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Don't Try This at Home: Totally Dangerous Experiments

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Learning about science and the experimental method is a lot of fun. Mix this with that and see what you get! Sometimes the result can be, well, hazardous to your health. But if you survive such an encounter, you have to tell all your friends. With the internet, you can tell everyone, and even show the video. But seeing it done doesn't make these experiments any safer. Remember, the ones who survived to tell their tales are the lucky ones. Most of the experiments detailed here were done by professionals.

Theodore Grey has an index of Fun/Dangerous Experiments. He includes a special note for teenagers about mortality and how it will mean something in a few years. And about safety glasses.

Why are glasses so important? Because having your cheeks ripped off by shrapnel, your hair burned to the roots, and your nose split open and folded up over your forehead is nothing, nothing compared to being blind for the rest of your life. Not even close.

He then documents quite a few experiments with the elements, including this fascinating account of his Sodium Party. Besides the explosive combination of sodium and water, I found out there are butterflies who collect sodium, and how to protect fish from exploding sodium.

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Unwise Microwave Oven Experiments has a scary disclaimer, pointing to the fact that these experiments were done by a professional electrical engineer with his own microwave ovens. Then there are lnks to different microwave effects, including superheated liquids that we should all be aware of. Other experiments include nuking flames, light bulbs, molten materials such as Pyrex, and other very dangerous things you should never put in a microwave.

More dangerous experiments after the jump.

Powerlabs Unwise Liquid Nitrogen Experiments describes the Liquid Nitrogen Baseball Bat Cannon and Pressure Bomb projects. Liquid nitrogen is a cryogenic fluid much colder than frozen water, and can cause frostbite if it comes in contact with skin. As its temperature rises, it expands so much that it is used as a pressurant. Not something you play with unless you know what you are doing.
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A Tesla Coil consists of two or three coupled resonant electric circuits. The explanation is complicated, but it appears to come down to sending electricity through the air. Adam posted pictures of things he has zapped on the page Fun with Tesla Coils. This picture shows the effect of a Tesla Coil on an old CD. He also documented some other Extremely Stupid and Dangerous Experiments.
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Fantastically Dangerous Capacitor-Bank Discharge Experiments has an extensive disclaimer, including the caveat that these experiments require expensive lab equipment and otherwise cannot be reproduced. I don't understand the science involved at all, but the watergun experiment mentioned 150,000 volts, which is enough to make me run away screaming. A link on this page took me to T. Johnson's Can Crusher, the apparatus pictured. He used a pulse capacitor to crush cans with electricty. He started with 200 volts and worked his way up to 2700 volts, detailing the effects of each voltage increase. At least he warned the neighbors.
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Thermite is a combination of materials that will produce a large amount of heat. The process is used to weld railroad ties. From Wikipedia:

Although the reactants are stable at room temperature, they burn with an extremely intense exothermic reaction when they are heated to ignition temperature. The products emerge as liquids due to the high temperatures reached (up to 2500 °C (4500 °F) with iron(III) oxide)—although the actual temperature reached depends on how quickly heat can escape to the surrounding environment. Thermite contains its own supply of oxygen and does not require any external source of air. Consequently, it cannot be smothered and may ignite in any environment, given sufficient initial heat. It will burn well while wet and cannot be extinguished with water.

Of course, with a reaction like that, people are going to use it for entertainment. Thermite is not difficult to make. The danger of igniting the stuff should be apparant in this video.

The story of The Radioactive Boy Scout sounds like a movie script. 17-year-old David Hahn endangered 40,000 people with radioactive materials he was using to build a nuclear reactor. The EPA packed his experiment into 39 barrels and buried it in a nuclear waste dump. Hahn apparently did not learn his lesson, as he was recently arrested for stealing smoke detectors to obtain radioactive materials. Don't try this at home.
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Other dangerous links:
Dangerous Laboratories
Mad Coiler's High Voltage Page
Fun Things to Do with Microwave Ovens
The Dangerous Experiments Flickr pool.

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iStock // Ekaterina Minaeva
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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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May 23, 2017
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