RE: Fwd: Implementation/Relativity

From: Higgo James <>
Date: Fri, 30 Jul 1999 12:19:58 +0100

Right, so 'Let a=a+1 goto start" is a mathematical structure with SASs.
That's how far we can compress an MWI universe. But you cannot compress a
single classical universe.

> -----Original Message-----
> From: Christopher Maloney []
> Sent: Friday, July 30, 1999 12:06 PM
> To: everything-list
> Subject: Re: Fwd: Implementation/Relativity
> Russell Standish wrote:
> >
> > Not every position, momentum etc of particles are relevant to the
> > existence of ouselves as SASes. However, other properties, are, such
> > as the value of the fine structure constant. To describe a universe
> > which gives rise to human-like conscious being probably does not
> > require very much information - the axioms of quantum mechanics,
> > axioms of probability theory, the values of a few fundamental
> > quantities etc. etc. In all probability, the universe could be
> > described by something fitting on a conventional floppy disk. However,
> > the program required to expand this description could not be executed
> > within our universe, for reasonably obvious reasons.
> >
> This is from Tegmark's paper (although I think he was paraphrasing
> Tipler from Physics of Immortality):
> Let us imagine a hypothetical Universe much larger than our own,
> which contains a computer so powerful that it can simulate the time-
> evolution of our entire Universe. By hypothesis, the humans in this
> simulated world would perceive their world as being as real as we
> perceive ours, so by definition, the simulated universe would have
> PE [physical existence]. Technical objections such as an infinite
> quantity of information being required to store the data appear to
> be irrelevant to the philosophical point that we will make. For
> instance, there is nothing about the physics we know today that
> suggests that the Universe could not be replaced by a discrete and
> finite model that approximated it so closely that we, its
> inhabitants, could not tell the difference. That a vast amount of
> CPU-time would be needed is irrelevant, since that time bears no
> relation to the subjective time that the inhabitants of the Universe
> would perceive. In fact, since we can choose to picture our Universe
> not as a 3D world where things happen, but as a 4D world that merely
> is, there is no need for the computer to compute anything at all --
> it could simply store all the 4D data, and the "simulated" world
> would still have PE. Clearly the way in which the data is stored
> should not matter, so the amount of PE we attribute to the stored
> Universe should be invariant under data compression. The physical
> laws provide a great means of data compression, since they make it
> sufficient to store the initial data at some time together with the
> equations and an integration routine. In fact, this should suffice
> even if the computer lacks the CPU power and memory required to
> perform the decompression. The initial data might be simple as well,
> containing so little algorithmic information that a single CD-ROM
> would suffice to store it. After all, all that needs to be stored
> is a description of the mathematical structure that is isomorphic to
> the simulated universe. Now the ultimate question forces itself
> upon us: for this Universe to have PE, is the CD-ROM really needed
> at all? If this magic CD-ROM could be contained within the simulated
> Universe itself, then it would "recursively" support its own PE.
> This would not involve any catch-22 "hen-and-egg" problem regarding
> whether the CD-ROM or the Universe existed first, since the Universe
> is a 4D structure which just is ("creation" is of course only a
> meaningul notion within a spacetime). In summary, a mathemtaical
> structure with SASs would have PE if it could be described purely
> formally (to a computer, say) -- and this is of course little else
> than having mathematical existence.
> --
> Chris Maloney
> "Donuts are so sweet and tasty."
> -- Homer Simpson
Received on Fri Jul 30 1999 - 04:23:17 PDT

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