Last night I attended a lecture by the astrophysicist Paul Davies entitled ‘The Origin of Life’. Davies, professor at Arizona State University and chair of the SETI Post-Detection task group (you know someone’s legit if they have an asteroid named after them), discussed the “where, when, and how” of the origin of life on earth, and ways we might begin to answer the question of whether there is life on other planets.
His discussion of the ‘where’ and ‘when’ of life’s origin was pretty vague (a ‘warm pool’ several billion years ago), this shouldn’t be too surprising, since knowledge of that important event is itself pretty vague. His focus was really on the ‘how’, especially in relation to the question: is life special? That is, is it singular event or a cosmic imperative?
An important question that arises in the search for extraterrestial life is: how will we know it when we see it? If a meteorite landing on earth contained traces of life, how would we know? In Davies’ words, “If it looks too much like life we know, we say it’s contaminated. If it doesn’t look enough like life we know, we say it isn’t alive.” He talked a little bit about the role of information theory in determining the rise of complex lifeforms, and how life might better be understood and identified from an information processing point of view, rather than from a chemical one. Life has a way of taking information from its surroundings (environmental conditions, energy sources) and using it to react or produce something. Perhaps we can identify life by looking at these information processing pathways.
Davies’ final remarks were about the search for alternate life on earth. If life is common and will readily occur under the right conditions, then it is likely that it has arisen multiple times here on our own planet. If this is the case, then we should be able to find evidence for organisms (almost certainly microscopic) from an alternate ‘tree of life’ unlike any we’ve seen before (perhaps identified on the basis of amino acid chirality). But we first have to look.