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iStock

Watch a Former NASA Engineer Turn Sand Into Liquid—Then Take a Dip

iStock
iStock

NASA engineer-turned-YouTube host Mark Rober is known for regularly conducting zany science experiments in his own backyard and filming the results. More than a year after he went swimming in a sea of Orbeez, Rober's latest stunt features him taking a dip in a hot tub filled with liquid sand.

But wait: Wouldn't bathing in liquid sand be akin to taking a really grainy mud bath (albeit with great exfoliation potential)? Rober isn't technically wetting down the granular material, as he explains in the video below—he's making the sand sift, blow, and bubble using nothing but a nitrogen tank and some PVC pipe.

“If you take a tub of sand ... and then add air in just the right way, it basically becomes a liquefied soup,” Rober explains of the seemingly magical process. “In science this is known as a fluidized bed," or a bed of small, solid particles that are suspended and galvanized by an upward flow of gas.

The upwards-blowing air is equal to the downward force of gravity. This causes the sand to hover in equilibrium, and allows the grains to slide around like water. The top surface of the mix "is nearly frictionless," Rober says. "It's like an air hockey table. And then when you cut off the air, it freezes everything exactly where it's at," prompting the tub's ingredients to transform back into ordinary, heavy sand.

[h/t Twisted Sifter]

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NASA, Getty Images
Watch Apollo 11 Launch
Vice President Spiro Agnew and former President Lyndon Johnson view the liftoff of Apollo 11
Vice President Spiro Agnew and former President Lyndon Johnson view the liftoff of Apollo 11
NASA, Getty Images

Apollo 11 launched on July 16, 1969, on its way to the moon. In the video below, Mark Gray shows slow-motion footage of the launch (a Saturn V rocket) and explains in glorious detail what's going on from a technical perspective—the launch is very complex, and lots of stuff has to happen just right in order to get a safe launch. The video is mesmerizing, the narration is informative. Prepare to geek out about rockets! (Did you know the hold-down arms actually catch on fire after the rocket lifts off?)

Apollo 11 Saturn V Launch (HD) Camera E-8 from Spacecraft Films on Vimeo.

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YouTube/Great Big Story
See the Secret Paintings Hidden in Gilded Books
YouTube/Great Big Story
YouTube/Great Big Story

The art of vanishing fore-edge painting—hiding delicate images on the front edges of gilded books—dates back to about 1660. Today, British artist Martin Frost is the last remaining commercial fore-edge painter in the world. He works primarily on antique books, crafting scenes from nature, domestic life, mythology, and Harry Potter. Great Big Story recently caught up with him in his studio to learn more about his disappearing art. Learn more in the video below.

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