Puffers and Rakes

Jason Summers and I independently discovered a small pattern that acts like a period-38 c/2 "chaos puffer" -- it repeats after 38 generations with a chaotic mess behind it. It is shown below in two forms; the larger one is more robust to perturbations, but nevertheless is eventually killed off by the growing chaos behind it. The third pattern below is a larger almost-puffer found by Jason, that also eventually gets killed off by its own debris.

p38 chaos puffer robust p38 chaos puffer almost-puffer

We don't know how to make a tame p38 puffer from these patterns. Fortunately, by perturbing the smoke very early, Jason was able to make spaceships of other periods, such as 8, 10, and 20:

4c/8 spaceship 5c/10 spaceship 10c/20 spaceship

He also found another chaos puffer perturbation, with period 24.

p24 chaos puffer

The p20 spaceship is easy to turn into a simple puffer that puffs 2 or 4 tubs:

p20 four-tub puffer

It proved to be difficult to turn this into a rake (puffer that emits only gliders), but after considerable noodling around, Jason came up with this p40 example:

p40 sideways rake

The rake about sends its gliders sideways, to the right. It would also be useful to send gliders forwards and backwards. Period 40 is not large enough to build a forward rake. Using a 3c/6 spaceship, the rake can be thinned out to p120, allowing a forward rake to be built. Jason thinks there's probably a better way to do this; e.g. using p4 c/2 spaceships to turn the 2c/5 spaceships.

p120 forward rake

Period 80 would also work, but we don't know how to build a p80 sideways rake. Here's a way to build a chaotic "p80" puffer based on de-phasing a p6 spaceship:

p80 rake to chaos reaction

Now that we have rakes, it should also be possible to use them to construct breeders. However, since these rakes are unable to produce closely-spaced glider salvos directly, one would either need to combine forward and back rakes to make such salvos, or to use a gun synthesis that allows the gliders to come in one-at-a-time.

B35/S236 -- Cellular Automata -- D. Eppstein -- UCI Inf. & Comp. Sci.