drc wrote:Challenge: Create the largest object possible (and/or prove that infinitely many objects are synthesizable) using only 1 glider per step and a 2-glider base. All collisions must settle before the next collision can begin.

Ooh, I know this one! A year ago simeks came up with

the basis for a slow salvo to stretch a ship. These days you can just figure out how to clean up the leftover junk from either of those reactions to get a block at a decent distance, and feed either of those two initial constellations into slmake (with a ship or a long boat instead of a long long ship as the base object to be extended).

Tell slmake that the starting block location is at (-1, -1) from where you know it will end up, and run another round of compilation with slmake, building just the blinker or the loaf+blocks constellation that will be used up in each new cycle -- and hey presto, if you have an unlimited-length slow salvo, you can get an unlimited number of different still lifes.

`x = 216, y = 213, rule = LifeHistory`

52.C$2C49.C.C$C.C49.C.C$.2C50.2C5$7.C52.2C$7.C51.C2.C$7.C52.C.C$55.2C

4.C$55.2C3$61.2C$61.2C2$11.2A$11.A.A$11.A3$80.2A$80.A.A$80.A21$35.2A$

34.2A$36.A17$66.3A$66.A$67.A29$83.2A$82.2A$84.A17$112.2A$111.2A$113.A

19$143.2A$143.A.A$143.A23$167.2A$166.2A$168.A47$213.2A$213.A.A$213.A!

In point of fact it's well within reach now to write a universal script that will solve this problem for any constructable object that you can throw at it. Given a glider recipe for any object, we know how to create a constellation of small still lifes that can be hit with a single glider to produce that exact arrangement of gliders.

And theoretically we can compile any constellation of small still lifes with slmake. The result is a slow salvo recipe aimed at a single block, which we can create with two gliders.

I wish somebody would write that script, actually. It would make horribly inefficient seed patterns, at least if it was written the easy way -- but it would be fun to watch a huge constellation collapse into a relatively tiny object.

Probably it's not a good idea to try compiling something like a Gemini spaceship this way, due to memory limitations, but in principle it would work just like any other glider recipe.