Kickback

x = 7, y = 12, rule = B3/S23 5bo$4bo$4b3o7$b2o$obo$2bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBNAIL THUMBSIZE 3 ZOOM 15 WIDTH 500 HEIGHT 400 GPS 20 THEME 6 GRID OFF AUTOSTART T 0 PAUSE 2 T 49 PAUSE 1 LOOP 50 ]] The 180-degree kickback (click above to open LifeViewer) RLE: here Plaintext: here

x = 7, y = 12, rule = B3/S23 5bo$4bo$4b3o7$bo$2o$obo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBNAIL THUMBSIZE 3 ZOOM 15 WIDTH 500 HEIGHT 400 GPS 20 THEME 6 GRID OFF AUTOSTART T 0 PAUSE 2 T 49 PAUSE 1 LOOP 50 ]] The 90-degree kickback (click above to open LifeViewer) RLE: here Plaintext: here

A kickback is any of the two 2-glider collisions resulting in a single glider travelling in the opposite direction to one of the original gliders. In a 90-degree kickback, the two gliders collide at right angle, while in a 180-degree kickback they are head-on. Both output gliders are one half-diagonal away from the lane of one of the inputs.

The 90-degree kickback is important in the original proof of the existence of a universal constructor (using an elbow ladder) and in Bill Gosper's total aperiodic, as well as a number of other constructions and glider syntheses. Thus the term kickback reaction may also refer to the 90-degree one specifically. The 180-degree kickback is rarely used in signal circuitry or in self-supporting patterns like the Caterpillar or Centipede, because it is generally less easy to arrange.

External links

• Kickback at the Life Lexicon
• Kickback reaction at the Life Lexicon
• 180-degree kickback at the Life Lexicon