The wait is finally over: Hannah Fry introduces Michael Stevens to her beloved fountain pen collection and the beautiful physics behind how fountain pens work. From a £20 Lamy Safari to vintage Waterman and Montblanc pens, Hannah explains how capillary action, surface tension, air pressure and carefully engineered feeds control the flow of fountain pen ink. Michael tests the collection, chooses his favourite and discovers why the most expensive pen is not necessarily the nicest to write with. Then Hannah and Michael answer your questions: which words are terrible at their jobs, how do aeroplane wings actually generate lift, and which moment in history would they most like to witness? ------------------- For more information about Cancer Research UK, their research, breakthroughs and how you can support them, visit https://cancerresearchuk.org/restisscience Cancer Research UK is a registered charity in England and Wales (1089464), Scotland (SC041666), the Isle of Man (1103) and Jersey (247). A company limited by guarantee. Registered company in England and Wales (4325234) and the Isle of Man (5713F). Registered address: 2 Redman Place, London, E20 1JQ. ------------------- Video Producer: Adam Thornton + Oli Oakley + Jack Meek Animator: Sam Benson Video & Social: Bex Tyrrell Assistant Producer: Lucy Lipscombe Producer: Simona Rata Senior Producer: Lauren Armstrong-Carter Chief Digital Officer: Samuel Oakley Exec Producer: Neil Fearn"