TAKE any child outside on a clear night and science becomes exciting. But science lessons at school are often dismal. Teachers drone on in front of whiteboards that are filled with perfect spheres rolling down frictionless inclined planes (usually in some strange airless world without any wind resistance).
But it does not have to be this way. Randall Munroe is a former NASA roboticist who now draws the webcomic “xkcd”, which offers up an eclectic mixture of science, maths and whimsy three times a week. One of its spin-offs is a website called “What If?”, in which readers can submit questions to Mr Munroe that he will attempt to answer to the best of science’s ability. That website has, in turn, spawned a book full of such questions (half of which are recycled from the web, half of which are new).