Maybe we really are alone in the universe

Paul Davies, a cosmologist at Arizona State University and the author of the book Eerie Silence—which takes exactly the dim view of our ever encountering an alien intelligence that its title suggests—finds almost no part of the intelligent-life argument persuasive. The biggest hole he finds in the Drake equation is the one involving the subset of planets that could support life that actually do. The fact is, we have absolutely no empirical data that allows us to put a value on that variable in a responsible way. We know of precisely one world on which life has existed, and the rest is largely guesswork. Fill in that one Drake blank with a zero, and the entire equation collapses to zero too.

Davies, though, goes well beyond the flaws of the equation, arguing that there is a perfectly credible case to be made for the presence of life on Earth as a result of a succession of flukes, each more improbable than the one before it, which, together, could occur only a single time in a trillion trillion tries. A chimp randomly pounding a typewriter might indeed come up with Hamlet. Once. It wouldn’t matter if there were 40 billion other chimps hammering away, just as, as Davies has written, it doesn’t matter if there are 40 billion planets in the Milky Way capable of sustaining life. Only a single one will.