World's Lightest Material

The worlds lightest (ahem, least dense) material is about 100 times less dense than Styrofoam. That's just a little bit absurd. It consists of a microlattice of metallic tubes that are only about 100nm thick and the rest is just air. It is pretty tough, too. It can deform by 50% and still spring back to its original shape, unlike aerogels, which just shatter if you squeeze them too hard. I'm sure there will be many applications for this stuff, but super light electromagnetic shielding for is the first one that comes to mind.

Rayleigh Air Bearing

Air moving at high speeds can cause some neat effects. Jet engines, for example, basically just throw a lot of air really fast in one direction, which causes the plane to move in the opposite direction, because of Newton's second law of motion. Air can also be used as a cushion, like in a hovercraft. Air bearings put that air cushion to work to reduce the friction between two spinning shafts by inducing a levitation effect. The video below shows a demonstration of an old air bearing. Yay!