Inventor and former NASA JPL engineer Mark Rober (previously featured here) is back with his funnest experiment to date: pumping air into a hot tub filled with sand so that it behaves just like a fluid.
Fluidized beds are used in industry for various reasons. They also happen to be really cool to play with and swim in. I made a liquid sand hot tub by adding air in just the right way.
Watch Rober play in his liquid sand hot tub and learn how it was made: