Carlo Rovelli, a professor of quantum gravity, takes on another kind of mystery in Helgoland(Allen Lane). The book is named after the North Sea rock where in 1925 the young Werner Heisenberg inched open the door to the quantum realm with calculations that left him reeling. This is not the story of Heisenberg, however. It is Rovelli’s take on how physicists have strayed off course in thinking about the quantum world. He is no fan, for example, of the many worlds theory, where reality cleaves to accommodate all possible futures. He pushes instead his “relational interpretation”, where objects are defined by whatever they interact with. This conjures a bewildering world. “We must abandon something that seemed most natural to us,” he writes: “the simple idea of a world made of things.”