Negative spaceship

A negative spaceship (or agar crawler, or bubble) is a finite signal pattern traveling ("crawling") through a periodic agar such as zebra stripes, and thus comparable to a spaceship. The leading edge of the signal removes the agar, and the trailing edge rebuilds the agar some time later. The distance between the two edges is sometimes adjustable, as shown in lightspeed bubble. The central part of the "spaceship" may consist of dying sparks or even simple empty space.

Below is a sample period-5 negative spaceship, found by Hartmut Holzwart in March 2007, travelling to the left at the speed of light:

x = 55, y = 31, rule = B3/S23:T55,32 55o2$29o2b3o2b19o$30b2o3b2o$24o2b3o3b2o3b4o2b12o$25b2o15b2o$24o2b3o3b 2o5b2o3b2o2b7o$30b2o3bob2o8b2o$24o2b3o2b3o3b2o5b2o3b6o$25b2o12b2ob2o$ 24o3b5o10b2o5b6o$28bo15b2ob2o$24o5bo9bo7b2o2b4o$25bobo6bo3bo10b2o$24o 3bobob5o6bo7b5o$30b3o3bo6bo$24o3bobob5o6bo7b5o$25bobo6bo3bo10b2o$24o5b o9bo7b2o2b4o$28bo15b2ob2o$24o3b5o10b2o5b6o$25b2o12b2ob2o$24o2b3o2b3o3b 2o5b2o3b6o$30b2o3bob2o8b2o$24o2b3o3b2o5b2o3b2o2b7o$25b2o15b2o$24o2b3o 3b2o3b4o2b12o$30b2o3b2o$29o2b3o2b19o2$55o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBNAIL THUMBSIZE 2 THEME 6 HEIGHT 480 GPS 6 ZOOM 11 AUTOSTART ]]

Period-5 negative spaceship (click above to open LifeViewer) RLE: here Plaintext: here

All agar crawlers currently known are faster than c/2, so it is not possible to put one in a greyship without it eventually crashing into the front.

See also

• Against the grain
• With the grain

External links

• Negative spaceship at the Life Lexicon