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Scientists Created a Water Tractor Beam

Tractor beams have long been a science fiction fantasy—a magical force that attracts objects from a distance, like an alien’s spaceship sucking up its earthling specimens. We’re not quite that advanced, but physicists at The Australian National University have created a “tractor beam on water” that makes floating objects move wherever they are directed.

The group, led by Professor Michael Shats, started with a ping pong ball. Placing it in a small pool, they created waves using a thin, cylindrical device with suction cups on the bottom. When the device vibrates up and down, these cups come in contact with the water, creating waves. Different wave frequencies and sizes, along with different cup shapes, create different kinds of currents. Some pulled the ball inward, some pushed it outward.

Dr. Horst Punzmann, from the Research School of Physics and Engineering, said the team even found a way of “creating waves that can force a floating object to move against the direction of the wave.”

This doesn’t sound like rocket science. It seems quite obvious that waves make floating objects move, right? But actually, what propels floating objects aren’t the waves themselves, it’s the currents they create. Never before have we identified the precise wave patterns that make an object go one way or another, or how to replicate them. “It’s one of the great unresolved problems, yet anyone in the bathtub can reproduce it,” Punzmann said. Interestingly, there’s still no mathematical theory to explain why these experiments work. That said, this new knowledge could help us clean up oil spills and ocean trash, or retrieve drifting boats.

"The applications could be numerous," Shats said. A paper documenting the findings is featured in the journal Nature Physics.

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26 Facts About LEGO Bricks

Since it first added plastic, interlocking bricks to its lineup, the Danish toy company LEGO (from the words Leg Godt for “play well”) has inspired builders of all ages to bring their most imaginative designs to life. Sets have ranged in size from scenes that can be assembled in a few minutes to 5000-piece behemoths depicting famous landmarks. And tinkerers aren’t limited to the sets they find in stores. One of the largest LEGO creations was a life-sized home in the UK that required 3.2 million tiny bricks to construct.

In this episode of the List Show, John Green lays out 26 playful facts about one of the world’s most beloved toy brands. To hear about the LEGO black market, the vault containing every LEGO set ever released, and more, check out the video above then subscribe to our YouTube channel to stay up-to-date with the latest flossy content.

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Of Buckeyes and Butternuts: 29 States With Weird Nicknames for Their Residents
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Tracing a word’s origin and evolution can yield fascinating historical insights—and the weird nicknames used in some states to describe their residents are no exception. In the Mental Floss video above, host John Green explains the probable etymologies of 29 monikers that describe inhabitants of certain states across the country.

Some of these nicknames, like “Hoosiers” and “Arkies” (which denote residents of Indiana and Arkansas, respectively) may have slightly offensive connotations, while others—including "Buckeyes," "Jayhawks," "Butternuts," and "Tar Heels"—evoke the military histories of Ohio, Kansas, Tennessee, and North Carolina. And a few, like “Muskrats” and “Sourdoughs,” are even inspired by early foods eaten in Delaware and Alaska. ("Goober-grabber" sounds goofier, but it at least refers to peanuts, which are a common crop in Georgia, as well as North Carolina and Arkansas.)

Learn more fascinating facts about states' nicknames for their residents by watching the video above.

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