Block agar

The block agar is an agar consisting of blocks arranged periodically in rows and columns, with distance of 1 cell between any two adjacent rows or columns. The average field density of the block agar is 4/9.

Sometimes, more sparse arrangements of blocks are also described as block agars.

Reactions in the block agar

x = 20, y = 17, rule = B3/S23 2ob2ob2ob2ob2ob2ob2o$2ob2ob2ob2ob2ob2ob2o2$2ob2ob2ob2ob2ob2ob2o$2ob2ob 2ob2ob2ob2ob2o2$2ob2ob2ob2ob2ob2ob2o$2ob2ob2ob2ob2ob2ob2o$9bo$2ob2ob2o b2ob2ob2ob2o$2ob2ob2ob2ob2ob2ob2o2$2ob2ob2ob2ob2ob2ob2o$2ob2ob2ob2ob2o b2ob2o2$2ob2ob2ob2ob2ob2ob2o$2ob2ob2ob2ob2ob2ob2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 ZOOM 16 HEIGHT 450 GPS 8 THEME Book AUTOSTART T 0 PAUSE 3 T 22 PAUSE 2 LOOP 23 ]] A pattern doomed by a virus (from Lifeline Volume 9) (click above to open LifeViewer)

If an alive cell ("virus") is added to the block agar so that it touches the corners of four blocks, the agar self-repairs in two ticks. However, when a single cell is added so that it touches cells of two different blocks, it initiates an expanding disintegration of the agar.

Space clearers for the block agar and for one quarter of the block agar were found by Hartmut Holzwart; these space clearers are reactions that expand through the infinite agar and leave empty space behind.

There are known p3 lightspeed "trimmers" on an array of blocks with zebra stripes boundary.

Finite patches

Finite rectangular patches of the block agar (n-by-m block arrays) are pseudo still lifes; the simplest example is the bi-block, which is the 1 × 2 block array.

x\y	1	2	3	...
1				→
2
3
...	↓			↘

Glider synthesis

x = 39, y = 45, rule = B3/S23 bo$2bo$3o2$28bo$28bobo$6bobo19b2o$7b2o$7bo5$38bo$18bo5bo11b2o$17bobo3b obo11b2o$17bo2bobo2bo$18b2o3b2o3$7b2ob2ob2ob2o$7b2ob2ob2ob2o3b2o$20bo 2bo$7b2ob2ob2ob2o3b2o$7b2ob2ob2ob2o3$18b2o3b2o8b3o$17bo2bobo2bo7bo$17b obo3bobo8bo$18bo5bo6$7bo$7b2o$6bobo19b2o$28bobo$28bo2$3o$2bo$bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 ZOOM 10 HEIGHT 500 GPS 8 THEME Book AUTOSTART T 0 PAUSE 1 T 20 PAUSE 3 T 68 PAUSE 2 LOOP 69 ]] A way to extend a 2 × n block array (click above to open LifeViewer)

In 2005, Jason Summers found a way to extend any 2 × n block array. The method involves building a constellation of beehive and four loaves and hitting it with 8 gliders.

On December 3, 2015, Martin Grant found a method of constructing a 3 × n block array via glider synthesis.

On May 6, 2020, Goldtiger997 found a method of constructing a 4 × n block array.

The problem of constructing an arbitrary m-by-n block array is still unsolved.