Replicators: B368/S12578

I found this replicator in rule B368/S12578 in 1999. It replicates itself every 13 generations, on a one-dimensional 4-unit grid. The same replicator works also in B3678/S12578.

B368/S12578 4c/13 replicator

Arbitrarily high period oscillators can be made by terminating a row of replicators by still lifes in any of several ways.

This rule has several known spaceships, including a small c/8 diagonal glider. As I discovered, two replicator-based oscillators can crash to form a glider and some random debris, which can be removed by more replicators. The following cleaned-up versions of this glider gun idea were made by Dean Hickerson.

B368/S12578 p52 glider gun

B368/S12578 p104 glider gun

It would be of interest to find puffers or spaceships based on this replicator, that move at speed 4c/13. However, much slower spaceships may also exist: Dean Hickerson has found "push" and "pull" reactions in which a set of replicators pushes or pulls a still life by twelve units. It should be possible to set up arbitrarily-slow replicator-based spaceships in which a set of replicators periodically forms a push reaction at the front end and a pull reaction at the other end. However, the likely size of these things is so huge (exponential in the period) that no explicit example has been made.

Replicators -- Cellular Automata -- D. Eppstein -- UCI Inf. & Comp. Sci.