On Sat, Jan 17, 2004 at 11:05:18PM -0800, Hal Finney wrote:

> Yes, I see that that is true.  I think it points to a problem with some
> of the simple conceptualizations of measure, about which I will say
> more below.But let me ask if you agree that considering Conway's 2D
> Life world with simply-specified initial conditions as in your example,
> that conscious life would be extraordinarily rare?

Life is an universal CA (it is possible to implement Life in Life e.g.), 
but not all universal CAs are suitably structure to
support emergence of life from a random pattern.

Biggest problem is translation, Life doesn't support translation of large
blocks, so you have to implement storage/copy, it doesn't have noniteractive
particles natively, it doesn't conserve noise naturally (you get increasingly
rare splotches of noise of gliders colliding with stationary/evolving

You could implement a more suitable CA (or any other machine) in Life, but it
couldn't emerge naturally (it would have a huge cell unit size), and it's not
obvious it could eventually overgrow the entire substrate, once emerged
(there might be tricks with perimeter guards, etc., but the whole point is
that Life is pretty hostile to emergence of life.
> I want to say, vastly more rare than in our universe, but of course we
> don't know how rare life actually is in our universe, so that may be a

It would be nice if we could find several independently emerged life
nucleation points in our solar system (difficult, given the high rates of
crosscontamination through impact ejecta).

If we don't find them, the emergence of local life is of course causally
linked to us, so it's still biased by the anthropic principle. We need other
data points, maybe from nearby systems.

> hard claim to justify.  But the point is that our universe has stable
> structures; it has atoms of dozens of different varieties, which can form
> uncountable millions of stable molecules.  It has mechanisms to generate
> varieties of these different molecules and collect them together in
> environments where they can react in interesting ways.  We don't have a
> full picture of how life and consciousness evolved, but looking around,
> it doesn't seem like it should have been THAT hard, which is where the
> Fermi paradox comes from.  In many ways, our universe seems tailor made

There's not much of a paradox, if you look at Fermi from anthropic principle
angle. And we absolutely can't say how probable emergence of an advanced
culture is (given the above).  We have been leading unusually sheltered
lifes, and there's nothing particularly obvious about us coming into being
scant few 100 megayears before the curtain falls on life in the local

> for creating observers.
> In contrast, in the Life world there are no equivalents to atoms or
> molecules, no chemical reactions.  It's too chaotic; there's not enough

Life's about patterns, not atoms or reactions. I agree that Life is sterile,
however, and there are no obvious tweaks in how make it work better.

However, most digital physics people seem to think the unit cell is at Planck
scale, or below, and I have absolutely no idea how a Plack scale life would
look like on macroscale, considering how much volume one has, and how many
iterations occur there.

I never figured out how to get rid of grid assymetries shining through to
macroscale, and how to generate rule tables with conservation laws intact,
but then there are perfectly spherical sound waves, and wave interferece in
stupid lattice gas automata, of all things.

That's pretty surprising, so perhaps it doesn't make sense to rule out too
much yet.

> structure.  Replicators and life seem to require a balance between
> chaos and stasis, and Life is far too dynamic.  It just looks to me
> like it would be almost impossible for replicators to arise naturally.
> Almost impossible, but not absolutely impossible, so if you tried enough
> initial conditions as you suggest, it would happen.  I won't belabor
> this argument unless you disagree about the ease with which life might
> arise in a Life universe, and consciousness evolve.

I'd rather amazed to see large assemblies capable of translation in Life
universe, already.
> that those are too parochial.  But as I recall he had a number of broad
> arguments that would apply even to a Life-like universe.
> This was the motivation for the idea I proposed a few days ago, that
> for applying anthropic reasoning, a universe should get a "bonus" if
> it had a high density of observers, rather than merely a high absolute

I'm not sure how that follows, using anthropic principle and relativistic
pioneer expansion wavefront (which directly follows from Darwin, and
current knowledge of propulsion methods) the Fermi paradoxon completely 

> number of them.  It's too easy to create universes with low-density
> observers, as your example of Life suggests.  But just as the existence
> of a counting program does not give a typical integer a low complexity,
> so the existence of universes that are simple but contain super-rare
> life forms should not give those observers a high measure.

I'm not following you here. How does the fact that we observe our existance
follow from prediction that this universe is likely to be teeming with life?

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