CLOSE
Original image

Tonight on NOVA: Ghosts of Machu Picchu

Original image

(Image of Machu Picchu courtesy of Martin St-Amant - Wikipedia.)

Airing tonight (February 2, 2010) at 8pm on PBS stations: NOVA's Ghosts of Machu Picchu. Set your DVRs now! If you miss the program, it will be streaming online starting February 3.

Machu Picchu is an Inca engineering marvel: located 8,000 feet above sea level, it contains 200 stone structures placed on a complex set of roughly 700 terraces. What's most surprising is not its buildings, though -- it's all about what was built underneath the structures. Underground, complex engineering has allowed the site to withstand 76 inches of rainfall per year (that's 2.5 times what Chicago gets) for over 500 years. Machu Picchu is all about water: it is constructed to last, using complex engineering to manage and divert water. Within the complex, more than 100 drains divert rainfall down the mountain; a system of 16 fountains (flowing at between 6-30 gallons per minute depending on the time of year) provided drinking water for a population of up to 1,000 people; and complex soil engineering allowed the terraces to withstand the pressures of rain and earthquakes. So how did the Inca -- lacking steel tools and the wheel -- make this place? How could people live in such a remote place, and how did they grow so much corn -- a "royal food" of the time? This week's NOVA explains.

Included after the video is an interview with Ken Wright, a hydrologist who appears in the documentary. Click on through to check it out!

Interview With Ken Wright, Hydrologist

Ghosts of Machu Picchu features the work of Ken Wright, a hydrologist who has worked on the site for 15 years, in cooperation with National Geographic. Wright and his wife Ruth wrote several books on Machu Picchu including, Machu Picchu: A Civil Engineering Marvel and The Machu Picchu Guidebook: A Self-Guided Tour. Together, the Wrights have garned incredible accolades for their work (check out this image showing their collection of awards, including honorary professorships). I was able to ask Mr. Wright a few questions after previewing tonight's NOVA episode -- read on for his answers!

mental_floss: As a modern hydrologist, were you surprised to discover the hydraulic engineering sophistication of the Inca?

Ken Wright: Both my field research colleagues and I were surprised to discover the level of hydraulic engineering performed by the Inca.  Field evidence leaves no doubt about what they knew and how they accomplished their engineering feats.

m_f: Do you have a sense of what tools were available to the Inca -- how might they have determined a level surface, or measured a precise grade over distance?

KW: Yes, we do know what tools they had.  The Inca had a variety of hammerstones, bronze levers, bronze knives, plumb bobs, rope and string.  They used clay models for conceptualization and for determining a precise grade, they had nice pottery and stone basins, about 18 inches in diameter, that they filled with water to use as levels.

m_f: What first drew you to study Machu Picchu?

KW: I was first drawn to Machu Picchu by the then-unanswered question: where did the Inca get their water for Machu Picchu?

m_f: This is a slightly silly question, but it nagged me a bit while watching the documentary.  The terraces appear to be covered by grass today (though perhaps in the past they were planted with corn).  The grass looked very tidy.  Do you know if someone mows the grass?

KW: The trimmed grasses on the terraces of Machu Picchu are maintained by free-range llamas and alpacas.  For the steep terraces like Huayna Picchu, where the animals can't get, the Peruvian government hires macheteros (laborers with machetes) to keep the grasses under control.

For more from Ken Wright check out this excellent interview on the NOVA website.

Images From The Documentary

Images courtesy of Ricardo Preve, showing some scenes from Ghosts of Machu Picchu.

Ghosts of Machu Picchu image 1

Ghosts of Machu Picchu image 2

Ghosts of Machu Picchu image 3

Blogger Disclosure

Thanks to WGBH for providing an advance copy of the episode, the images above, and access to Ken Wright. I was not paid or otherwise compensated to review this episode of NOVA -- I wrote about it because it's awesome, and you should watch it!

Original image
iStock // Ekaterina Minaeva
arrow
technology
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
Original image
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!

Original image
iStock
arrow
technology
Why Your iPhone Doesn't Always Show You the 'Decline Call' Button
Original image
iStock

When you get an incoming call to your iPhone, the options that light up your screen aren't always the same. Sometimes you have the option to decline a call, and sometimes you only see a slider that allows you to answer, without an option to send the caller straight to voicemail. Why the difference?

A while back, Business Insider tracked down the answer to this conundrum of modern communication, and the answer turns out to be fairly simple.

If you get a call while your phone is locked, you’ll see the "slide to answer" button. In order to decline the call, you have to double-tap the power button on the top of the phone.

If your phone is unlocked, however, the screen that appears during an incoming call is different. You’ll see the two buttons, "accept" or "decline."

Either way, you get the options to set a reminder to call that person back or to immediately send them a text message. ("Dad, stop calling me at work, it’s 9 a.m.!")

[h/t Business Insider]

SECTIONS
BIG QUESTIONS
arrow
BIG QUESTIONS
WEATHER WATCH
BE THE CHANGE
JOB SECRETS
QUIZZES
WORLD WAR 1
SMART SHOPPING
STONES, BONES, & WRECKS
#TBT
THE PRESIDENTS
WORDS
RETROBITUARIES