulate, with arbitrary accurasy, any classical system, given
*

*> > > sufficient "Hilbert space" dimensions - which play the role of
*

"physical

*> > > resources" for QM systems.
*

*> > >
*

*> > > See: http://arxiv.org/abs/quant-ph/0204157
*

*> > >
*

*> > >
*

*> > >
*

*> > > This leads me to the idea that maybe space-time itself is
*

something

*> > that
*

*> > > is secondary. It and all of its contents (including our physical
*

bodies)

*> > > might just be a simulation being generated in some sufficiently large
*

*> > > Hilbert space. This idea, of course, requires us to give Hilbert space
*

*> > (and
*

*> > > L^2 spaces in general?) the same ontological status that we usually
*

only

*> > > confer to space-time. ;-)
*

*> > >
*

*> > >
*

*> >
*

*> > Interesting speculation. I'm not sure that it follows from the ref you
*

*> > give above, however if indeed our space-time structure can emerge from
*

*> > a computation on a Hilbert space as you suggest, then this would be a
*

*> > powerful result. I have already shown (viz my Occam's Razor paper)
*

*> > that the Hilbert space stucture follows from Anthropic arguments on
*

*> > ensemble theories. Getting the space time structure is the next big
*

*> > task to be solved.
*

*> >
*

*> > Cheers
*

*> >
*

*>
*

*> --------------------------------------------------------------------------
*

*> --
*

*> > A/Prof Russell Standish Director
*

*> > High Performance Computing Support Unit, Phone 9385 6967, 8308 3119
*

*> (mobile)
*

*> > UNSW SYDNEY 2052 Fax 9385 6965, 0425 253119 (")
*

*> > Australia R.Standish.domain.name.hidden
*

*> > Room 2075, Red Centre
*

*> http://parallel.hpc.unsw.edu.au/rks
*

*> > International prefix +612, Interstate prefix 02
*

*>
*

*> --------------------------------------------------------------------------
*

Received on Sun Feb 22 2004 - 23:47:27 PST

Date: Sun, 22 Feb 2004 23:45:20 -0500

Dear Russell,

Let me add that I do not think that it is sufficient to embed space-time

in Hilbert space, we also need some way of explaining how space-time

phenomena acts on the Hilbert space's vectors. The infamous "back-action"...

I have an idea but it is pure vapor at this point ...

Kindest regards,

Stephen

----- Original Message -----

From: "Stephen Paul King" <stephenk1.domain.name.hidden>

To: "Russell Standish" <R.Standish.domain.name.hidden>

Cc: <everything-list.domain.name.hidden>; <issues.domain.name.hidden.org>

Sent: Sunday, February 22, 2004 11:39 PM

Subject: Re: Is the universe computable?

can

just

QM

and

representation

has

"physical

something

bodies)

only

Received on Sun Feb 22 2004 - 23:47:27 PST

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