This week's featured article
| 2×2 is a Life-like cellular automaton in which cells survive from one generation to the next if they have 1, 2 or 5 neighbours, and are born if they have 3 or 6 neighbours. That is, it is governed by the rulestring "B36/S125". Patterns under the rule have a chaotic evolution similar to those under the standard Life rules, but the chaos tends to die out much more quickly.
The 2×2 rule gets its name from the fact that it can emulate a simpler cellular automaton that acts on each 2×2 block. The emulated automaton is a block cellular automaton that makes use of the Margolus neighbourhood. As a result, patterns that are originally made up of 2×2 blocks will forever be made up of 2×2 blocks, but the block partition will be offset by one cell in the odd generations from the even generations. There are 212 = 4096 such Life-like automata, of which 2×2 is the most well-known.
In the news
- Apr. 21: Improvements to glider syntheses mean that every 15-bit still life has a recipe with at most 13 gliders. The upper limit is currently 12 gliders for 14-bit still lifes, 10 gliders for 13 bits, 8 gliders for 12 bits, and 7 gliders for 11 bits.
- Apr. 17: Tanner Jacobi and Matthias Merzenich set several new bounding-box records with a new glider gun mechanism based on filtered MWSSes.
- Apr. 10: Jeremy Tan releases a new glider recipe database, Shinjuku, specifically for tracking lowest-cost syntheses.
- Apr. 6-7: LifeViewer standardizes support for triangular neighbourhoods starting with Build 320.
- Apr. 5: An exhaustive computer search run by Nathaniel Johnston reveals that there are 14,223,867,298 strict and 15,851,861,075 pseudo 33-bit still lifes, including eleven pseudo still lifes that can be partitioned into three stable pieces but not two, and none that can be partitioned into four stable pieces but not two or three.
| The LifeWiki contains one of the most comprehensive catalogues of patterns available on the internet. Within it you will find:
Did you know...
- ... that the bounding box and recovery time of the current fastest stable reflector, Mike Playle's Snark, are both more than two full orders of magnitude smaller than the first stable reflector, constructed by Paul Callahan in 1996?
- ... that the longest interesting pattern constructed, the caterpillar, contains over 11 million cells, and the 0E0P metacell contains over 18 million cells?
- ... that the Gosper glider gun was the first pattern to be discovered that exhibits infinite growth?
- ... that the block-laying switch engine and the glider-producing switch engine (and various combinations of two switch engines) are the only infinitely-growing patterns that are known to have ever occurred naturally from an asymmetric random starting configuration?
- ... that oscillators are known that oscillate at all periods other than 19, 23, 34, 38 and 41?
- ... that the pentadecathlon and the blinker are the only known oscillators that are polyominos in more than one phase?
- ... that it is impossible for a period 3 oscillator to be a phoenix?
- ... that the 16×16 soup with the longest known lifespan lasts for over 47,000 generations before stabilizing?
- ... that replicators with quadratic population growth have been known to exist in Conway's Game of Life since the early 1970s, but none were found until 2018 when Adam P. Goucher constructed the 0E0P metacell?
- ... that the first known period 37 and 51 oscillators were found in 2009?