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 As a result, patterns that are originally made up of 2×2 blocks will forever be made up of 2×2 blocks, but the block partition will be offset by one cell in the odd generations from the even generations.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.
| The LifeWiki contains one of the most comprehensive catalogues of patterns available on the internet. Within it you will find:
Did you know...
- ... that quadratically-growing patterns have been found with as few as 23 initial cells?
- ... that the blinker is the only known oscillator that is one cell thick?
- ... that the first spaceship found in Conway's Game of Life that travels in an oblique direction was discovered in 2010?
- ... that there are still lifes that can be split into four stable islands, but not two or three?
- ... that no new spaceships were discovered after 1970 until 1989?
- ... that the first stable reflector was found in October 1996, and the first fast stable reflector appeared in 2013, allowing the construction of oscillators of all periods ≥43 ticks?
- ... that twenty-four spaceship velocities have been constructed, including five infinitely adjustable families of ships?
- ... that there are 71 distinct ways for two gliders to collide, but it is unknown how many distinct 3-glider collisions there are?
- ... that to display the smallest known gun pattern for a Gemini spaceship at 1 cell = 1 pixel, on a standard-density video monitor, a screen over one mile square would be needed?
- ... that no odd-period glider guns were known before 1995, when a period 565 p5-spark-assisted B-heptomino loop was constructed by David Buckingham?