[extropy-chat] LIMBOIDS

[scerir]

> LIMBOIDS 
> What, if anything, separates life from nonlife?

[miscellanea]

At Caltech, Chris Adami is studying exactly that, imo.
http://dllab.caltech.edu/avida/
http://dllab.caltech.edu/research/

"According to our approach living organisms 
and computer programs are beautiful structures 
and are pretty much the same thing." (?!)
http://physis.sourceforge.net/ 

John Baez wrote: 'Is life improbable?', 
in Found. Phys. 19 (1989), 91-95,
and sometimes this paper appears here too
http://math.ucr.edu/home/baez/improbable.pdf
According to J.B. his paper explains the flaw 
in a famous proof by Wigner. What his [Wigner's] 
argument actually proves is something much 
weaker than what he wanted to prove. Roughly, 
he proves that if you first pick a specific 
design of a machine and then randomly choose 
the laws of physics, it's unlikely this machine 
will be able to reproduce itself in a specific 
amount of time. This should not be surprising: 
to design a machine that does a specified task, 
one usually needs to know a little about the laws 
of physics ahead of time.  When I restated the problem 
- says J.B. - and redid Wigner's calculation,
I got drastically different results.

See also: quant-ph/0303124
'Quantum Mechanical Universal Constructor'
by Arun K. Pati, and Samuel L. Braunstein
" Arbitrary quantum states cannot be copied. 
In fact, to make a copy we must provide complete 
information about the system. However, can a quantum 
system self-replicate? This is not answered by the 
no-cloning theorem. In the classical context, Von Neumann 
showed that a 'universal constructor' can exist which 
can self-replicate an arbitrary system, provided that 
it had access to instructions for making copy of the 
system. We question the existence of a universal 
constructor that may allow for the self-replication
of an arbitrary quantum system. We prove that there 
is no deterministic universal quantum constructor 
which can operate with finite resources.
Further, we delineate conditions under which such 
a universal constructor can be designed to operate 
deterministically and probabilistically. "

For now, beautiful  manmade boids are here
http://www.red3d.com/cwr/boids/
(no need of a universal quantum constructor!)