Early in the 20th century, when the general public started to hear about statistical thermodynamics, science writers became interested in finding striking metaphors for impossible happenings. They were motivated in particular by the need to say just how unlikely it would be for a glass of water, on the kitchen table, to suddenly freeze... in spite of the theoretical possibility that this could happen.
In The Blind Watchmaker [pages 47-52], Richard Dawkins proposed a variation of the monkeys-and-typewriters metaphor in which the goal consists of producing a single line of Hamlet: Methinks it is like a weasel. If you use an algorithm that examines periodically the monkeys' output and retains, as a new point of departure, only the line whose letters are closest to those of the target, then the goal is reached quite rapidly. But I always thought it a pity that Dawkins should introduce this twisted version of the metaphor, because it might cause adepts of so-called "intelligent design" to imagine—for a misguided instant—that Dawkins is suggesting that evolution operates with a target "in mind"... which, of course, is nonsense.
In The God Delusion [page 113], Dawkins introduced a new metaphor to illustrate quasi-impossibility: that of the Ultimate Boeing 747, borrowed from the English astronomer Fred Hoyle [1915-2001].
The basic image is that of a hurricane, sweeping through a scrapyard, which just happens to blow together various bits and pieces in such a way as to build a Boeing 747. People who believe erroneously that evolution is a theory of chance and random constructions consider that this metaphor illustrates the absurdity of imagining that a living animal could be the outcome of the random shuffling of its components. In fact, they're spot on. That would indeed be a stupid way of looking at Creation of any kind, with or without a capital C. Fortunately, Darwin's theory of evolution never calls upon processes of that absurd kind. On the other hand, Dawkins points out that something like the Ultimate Boeing 747 process would have been required—at some eternal instant in the Dreamtime (that precision comes from me, not Dawkins)—in order to create the kind of mysterious entity known as God.
A week ago, in a funereal setting in Melbourne, Dawkins was interviewed by a local journalist named Robyn Williams... who seems to have a sound reputation in Australia. I make that last point because I was rather horrified by the stupid way in which this fellow tried to get the ball rolling. He had invented his own silly and fuzzy little metaphor for impossibility: something to do with the chance that all the people in the audience might find their correctly-numbered seats, by pure chance, if they were to sit down in a random fashion. A lesser man than Dawkins might have asked: "What the fuck does that have to do with Darwin's theory of evolution?" But Dawkins is, of course, an unruffled gentleman... and he put Robyn Williams back on course in a polite and even pedagogical manner. It was a truly beautiful example of the Dawkins style.