hal.domain.name.hidden wrote:
> Jerry Clark, <Jerry.Clark.domain.name.hidden>, writes:
> > More relevantly, it is posulated as highly likely that, starting with
> > a random Life formation, SAS's will evolve of their own accord. One
> > proves this by showing that our UTM is also a universal constructor
> > (can take a coded blueprint and build out of it a machine at least as
> > complex as itself). UTM is also a universal destructor and therefore
> > mobile. Eventually you get evolution and SAS's.
>
> There are difficulties with this, due to the difficulty of a formation
> defending itself against noise from outside. The Life universe does not
> seem to lend itself to constructing barriers. No one has ever built a
> wall that could withstand random Life noise.
Life creatures could perhaps overcome these problems by making multiple
copies of themselves and allowing the majority of them to die. Or life
organisms
could detect empy regions of space using the sort of switchback formations
which
are used in designing the universal constructor.
The problems you are suggesting are substantial I agree, but perhaps not
insurmountable.
>
>
> Of course, the same thing is true in our universe. There is no wall
> that can withstand everything that can be thrown at it (ultra-high
> temperatures, relativistic collisions, etc.). Life has evolved in
> special regions which are relatively gentle.
>
> Now, perhaps if the Life universe was big enough there would be regions
> that just happened to be formed of islands large enough to form living
> entities, surrounded by empty spaces so that these entities would not
> be destroyed from the outside. But these would be very rare, without
> any systematic large-scale phenomena to self-organize biospheres as we
> have in our universe.
>
> > Such 'Life' evolution raises an interesting question: These SAS's
> > would build universities and study mathematics, computer science and
> > physics. Some J.H.Conway of the Life universe would discover the amusing
> > and diverting Life game, and start discovering gliders, glider guns,
> > space rakes etc. Sooner or later a physicists would hear about this new
> > development and the realisation would be made that their universe *is*
> > a Life simulation. Such a discovery would of course revolutionise the
> > study of physics for these SAS's.
>
> This is simply an analog to what is happening in our own universe,
> as we discover regularities and create models of fundamental physics.
> Newtonian mathematics was found to apply with tremendous accuracy to
> the basic behavior of physical objects, and this has provided insight
> into the possible nature of the universe.
What do you mean by "Newtonian mathematics"? If you mean the basic tools
of analysis (calculus) then I was always under the impression that it was
with
a view to solving problems in physics that Newton made these discoveries in
the first place.
I'm talking about someone discovering a model of purely abstract interest and
then
realising that this model accurately represents their world. I don't think
anything
like this has happened to us yet. My hunch is that it will...
>
>
> > More interestingly still: when are *we* going to discover some CA or
> > similar which turns out to be *our* universe? In my lifetime I hope.
>
> There is nothing special about a CA; any set of mathematical laws which
> fully describe our universe. What you are really asking is when or
> whether we will find a fully unified and universal physical theory.
Yes I am. But I'm also suggesting that such a theory may turn out to be a CA.
That doesn't mean that CA's are special. Or even that I think that our world
is a CA.
>
> Whether this theory can be expressed in a formulation based on CAs is
> insignificant in my opinion.
> In particular this would shed no light
> whatsoever on the likelihood that we are in some sense actually part
> of a computer simulation. Computers can simulate any mathematical or
> logical structure, and there is nothing special and CAs.
>
Of course not. But if we did turn out to be a CA (say) then it would be a bit
bloody-minded
to say that this fact was an illusion and we could equally assume our
universe was
a LISP program or whatever, even though all such are computationally
equivalent. Doesn't
physics search for the most *elegant* formulation of our universe's laws? And
doesn't
the coding theorem or some such say, in essence, that the most elegant
explanations
(in terms of low Kolmogorov complexity) can be assumed to be the only ones as
far as
probability computations (and anthropic arguments) are concerned?
Also: I don't think that your question of whether we are "actually" part of a
computer
simulation has any meaning at all. Our world simply exists, as do all
possible worlds. Would
running our world's laws on a giant supercomputer make it exist "more"?
>
> Hal Finney
Received on Mon Dec 06 1999 - 09:09:29 PST
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