Hover

Floating is the new flying, at least according to a handful of companies focused on building futuristic blimps, airships, and hot-air balloons.

Lighter-than-air vehicles (or LTAs) depend on the same basic physics that creates bubbles in water. They’re filled with extremely light gas, like helium, which allows them to achieve lift and hover in the air without burning fuel. They’ve never been particularly popular: they’re big and comparatively slow, and they have faced safety concerns ever since the 1937 Hindenburg disaster, which left 36 people dead.

Still, some companies say modern LTAs can be extremely safe. They argue that these aircraft can play a critical role in cutting down on carbon emissions associated with transportation, especially for moving people and things that don’t need to travel very quickly.