Day & Night period-256 butterfly gun in Day & Light , constructed in 1999 by David I. Bell . This article is about a cellular automaton rule . For the single by Billie Piper , see Day & Night ( single ) . Day & Night is a cellular automaton in the same family as Game of Life , defined by rule notation 34678/3678 . It was invented and named by Nathan Thompson in 1997 , and investigated extensively by David I. Bell . The rule is given the name `` Day & Night '' because its on and off states are symmetric : if all the cells in the Universe are inverted , the future states are the inversions of the future states of the original pattern . A pattern in which the entire universe consists of off cells except for finitely many on cells can equivalently be represented by a pattern in which the whole universe is covered in on cells except for finitely many off cells . Although the detailed evolution of this cellular automaton is very different from Conway 's Game of Life , it exhibits complex behavior similar to that rule : there are many known small oscillators and spaceships , and guns formed by combinining oscillators in such a way that they periodically emit spaceships of various types . External links David I. Bell ( 1997 ) . Day & Night - An Interesting Variant of Life . See also Bell 's Day & Night pattern archive . Pete Carlton . Pete 's Game of Life Page : B3678 S34678 . Categories : Cellular automaton rules In other languages : Français a cellular automaton rule the single by Billie Piper Day & Night ( single ) David I. Bell 1997 http : //www.tip.net.au/~dbell/articles/DayNight.zip Day & Night - An Interesting Variant of Life See also Bell 's Day & Night pattern archive Pete Carlton http : //www.ocf.berkeley.edu/~pcarlton/CA.html Pete 's Game of Life Page : B3678 S34678 