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How Did Egyptians Move Heavy Rocks For The Pyramids?

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The pyramids aren't just old, they're really really old: We are closer in time to Cleopatra than she was to the building of the first pyramids. That mind-boggling time-chasm might explain why the pyramids have proved to be a source of fascination and speculation for modern humans, who can't imagine how our ancient forefathers got anything done without technology, let alone building structures large enough to be seen from space.

Stacking the blocks into the towering iconic shape is often marveled at as a feat of mystery, but just assembling the necessary materials is equally miraculous.

For the Great Pyramid of Giza—which is thought to have been built over a span of two decades for fourth dynasty pharaoh Khufu—over 2,300,000 giant blocks of limestone and granite weighing an average of two and a half tons had to be transported to the site from quarries—some from places like Aswan, more than 500 miles away.

Archeological evidence suggests that the ancient Egyptians used crude wooden sleds to transport the heavy building blocks. But if you've ever dragged something through the sand, you can understand why these sleds might not have eased this task. The weight of the blocks would cause the sled to sink slightly and, as you dragged them, sand would accumulate in front of the sled, increasing the resistance.

A recent study in the journal Physical Review Letters proposes an explanation for how the Egyptians made use of the sleds that is based on a principle most people are familiar with: While dry sand is easily pushed around, wet sand is malleable but more rigid. This is why you need moist sand to give your sandcastles structural integrity at the beach. The correct ratio of water to sand—which is variable, but typically between 2 percent and 5 percent of the volume of sand—causes the water droplets to create capillary bridges that bind the individual grains of sand into a smoother, stronger surface.

In experiments, the force required to pull sleds across sand was reduced by a full 50 percent when the right amount of water was added. Not only would it make sense for the ancient Egyptians to have utilized this tactic, there's evidence to suggest that they did. A wall painting from the tomb of Djehutihotep shows a hoard of workers moving a statue of the Upper Egypt nomarch on a sled. While rows of workers are shown heaving heavy ropes attached to the statue, a single figure is painted perched atop the sled pouring what could certainly be water on to the ground in front of him.

"In fact, Egyptologists had been interpreting the water as part of a purification ritual, and had never sought a scientific explanation," Daniel Bonn, who led the study, told the Washington Post.

The science is sound, but that doesn't necessarily mean it overrules the Egyptologists' theories about Djehutihotep's wall painting or that it applies to the pyramids, which were built over 600 years before Djehutihotep lived. Most reports of the study have assumed that applying their findings to the pyramids is something of a foregone conclusion. Adding water to the sand to decrease friction certainly makes sense, but that doesn't necessarily mean it's what the Egyptians did.

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iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Nick Briggs/Comic Relief
What Happened to Jamie and Aurelia From Love Actually?
May 26, 2017
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Nick Briggs/Comic Relief

Fans of the romantic-comedy Love Actually recently got a bonus reunion in the form of Red Nose Day Actually, a short charity special that gave audiences a peek at where their favorite characters ended up almost 15 years later.

One of the most improbable pairings from the original film was between Jamie (Colin Firth) and Aurelia (Lúcia Moniz), who fell in love despite almost no shared vocabulary. Jamie is English, and Aurelia is Portuguese, and they know just enough of each other’s native tongues for Jamie to propose and Aurelia to accept.

A decade and a half on, they have both improved their knowledge of each other’s languages—if not perfectly, in Jamie’s case. But apparently, their love is much stronger than his grasp on Portuguese grammar, because they’ve got three bilingual kids and another on the way. (And still enjoy having important romantic moments in the car.)

In 2015, Love Actually script editor Emma Freud revealed via Twitter what happened between Karen and Harry (Emma Thompson and Alan Rickman, who passed away last year). Most of the other couples get happy endings in the short—even if Hugh Grant's character hasn't gotten any better at dancing.

[h/t TV Guide]