Two pond and two block reaction

When a specific constellation of two ponds and two blocks is perturbed by a dot spark on each side, it returns to its original form in 20 generations. It was found by Jason Summers in 2005. Sparkers can make this into an oscillator.

Period-multiplying oscillators involving this reaction are currently known for periods 20, 21, 22, 24, 26, 27, 28, 30, 32, and 36. Oscillators with these periods are shown below.

x = 37, y = 24, rule = B3/S23 6bo$5bobo$5bobo$2b2obob2o19bo$o2bobo4bo16bobo$2o3b3o19bobo$4bo2bo3bo 14b2obob2o$4b2o8b2o8bo4bobo2bo$10bo3b2o11b3o3b2o$4b5o14bo3bo2bo$3bo25b 2o$4b5o5b2o4b2o2bo$10bo2bo2bo2bo2bo3b7o$4b2o7bo2bo2bo2bo10bo$4bo2bo3bo 2b2o4b2o6b5o$2o3b3o18bo$o2bobo4bo20b2o$2b2obob2o11b2o3bo3bo2bo$5bobo 12b2o7b3o3b2o$5bobo18bo4bobo2bo$6bo21b2obob2o$29bobo$29bobo$30bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 50 THUMBLAUNCH THUMBSIZE 2 THEME 6 ZOOM 12 HEIGHT 600 WIDTH 600 ]]

p20, using 55P10 and its skewed variant (click above to open LifeViewer) RLE: here Plaintext: here Catagolue: here

x = 32, y = 18, rule = B3/S23 18b2o5bo$18bo5bobo$19b3obo2bo$12b2o7bobobob2o$12b2o9bobobobo$4bo21bo2b o$3bobo21bob2o$3bobo6b2o4b2o2bo2b3obo$2obob2o4bo2bo2bo2bo2bo4bo2bo$o2b o4bo2bo2bo2bo2bo4b2obob2o$2bob3o2bo2b2o4b2o6bobo$b2obo21bobo$2bo2bo21b o$2bobobobo9b2o$3b2obobobo7b2o$5bo2bob3o$5bobo5bo$6bo5b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 50 THUMBLAUNCH THUMBSIZE 2 THEME 6 ZOOM 12 HEIGHT 600 WIDTH 600 ]]

p21, using a 42-cell variant of 41P7.2 (click above to open LifeViewer) RLE: here Plaintext: here Catagolue: here

x = 36, y = 18, rule = B3/S23 22b2o$23bo$23bob2o$14b2o8bo6bo$7bo6b2o12bobobob2o$6bobo19bobobob2o$7b o20bobobo$14b2o4b2o2bo2bob2obo$5b5o3bo2bo2bo2bo2bo5bo$4bo5bo2bo2bo2bo 2bo3b5o$3bob2obo2bo2b2o4b2o$3bobobo20bo$2obobobo19bobo$2obobobo12b2o6b o$4bo6bo8b2o$9b2obo$12bo$12b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 50 THUMBLAUNCH THUMBSIZE 2 THEME 6 ZOOM 12 HEIGHT 600 WIDTH 600 ]]

p22, using p11 thumb (click above to open LifeViewer) Catagolue: here

x = 22, y = 20, rule = B3/S23 19b2o$19b2o2$20bo$7b2o10bobo$7b2o9bo2bo$17bo2bo2$7b2o4b2o2bo2bo$6bo2bo 2bo2bo3b2o$b2o3bo2bo2bo2bo$bo2bo2b2o4b2o2$bo2bo$o2bo9b2o$obo10b2o$bo2$ b2o$b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 50 THUMBLAUNCH THUMBSIZE 2 THEME 6 ZOOM 12 HEIGHT 600 WIDTH 600 ]]

p24, using blockers (click above to open LifeViewer) RLE: here Plaintext: here Catagolue: here

x = 32, y = 40, rule = B3/S23 20bobobobo$19bob2ob2obo$17b3o7b3o$16bo4b2ob2o4bo$16bo2b2obobob2o2bo$ 15b2obobobobobobob2o$16bobobo5bobobo$16bobo2bo3bo2bobo$17bo4b3o4bo5$ 22b3o$12b2o$12b2o7bo3bo$21bo3bo$3bo$3b3o6b2o4b2o2bo3bo$6bo4bo2bo2bo2bo 5bo$5bo5bo2bo2bo2bo4bo$5bo3bo2b2o4b2o6b3o$28bo$6bo3bo$6bo3bo7b2o$18b2o $7b3o5$2bo4b3o4bo$bobo2bo3bo2bobo$bobobo5bobobo$2obobobobobobob2o$bo2b 2obobob2o2bo$bo4b2ob2o4bo$2b3o7b3o$4bob2ob2obo$5bobobobo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 50 THUMBLAUNCH THUMBSIZE 2 THEME 6 ZOOM 12 HEIGHT 600 WIDTH 600 ]]

p26, using 66P13 (click above to open LifeViewer) RLE: here Plaintext: here Catagolue: here

x = 32, y = 18, rule = B3/S23 25b2o$25b2o2$12b2o9b6o$12b2o9bo5bo$6b2o17b4o$5bobo18bo2b3o$b2o2bo6b2o 4b2o2bo5bo2bo$bobobobo3bo2bo2bo2bo2bo2bobo$3bobo2bo2bo2bo2bo2bo3bobobo bo$o2bo5bo2b2o4b2o6bo2b2o$3o2bo18bobo$3b4o17b2o$2bo5bo9b2o$3b6o9b2o2$ 5b2o$5b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 50 THUMBLAUNCH THUMBSIZE 2 THEME 6 ZOOM 12 HEIGHT 600 WIDTH 600 ]]

p27 using thumb 1 (see 94P27.1) (click above to open LifeViewer) RLE: here Plaintext: here Catagolue: here

x = 42, y = 22, rule = B3/S23 30b2o5b2o$30b2o5b2o4$17b2o11b2o5b2o$17b2o10bo2bo3bo2bo$3b2o5b2o16bo3bo 3bo3bo$2bo2bo3bo2bo19b2ob2o$2bo9bo4b2o4b2o2bo5bobo5bo$5bo3bo6bo2bo2bo 2bo2bo3bo3bo3bo$bo3bo3bo3bo2bo2bo2bo2bo6bo3bo$o5bobo5bo2b2o4b2o4bo9bo$ 5b2ob2o19bo2bo3bo2bo$bo3bo3bo3bo16b2o5b2o$2bo2bo3bo2bo10b2o$3b2o5b2o 11b2o4$3b2o5b2o$3b2o5b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 50 THUMBLAUNCH THUMBSIZE 2 THEME 6 ZOOM 12 HEIGHT 600 WIDTH 600 ]]

p28 using 34P14 shuttle (click above to open LifeViewer) RLE: here Plaintext: here Catagolue: here

x = 40, y = 20, rule = B3/S23 30bo4bo$28b2ob4ob2o$30bo4bo2$16b2o$16b2o2$28b3o4b3o$16b2o4b2o2b6o2b6o$ 15bo2bo2bo2bo3b3o4b3o$2b3o4b3o3bo2bo2bo2bo$6o2b6o2b2o4b2o$2b3o4b3o2$ 22b2o$22b2o2$4bo4bo$2b2ob4ob2o$4bo4bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 50 THUMBLAUNCH THUMBSIZE 2 THEME 6 ZOOM 12 HEIGHT 600 WIDTH 600 ]]

p30, using Karel's p15 (click above to open LifeViewer) RLE: here Plaintext: here Catagolue: here

x = 36, y = 18, rule = B3/S23 6b2o$5b4o$4b2ob3o$3b3o3bo4b2o12b2o$bobo5b3o2b2o11b4o$ob2ob3obo16b3ob2o $b2o3b2o18bo3b3o$14b2o4b2o2b3o5bobo$b2o3b2o5bo2bo2bo2bo3bob3ob2obo$ob 2ob3obo3bo2bo2bo2bo5b2o3b2o$bobo5b3o2b2o4b2o$3b3o3bo18b2o3b2o$4b2ob3o 16bob3ob2obo$5b4o11b2o2b3o5bobo$6b2o12b2o4bo3b3o$26b3ob2o$27b4o$28b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 50 THUMBLAUNCH THUMBSIZE 2 THEME 6 ZOOM 12 HEIGHT 600 WIDTH 600 ]]

p32, using Rich's p16 (click above to open LifeViewer) RLE: here Plaintext: here Catagolue: here

x = 42, y = 28, rule = B3/S23 23b2o$23b2o3$22b3o12b4o$22b2obo2b2o6bo4bo$24b2o2b2o5bobo3bo$24b2o8bobo 3bo$17b2o15bo$17b2o15bo$34bo2bo$29b3o3b2o$17b2o4b2o2b3o$16bo2bo2bo2bo 3b3o$10b3o3bo2bo2bo2bo$12b3o2b2o4b2o$5b2o3b3o$4bo2bo$7bo15b2o$7bo15b2o $bo3bobo8b2o$o3bobo5b2o2b2o$o4bo6b2o2bob2o$b4o12b3o3$17b2o$17b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 50 THUMBLAUNCH THUMBSIZE 2 THEME 6 ZOOM 12 HEIGHT 600 WIDTH 600 ]]

p36, using p18 bi-block hasslers (click above to open LifeViewer) RLE: here Plaintext: here Catagolue: here

In other rules

In rules including the eight-neighbor survival condition S8, starting with EightLife (B3/S238), there are two cells which survive due to S8 but do not impact the period or function of the reaction, and each die as an obo! spark. This has been used to demonstrate the existence of alien oscillators in this rule for all periods 20+ with sufficient sparkers.