Have you ever tried swimming in sand? All you need is a hot tub, PVC pipe, and an air compressor. If swimming in sand sounds impossible, then you are forgetting the scientific principle of fluidization. Fluidization occurs when the force of the air pushing upward on an object (in this case, a grain of sand) is equal to the downward force of gravity, causing the grains of sand to hover in equilibrium. The result is sand that behaves more like water and must be seen to be believed.