Linux gamer, retired aviator, profanity enthusiast

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Joined 1 year ago
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Cake day: June 20th, 2023

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  • To expand on this, the rainbow of colors which start at a straw then turn yellow, red, brown and then that vivid blue, are caused by refraction. The oxide layer on the surface is transparent or translucent, and the thickness of the layer determines what wavelength of light it scatters. The hotter it gets, the thicker the oxide layer forms, so you can fairly reliably tell the temperature the metal has been heated to by eye, and you might use different amounts of heating to achieve hard-but-brittle or soft-but-tough.

    I’ve even seen it done by Chris of Youtube channel Clickspring for decorative purposes. It’s how he made the steel hardware of his brass clock blue.

    Exactly how you temper something the size of a sword using a forge is a bit outside my understanding; I’ve done it with relatively small bits of drill rod to make lathe tools with a gas torch, but that’s about it.



  • Yeah Tom Scott did one of his linguistics videos about that, he had a word for it but some questions aren’t really questions they’re basically just rituals, though rephrased a different way makes them genuine questions, and when you have major dialects of the “same” language like British and American English, we use different ones. “Are you alright?” is basically a noise of greeting in Britain and an expression of genuine concern in America, while “How are you?” is the reverse.














  • A short version of the story:

    America developed nuclear weapons in WWII, and they made more spherical plutonium “cores” than they ended up needing, so some nuclear physicists ended up using one of the spares for a series of experiments in criticality. Two of said scientists, in two separate experiments, negligently gave themselves fatal doses of radiation via accidental criticality incidents.

    One was stacking bricks around the core which would reflect free radicals back at the core to bring it close to, but not quite to the point of criticality. As he was placing the last brick, his instruments told him it was about to go critical, so he started moving the brick away, and then dropped it. The core went critical, there was a blast of heat and brilliant blue light from Cherenkov radiation, and he spent the last couple weeks of his life in a hospital as his body turned to mush.

    Another physicist was doing a similar experiment, this time enclosing the core in two metal half-spheres, and adjusting the distance between the half spheres with a flathead screwdriver. He had removed the spacers designed to prevent the shell from closing completely and causing criticality so he could get closer. And the screwdriver slipped. Heat, blue light, physicist spends the next couple weeks dying hideously in a hospital.

    The plutonium sphere was nicknamed the “demon core” and its fate is…undisclosed. A popular youtuber reported in a popular video on the topic that it was melted down and returned to the US nuclear stockpile where its fate becomes impossible to track, then later reported that someone in that field replied to that along the lines of “Is that what they said happened to it? Hahaha interesting.”

    The demon core wrapped in its half-sphere criticality experiment hardware has become internet shorthand for something that is egregiously reckless.

    TL;DR: Of the plutonium cores that were made for America’s nuclear weapons program, the one that was named the Demon Core wasn’t one of the ones that blew up a Japanese city, it was the one two white guys killed themselves with.




  • I was a pilot in a past life. Night flight is quite different than day flight, because it’s darker up there than you think. A lot of nations outright don’t allow night VFR requiring night flight to be done IFR, some others have optional night flight endorsements or ratings for night VFR. But it’s a training requirement for American private pilots.

    Because it is a regulatory matter, there has to be a strict definition of “night time.” Which is where we get the concept of “civil twilight” which IIRC is the moment when the center point of the sun’s disc is between 0 and 6 degrees below the horizon. “Night time” is officially the time when the sun is 6 or more degrees below the horizon. Exactly when this happens changes every single day as the days get longer and shorter, so you still have to look it up. The exact moment of local solar noon is even less important unless you’re navigating by sextant, and the way we currently solve this kind of problem is we maintain an accurate clock calibrated in GMT, UTC or Unix Timecode depending on your exact use case, and then we do the math on the fly to convert to local time. When is local solar noon today at my exact location? 18:32:40 GMT.