One bright February afternoon, on a beach in Cornwall, Gavin Pretor-Pinney took a break from cloudspotting and started watching the waves rolling into shore. Mesmerised, he wondered where they had come from, and decided to find out. He soon realised that waves don't just appear on the ocean, they are everywhere around us, and our lives depend on them. From the rippling beats of our hearts, to the movement of food through our digestive tracts and of signals across our brains, waves are the transport systems of our bodies.