

"X" in this case is an enormous black cloud heading towards the solar system at a speed which means the possible extinction of all life in the next year and a half. This is what is known as "hard" sci-fi: a story about what would proceed if X happened, using impeccable science. There are no upset-Scrabble-board names, no silliness with space empires or allegories. When a scientist endorses – or indeed writes – science fiction it is usually a good idea to take note, and if you are going to have science fiction then I would rather have it like this. Much though Dawkins can comport himself in a manner that makes one want to do the opposite of what he proposes, I'm with him on this one. And it is also, for good measure, "one of the greatest works of science fiction ever written, up there with the best of Isaac Asimov and Arthur C Clarke".
