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]

The Palos Verdes Blue: The Beautiful Butterfly That Wasn't Extinct After All

U.S. Fish and Wildlife Service, Wikimedia // Public Domain
U.S. Fish and Wildlife Service, Wikimedia // Public Domain

Terrible extinction news frequently makes the headlines, but sometimes, conservationists declare defeat too early. The Palos Verdes blue (Glaucopsyche lygdamus palosverdesensis) is one such example: Presumed extinct in 1983 after it seemed to vanish from its habitat in California's Palos Verdes Peninsula, it was discovered flitting among the grass in San Pedro again 11 years later.

Aside from coming back from the edge, the butterfly is notable for fuzzy wings that look brownish when closed, but a stunning silvery blue once they open up. Today it's still listed as threatened, but there's a captive breeding program to help make sure the beautiful species never goes missing again. Learn more—and see the butterfly up-close—in the video from Great Big Story below.

Why Cutesy Names Are the Most Effective Way of Getting Your Cat's Attention

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iStock

When you were naming your cat, you probably didn’t consider your feline friend’s hearing range. But according to Vancouver, Canada-based veterinarian Uri Burstyn, you probably should have—at least if you want your cat to pay attention when you talk to it.

According to Dr. Uri, the name he goes by in his adorable YouTube videos, Felix isn’t a great cat name. Nor is Garfield. But Fluffy? A great choice.

Cat ears are finely attuned to high-pitched noises. Since most of their prey communicate at high frequencies—think mouse squeaks and bird chirps—cats are not as good at hearing low-frequency sounds. Ideally, you want your cat’s name to end in a high frequency, since that’s the kind of sound cats hear best and naturally pay attention to.

For human speech, that basically means that it should end in an “eeeee” sound rather than a consonant. Grumpy Cat? A bad name. Just “Grumpy?” Perfect. That's why "kitty kitty" works pretty well to get a cat to pay attention or come toward you. It's a squeaky sound.

Luckily, many nicknames in English tend to end in an ie or a y, so you probably already have a cat-friendly name for your pet waiting in the wings. Now you know why your cat is more likely to respond to your high-pitched, baby-voiced nicknames than its full name.

Enjoy Dr. Uri's explanation, and his helpful demonstration with his noble friend Lancelot, in the video below.

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