It has been over a century since the groundwork of quantum physics was first formulated and yet the strange consequences of the theory still elude both scientists and philosophers. Why does light sometimes behave as a wave, and other times like a particle? Why does the outcome of an experiment apparently depend on whether the particles are being observed or not? In the first of two episodes, Ian Sample sits down with physicist Carlo Rovelli to discuss the strange consequences of quantum and the explanation he sets out in his new book, Helgoland. Help support our independent journalism at <a href="https://www.theguardian.com/sciencepod">theguardian.com/sciencepod</a>