Scientific theories have always gone hand in hand with inventions: first comes the idea, then the formula, and finally the invention. In this new section, as well as publishing the most famous ones, we gather hypotheses, theses, models and lines of reasoning that seek to explain the world and, sometimes, to change it. Not only blackboards and numbers: also those slightly eccentric intuitions which, starting from a sheet of calculations, can become a prototype, a patent, a product. Some people will turn up their noses at a theory that seems too bold, or too far from common sense. That is the fate of many discoveries: at first they spark debate, then they become obvious. Here you will find precisely that middle ground, where science meets the ingenuity of inventors, and where a formula written in chalk may, one day, reach the global market.