switch engine

Noun

1. A switcher or shunter: a railroad locomotive used for shunting.
2. A particular methuselah in Conway's Game of Life that temporarily exhibits glide reflection symmetry while leaving debris behind, allowing for the construction of spaceships, puffers, and rakes.
   • 2. Is it possible to make the switch engine leave debris other than the normal 8 blocks/288 generations? - 1990 May 17, David Moews, “Life questions”, in comp.theory.cell-automata (Usenet):
   • He did this by placing a large number of switch engines together so as to eliminate all debris. His original ship required 13 switch engines, but his smaller one given here only uses 10 of them. - 1992 August 13, David...
   • The average random Life pattern settles down instead of exploding (if you ignore output gliders and spaceships). There are exceptional quadratic-growth cases, mostly involving switch engines, but most random patterns...