ABSTRACT
Counterfactual biochemistry, in more recent times, has captured many youthful imaginations. Silicon-based life forms have been a staple of science ction. In one form, the computer network, silicon-based life now seems to be on the verge of becoming a reality. Naturally occurring life, on other worlds, may have biochemistry similar to our own, but it would be foolhardy to rule out alternatives. Life, as we see it, on this planet seems to use chemical mechanisms in a manner quite distinct from the now emerging silicon-based life forms. It is very difcult to see how the elegantly efcient large-scale deterministic mechanisms of electronic life could have arisen without preexisting intelligences. Natural terrestrial life, as bets its molecular nature, in contrast exhibits elements of haphazardness and chance. Given modern DNA sequence analysis, to doubt the apparent role of chance in the evolution of species would be as contrarian and insensitive to masses of observations. Nevertheless the precise way terrestrial life arose in the rst place must be counted a contemporary mystery. What if things had been different? What if key molecular ingredients of modern living things were unavailable, would life have been impossible? Can we, ourselves, create synthetic life with only marginal design input?
