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From: Kory Heath <kory.heath.domain.name.hidden>

Date: Sat, 17 Jan 2004 22:23:14 -0500

At 1/17/04, Hal Finney wrote:

*>By natural I mean that we could have simple laws of physics and initial
*

*>conditions in which the creatures evolve over a long period of time,
*

*>as we have seen in our universe.
*

It is very likely that even Conway's Life universe has this feature. Its

rules are absurdly simple, and we know that it can contain self-replicating

structures, which would be capable of mutation, and therefore evolution. We

can specify very simple initial conditions from which self-replicating

structures would be overwhelmingly likely to appear, as long as the lattice

is big enough. (The binary digits of many easily-computable real numbers

would work.) Moving from this 2D world, in which each cell can be pictured

as a square with 4 orthogonal neighbors, we can consider 3D CA in which

each cell is a cube with 6 orthogonal neighbors. There are rule sets and

initial conditions for this lattice structure that are just as simple as

Conway's life, which can similarly contain evolving self-replicating

structures. We can go further and envision a 4D CA in which each cell is a

hypercube with 8 orthogonal neighbors. Without a doubt, there are absurdly

simple rulesets for this lattice structure which are computation universal,

support stable structures like gliders, and support self-replicating

structures which would grow and evolve.

*>Universes of the natural type would seem likely to have higher measure,
*

*>because they are inherently simpler to specify.
*

If that's true, then the CA universes described above should have very high

measure, because they are extremely simple to specify.

*>Tegmark goes into some detail on the
*

*>problems with other than 3+1 dimensional space.
*

Once again, I don't see how these problems apply to 4D CA. His arguments

are extremely physics-centric ones having to do with what happens when you

tweak quantum-mechanical or string-theory models of our particular universe.

-- Kory

Received on Sat Jan 17 2004 - 22:24:44 PST

Date: Sat, 17 Jan 2004 22:23:14 -0500

At 1/17/04, Hal Finney wrote:

It is very likely that even Conway's Life universe has this feature. Its

rules are absurdly simple, and we know that it can contain self-replicating

structures, which would be capable of mutation, and therefore evolution. We

can specify very simple initial conditions from which self-replicating

structures would be overwhelmingly likely to appear, as long as the lattice

is big enough. (The binary digits of many easily-computable real numbers

would work.) Moving from this 2D world, in which each cell can be pictured

as a square with 4 orthogonal neighbors, we can consider 3D CA in which

each cell is a cube with 6 orthogonal neighbors. There are rule sets and

initial conditions for this lattice structure that are just as simple as

Conway's life, which can similarly contain evolving self-replicating

structures. We can go further and envision a 4D CA in which each cell is a

hypercube with 8 orthogonal neighbors. Without a doubt, there are absurdly

simple rulesets for this lattice structure which are computation universal,

support stable structures like gliders, and support self-replicating

structures which would grow and evolve.

If that's true, then the CA universes described above should have very high

measure, because they are extremely simple to specify.

Once again, I don't see how these problems apply to 4D CA. His arguments

are extremely physics-centric ones having to do with what happens when you

tweak quantum-mechanical or string-theory models of our particular universe.

-- Kory

Received on Sat Jan 17 2004 - 22:24:44 PST

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