Period-156 glider gun

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Period-156 glider gun
x = 42, y = 42, rule = B3/S23 20b2o$20b2o$6b2o$5b2o$7bo$3bo$2b2o18b2o$2bobo17bo$22bo$23bo9$32bo2bo$ 33b3o$2o38b2o$2o38b2o$6b3o$6bo2bo9$18bo$19bo$19bo17bobo$18b2o18b2o$38b o$34bo$35b2o$34b2o$20b2o$20b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ]] #C [[ ZOOM 10 HEIGHT 600 ]]
Pattern type Gun
Number of cells 36
Bounding box 42 × 42
Period 156
Barrels 8
Discovered by Jason Summers
Year of discovery 2004

Period-156 glider gun is a glider gun with 8 barrels that was found by Jason Summers on October 28, 2004[1] in a RandomAgar search. It consists of four pi-heptominoes hassled by four blocks, where the pi-block reaction is also present in three-block shifter. Two butterfly sequences and four half-blockades appear in some phases.

In terms of its 36 cells it is the same population as the Gosper glider gun, but the Simkin glider gun is still smaller at 29 cells. In terms of its 42 × 42 bounding box, it is also the smallest gun of this period.[2]

The gun first appeared semi-naturally in January 2015 in a soup found by Dongook Lee using apgsearch,[3] making it the first semi-natural gun.[4]

Derivative oscillators

There are several ways in which the period-156 gun can be suppressed to form oscillators.


It is trivially possible to cap the eight glider streams with an eater 1 to form an oscillator. The form with all eight barrels capped as close as possible to the main body of the gun is shown below.

#N 92P156 #O Jason Summers, 31 October 2004 #C Oscillator, or actually an eight-barrelled glider gun, #C discovered in a RandomAgar search. Also known as "Jason's p156". #C x = 42, y = 42, rule = B3/S23 20b2o$20b2o4$8b2o22b2o$9bo12b2o8bo$9bobo10bo7bobo$5bo4b2o10bo7b2o4bo$ 5b3o15bo10b3o$8bo24bo$7b2o24b2o7$32bo2bo$33b3o$2o38b2o$2o38b2o$6b3o$6b o2bo7$7b2o24b2o$8bo24bo$5b3o10bo15b3o$5bo4b2o7bo10b2o4bo$9bobo7bo10bob o$9bo8b2o12bo$8b2o22b2o4$20b2o$20b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ZOOM 8 HEIGHT 460 ]]
The minimally-capped period-156 glider gun (click above to open LifeViewer)
RLE: here Plaintext: here

On January 14, 2023, Charity Engine found that a constellation of two blocks and two beehives can absorb the glider pair emitted by this gun.[5] The two beehives is arranged as in the ash of teardrop, but the eating reaction does not involve a teardrop sequence.


In addition to creating period-156 oscillators, there exist several mechanisms which permit period-312 oscillators to be created.

One simple period-doubling method which can also be used on other guns to make higher-period oscillators is via the use of the boat-bit reaction. Objects such as two correctly-placed snakes can allow for this in much the same way as it does for other guns, however a more intriguing option is to use a loaf or pond. If placed correctly, this will result in two gliders being converted into two boats simultaneously, which are then annihilated by the next set. A gun using this reaction with two ponds and two loaves appeared semi-naturally on September 22, 2018, in a soup submitted by carybe, forming what is currently the highest-period oscillator to have occurred semi-naturally,[6] and the paired boat-bit reaction continues to be found in many variants of the period-156 glider gun recorded in Catagolue.[7]

Perhaps a more interesting option than boat-bits is to use a reaction in which the two-glider units emitted by this oscillator are capable of flipping the position of a beehive. When placed in the correct position, another type of period-312 oscillator can be created with a higher kinetic symmetry[which?] than the boat-bit versions, as well as a lower minimum population of 60. This reaction was discovered by Dave Greene on 1 November 2004.

x = 42, y = 42, rule = B3/S23 20b2o$20b2o4$9b2o$8bo2bo10b2o$9b2o11bo$22bo12bo$23bo10bobo$34bobo$35bo 7$32bo2bo$33b3o$2o38b2o$2o38b2o$6b3o$6bo2bo7$6bo$5bobo$5bobo10bo$6bo 12bo$19bo11b2o$18b2o10bo2bo$31b2o4$20b2o$20b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ZOOM 8 HEIGHT 460 ]]
Dave Greene's period-312 capped gun oscillator (click above to open LifeViewer)
RLE: here Plaintext: here

As the beehive positions are bistable, there are three variants of this oscillator that can be constructed, one of which has a mod a quarter of its overall period (78).

Beacon-pulling reaction

This gun emits tandem gliders, where a pair of parallel gliders is separated by 7 half-diagonals. Each pair of such gliders can pull a beacon by 2 cells diagonally toward the gun. If equipped with beacon-generating catalysts and reflectors, a class of p468+156n glider guns can be constructed.[8]

Glider synthesis

A 16-glider synthesis was discovered for this gun by Goldtiger997 on June 2, 2019,[9] which was improved to 14 gliders the next day by Oscar Cunningham.[10]

x = 74, y = 80, rule = B3/S23 66bobo$66b2o$67bo14$39bo11bobo$39bobo9b2o$39b2o11bo3$54b3o$54bo$55bo7$ 51bo$49b2o$50b2o4$23bo$24bo$22b3o46b3o$bo69bo$2bo69bo$3o46b3o$49bo$50b o4$22b2o$23b2o$22bo7$18bo$19bo$17b3o3$21bo11b2o$21b2o9bobo$20bobo11bo 14$6bo$6b2o$5bobo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THEME Book ZOOM 8 WIDTH 650 HEIGHT 650 AUTOSTART GPS 16 T 0 PAUSE 5 T 95 PAUSE 1 T 299 PAUSE 2 LOOP 300 ]]
14-glider synthesis of period-156 glider gun (click above to open LifeViewer)
RLE: here Plaintext: here


  1. Jason Summers' jslife pattern collection.
  2. Chris Cain. "Attempt at organising small glider guns in Conway's Game of Life". Retrieved on 2018-10-04.
  3. Dongook Lee (January 9, 2015). Re: Soup search results (discussion thread) at the forums
  4. Dongook Lee (January 9, 2015). Re: Soup search results (discussion thread) at the forums
  5. Matthias Merzenich (January 15, 2023). Re: Oscillator Discussion Thread (discussion thread) at the forums
  6. Ian07 (September 22, 2018). Re: Soup search results (discussion thread) at the forums
  7. Adam P. Goucher. "yl312_1_40_36397c30a42c720a5055f5bc3b267c63". Retrieved on 2018-09-22.
  8. praosylen (October 22, 2019). Re: Thread For Your Useless Discoveries (discussion thread) at the forums
  9. Goldtiger997 (June 2, 2019). Re: Thread for basic questions (discussion thread) at the forums
  10. Oscar Cunningham (June 3, 2019). Re: Thread for basic questions (discussion thread) at the forums

External links