LIFE REVISITED
MINI-UNIVERSE ON YOUR ATARI SCREEN
PROGRAM BY CHARLES JACKSONARTICLE BY GIGI BISSON
Life is a classic computer simulation in which "cells" live and die according to a set of mathematical rules. These cells form fascinating and sometimes beautiful color patterns that continue changing-perhaps forever. This BASIC listing works on all 8-bit Atari computers with disk or cassette. A joystick is required.
Life," as philosopher Thomas La Mance said, "is what happens while we're busy making other plans." But to the computer user, Life is something altogether different. William Poundstone, author of The Recursive Universe, calls this mathematical computer simulation "a video kaleidoscope-the Life screen is a world unto itself. It has its own objects, phenomena and physical laws. It is a window onto an alternate universe."
LEGEND OF LIFE
The Life game, created in 1970 by Cambridge mathematician John Horton
Conway, was introduced to the world by Martin Gardner's column in the February,
1971 issue of Scientific American magazine. The program has had a cult
following ever since and holds a place in history as one of the earliest
achievements in both computer gaming and artificial intelligence.
Without mention of Massachusetts Institute of Technology
computer wizard Bill Gosper, the history of Life would be incomplete. Conway
offered a $50 prize to the first person who could prove or disprove that
a population could grow without limit. In the early '70s, Gosper zealously
hacked Life on a PDP-l computer for 18 months, to the point of believing
it could potentially generate life itself.
"It could run off and do something incredibly random,"
Gosper later told Steven Levy, author of Hackers. Obsessive tinkering
with Life was virtually the beginning of U.S. research into what would
later be called Artificial Intelligence. MIT Life hackers would sit mesmerized,
staring at the pulsating screen, wondering if Life would continue growing,
dying and multiplying forever.
Some computer hackers found fantastic philosophical and
mathematical implicatons in Life. They would experiment idly with different
patterns. A Star of David on screen multiplied and then died after 247
generations. A crucifix lasted just 121 generations. Did this reflect Judaism's
earlier lineage? The MIT whiz-kids experimented with spaceships and swastikas,
stars and "stoplights" (patterns that would flash on and off repeatedly),
searching for the meaning of Life. Gosper imagined a super computer dedicated
to Life. In his hypothetical world of computer Darwinism, only the fittest
cells would survive against impossible mathematical odds. After billions
of generations, he theorized, the computer might create intelligent lifeforms.
Today, Life is a public-domain program you can play on
an Atari computer in your own home, instead of requiring an MIT computer
lab. You may find, alas, that Life is pretty dull stuff by 1986 standards.
Or, you might go Conway, Gosper and the MIT hackers one better, and create
a pattern that multiplies and lives and dies and mutates into a more complex
form-computer life itself.
CREATING LIFE
Life is more like a lava lamp than a game. The player is virtually
nonexistent. Life simply plays itself like a self-perpetuating game of
computerized cellular solitaire.
The core of Life is a growing, dying population of "living"
computer organisms. Think of this as a metaphor for a colony of micro-organisms
multiplying and dividing under a blown-up electronic microscope display.
To create Life, type in Listing 1, LIFE.BAS, check it
with TYPO II and SAVE a copy before you RUN it.
When the program runs, a blinking asterisk [*] cursor
will appear on screen. Using your joystick, move the asterisk to the section
of the screen where you want to place the first cell, and press the trigger.
The cell will look like an X. To erase any X, move the asterisk on top
of it and press the trigger again. The X won't be visible until you move
the asterisk away from it with the joystick.
Continue doing this to create a pattern of cells onscreen.
You might try a box formed of four sets of clusters of three cells each,
or a crucifix composed of six cells-just about any two-dimensional shape
can be used. The fewer cells you use, the faster the pattern will regenerate
and grow. Watching a pattern made of 35 cells, for example, will be about
as exciting as watching grass grow, and not much faster.
The fun here is in discovering which patterns will mutate
and multiply-and which patterns will die after a few short generations.
The shape that Bill Gosper invented, the Glider, will actually "glide"
accross the screen, and return for many generations. The Glider is a simple
"V" pattern composed of five cells. A hexagon formed from six cells is
a "stable form'-once created, it will never change.
Unlike the complexities of real life, simulated Life has
but three simple rules. Each move (or "generation") changes the pattern
of cells according to these rules. The generations will alternate colors
between gold and black cells on a blue screen.
1. The rule of death-A cell with four or more adjacent neighbors dies of over-population. A cell with one or zero adjacent neighbors dies of loneliness. In this version of Life, cells will also die if they hit the edge of the screen.
2. The rule of survival-If a cell has two or three cells for neighbors, it lives to the next round.
3. The rule of birth-If exactly three neighbors are adjacent to an empty cell-sized space, a new cell will be born.
Your Atari will follow these rules and do all the necessary
calculations for you in a matter of seconds. Without the computer's help,
you would be required to tediously figure out all possible birth and death
combinations for each cell on the screen. When the computations are completed,
the computer moves on to the next generation of the cell colony, and a
new pattern appears.
This continues-perhaps for only a few more generations,
perhaps forever-until the entire cell colony dies, or you get tired of
the ever-changing display and turn off the computer.
RECOMMENDED BOOKS
WHEELS, LIFE & OTHER MATHEMATICAL AMUSEMENTS
by Martin Gardener
W.H. Freeman, 1983
HACKERS,
by Steven Levy
Anchor Press/Doubleday, 1985
THE RECURSIVE UNIVERSE
by William Poundstone
Morrow & Co., 1984
Listing 1 LIFE.BAS Download