Total aperiodic
From LifeWiki
Total aperiodic  
Pattern type  Miscellaneous  

Number of cells  182  
Bounding box  59×57  
Discovered by  Bill Gosper  
Year of discovery  1997  

A finite pattern is total aperiodic if it evolves in such a way that no cell in the plane is eventually periodic. The first example was found by Bill Gosper in November 1997. A few days later he found the much smaller example that consists of three copies of backrake 2 (by David Buckingham), shown to the right.
On June 24, 2004, Gosper found that a block can be added to the pattern to make the total periodic pattern shown below, in which every cell eventually becomes periodic (albeit incredibly slowly). The block remains untouched for about 3^{63} generations. It deletes its n^{th} glider (and is shifted) at about generation 3^{57.5+5.5n}.^{[1]}
Image gallery
References
 ↑ Jason Summers' jslife oversize pattern collection.
External links
 Total aperiodic at Eric Weisstein's Treasure Trove of Life
 Total aperiodic at the Life Lexicon