Part of the show Naked Science Q&A and the Science of Happiness
Brian in Norwich asked:
Why doesn't nature make any straight lines?
Well it produces crystals and beams of light, which travel in straight lines until they hit something. Crystals are probably the obvious example of something solid that is made with straight lines. If you look at a salt crystal it will have flat faces and the corners will be sharp. The corners will be in straight lines because of all the little atoms that stack in a big pile.