Air. I bet you never even notice that it’s there. Yet you are swimming in an ocean of it every day. If there’s a literal ton of air pressing down on you all the time, so why don’t we feel it? We look back at the history of physics to learn how we figured out air pressure, why vacuums don’t suck, and how people like Galileo, Torricelli, and Otto von Guericke changed science forever with a few simple experiments.