My favourite T-shirt has four words on it – the elements Fluorine, Uranium, Carbon and Potassium. When I first saw it, I loved the joke and bought it. Since then, I’ve worn it frequently, including at many technical events and conferences around the world. Yet I’ve only found around a dozen people who have got it. Even when amongst fellow engineers, I’m more likely to be asked what it means. So, I’ve made up a story about it. Which goes like this:





