Re: Is the universe computable?

From: Stephen Paul King <stephenk1.domain.name.hidden>
Date: Thu, 8 Jan 2004 09:53:19 -0500

Dear Jesse,

    A very good question, containing its own answer!

You wrote:

> Why, out of all possible experiences compatible with my existence, do I
only
> observe the ones that don't violate the assumption that the laws of
physics
> work the same way in all places and at all times?

    Have you taken into account the idea that observers can communicate
their finding to each other and that, maybe - just maybe - this plays into
the wave function's behavior? David Deutsch has just posted a paper
discussing a related subject (http://xxx.lanl.gov/abs/quant-ph/0401024).
    Let us take some time to read it and then pick this discussion back up.
;-)

Kindest regards,

Stephen


----- Original Message -----
From: "Jesse Mazer" <lasermazer.domain.name.hidden>
To: <everything-list.domain.name.hidden>
Sent: Thursday, January 08, 2004 1:17 AM
Subject: Re: Is the universe computable?


> Stephen Paul King wrote:
> >
> >Dear Jesse,
> >
> > Would it be sufficient to have some kind of "finite" or
"approximate"
> >measure even if it can not be taken to infinite limits (is degenerative?)
> >in
> >order to disallow for "white rabbits"? A very simple and very weak
version
> >of the anthropic principle works for me: Any observation by an observer
> >must
> >not contradict the existence of that observer.
>
> But there are plenty of observations that would not result in my
> destruction, like seeing a talking white rabbit run by me, anxiously
> checking its pocket watch. To pick a less fantastical example, it would
also
> not be incompatible with my existence to observe a completely wrong
> distribution of photons hitting the screen in the double-slit experiment.
> Why, out of all possible experiences compatible with my existence, do I
only
> observe the ones that don't violate the assumption that the laws of
physics
> work the same way in all places and at all times?
>
> >
> > I disagree with David's claim that "The universe doesn't depend on
the
> >rock for its existence..." since the notion of quantum entanglement, even
> >when considering decoherence, implies that the mere presense of a rock
has
> >contrapositive effects on the whole of the "universe". The various
> >discussions of "null measurements" by Penrose and others given a good
> >elaboration on this.
>
> I think you're talking about a different issue than David was. You're
> talking about a rock that's a component of our physical universe, while I
> think David was responding to Chalmers' question about whether random
> thermal vibrations in a rock instantiate all possible computer
simulations,
> including a complete simulation of the entire universe (complete with all
> the rocks inside it).
>
> >
> > To me the computational question boils down to the question of how
> >does
> >Nature solve NP-Hard (or even NP-Complete) problems, such as those
involved
> >with "protein folding", in *what appears to be* polynomial time.
>
> What do you mean by "the" computational question? Are you addressing the
> same question I was, namely how to decide whether some computer simulation
> is instantiating a copy of some other program? If we imagine something
like
> a detailed physical simulation of some computer circuits running program
X,
> it seems intuitive that this simulation instantiates a copy of program X,
> but Chalmers' paper suggests we don't have a general rule for deciding
> whether one program is instantiating any other given program. And as I
said,
> this is relevant to the question of measure, and a measure on
> observer-moments is probably key to solving the white rabbit problem.
>
> --Jesse
>
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Received on Thu Jan 08 2004 - 09:59:45 PST

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