Hacker News Reader

as long as execution is proceeding without generating any gliders, then you don't know whether gliders will be generated in the future. in addition, if you have gliders, you have no guarantees that another structure won't catch up to it and end its gliding.

View on HN

Many gliders move at the theoretical maximum rate on the Life board, so it won’t be possible to catch them.

I believe c/4 is indeed the fastest possible diagonal speed for a spaceship, does anyone know if a proof exists?

Yes, there's a fairly simple proof, specific to the B3/S23 Life rule, not true for all similar CA rules. Unfortunately this comment box is too small to contain it... and the proof only applies to structures traveling through empty space. If you're allowed to have pre-existing live cells ahead of the glider, there are known "wires" that transmit information diagonally at 2c/3, easily fast enough to get ahead of a glider and stop it.

This blog post has a explanation of the proof. http://www.njohnston.ca/2009/10/spaceship-speed-limits-in-li...

Reply on news.ycombinator.com