Buoyancy
Balloons and airships lift because they are buoyant, meaning that the total weight of the airship or balloon is less than the weight of the air it displaces. The Greek philosopher Archimedes first established the basic principle of buoyancy.Hot air balloons were first flown by the brothers Joseph and Etienne Montgolfier as early as the spring of 1783. While the materials and technology are very different, the principles used by the earliest eighteenth-century experimenters continue to carry modern sport and weather balloons aloft.
