|View static image|
|Number of cells||197896|
|Bounding box||13295 × 28010|
|Discovered by|| Brett Berger|
|Year of discovery||2014|
Waterbear is an oblique spaceship constructed by Brett Berger on December 28, 2014. It was the smallest (in terms of bounding box) known oblique spaceship, superseding parallel HBK, until the discovery of Sir Robin in March 2018. It was also the first "fast" oblique spaceship discovered in Conway's Game of Life.
An early mention of such a spaceship came from Nicolay Beluchenko in his 2006 LifeCA post announcing the discovery of the (23,5)c/79 Herschel climber. The idea was later mentioned in an "open problem" list from Jason Summers in February 2008, which was reposted to the ConwayLife forums in June 2013. Further discussion below that eventually spawned a dedicated thread a month later. A thread announcing its completion came in December 2014.
The base reaction consists of a crawler where a Herschel runs on a track of gliders. The Herschel consumes a southwest glider and emits two gliders, one southwest and the other southeast, every 79 generations. Interactions between neighboring tracks are used to create the necessary components to recreate the helix.
In July 2013, Ivan Fomichev proposed a very rough blueprint for the spaceship giving the shape below.
Being made from gliders, the track gradually moves away from the helix, giving rise to the triangular bodies. This increasing distance means that each new *WSS added to the helix requires a proportionally larger addition to the length of the waterbear than the previous helix addition. A waterbear composed of a single large triangle would be somewhat easier to construct, but it would be unnecessarily large.
To avoid this problem, the same procedure used to build the helix can be used to "reset" the track. In the Waterbear design, this reset occurs at two points, resulting in three smaller triangles instead of one much larger one. The reset comes at the cost of a fair amount of output-suppressing cleanup, so the design balances the exponential size increase with the constant cleanup cost to achieve a reasonably small final area.
- Brett Berger (December 28, 2014). (23,5)c/79 knightship caterpillar complete! (discussion thread) at the ConwayLife.com forums
- 77topaz (March 7, 2018). Re: Belated Pattern of the Year 2014 competition: Voting (discussion thread) at the ConwayLife.com forums
- Dave Greene (June 18, 2013). Re: Incomplete search patterns - try to complete (discussion thread) at the ConwayLife.com forums
- Ivan Fomichev (July 8, 2013). (23,5)c/79 spaceship components (discussion thread) at the ConwayLife.com forums
- Brett Berger (October 6, 2014). Re: (23,5)c/79 spaceship components (discussion thread) at the ConwayLife.com forums
- Ivan Fomichev (July 9, 2013). Re: (23,5)c/79 spaceship components (discussion thread) at the ConwayLife.com forums