softalk-pc-1982-12-reduced

known multiphase oscillator is the pentadecathlon, which, as thename implies, repeats itself after fifteen generations. (Space doesnot permit us to show all its mutations.) Life enthusiasts enjoy settingup complex systems of patterns. The pentadecathlon is popularbecause it can, when phased properly, absorb or reflect movingpatterns called gliders.Moving Patterns. Some oscillators just won't stay put. After afew phases, you see the same pattern-surprise !-in a different loca-tion. The simplest is the glider, a four-phase pattern comprising fivecells. It creeps diagonally around the board like a crab. In fourgenerations a glider moves one square. Because the glider is such asimple pattern, it appears again and again in Life literature. If yousee a picture of a Life pattern, no matter how sprawling or uncouth,you can bet that someone, somewhere, has tried to create one by acollision of gliders.Gliders do have some limitations. They are slow and can onlyBlock • •• •Tub••• ••• • •• • PondBoat•Loaf•• •• •• •• BeehiveEaterII••Still Lifes• ••• •• •• • Ship• • ••• • • •• • • SnakeThe Origins of LifeFundamentalists may disagree, but the fact is that Life wascreated in 1970 by John Horton Conway, a mathematician at Gonvilleand Caius College at Cambridge. The "game" was not the firstof its type. It belongs to a branch of mathematics called cellular automatatheory, and many similar games have been created over the lastthirty years, most limited to the dusty pages of scholarly journals.Conway experimented for years before settling on the rules. Hewanted to create a game in which the patterns tended to avoid theextremes of growing without limit and fading quickly into nonexistence.He had three other goals:1. There should be no initial pattern for which there is a simpleproof that the population could grow without limit. ...2. There should be initial patterns that apparently grew withoutlimit.3. There should be initial patterns that grew and changed for aconsiderable period before coming to an end in three possible ways:fading away completely, settling into a stable configuration, orentering an oscillating series of patterns.The first Life games were played with counters, but Conwayfound it convenient to use a PDP-7 computer for the more longlivedpatterns. Conway deYised many of the classic patterns-stilllifes like the block and tub, oscillators like the beacon and clock, thefive-cell glider, and the famous r-pentomino.Conway didn' t publish his Life game, perhaps feeling it tootrivial for a distinguished academic like himself. Instead, he wrote tohis friend Martin Gardner, who described it in his column· inScientific American.Conway had hypothesized that no pattern could grow withoutlimit. Through Gardner's column, he offered a $50 prize to anyonewho could prove or disprove his conjecture. The prize was takenalmost immediately by a group of six researchers in MIT's ArtificialIntelligence Project. Their proof took the form of a glider gun(see accompanying article) that generated endless cells.Gardner's initial column had sparked a reaction not only atPentadecathlon• •• • • • • • ••• •Blinker Beacon Toad Clock Barber Pole• •• • • • • • • • •• • • • •• • •• • • • • ••• • •• • • • •• • • • • • • • • •OscillatorsMIT, but also in computer science departments and data processingoffices all over the country. He started to get material back fromhis readers, enough for several new columns about the game. Soonthere was a regular newsletter called Lifeline, edited by RobertWainwright.By 1974, interest in Life had peaked. " Computer specialistseverywhere had developed such a mania for Life that millions ofdollars in illicit computer time may have already been wasted by thegame's growing number of addicts," rumbled Time that year.In 1975, the game gained some academic recognition when apaper on it was published in the Proceedings of the National Academyof Sciences . In a sense, though, the game was already declining.The most obvious patterns had been explored, and the more complicatedpatterns had only a limited following. In addition,computer security was getting more sophisticated. Administratorswere less willing to let their machines be used as expensive toys forprogrammers. The game was losing its original following. Lifelineceased publication.But something else was happening. The invention of the microcomputerwas moving computer power from centralized mainframesto homes and garages. And having bbught computers,hobbyists were wondering what the devil to do with them.Life provided a partial answer. The game was ideal for the earliestmicrocomputers, since it could be programmed to run in as littleas 2K of memory. As Life gradually disappeared from academicjournals, it began to appear in computer magazines like Byte andRecreational Computing. With the spreading popularity of personalcomputers, each year brings a new generation to be initiated to themysteries of Life.•Readers desiring more information are invited to consult the programs Lifeand Microcosm , reviewed in this issue; Softalk (Apple edition), " Countingwith Colors," June 1982; Byte magazine, December 1978; and ScientificAmerican, " Mathematical Games" section, various issues from October 1970to January 1972 ............................................. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~- 33softolk for the IBM Personal Computer December 1982