A lightspeed bubble is a type of negative spaceship traveling through the zebra stripesagar. The center of the bubble is simple empty space, and the length and/or width of the bubble can usually be extended to any desired size.
Below is a small stabilized section of agar containing a sample lightspeed bubble, found by Gabriel Nivasch in August 1999. The bubble travels to the left at the speed of light, so it will eventually reach the edge of any finite patch and destroy itself and its supporting agar.
An open problem related to lightspeed bubbles was whether large extensible empty areas could be created whose length was not proportional to the width (as it must be in the above case, due to the tapering back edge). This was solved in February 2017 by Arie Paap;[1] a simple period-2 solution is shown below.
x = 61, y = 49, rule = B3/S23
3bo2bo2bo2bo2bo2bo2bo2bo2bo2bo2bo2bo2bo2bo2bo2bo2bo2bo2bo$b59o$o59bo$b
59o2$b59o$o53bo5bo$b20o2b3o2b3o2b3o2b8o2b4o3b5o$22b2o3b2o3b2o3b2o8b2o
5bo$b20o3b2o3b2o3b2o3b7o3bob2o2b5o$o41bo8b2o7bo$b20o22b2obo6b7o$43bo
12bo$b20o22bo13b3o$o42b2o5b2o4bo3bo$b20o22b2o3b2o3bob5o$43bo2bob2o3bo$
b20o22bo6b2o3b5o$o42b2o10bo4bo$b20o22b2o10b5o$43bo6b2obo$b20o22bo2bob
2o3bob5o$o42b2o3b2o6bo3bo$b20o22b2o5b2o5b3o$43bo12bo$b20o22bo11b5o$o
42b2o5b2ob2o5bo$b20o22b2o3b2o3b2o2b3o$43bo2bob2o5b2o$b20o22bo6b2o4b4o$
o42b2o15bo$b20o22b2o11b4o$43bo6b2o3b2o$b20o22bo2bob2o3b2o2b3o$o42b2o3b
2o3b2o5bo$b20o22b2o5b2o3b5o$43bo12bo$b22o5bo5bo5bo2bobo11b3o$o25b2o4b
2o4b2o3bo3bobo7bo2bo$b24ob2ob2ob2ob2ob2ob9o7b3o$56bo$b49o3b7o$o50b2o7b
o$b49o2b8o2$b59o$o59bo$b59o$3bo2bo2bo2bo2bo2bo2bo2bo2bo2bo2bo2bo2bo2bo
2bo2bo2bo2bo2bo!
#C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]]
#C [[ THEME 6 GRID GRIDMAJOR 0 THUMBLAUNCH THUMBSIZE 2 GPS 8 ]]
#C Will it be better if people can see the sides of the torus?