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I spent forty minutes this week looking for my keys while holding them. |
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The gorilla that twenty of twenty-four radiologists never saw |
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In 1999, two psychologists filmed six people passing basketballs, three players in white shirts and three in black, and asked volunteers to count how many passes the white team completed. Partway through the video, someone in a full gorilla suit walked into the frame, stopped, thumped its chest, and walked off nine seconds later. More than half the volunteers, asked afterward if they'd seen anything unusual, said no. Daniel Simons and Christopher Chabris named the effect sustained inattentional blindness, and it scaled with difficulty: harder versions of the counting task made people miss the gorilla more often than easier ones did. Attention behaves less like a floodlight than a spotlight, and a harder task narrows the beam everywhere it isn't pointed, gorilla suit included. Fourteen years later, a team led by Trafton Drew ran a version of the same test on twenty-four practicing radiologists searching chest CT scans for cancerous nodules, the exact task they do for a living. On the final scan, researchers inserted a small photograph of a gorilla, sized about forty-eight times larger than the nodules they were hunting for. Twenty of the twenty-four never reported seeing it, and eye-tracking showed that most who missed it had looked directly at its location for over a second. Looking hard at a screen and seeing what is actually on it turned out to be two different skills, and years of training sharpen the first one without doing much for the second. |
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A monument's tip was cast from a metal pricier than silver |
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A hundred-ounce pyramid of cast aluminum sits at the very top of the Washington Monument, fitted into place on December 6, 1884, by a Philadelphia chemist named William Frishmuth. That metal cost around sixteen dollars a pound the year it went up. Frishmuth had spent nearly three decades and tens of thousands of dollars perfecting a process that heated ore until the alumina vaporized, then added sodium gas to draw out the pure metal. It was slow and expensive, the only method anyone had, which is why the government wanted the capstone in aluminum: nothing so ordinary-looking was that hard to make. Two years later, a student named Charles Martin Hall worked out a cheap electrolytic method for extracting it. The price fell to about two dollars a pound within a couple of years, then to fifty cents within the decade. The tip is still up there: metal that briefly cost more per pound than silver, now outlasted by the stuff we wrap sandwiches in. |
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One word choice in 1659 kept a town out of France |
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Llívia is a Spanish town completely surrounded by French territory, a quirk that traces back to one word in a seventeenth-century treaty. The 1659 Treaty of the Pyrenees ended a war between France and Spain and handed France thirty-three villages in the Cerdanya valley. Llívia, the valley's old capital, was not among them, because under Catalan law it held the status of a town rather than a village, and the treaty only covered villages. The maps were poor enough that neither side grasped what this meant until surveyors drew the new border: France owned the land in every direction around Llívia, and Spain still owned Llívia itself. Spain ceded the neighboring Carol valley as compensation, and the border was formalized in 1866. The arrangement never got undone. Around fifteen hundred people live in Llívia today, and the road linking it to the rest of Spain still crosses about a mile of French territory, a quirk nobody in 1659 set out to create. |
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GPS works because its clocks are built to run wrong |
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Every GPS satellite carries an atomic clock accurate to a few billionths of a second, and every one of those clocks is deliberately mistuned before launch. Left alone, a clock orbiting about twelve thousand miles up would drift from ground clocks by roughly thirty-eight microseconds a day: gaining time in weaker gravity, losing a smaller amount from moving fast enough to circle the Earth twice daily. Thirty-eight microseconds sounds too small to matter until multiplied by the speed of light. Left uncorrected, the resulting position error works out to around ten kilometers a day, meaning a location fix would be useless within about two minutes of a clock going unadjusted. Engineers solved this before a single satellite launched, by shifting each clock's oscillator to a frequency that only reads correctly once it is moving at orbital speed inside a weaker gravitational field. The fix for a phone telling you which street you're on is sitting inside a 1915 paper about gravity bending time. |
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Usenet's most famous rule began as a deliberate experiment |
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A young lawyer named Mike Godwin got tired of watching online arguments end with a Hitler comparison, so in 1990 he built a small, deliberate experiment out of it. He started seeding a single sentence into Usenet threads himself: "As an online discussion grows longer, the probability of a comparison involving Hitler or Nazis approaches one." He wanted to see whether a catchy, science-sounding claim about internet behavior could spread on its own, the way the lazy Nazi comparisons it mocked already did. It worked better than he expected. The line got repeated, then cited, then formalized into "Godwin's Law," and it has now outlived Usenet itself by about three decades. Godwin has described the whole exercise as a kind of smoke alarm, something built to make people flinch and reconsider before reaching for the comparison. He says he is still disappointed by how often it goes off. |
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If you only remember one of these tomorrow, make it the gorilla nobody saw. |
