On Tue, Dec 6, 2011 at 10:26 PM, Warren Smith <warren.wds@gmail.com> wrote:
Of course, region (3) could not be "isolated" from regions (1) and (2) because no known isolation method has ever been invented.
This is a question that this thread has gotten me to think about. Can you build an "indestructible wall" in life? More precisely, is there a finite configuration S, and a particular cell P in S that is in the "on" state, such that given any configuration of the infinite plane that is a extension of S to the whole plane, cell P will remain in the "on" state forever. This is a wall that protects a single cell; you can ask an analogous question about protecting a larger configuration, but I suspect the answer will be the same. But I have no idea what the answer is. Can the right collection of gliders aimed at it in the right order break through any wall? Or are there impenetrable configurations? Andy