Hadn’t this question already been answered? We all know about computation-universal Turing Machines. And we know that any such machine can simulate a space–time dynamics not unlike von Neumann’s cellular automaton (CA), which is computation- and construction-universal and among other things can play host to self-replicating machines. And that self-replication sprinkled with a bit of randomness should inexorably lead to descent with variation, competition, and thence to evolution and all that. “So what?” Enrico Fermi would have asked, “Where is your emergent life?” (and note that our understanding of both natural and artificial life has much advanced in the 50 years since). It turns out that life is by its very nature a marginal, fragile, and ephemeral kind of phenomenon. For a substrate or a “culture medium” to be able to support the emergence from scratch of a lifelike lineage, computation- and construction-universality are necessary—but by no means sufficient! Paraphrasing Fermi, what automata that you know—including von Neumann’s CA and Conway’s very game of Life—have managed so far to “capture for us on film” the origin of some kind of life? What questions, then, should we ask of a prospective medium—be it a Turing machine, a CA, or some other kind of automaton—that will best probe its capabilities to originate (as well as sustain) some form of life, and which will provide us with a sense of direction to help us more quickly converge in this quest.
