A timeline of Life
Eighty years from a question about self-reproducing machines to a computer built out of gliders - and it has not stopped.
Ulam's lattice models
At Los Alamos, Stanisław Ulam uses the laboratory's early computers to study crystal growth on a discrete lattice - among the first cellular automata, though nobody calls them that yet.
Von Neumann's universal constructor
John von Neumann, prompted by Ulam to abandon his 'robot in a lake of parts' model, designs a 29-state cellular automaton containing a machine that can build a copy of itself from a description tape. The separation of description from machinery anticipates the logic of DNA.
The Garden of Eden theorem
Edward Moore and John Myhill prove that a cellular automaton has configurations with no possible predecessor exactly when it has distinct configurations that evolve identically.
Theory of Self-Reproducing Automata
Von Neumann's manuscript is completed and published by Arthur Burks, thirteen years after his death.
Conway's search
Conway and a group of Cambridge colleagues test candidate rules on a Go board, looking for one that neither dies nor explodes. They settle on B3/S23. Richard Guy spots the glider while the group is tracking the R-pentomino by hand.
Publication
Martin Gardner's Mathematical Games column in Scientific American introduces the Game of Life to a general audience. Conway offers $50 for a proof that some pattern grows without limit - or that none can.
The glider gun
Bill Gosper's team at MIT finds a pattern that emits a glider every thirty generations forever, collecting the prize and establishing that Life supports unbounded growth.
Puffers, breeders and methuselahs
Gosper finds the puffer train and the first breeder - a pattern whose population grows quadratically. Charles Corderman discovers the acorn, seven cells that run for 5,206 generations. Robert Wainwright starts the newsletter Lifeline, the field's first regular publication.
Logic gates
Techniques for building AND, OR and NOT gates from glider streams are established, along with the eaters and reflectors that make routing possible.
Winning Ways
Berlekamp, Conway and Guy publish a sketch proof that Life is Turing complete, using glider streams as signals in a general-purpose computer.
Wolfram's classification
Stephen Wolfram systematically studies the 256 elementary one-dimensional automata, introduces the four behavioural classes, and conjectures that Rule 110 is universal. Christopher Langton coins 'artificial life' and introduces Langton's Ant.
WireWorld
Brian Silverman designs a four-state automaton purpose-built for modelling electronics. Working logic circuits follow almost immediately.
HashLife and Golly's ancestors
Bill Gosper's HashLife algorithm memoises repeated regions of space-time, allowing highly regular patterns to be advanced by astronomically many generations in seconds. Dean Hickerson and David Bell find new oscillators, spaceships and the first sawtooth patterns.
Minimal infinite growth
Paul Callahan finds the smallest pattern within a 5x5 bounding box that grows forever - ten cells.
A Turing machine in Life
Paul Rendell constructs an explicit Turing machine inside Life, later extended in 2010 with an unbounded tape, making it a genuine universal machine rather than a bounded approximation.
A New Kind of Science
Wolfram's 1,200-page argument that simple programs, rather than equations, are the appropriate language for describing nature. Widely read, widely disputed, undeniably influential.
Rule 110 proved universal
Matthew Cook publishes the proof that the simplest interesting class of cellular automaton is already capable of universal computation.
Life inside Life
Brice Due completes the OTCA metapixel: a 2048x2048 Life pattern that behaves exactly like a single Life cell. Tile the plane with it and Life runs inside itself, recursively, forever.
Universal constructor
Adam P. Goucher's Spartan universal computer-constructor can build arbitrary patterns from a program tape - von Neumann's original goal, realised inside Conway's minimal rule.
Self-replication
Distributed search and construction efforts produce genuine self-replicating patterns in Life, including the Gemini spaceship, which carries its own construction blueprint.
Copperhead
A user known only as 'zdr' finds a small c/10 orthogonal spaceship - a speed and size class nobody had managed after forty-five years of searching. Proof that the space is nowhere near exhausted.
The first elementary knightship
Sir Robin, discovered by Adam P. Goucher and Tomas Rokicki using SAT solvers, is the first spaceship found to move at an oblique (knight's move) angle without being assembled from other components.
Conway dies
John Horton Conway dies of COVID-19 on 11 April, aged 82. Tributes across mathematics and computing overwhelmingly take the form of a glider.
Still going
Distributed soup-searching projects such as Catagolue have processed trillions of random starting configurations and continue to find objects nobody has seen before. Every year produces new oscillator periods, new spaceship speeds and new engineering. The search space is effectively infinite.