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Corbis

AC/DC: The Tesla–Edison Feud

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Corbis

You’ve probably heard about the famous rivalry between Nikola Tesla and Thomas Edison—both giants of electrical engineering whose innovations changed history. But what exactly was their history with one another?

That whole boss/employee thing. Tesla, a Serbian by parentage, began working for the phone company in Budapest. In 1882, he headed for Paris, where he took a job with the Continental Edison Company. He was invited to work stateside after his supervisor wrote a recommendation praising the young man as a genius on par with Edison himself. While he hired Tesla, Edison thought the man's ideas were “splendid” but “utterly impractical.”

Clash of the methods.

Edison relied heavily on tedious experimentation for most of his discoveries, a commitment which some historians attribute partially to his lack of formal education. Tesla, in contrast, was an emotionally driven dreamer with years of engineering training, which allowed him to work out theories before physically implementing them. Later in life, each man publicly criticized the other’s work.

Clash of the lifestyles. Tesla was a germaphobe, fastidiously clean to the point of (allegedly) using seventeen clean towels a day, and claiming to have a “violent aversion against the earrings of women.” He once told the New York Times that Edison "had no hobby, cared for no amusement of any kind and lived in utter disregard of the most elementary rules of hygiene."

Clash of the...similarities? Edison and Tesla were alike in some equally irreconcilable ways. Both were egocentrics who abhorred egocentricity in others. And both men required little sleep, which would have made for many long, grumpy hours in the workshop.

War of Currents! Edison’s least favorite of Tesla’s “impractical” ideas was the concept of using alternating current (AC) technology to bring electricity to the people. Edison insisted that his own direct current (DC) system was superior, in that it maintained a lower voltage from power station to consumer, and was, therefore, safer. But AC technology, which allows the flow of energy to periodically change direction, is more practical for transmitting massive quantities of energy, as is required by a large city, or hub of industry, say. At the time, DC technology only allowed for a power grid with a one-mile radius from the power source. The conflict between the two methods and their masters came to be known as the War of Currents, forever immortalized by the band AC/DC.

The Bet. Tesla insisted that he could increase the efficiency of Edison’s prototypical dynamos, and eventually wore down Edison enough to let him try. Edison, Tesla later claimed, even promised him $50,000 if he succeeded. Tesla worked around the clock for several months and made a great deal of progress. When he demanded his reward, Edison claimed the offer was a joke, saying, “When you become a full-fledged American, you will appreciate an American joke.” Edison offered a $10/week raise, instead. Ever prideful, Tesla quit, and spent the next few months picking up odd jobs across New York City. Nikola Tesla: ditch digger.

The rift. Tesla eventually raised enough money to found the Tesla Electric Light Company, where he developed several successful patents including AC generators, wires, transformers, lights, and a 100 horsepower AC motor. Always more of a visionary than a businessman, Tesla ended up selling most of his patents (for the healthy but finite sum of $1 million) to George Westinghouse, an inventor, entrepreneur, and engineer who had himself been feuding with Edison for years. In fact, Westinghouse was a more economic participant in the War of Currents than was Tesla. Their partnership, one can imagine, made the eventual popularizing of AC that much more bitter for Edison.

“Post-war” history. In the end, AC won out. Mostly. Westinghouse fulfilled Tesla’s dream of building a power plant at Niagara Falls to power New York City, and built upon its principles the same system of local power grids we use today. Edison’s original point about the practicality of DC is well-taken, however: The average person can’t have alternating currents flooding massive amounts of energy into their household appliances, so most plug-in devices must internally convert AC back to DC (that’s what’s going on inside the brick of your laptop cord). That conversion wastes a lot of energy (think of all the heat coming from the brick of your laptop cord). Major studies are beginning to examine ways in which AC and DC power can work together with modern energy-harnessing technology, to run our overall grid more efficiently.

Tesla on Edison: "If he had a needle to find in a haystack he would not stop to reason where it was most likely to be, but would proceed at once, with the feverish diligence of a bee, to examine straw after straw until he found the object of his search. ... I was almost a sorry witness of such doings, knowing that a little theory and calculation would have saved him ninety per cent of his labor."
New York Times, October 19, 1931 (the day after Edison died)

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science
The Surprising Reason Why Pen Caps Have Tiny Holes at the Top
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iStock

If you’re an avid pen chewer, or even just a diehard fan of writing by hand, you’re probably well acquainted with the small hole that tops off most ballpoint pen caps, particularly those classic Bic Cristal pens. The reason it’s there has nothing to do with pen function, it turns out. As Science Alert recently reported, it’s actually designed to counter human carelessness.

Though it’s arguably unwise—not to mention unhygienic—to chomp or suck on a plastic pen cap all day, plenty of people do it, especially kids. And inevitably, that means some people end up swallowing their pen caps. Companies like Bic know this well—so they make pen caps that won’t impede breathing if they’re accidentally swallowed.

This isn’t only a Bic requirement, though the company’s Cristal pens do have particularly obvious holes. The International Organization for Standardization, a federation that sets industrial standards for 161 countries, requires it. ISO 11540 specifies that if pens must have caps, they should be designed to reduce the risk of asphyxiation if they’re swallowed.

It applies to writing instruments “which in normal or foreseeable circumstances are likely to be used by children up to the age of 14 years.” Fancy fountain pens and other writing instruments that are clearly designed for adult use don’t need to have holes in them, nor do caps that are large enough that you can’t swallow them. Any pen that could conceivably make its way into the hands of a child needs to have an air hole in the cap that provides a minimum flow of 8 liters (about 2 gallons) of air per minute, according to the standard [PDF].

Pen cap inhalation is a real danger, albeit a rare one, especially for primary school kids. A 2012 study [PDF] reported that pen caps account for somewhere between 3 and 8 percent of “foreign body aspiration,” the official term for inhaling something you’re not supposed to. Another study found that of 1280 kids (ages 6 to 14) treated between 1997 and 2007 for foreign body inhalation in Beijing, 34 had inhaled pen caps.

But the standards help keep kids alive. In that Beijing study, none of the 34 kids died, and the caps were successfully removed by doctors. That wasn’t always the case. In the UK, nine children asphyxiated due to swallowing pen caps between 1970 and 1984. After the UK adopted the international standard for air holes in pen caps, the number of deaths dropped precipitously [PDF]. Unfortunately, it’s not foolproof; in 2007, a 13-year-old in the UK died after accidentally swallowing his pen cap.

Even if you can still breathe through that little air hole, getting a smooth plastic pen cap out of your throat is no easy task for doctors. The graspers they normally use to take foreign bodies out of airways don’t always work, as that 2012 case report found, and hospitals sometimes have to employ different tools to get the stubbornly slippery caps out (in that study, they used a catheter that could work through the hole in the cap, then inflated a small balloon at the end of the catheter to pull the cap out). The procedure doesn’t exactly sound pleasant. So maybe resist the urge to put your pen cap in your mouth.

[h/t Science Alert]

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Big Questions
What Causes Sinkholes?
Mark Ralston/AFP/Getty Images
Mark Ralston/AFP/Getty Images

This week, a sinkhole opened up on the White House lawn—likely the result of excess rainfall on the "legitimate swamp" surrounding the storied building, a geologist told The New York Times. While the event had some suggesting we call for Buffy's help, sinkholes are pretty common. In the past few days alone, cavernous maws in the earth have appeared in Maryland, North Carolina, Tennessee, and of course Florida, home to more sinkholes than any other state.

Sinkholes have gulped down suburban homes, cars, and entire fields in the past. How does the ground just open up like that?

Sinkholes are a simple matter of cause and effect. Urban sinkholes may be directly traced to underground water main breaks or collapsed sewer pipelines, into which city sidewalks crumple in the absence of any structural support. In more rural areas, such catastrophes might be attributed to abandoned mine shafts or salt caverns that can't take the weight anymore. These types of sinkholes are heavily influenced by human action, but most sinkholes are unpredictable, inevitable natural occurrences.

Florida is so prone to sinkholes because it has the misfortune of being built upon a foundation of limestone—solid rock, but the kind that is easily dissolved by acidic rain or groundwater. The karst process, in which the mildly acidic water wears away at fractures in the limestone, leaves empty space where there used to be stone, and even the residue is washed away. Any loose soil, grass, or—for example—luxury condominiums perched atop the hole in the ground aren't left with much support. Just as a house built on a weak foundation is more likely to collapse, the same is true of the ground itself. Gravity eventually takes its toll, aided by natural erosion, and so the hole begins to sink.

About 10 percent of the world's landscape is composed of karst regions. Despite being common, sinkholes' unforeseeable nature serves as proof that the ground beneath our feet may not be as solid as we think.

A version of this story originally ran in 2014.

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