Watch Sand Magically Flow Like a Liquid When Pumped Full of Air

The playground you frequented as a kid was probably blanketed in sand to help soften the impact every time you tumbled off the jungle gym. But did you know that something magical happens when you pump a pile of sand full of air? It suddenly enters a liquid-like state.


The effect is known as fluidization, and it will happen with almost any fine powder or granular material when you introduce a constant flow of air from underneath. As the air makes it way towards the surface and through the particles, it gets in-between each granule and reduces the friction that normally makes sand behave more like a solid. The resulting mixture moves and flows like water, even allowing certain objects to float or sink.

In theory this approach could be used to surround and protect your home with a moat full of switchable quicksand. You’d be easily able to walk across it, but when an intruder is detected, switching on a compressor would cause them to sink like a stone.


[YouTube via Reddit]

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I sort of miss the days of playing in the sandbox, and think I need a new (better/bigger/more) sandbox now as an “adult” for stress relief (complete with Tonkas to build roads, and Hot Wheels to drive on them, but, without the neighborhood cats).