Why red and yellow cards trace back to a language mix-up at Wembley in 1966, plus a startup’s radio-wave camera prototype that it says can map inside walls to 1 mm accuracy. There’s also a coin-flip maths puzzle, an adhesive that sticks to Teflon but washes off with ethanol, and low Danube levels disrupting nuclear power. [DVYio Newsletter](https://newsletter.dvy.io/visit/atL7SKJG) Thanks for voting on last week’s poll about the newsletter format. Around 80% of you prefer this new style, so I’ll keep it going. But don’t worry, the newsletter won’t become just a list of links any time soon. This Week I Learnt [Infographic: a 1966 language barrier between referee and captain leads to yellow and red cards, leaving a team short-handed.](https://newsletter.dvy.io/visit/JbNBNKED) [Football’s red and yellow cards grew out of a language mix-up at Wembley](https://newsletter.dvy.io/visit/JbNBNKED) [At Wembley in 1966, a refereeing language mix-up helped create a permanent fixture of football. Ten minutes before half-time in England’s World Cup quarter-final against Argentina, West German referee Rudolf Kreitlein gave Argentina captain Antonio Rattín a second caution, which meant he was sent off. Kreitlein spoke German, Rattín spoke Spanish, and the dismissal caused several minutes of confusion before police escorted Rattín from the pitch. After the match, former English referee Ken Aston proposed a system that needed no shared language: yellow for a caution and red for a sending-off. FIFA introduced it at the 1970 World Cup. That story opens a study in Empirical Economics by Jakub Červený, Jan van Ours, and Martin van Tuijl, who looked at what a red card actually does to a match. They analysed World Cup games from 1998 to 2014 using a method that tracks how often goals happen throughout a match, rather than just the final score, and found two things happening at once after a sending-off: the team down to ten players scores less often, and the team still with eleven scores more often. Some earlier research on other leagues had suggested a “ten do it better” effect, where losing a player sharpens the remaining team’s focus and defence. This World Cup study found no sign of it; the numerical disadvantage just hurt. They also found that teams already losing were more likely to receive a red card, which the authors suggest may reflect players taking bigger risks and committing rougher fouls while chasing the game.](https://newsletter.dvy.io/visit/JbNBNKED) Poll If you could make one invisible thing visible, which would you choose? Radio and Wi-Fi signals Heat Air pollution Electricity flowing Stress and cracks inside materials Last Week's Poll Would you choose a guaranteed $50,000 or a 50% chance at $1 million? Guaranteed $50,000 48% 50% chance at $1 million 52% I actually did the maths on this, and if your goal is to maximise expected value in pounds, there’s a clear answer: take the 50% chance of £1 million. Half the time the coin flip pays £1 million and half the time it pays nothing, so its expected value is £500,000, ten times the certain amount. Put another way, you’re risking £50,000 for a shot at an extra £950,000, so the gamble’s expected value is £450,000 higher than the certain cash. But that only settles the question if expected pounds are what you care about. If you would rather guarantee that you leave with something, or if £50,000 would prevent an eviction or clear debt that is wrecking your life, taking the cash can be rational because you are maximising your own wellbeing, not an abstract average. There’s a version of this that shows how wobbly our instincts are: imagine the £50,000 has already landed in your account, and you’re asked whether you’d hand it back for a 50% shot at £1 million. Mathematically, it’s the same decision: same odds, same numbers. But plenty of people who would choose the coin flip when £50,000 is only an offer will not hand back £50,000 once it is theirs, even though the maths has not changed. That is loss aversion: giving something up feels worse than never having had it, even when the two versions have exactly the same possible outcomes. Tech [Collage of eight purple-and-orange radio-wave scans revealing pipes, cables, fans, tools, and household appliances.](https://newsletter.dvy.io/visit/HeXtaxRU) [A startup says its radio-wave camera can map what’s hidden inside walls](https://newsletter.dvy.io/visit/HeXtaxRU) [Applied Electrodynamics says its WaveSight prototype uses radio waves to map pipes, cables, and structural elements behind plasterboard, tile, marble, brick, and insulation, with accuracy down to 1 mm. It turns the scan into a correctly scaled 3D point cloud (a map built from measured points), without cutting into or touching the wall. The company says hidden surprises cause more than $20 billion of construction rework each year in the US. The company sees the same technology being used to inspect composite parts and screen bags or deliveries without sending them through a fixed checkpoint. The team has built the imaging hardware and algorithms; a handheld version combining radio-wave, colour, and thermal imaging is the next step. The company says its four founders have worked together for more than eight years and hold over 250 patents between them. Bilgehan Avser led antenna technology on four iPhone generations, including the first phones with ultra-wideband (UWB) and millimetre-wave 5G. Brian Huppi built early iPhone prototypes and co-invented multitouch and the Nest Learning Thermostat. George McLean is an MIT physicist who has built X-ray imagers and retinal implants. Paul Leutheuser led product design at Apple and Humane. Ordinary cameras capture only the narrow slice of the electromagnetic spectrum our eyes can see. Other wavelengths carry information about internal structure, temperature, and material composition. WaveSight is their first attempt to turn one more part of that spectrum into an image people can read, and they are looking for general contractors, industrial inspection teams, and US defence organisations to test it.](https://newsletter.dvy.io/visit/HeXtaxRU) [A white electric vertical take-off and landing aircraft hovers above an airfield as a crowd watches.](https://newsletter.dvy.io/visit/UBgKUssy) [A flying car just landed vertically at an airshow](https://newsletter.dvy.io/visit/UBgKUssy) Vertical Aerospace says its full-scale electric vertical take-off and landing (eVTOL) prototype completed the first public eVTOL transition flight at the Farnborough Airshow this week. It took off vertically, moved into forward flight on its wings, then landed vertically again without a runway. The Bristol firm also says it is in advanced talks with the UK government for up to £10 million to establish its first full-scale production facilities. A separate £3.4 million government-backed programme will develop faster charging for electric aircraft. The company is still targeting full certification in 2029. [A human profile transitions into glowing neural pathways, dots, nodes, and data bars, symbolizing hidden AI reasoning.](https://newsletter.dvy.io/visit/RRdYXF2Z) [Even if you turn "thinking" off, an AI model can still think if you give a list of dots in your prompt](https://newsletter.dvy.io/visit/RRdYXF2Z) DeepSeek V3 and Kimi K2 can solve some multi-step problems when their only workspace is a string of meaningless dots, leaving no readable trail of “thinking” in the output. Researchers presenting at ICML’s Mechanistic Interpretability Workshop found that the working had moved into the models’ internal activations. An unsupervised decoding pipeline recovered intermediate values, including retrieved facts and partial sums, with 80–95% accuracy across fact retrieval, arithmetic, and string-manipulation tasks. [Amazon listing for a $37.99 H96MAX 4K streaming stick with remote, rated 2.3 stars from 51 reviews.](https://newsletter.dvy.io/visit/HxntKe3v) [Some cheap Android TV boxes secretly rent out internet connections and generate fake ad clicks](https://newsletter.dvy.io/visit/HxntKe3v) That impressively inexpensive streaming stick you plugged into the TV isn't just renting out your internet connection to strangers, according to security firm Bitsight: when the TV's off, it switches to pretending to be a Samsung or Xiaomi phone and starts clicking ads on AI-generated websites. It's part of a China-based fraud network that pulls in roughly $50,000 a day from around 38,000 devices. [An interior shot of a minimalist space featuring raw concrete walls, a block platform, and stairs leading to another room.](https://newsletter.dvy.io/visit/Yo3pW4bf) [Minimalist store interior with a marbled cylindrical table, sculptural white chairs, and gray pleated curtains.](https://newsletter.dvy.io/visit/Yo3pW4bf) [Interior of the Jil Sander flagship store in Tokyo with textured concrete walls, curved columns, and a slatted white ceiling.](https://newsletter.dvy.io/visit/Yo3pW4bf) [A transparent construction enclosure stands in front of a modern glass building, with a person and white display visible inside.](https://newsletter.dvy.io/visit/Yo3pW4bf) [Jil Sander flagship store in Tokyo, with a textured gray facade, illuminated display windows, and the brand name above the entrance.](https://newsletter.dvy.io/visit/Yo3pW4bf) [Jil Sander Flagship Store](https://newsletter.dvy.io/visit/Yo3pW4bf) [Tokyo, Japan](https://newsletter.dvy.io/visit/Yo3pW4bf) Science [A person dressed as Batman stands on a crowded train next to a pregnant woman.](https://newsletter.dvy.io/visit/P2G2YgHi) [Passengers were more likely to offer a pregnant woman their seat when Batman was nearby](https://newsletter.dvy.io/visit/P2G2YgHi) Researchers in Milan wanted to know if a jolt of the unexpected could make strangers kinder to each other, so they tested it on the metro. Across 138 train rides with every seat taken, an experimenter wearing a fake pregnancy belly boarded and researchers watched to see who offered her a seat. Sometimes she boarded alone with a silent observer (the control); other times, a second experimenter dressed as Batman (cape, cowl, logo, though no full mask, so as not to startle anyone) walked in through a different door about three metres away, with zero interaction between the two of them. Without Batman, 37.66% of passengers gave up their seat. With him standing nearby, that jumped to 67.21%, and the researchers' model put the odds of helping at over three times higher when he was there (p < 0.001, so unlikely to be chance). In follow-up interviews, 44% of the people who gave up their seat in the Batman condition said they had not seen him, and nobody directly linked their gesture to his presence. That makes a simple “superhero is watching” explanation less likely, but it does not rule one out. The researchers’ main hypothesis is that commuting runs on autopilot (you tune out, stare at your phone, and barely register the people around you), and something unexpected briefly breaks that routine. The resulting attention may spill over into noticing a pregnant woman standing nearby, even among people who never consciously registered Batman. They also acknowledge that the superhero may have acted as a cue to behave helpfully, so the mechanism is not settled. It was one field study in one city, so the result may not generalise. If it does, breaking commuters out of autopilot may be enough to make them notice someone who needs help, without any lecture on kindness. [A hostile person in a social network sends stress toward a DNA hourglass, symbolizing faster biological aging.](https://newsletter.dvy.io/visit/s7FZkfep) [Nearly 30% of people have a "hassler" in their close network, and each one ages you faster](https://newsletter.dvy.io/visit/s7FZkfep) In a representative sample of 2,345 Indiana adults, nearly 29% reported at least one “hassler” in their close network, meaning someone who often caused problems or made life harder. Each additional hassler was associated with about 1.5% faster biological ageing and roughly nine months of extra biological age, measured with DNA-methylation clocks (estimates based on chemical marks on DNA). The researchers measured relationships and biological age at the same point in time, so the study cannot show that difficult relationships caused the difference. Hasslers among relatives and other close contacts were linked to faster ageing, while spouses were not. [A white adhesive strip supports several stacked metal weights, suspended from a hook during a strength test.](https://newsletter.dvy.io/visit/GjW7rsWd) [A new adhesive can lift 8 kg by sticking to Teflon, then peel off with a wipe of hand sanitiser](https://newsletter.dvy.io/visit/GjW7rsWd) Teflon pans are famously the surface nothing sticks to, yet a new glue from Takuzo Aida's team at the University of Tokyo bonds to it so well that a patch just 7 cm² wide (smaller than a stamp) held up an 8 kg weight. A wipe of ethanol, the stuff in hand sanitiser, peels it straight back off with no residue, and the glue itself can be reused at full strength (though outside scientists note it's likely a PFAS "forever chemical" and its environmental impact still needs checking). Before this issue, how did you picture a plucked guitar string moving? As a smooth wave Like a skipping rope As sharp corners travelling along it I'd never thought about it Data [Stacked area chart of arms exports, 1954–2025: Russia’s share falls to 7% while the U.S. reaches 42%.](https://newsletter.dvy.io/visit/UGPDzmEh) [Global arms exports for the USSR/Russia and the United States from 1954 to 2025](https://newsletter.dvy.io/visit/UGPDzmEh) [Russia's share of global arms exports has slid from 42% in the Cold War years to just 7% now, according to SIPRI's trade data, with India left as its main customer mainly filling orders placed years ago. The war in Ukraine seems to have wrecked Russia's reputation for air defence and forced it to ditch next-generation tanks and jets for cheaper, older designs, possibly costing it that whole future market for good.](https://newsletter.dvy.io/visit/UGPDzmEh) History [Medieval illustration of a crowned King Arthur holding a sword, flanked by two robed figures.](https://newsletter.dvy.io/visit/3PxEJcjR) [The Case for King Arthur](https://newsletter.dvy.io/visit/3PxEJcjR) [A chronicle compiled at the Welsh monastery of St David’s in the late 700s records that “Arthur and Medraut fell” at the Battle of Camlann in 537, alongside a plague outbreak that matches the timing of the Justinianic Plague. That is one reason historian Ken Dark argues that a historical Arthur cannot be ruled out. He also points to a cluster of well-documented sixth- and seventh-century kings named Arthur, born within about a century of each other around the Irish Sea. Dark says they may have been named after an earlier, genuinely famous Arthur, though he notes other explanations are possible.](https://newsletter.dvy.io/visit/3PxEJcjR) [Two women operate Colossus, a large wartime electronic computer covered in switches, wiring, and control panels.](https://newsletter.dvy.io/visit/ceyn34Y2) [Colossus: the secret code-breaking machine Britain hid for decades](https://newsletter.dvy.io/visit/ceyn34Y2) Colossus was built in Britain in 1944 to crack Nazi Germany’s encrypted teleprinter traffic (messages sent between typewriter-like machines). It is recognised as the world’s first large-scale programmable electronic digital computer, and the Institute of Electrical and Electronics Engineers (IEEE) has now recognised it as an IEEE Milestone. Where the earlier Bombe machines helped break Enigma, Colossus tackled the more advanced Lorenz cipher, giving Allied commanders access to high-level German messages in the run-up to D-Day. Britain maintained strict secrecy after the war and ordered the machines broken up; only two were initially spared, and those were dismantled in the 1960s. Random [A taut string stretches across a blue background, with “Minute Physics” written above where the strings cross.](https://newsletter.dvy.io/visit/skRJdqoS) [Strings Don't Vibrate The Way You Think](https://newsletter.dvy.io/visit/skRJdqoS) [Pluck a guitar string in the middle and it doesn’t wobble like a skipping rope. It folds into a triangle, flattens, and splits into two sharp corners that bounce back and forth off each end. The wavy shape you see in phone videos is a rolling-shutter artefact caused by the camera scanning the frame line by line, not the string itself.](https://newsletter.dvy.io/visit/skRJdqoS) [Title card reading “The Phone in Your Hand,” with subtitle “A layer-by-layer teardown...” and labels Screen, Senses, Head, Body.](https://newsletter.dvy.io/visit/evRGvvkw) [A layer-by-layer teardown of the phone in your hand](https://newsletter.dvy.io/visit/evRGvvkw) Your phone’s screen wipes clean more easily because it is coated in a layer of fluoropolymer one molecule thick, and every swipe of your thumb wears a tiny bit of it away. Meanwhile the glass beneath owes its toughness to Steve Jobs finding his keys had scratched an early prototype, prompting a last-minute switch to chemically strengthened glass seven times stronger than ordinary glass. The interactive teardown reveals how the phone is built, layer by layer. [A nuclear power plant stands beyond a shallow, muddy river with exposed sandbars and cooling-water spray.](https://newsletter.dvy.io/visit/4aaDcFvk) [Drought along the Danube exposes shipwrecks and mammoth bones, and disrupts nuclear power in Hungary and Romania](https://newsletter.dvy.io/visit/4aaDcFvk) Hungary’s Paks nuclear plant is preparing to shut down completely for the first time in its 44-year history because the Danube has fallen below the reach of its cooling-water intakes. Prime Minister Péter Magyar warned that the country’s power supply could turn “critical” as the shutdown coincides with a week-long heatwave near 37 °C. He is asking people to cut electric-vehicle charging and air-conditioning use during the 5 pm to 10 pm peak. [A man holds a large slate displaying the fossilized skeleton of an ancient marine reptile beside a coastal cliff.](https://newsletter.dvy.io/visit/BBYwArMR) [The Welsh beach where families stumble on 200-million-year-old sea dragon bones](https://newsletter.dvy.io/visit/BBYwArMR) After being buried under more than a metre of snow on Yr Wyddfa (Snowdon) for 20 minutes in 2014, Matthew Myerscough swapped mountaineering for searching beaches, where the slow, focused hunt for fossils helped his stress “melt away”. That search paid off at Lavernock Point: he and two other fossil hunters spotted a 201-million-year-old jawbone in the limestone, later identified as belonging to a rhomaleosaur, an early plesiosaur never before found in Wales. [“I used to think the brain was the most wonderful organ in my body. Then I realized who was telling me this.”](https://newsletter.dvy.io/visit/aWvuXwMv) [Emo Philips](https://newsletter.dvy.io/visit/aWvuXwMv) [Web](https://newsletter.dvy.io/visit/gt8H5gMZ) · [Twitter](https://newsletter.dvy.io/visit/zmqkBsWi) · [LinkedIn](https://newsletter.dvy.io/visit/ARNqwD4G)