Re: Is the universe computable

From: Pete Carlton <>
Date: Tue, 20 Jan 2004 14:48:14 -0800

The following thought experiment might provoke some intuitions on this

Imagine a Life universe that contains, among other things, two SASes
talking to each other (and showing each other pictures, and in general
having a very lucid, conscious, conversation.) Imagine that instead of
being implemented on a computer, it's implemented by a large 2d array
of coins: heads represents "live", and tails represents "dead". Each
timestep, the coins are flipped over in concordance with the Life
Does this setup implement a universe?
  If you say it does, how about the next step:
Instead of doing flipping operations on one set of coins, each new
generation is laid down in the proper configuration on top of the
preceding one with a new set of coins. Does this >process< of laying
down coins also implement a universe?
If you say it does, then what about the stack itself? (One can imagine
pointing to each layer in succession, saying "This is the current
step", "Now this is the current step", etc..) Does the stack's bare
existence suffice for the implementation of a universe?

If not, then can you say what it is about the active process of
flipping or laying down that "counts" as computation but does not count
when the stack is a static block?

If you think the static block "counts" as the implementation of a
universe, then I think you can go all the way to abstract Platonism.
Because since the stack's just sitting there, why not knock it down?
Or melt it into a big ball? Or throw it into a black hole...the two
SASes won't care (will they?)

So I think the anti-Platonist must answer why exactly the coins need to
be actively flipped or laid down to "really" implement a Life universe
-- and by extension, why any universe needs to be "actively"

> Then question then becomes, I suppose, if in fact our universe is a
> digital
> one (if not strictly a CA) havng self-consistent emergent physics, then
> might it not follow that it is "implemented" (run?) via some
> extra-universal
> physical processes that only indirectly correspond to ours?
> (if the above is too painfully obvious (or goofy?) and/or old news
> then,
> again, do humor me..)
Received on Tue Jan 20 2004 - 17:50:17 PST

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