Can a vacuum balloon be built with current material technologies?
A balloon's bouyancy (lifting force) is a function of how much air it displaces. Today's balloons use hot air, hydrogen, helium and other lighter than air gases for lift. In 1670 Franceso de Lana, an italian monk, proposed the use of a vacuum. One major problem is how to make the structure light enough to support a vacuum without collapsing in on itself due to the outside pressure.