Re: Fwd: Implementation/Relativity

From: Christopher Maloney <>
Date: Fri, 30 Jul 1999 07:06:24 -0400

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 - 04:15:49 PDT

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