Total aperiodic

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Total aperiodic
Total aperiodic image
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 363 generations. It deletes its nth glider (and is shifted) at about generation 357.5+5.5n.[1]

Image gallery

Total periodic
RLE: here


  1. Jason Summers' jslife oversize pattern collection.

External links