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

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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]

19 Common Things Science Hasn’t Figured Out

YouTube
YouTube

Whether we want to admit it or not, everyone cries. And while experience has taught us that it's a seemingly natural reaction to being either incredibly sad or incredibly happy, scientists have yet to figure out exactly why that salty discharge pours from our eye sockets when we're feeling emotional. It could be a way to bond with our fellow humans, or a way to alert someone else that something is amiss. But these are all just guesses, as weeping is just one of many everyday behaviors the world's smartest brains still haven't quite cracked the code on yet.

Join editor-in-chief Erin McCarthy as she digs into the science—or lack thereof—of 19 seemingly normal things we do that are a mystery to scientists (you can add sleeping, laughing, and hiccuping to that list, too) with the first edition of our all-new Mental Floss List Show. There's a fancy new set, a fancy new host, and plenty of mind-boggling topics we'll be discussing. So put on your smartypants and check out the full episode below.

For more episodes like this one, be sure to subscribe here!

A Clue on the Ceiling of Grand Central Terminal Shows How Dirty It Was 30 Years Ago

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iStock.com/undercrimson

The mural above the concourse at Grand Central Terminal is one of the most gawked-at ceilings in New York City, but even daily commuters may have missed a peculiar feature. Tucked at the edge of the green and gold constellations is a rectangular black mark. The apparent blemish didn't get there by mistake: As Gothamist explains in its new series WHY?, it was left there by restorers when the ceiling was cleaned more than 20 years ago.

Prior to the Metropolitan Transportation Authority's renovation of Grand Central in the 1990s, the concourse was a lot dirtier. The station itself was constructed in Manhattan in the early 1900s, and the celestial scene that's on the ceiling today was painted there in the 1940s. It took only a few decades for tobacco smoke and other pollutants to stain the mural so badly that it needed to be restored.

Using Simple Green-brand cleaning solution and cotton rags, conservators spent two years scrubbing nearly every inch of the ceiling back to its former glory; the one part they skipped was a 9-inch-by-18-inch patch in the northwest corner. Sometimes, when doing a major cleaning project, preservationists will leave a small sample of the art or artifact untouched. If the cleaning products did any damage to the paint, the patch gives future preservationists something to compare it to. It also acts as a snapshot of what the mural looked like in its old condition.

To hear more about the mural and its dirty secret, watch the video from Gothamist below.

[h/t Gothamist]

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