Why exactly did the apocryphal apple fall on Isaac Newton’s head? That’s what Newton wondered, and set out to discover why. Many of us wonder in the same way about why things happen, but don’t have time to dedicate our lives to getting to the bottom of it. Most of us don’t have a nuclear reactor or particle accelerator in our garden shed. Here’s a course for armchair physicists around the world who want to be told how it all works by people who have done all the hard thinking.