Helen Czerski, physicist and oceanographer at UCL's Department of Mechanical Engineering, traces the physics and history of polar ice. She opens with Fridtjof Nansen's Arctic expeditions and the design of the Fram, a ship built to survive being crushed by pack ice, then moves into the science: why ice is not actually white, how albedo governs the reflection of solar energy, why ice floats at all, and how sea ice formation squeezes out freshwater in a process she calls the pink hedgehog. She distinguishes sea ice, glaciers, and icebergs, compares the Arctic and Antarctic, and revisits Scott's encounters with moving Antarctic ice. The lecture closes with the MOSAiC expedition, where scientists drifted with the ice for a year, and what that work reveals about Arctic amplification, climate change, and the emerging geopolitics of a melting polar frontier. Recorded at Gresham College's Barnard's Inn Hall in London.