The Day Of The Glider

Aleksey Tikhonov
Nov 30 · 3 min read

A few days ago, Pavel Gertman came to me with an interesting question. He asked if I know the exact dates when Conway’s Game of Life, R-pentomino and Glider were invited. They either already just turned 50 years old or it should happen in a few days and we wouldn’t miss the moment. Different sources give conflicting information, announcing the year of the appearance of Conway’s Game of Life, R-pentomino and Glider as 1969 or 1970, in different combinations. And the authorship (or rather the discovery) of Glider is attributed either to Conway or to Richard Guy.

From pieces, I got this picture: Conway formulated the rules of his Game of Life in the first half of 1969 in Cambridge, and at first iterated different initial patterns manually (on paper and board), but this process turned out to be difficult and boring. Therefore, he asked for help the Cambridge computer center, so Steve Bourne (the author of the first Unix shell, Bourne shell aka sh) and Mike Guy, both were working on the ALGOL 68C there at that moment, came to help Conway. They wrote a program for PDP-7, which facilitates the calculation of generations of Life, and together they began to observe the development of various combinations. At that time, they were especially occupied with r-pentomino, which demonstrates chaotic dynamics in the first 1000+ generations. Towards the end of the summer, Mike’s father, mathematician Richard Guy, joined the experiments, and it was he who, according to Conway’s memories, “at the very end of the fall” of 1969 accidentally noticed that at the 69th generation of R-pentomino development something interesting forms from chaos: a combination that moves steadily along space with period 4 and speed c/4.

Almost a year later, in October 1970, a great article by Martin Gardner about the Game of Life was published in Scientific American. This article brought great popularity on this topic, however, it did not specify explicit dates (“this month we consider Conway’s latest brainchild”), and Glider was named “one of the most remarkable of Conway’s discoveries”. Since then, in most sources, the year of the opening of the game Life, R-pentomino and the Glider is called 1970, and Conway himself is called the first discoverer of Glider.

Long story short, Pavel and I just decided that “Late in the fall of 1969” is today, hereby we declare today Glider Day (let’s celebrate the fiftieth anniversary!). And do not believe anyone, when in a year all scientific journals will celebrate the fiftieth anniversary of the Game of Life, just know that it has already passed;)

Also, if you are too bored reading this, look at my old 3D visualizations of Game of Life generations, read about the glider on the aperiodic mosaic of Penrose or play with convolutions of one-dimensional Wolfram automata into Peano curves.

Altsoph’s blog

Random notes on people and machines

Aleksey Tikhonov

Written by

http://altsoph.com, Data Analyst @ Yandex

Altsoph’s blog

Random notes on people and machines

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