|Number of cells||8|
|Discovered by||Charles Corderman|
|Year of discovery||1971|
A switch engine (or Corder engine) is a methuselah that was found by Charles Corderman in 1971. It produces a copy of itself after 48 generation, glide-reflected 4 cells northwest (in the case of the starting configuration shown to the right), along with some active junk. If left unattended, the accumulating exhaust overtakes and destroys the engine after 24 cycles, but it can be stabilized to make c/12 diagonal puffers and spaceships.
There are two basic types of stabilized switch engine, both of which were also found by Charles Corderman: the period 288 block-laying switch engine (the more common of the two) and period 384 glider-producing switch engine. These two puffers are the most natural infinite growth patterns in Life, being by far the most common ones to occur from non-symmetric random starting patterns. Switch engine-based puffers, and combinations thereof, are also the only infinite growth patterns observed to have emerged from asymmetric soups on Catagolue.
Because the switch engine lends itself so naturally to infinitely-growing patterns, it appears in many of the smallest known superlinear growth patterns, including the mosquitoes, catacryst, metacatacryst, Gotts dots, and 26-cell quadratic growth.
In addition to the puffers based on a single switch engine, puffers such as Noah's ark can be created by combining two switch engines. Such puffers are generally quite dirty. By combining even more switch engines, it is possible to create Corderships, which move at c/12 diagonally and are thus the slowest known spaceships in Life other than the engineerable ships. Such spaceships can be constructed by combining as few as three switch engines.
Like Herschels, switch engines can be supported by conduits made out of well-separated still lifes. These 'swimmer tracks' were discovered by David Bell in 2005, and can be any length. Stable converters have been constructed that convert Herschels to switch engines and back. The Herschel-to-swimmer converter could now be made much faster, smaller and more efficient with new technology, particularly Snark reflectors.
The stable pattern that results from the switch engine has 842 cells. It consists of 60 blocks, 33 beehives (including one honey farm), 50 blinkers (including eight traffic lights), 12 gliders, 11 boats, 11 loaves, four ships, two long boats, two ponds, and two tubs.
- "Corder engine". The Life Lexicon. Stephen Silver. Retrieved on June 10, 2009.
- "Census - Catagolue". Retrieved on September 28, 2015.
- Dave Greene. "Bobsled run update". Game of Life News. Retrieved on September 21, 2014.
- Dave Greene. "A New Kind of Signal". Work in Progress blog. Retrieved on September 21, 2014.
- Switch engine at Eric Weisstein's Treasure Trove of Life
- Switch engine at the Life Lexicon