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From: eed_wwhh@jhunix.HCF.JHU.EDU (William H Huggins)
Newsgroups: unix-pc.sources
Subject: Life game for the UNIX PC
Keywords: cellular automata, evolution
Message-ID: <3934@jhunix.HCF.JHU.EDU>
Date: 11 Jan 90 23:11:07 GMT
Organization: The Johns Hopkins University - HCF
Lines: 66

On 25 Oct 89, karl@zip.UUCP (Karl F. Fox) posted Article 446 of
unix-pc.sources which presented graphic programs for displaying the
outcome of Conway's Game of Life.  This fascinating 'Game' and
its realization by Fox on the UNIX-PC is more than just an
amusement because it casts light on some of the major intellectual
questions of the day (e.g. is an embryo a human being?).

In a Letter to NATURE, vol 342 14 December 1989, Per Bak,
Kan Chen & Michael Creutz of the Dept of Physics, Brookhaven National
Laboratory, Upton, NY 11973, USA, report fascinating experiments 
using the outcome of running the Game of Life as analyzed using the
concepts of statistical mechanics to study the long-time and large-scale
behaviour of the outcomes.  The abstract of the short letter is
reproduced below:
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Self-organized criticality in the 'Game of Life', Nature, vol 342,
14 December 1989, pps 780-781.

ABSTRACT:

 THE 'Game of LIfe' is a cellular automaton, that is a lattice system in
 which the state of each lattice point is determined by the local rules.
 It simulates, by means of a simple algorithm, the dynamical evolution
 of a society of living organisms.  Despite its simplicity, the complex
 dynamics of the game are poorly understood.  Previous interest in 'Life'
 has focused on the generation of complexity in local configurations;
 indeed, the system has been suggested to mimic aspects of the emergence
 of complexity in nature [1,2].  Here we adopt a different approach, by
 using concepts of statistical mechanics to study the system's long-time
 and large-scale behaviour.  We show that local configurations in the
 'Game of Life' self-organize into a critical state.  Such self-organized
 criticality provides a general mechanism for the emergence of scale-free
 structures [3-5], with possible applications to earth-quakes [6,7],
 cosmology [8], turbulence [9], biology and economics [10].  By
 contrast to these previous studies, where a local quantity was
 conserved, 'Life' has no local conservation laws and therefore
 represents a new type of universiality class for self-organized
 criticality.  This refutes speculations that self-organized criticality
 is a consequence of local conservation [11], and supports its relevance
 to the natural phenomena above, as these do not involve any locally
 conserved quantities.  The scaling is universal in the sense that the
 exponents which characterize correlation functions do not depend on
 details of the local rules.

 [1] Berlekamp, E.R., Conway, J.H & Guy, H.K. "Winning Ways for Your
     Mathematical Plays" vol 2 (Academic, 1982).
 [2] Gardner, M. Scientif. Am. 223(4), 120-124; (5), 118; (6), 114 (1970).
 [3] Bak, P., Tang, C. & Wiesenfeld, K.  Phys. Rev. Lett. 69, 381-384 (1987)
 [4] Bak, P. & Tang, C.  Phys Today 42, 527 (1989).
 [5] Kadanoff, L.P., Nagel, S.R., Wu, L. & Zhou, S. Phys. Rev. A39,
     6524-6537 (1989).

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I am indebted to Robert Ballentine, Dept. of Biology, Johns Hopkins
University for calling this Letter to my attention, and also for 
noting its relevance to the remarkable book by Richard Dawkins "The
Blind Watchmaker -- Why the evidence of evolution reveals a universe
without design", W.W. Norton & Company (1987) paperback $7.95; 
ISBN 0-393-30448-5 .  Norton provides a software program (for
Macintoshes) designed to demonstrate the arguments developed in
this book which has been acclaimed as perhaps the most influential
work on evolution written in this century.

W.H. Huggins
The Johns Hopkins University
eed_wwhh@jhunix.hcf.jhu.edu