#5. Leonardo’s Perpetual Motion Machines
Leonardo’s investigations into the possibility of perpetual motion were very thorough and scientific compared to the standards of his time. Da Vinci has two pages of notes with several designs showing possible perpetual motion machines. There is a scientific consensus that perpetual motion in an isolated system violates either the first law of thermodynamics, the second law of thermodynamics, or both. The first law of thermodynamics is a version of the law of conservation of energy. The second law can be phrased in several different ways, the most intuitive of which is that heat flows spontaneously from hotter to colder places.