Now that a few people have got the ball rolling, I thought I'd but
in. Like most people on this list, I had independently come up with
the idea of "all possibilities" existing in reality a few years ago as
being the simplest description of reality (I liked Max Tegmark's
description of it as being zero information - even a complete void has
one bit of information). It seems the obvious combination of the MWH
and the Anthropic principle. I am curious to know why David Deutsch
did not discuss the Anthropic principle much in his book. What is
great now is that a few like-minded souls are talking about this
stuff, rather than stewing over it in their heads.
I came up with a couple of twists, which I haven't heard mentioned to
date:
i) Take the "all possibilities" theory, add a few reasonable axioms
about probabilty, and _linearity_, and one ends up with a Hilbert
Space over a Complex field - the basic structure of Quantum
Mechanics. Add the correspondance principle, and one should have
generated QM as we know it, neatly explaining why it should be as it
is (I always found the need for the Complex field Hilbert Space kind
of strange).
Presumably correspondance to our known classical laws of physics is an
artifact of the particular universe we live in, but correspondance to
any self-consistent set of "classical" physical laws is probably
required for SASes to exist.
However the linear portion of the multiverse is quite a special
location - so what does this say about the necessity for linearity for
SASes to exist?
ii) Compare Evolution in the "frog" view (we would say the "worm's eye
view" in Australia) vs the "bird" view. In the bird view, all
possibilites can happen, removing contingency from evolution. In fact,
it would appear that evolution probably favours more simple organisms,
than complex (most viruses are recent evolutionary creations). It
has been my experience with certain artificial life systems, eg
Tierra, that usually organisms evolve to become more simpler, although
the jury is still out on this, and Chris Adami has some evidence of
the opposite trend in his Avida system.
>From our "frog" perspective, we must with great probability be sitting
at the end of a long chain of contingent events that ends up producing
a complex SAS. If we look at the history of evolution as we know it
today, most (maybe 60-70%) complexity growth occurred during Cambrian
Explosion (aka Life's Big bang) about 550 million years ago. There
were a couple of other minor complexity growth periods at other stages
during evolution, but for the bulk of evolutionary history, the
various sorts of complexity indicators used remain flat or actually
decrease in time. Tom Ray showed a hand drawn graph illustrating this
at Alife6 at UCLA this year.
My thought is that this indicates that evolution of complex SAS is
exteremely unlikely, a rather pessimistic view compared with the
optimism of Sagan, or for that matter most Alife theorists. This
doesn't indicate that Alife research is worthless - we know that Alife
is possible (it has been done once with B-life after all), but we will
probably need to be much cleverer than we have been to do it. It
probably means that when we all live to be a billion years old, in our
own separate universes (according to the Tegmark suicide discussion
thread) we will probably be seeing an environment largely unchanged
from what we see today.
I am actually proposing to do a "workshop" session at a conference I'm
organising in two weeks time to discuss this point. If I can stimulate
some lively debate, I will publish a transcript on the Internet.
My 1.26c worth
^ What Aussie 2c is worth
these days
Cheers
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Dr. Russell Standish Director
High Performance Computing Support Unit,
University of NSW Phone 9385 6967
Sydney 2052 Fax 9385 7123
Australia R.Standish.domain.name.hidden
Room 2075, Red Centre
http://parallel.hpc.unsw.edu.au/rks
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Received on Mon Nov 16 1998 - 18:51:04 PST