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Julia Margaret Cameron via Wikimedia // Public domain

Hypatia, Scholar and Teacher of Ancient Alexandria

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Julia Margaret Cameron via Wikimedia // Public domain

The late 4th and early 5th century philosopher and mathematician Hypatia was one of the most admired women in Alexandria, but she was also one of the most hated. She was the first known woman to both study and teach mathematics, astronomy, and philosophy, drawing students from far and wide, but she was also unabashedly pagan in a time when the city’s authority figures were Christian. In the end, her commitment to her beliefs would cost her her life.

Scholars differ on the date of Hypatia’s birth. It is thought that she was born between 350 and 370 CE in Alexandria, Egypt, which at the time was the sophisticated center of learning in the ancient world. She was the daughter of famed mathematician Theon, who wrote commentaries on works by the mathematicians Euclid and Ptolemy (his version of Euclid's Elements was the only one known until the 19th century), and who also wrote a popular treatise on the astrolabe, an instrument used to chart the position of celestial bodies.

Theon considered Hypatia his intellectual heir and tutored her in art, astronomy, literature, science, and philosophy. She taught math and philosophy at the university of Alexandria, where her father was director. She also wrote, producing several commentaries, and collaborated on more written works with her father. Sadly, none of her works survive, although some scholars believe that part of Theon’s version of Ptolemy’s Almagest was actually written by her.

Hypatia was a follower of the Neoplatonist school of thought, based partially on the teachings of the philosopher Plato. The Greek Neoplatonist philosopher Damascius described Hypatia’s work by saying: "The lady made appearances around the center of the city, expounding in public to those willing to listen on Plato or Aristotle." She is said to have been a popular teacher—and after her father died, was considered the foremost mathematician in the world.

Hypatia never married and most likely remained celibate due to her Neoplatonist beliefs. Damascius noted that she was "honest and chaste," while Socrates Scholasticus spoke of her "extraordinary dignity and virtue."

Orestes, the Roman prefect of Alexandria, admired her mind and sought her counsel. He was a Christian, but tolerant of all the faiths that co-existed in Alexandria, and he worked to form bonds between them. This tolerant attitude would place him in direct conflict with Cyril, the city’s new archbishop, and ultimately lead to Hypatia’s death.

Archbishop Cyril was not as tolerant of other faiths. When he became archbishop in 412, he closed and plundered churches belonging to another Christian sect. After a massacre of Christians by Jewish extremists, Cyril expelled all Jews from the city. Orestes opposed Cyril’s actions and complained to Rome, which led to an unsuccessful assassination attempt on the prefect’s life.

He survived, but Hypatia was less fortunate.

When a rumor spread that she was causing the conflict between Orestes and Cyril, a fanatical Christian sect murdered Hypatia in a particularly gruesome way.

On a March evening in the year 415 or 416 (accounts vary), a mob blocked her chariot as she was driving home. They pulled her from the chariot, stripped her naked, and stoned her to death with roofing tiles. The frenzied mob then reportedly tore her body apart, and burned what remained of her.

Some historians considered Hypatia’s death to be a deliberate act taken by Cyril against Orestes, who refused to reconcile with him. Other historians do not hold Cyril directly responsible for Hypatia’s death, while acknowledging that he did promote the intolerance that helped turn a mob against a prominent pagan figure.

Ironically, despite the fact that she was murdered by a Christian mob at least in part because she promoted Neoplatonist ideas, some of her teachings would eventually influence Christian doctrine. One of her students, Synesius, became a Christian bishop, and some scholars say that his earlier Platonic studies influenced the church’s doctrine of the Holy Trinity.

Today, she is remembered as one of the first women known to have studied math and philosophy, and her name lives on in a scholarly journal devoted to feminism and philosophy. She is sometimes credited with the line: "Reserve your right to think, for even to think wrongly is better than not to think at all."

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iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
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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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Why Your iPhone Doesn't Always Show You the 'Decline Call' Button
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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]