# Watch This "Impossible Object" Dovetail Cube Puzzle

Kenjamoto // CC BY 3.0

This puzzle is devious. Externally, it looks like a cube with dovetails cut on four sides—which should be impossible. Dovetail joints are normally cut to join two planes to each other, like the front of a drawer with its side. It shouldn't be possible to cut dovetails across four interlocking planes...so how does this puzzle do it?

You can just skip ahead to the video below if you'd like a visual explanation—or I'll spoil it for you now. In short, the "impossible dovetail" relies on a hidden set of diagonal cuts that allow the puzzle to slide apart diagonally. There's often a pin or other fastening mechanism to prevent an accidental slide, making the joints appear firm and fast until you press it.

The logic of this puzzle plays on our assumptions about how dovetail joints work. Because these joints typically prevent motion in two planes, those are the planes we look at. Is it possible to pull the top off the puzzle? Nope! How about side-to-side? Impossible! By adding a dimension to the puzzle, the solution is revealed in that extra dimension as well—you've got to slide the pieces apart diagonally. The joints, of course, aren't impossible...it's our assumptions about how dovetail joints are cut that are incorrect.

In this video, "Mr. Puzzle" walks us through the solution to a wooden version of the puzzle (the solution starts at 1:52). Have a look:

If you're curious how this thing was made, here's a similar project by Clickspring, but machined out of aluminum. Behold:

If you'd like to make your own puzzle, free plans are online for a wooden version (requires a hand saw, coping saw, and chisel) as well as a plastic version (requires 3D printer).

(Image by Kenjamoto // CC BY 3.0.)

# Amazing Timelapse Shows Florida Sky Turning Purple Following Hurricane Dorian

Scott Olson/Getty Images

Photographs taken of Hurricane Dorian's massive eye and the damage it caused in the Bahamas paint a picture of what it was like to live through the historic storm. But some of the most stunning images to come out of the event were captured after the hurricane had passed. As KENS5 reports, the time-lapse video below shows the sky over Florida turning a unique shade of purple in the wake of Hurricane Dorian.

Dorian skimmed the east side of Florida earlier this week, causing power outages and some flooding. The worst of the storm was over by Wednesday night, but the ominous purple clouds it left behind may have sparked concern among some Florida residents.

A purple sky following a hurricane is the result of a perfectly natural occurrence called scattering. The sky was super-saturated after Dorian arrived, and the moisture in the atmosphere refracted the light of the setting sun. Normally, only the longest wavelengths of light on the color spectrum are visible through the clouds—that's why sunsets often appear gold, pink, and orange.

Violet is the shortest wavelength on the spectrum, which means it's almost never visible in the sky. But the air's high dew point Wednesday night, combined with the dense low-hanging clouds, created the perfect conditions for a rare purple sky.

Locals who've lived through a few hurricanes may have recognized the phenomenon; the same thing happened after Hurricane Michael hit Florida last year.

[h/t KENS5]

# YouTube Decade Shows You the Most Popular Videos From 10 Years Ago

fizkes/iStock via Getty Images

If you’re the type of person who lives for Facebook’s "On This Day" notifications and religiously checks Timehop to see what you were tweeting about seven years ago, YouTube Decade might be your next nostalgia-related obsession.

According to Lifehacker, the site compiles the most popular videos uploaded to YouTube on that day exactly 10 years ago. Since it shows you the top video in each of eight different categories—music, comedy, film and animation, entertainment, news and politics, pets and animals, sports, and gaming—the site offers an intriguing snapshot of what was going on in the world at the time. For instance, on September 4, 2009, Mumford and Sons released the video for “Little Lion Man,” which helped catapult the band into the mainstream music scene, and actor Jon Voight appeared on national news to share his opinions on federal politics.

YouTube Decade also reminds us that some things never change. The top video in the “pets and animals” category on this day in 2009 is footage of a yellow Labrador retriever playing with a baby; 10 years later, we still can’t get enough quality pet-and-baby content. The top comedy video is a clip from a 1991 episode of Mr. Bean during which Mr. Bean makes a unique sandwich. The trend of rediscovering our favorite childhood shows lives on, though younger audiences now take to social media to reminisce about more recent programs like Nickelodeon’s Drake & Josh and Disney Channel’s Lizzie McGuire.

YouTube users know that it’s all too easy to accidentally spend an entire afternoon watching viral video after viral video, and YouTube Decade is no different: You can work your way backward through the calendar, exploring the top videos from each day prior. Though you can’t move forward in time—the site includes a countdown clock to let you know how many hours, minutes, and seconds you’ll have to wait to see tomorrow’s collection of videos.

To keep you busy while the countdown clock ticks away, find out which viral video is most popular in your state here.

[h/t Lifehacker]

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