Subject: Re: Hawking, Penrose: Our universe, highly unlikely. Date: Thu, 19 Jul 2001 00:59:51 -0700 From: "Brian Holtz" To: "Brian Holtz" "Paul Filseth" wrote : > > > > > Self-reproducing patterns that evolve by Darwinian selection > > > > > can exist in Conway's "Life" cellular automaton. > > > > > > [I find] no self-reproducing patterns evolving by natural selection. > > Tierra [..] can run on Turing machines. > You've just given an example proving my claim. If your claim were merely about the theoretical possibility of artificial life in a Turing machine, then I'm surprised you mentioned Conway's Life instead. If on the other hand you were saying artificial life has been demonstrated in Conway's Life, I'd be interested in a reference. > > still wrestling with issues of limits to evolvability. > > The patterns in Tierra evolve by Darwinian selection. As I understand Tierra, it has primitives built into it for things like replication and mutation and metabolism, and in effect is meticulously designed to exhibit natural selection. I built such an a-life system myself in the early 90's, and such systems are vastly higher-level then cellular automata like Life (not to mention actual physics!). > > I think artificial systems rich enough to call "life" are definitely > > in our future, but we aren't there yet. > > it doesn't > impact my statement or the issue I was addressing, which was the > dubious validity of anthropic reasoning. I just hope your point wasn't resting on the idea that (artificial) life has been observed to exist on systems that can plausibly be thought of as simply alternatives to actual physics, because a) Conway's Life has run no lifeforms, and b) Tierra et al. are hardly bio-agnostic alternative physical universes. -- Brian.Holtz@sun.com Knowledge is dangerous. Take a risk: http://humanknowledge.net