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In certain dialects of Chinese, Japanese, Korean, and Vietnamese, the word for ‘four’ sounds very similar to the word for ‘death’1. Consequently, the number 4 is considered by many people in East Asian nations to be unlucky. It is not unusual for buildings in that region to skip the number 4 when labeling floors, much in the same way 13th floors are omitted in some parts of the world2. In Hong Kong, at least one skyscraper avoids the proper numbering for floors 40-49. Four is the smallest positive non-prime number3. It is the only natural number where one can get the same result by multiplying its square roots (2×2), or adding them (2+2). Four happens to be the only number that has the same number of letters as its actual value4. The four color theorem tells us that four is an adequate number of colors for any two dimensional map–no two bordering regions would need to share a color. Four is the number of bonds that a carbon atom can make, which is why life can exist, a quality known as tetravalency. Fear of the number four is known as tetraphobia, and anyone suffering from it has almost certainly stopped reading by now, or at least uttered some four-letter words. It’s no secret that direct donations to Damn Interesting have been on a downward trend in recent years, so we are aiming to diversify. To that end, we’ve made something new, and it’s called Omiword. Continue reading ▶
Iceland is known to the rest of the world as the land of Vikings and volcanos, an island caught between continents at the extremities of the map. Remote and comparatively inhospitable, it was settled only as long ago as the 9th century, and has seen little additional in-migration since. Even today, more than 90 percent of Iceland’s 390,000 residents can trace their ancestry back to the earliest permanent inhabitants, a Nordic-Celtic mix. The tradition of the Norse sagas lives on in the form of careful record-keeping about ancestry—and a national passion for genealogy. In other words, it is not the place to stumble upon old family mysteries. But growing up in the capital city of Reykjavík in the 1950s, neurologist Dr. Kári Stefánsson heard stories that left him curious. Stefánsson’s father had come from Djúpivogur, an eastern coastal town where everyone still spoke of a Black man who had moved there early in the 19th century. “Hans Jónatan”, they called him—a well-liked shopkeeper who had arrived on a ship, married a spirited woman from a local farm, and became a revered member of the community. The local census did record a man by the name of Hans Jónatan, born in the Caribbean, who was working at the general store in Djúpivogur in the 19th century—but that was all. No images of the man had survived, and his time in Iceland was well before any other humans with African ancestry are known to have visited the island. If tiny, remote Djúpivogur did have a Black man arrive in the 19th century, the circumstances must have been unusual indeed. It was an intriguing puzzle—and solid grounds for a scientific investigation. Given the amount of homogeneity in the baseline Icelandic population, the genetic signature of one relative newcomer with distinct ancestry might still stand out across a large sample of his descendants. Geneticists thus joined locals and history scholars, and they pieced together a story that bridged three continents. Continue reading ▶
It’s been a busy summer, and the large shortfall in donations last month has been demoralizing, so we’re taking a week off to rest and recuperate. The curated links section will be (mostly) silent, and behind the scenes we’ll be taking a brief break from our usual researching, writing, editing, illustrating, narrating, sound designing, coding, et cetera. We plan to return to normalcy on the 11th of September. (The word “normalcy” was not considered an acceptable alternative to “normality” until 14 May 1920, when then-presidential-candidate Warren G. Harding misused the mathematical term in a campaign speech, stating that America needed, “not nostrums, but normalcy.” He then integrated this error into his campaign slogan, “Return to Normalcy.” Also, the G in Warren G. Harding stood for “Gamaliel.”) While we are away, on 06 September 2023, Damn Interesting will be turning 18 years old. To celebrate, here are the first emojis to ever appear in the body of a Damn Interesting post: 🎂🎉🎁 If you become bored while we are away, you might try a little mobile game we’ve been working on called Wordwhile. It can be played alone, or with a friend. If you enjoy games like Scrabble and Wordle, you may find this one ENJOYABLE (75 points). Launch Wordwhile → And, as always, there are lots of ways to explore our back-catalog. View this post ▶
We’re not going to post things on Twitter X anymore. The new owner keeps doing awful stuff. If you have enjoyed our mostly-daily curated links via the aforementioned collapsing service, we invite you to bookmark our curated links page, or follow us a number of other ways. Rather than linger any longer on this tedious topic, here are some home-grown dad jokes. If there is any order in this universe, the comments section will fill with more of the same. Q: What is the flavor of a chair? Do you even know the meaning of the word ‘rhetorical?’ Don’t answer that! My friend bought an alarm clock that makes loud farting sounds in the morning. He’s in for a rude awakening. You’re right, these ARE my orthopedic shoes. I stand corrected. I want a good game of hide and seek, but skilled players are hard to find. Like tight sweaters, corporate acquisitions are hard to pull off. I was offered a job at the mirror factory. I could see myself working there. Did you hear about the farmer in Colorado raising cannabis-fed cattle? The steaks are high. Q: What is the best stocking stuffer? I used to be addicted to soap, but I’ve gotten clean. I finally worked up the courage to tell my hot female coworker how I felt. She felt the same. So we turned down the thermostat. The universal remote: This changes everything. Q: How fast are donkey trucks? It smells like death in there, and not in a good way. My dad demanded that I go fetch some water from that deep hole in the ground. He means well. Calendar makers: Your days are numbered. A: I enjoy cooking with ghee, but I don’t buy it, I make my own. I will not rest until I find a cure for my insomnia. I bought my wife a new refrigerator. I can’t wait to see her face light up when she opens it. Did you hear about the hilarious thing that happened at the mandatory meeting? I guess you had to be there. Remember that sweet grandmother on Twitter who thought that ‘lol’ meant ‘lots of love’? “Sorry to hear about your uncle passing. lol.” Yesterday, we were standing at the edge of a cliff. Since then we have taken a huge step forward. We had to cancel the big game of tag because somebody got hurt. It was touch and go there for a while. “Of course you can count on me,” said the abacus. IBS is genetic, you know. Runs in the family. My grandfather once told me, “It’s worth investing in good speakers.” That was some sound advice. Extreme camping is in tents. The solar panel company wouldn’t let me pay for the installation. They said it was all on the house. I was chopping herbs all day, and now my hands are quite fragrant. I’ve got too much thyme on my hands. A weather balloon measures about 4 feet in diameter (adjusting for inflation). A: Have you ever had a flatulence-based tea? Like a German dietitian, I tend to see the wurst in people. I don’t care for rulers. That’s where I draw the line. Why did the farmer propose to his horse? He wanted a stable relationship. I still think whiteboards are one of mankind’s most remarkable inventions. The Earth has successfully rotated around its axis. Let’s call it a day. My daughter dropped a brand new tube of toothpaste and it made a big mess. She was crestfallen. You’ve got to hand it to customs agents: Your passport. My friend tried to steal a box of lipstick for us, but she accidentally grabbed a box of glue sticks. My lips are sealed. Elevators: They take things to a whole other level. A friend gave me an expired pack of batteries. They were free of charge. Comedy: To taste a bit like a comet. A: How many times do I have to apologize? My wife said that the battery in my hearing aid needed to be replaced. That was difficult to hear. I asked the ski lift operator if I could get a free ride to the top of the mountain. He didn’t take me up on it. What makes a sentence a tongue twister? It’s hard to say. If you visit Mexico, remember to use the word “mucho.” It means a lot to them. There are more hydrogen atoms in a single molecule of water than there are stars in the solar system. To whoever discovered the number zero: Thanks for nothing. View this post ▶
More in science
On 29 August 1949, the Soviet Union successfully tested its first nuclear weapon. Over the next year and a half, U.S. President Harry S. Truman resurrected the Office of Civilian Defense (which had been abolished at the end of World War II) and signed into law the Federal Civil Defense Act of 1950, which mobilized government agencies to plan for the aftermath of a global nuclear war. With the Cold War underway, that act kicked off a decades-long effort to ensure that at least some Americans survived nuclear armageddon. As the largest civilian federal agency with a presence throughout the country, the U.S. Post Office Department was in a unique position to monitor local radiation levels and shelter residents. By the end of 1964, approximately 1,500 postal buildings had been designated as fallout shelters, providing space and emergency supplies for 1.3 million people. Occupants were expected to remain in the shelters until the radioactivity outside was deemed safe. By 1968, about 6,000 postal employees had been trained to use radiological equipment, such as the CD V-700 pictured at top, to monitor beta and gamma radiation. And a group of postal employees organized a volunteer ham radio network to help with communications should the regular networks go down. What was civil defense in the Cold War? The basic premise of civil defense was that many people would die immediately in cities directly targeted by nuclear attacks. (Check out Alex Wellerstein’s interactive Nukemap for an estimate of casualties and impact should your hometown—or any location of your choosing—be hit.) It was the residents of other cities, suburbs, and rural communities outside the blast area that would most benefit from civil defense preparations. With enough warning, they could shelter in a shielded site and wait for the worst of the fallout to decay. Anywhere from a day or two to a few weeks after the attack, they could emerge and aid any survivors in the harder-hit areas. In 1957, a committee of the Office of Defense Mobilization drafted the report Deterrence and Survival in the Nuclear Age, for President Dwight D. Eisenhower. Better known as the Gaither Report, it called for the creation of a nationwide network of fallout shelters to protect civilians. Government publications such as The Family Fallout Shelter encouraged Americans who had the space, the resources, and the will to construct shelters for their homes. City dwellers in apartment buildings warranted only half a page in the booklet, with the suggestion to head to the basement and cooperate with other residents. This model fallout shelter from 1960 was designed for four to six people. Bettmann/Getty Images Ultimately, very few homeowners actually built a fallout shelter. But Rod Serling, creator of the television series “The Twilight Zone,” saw an opportunity for pointed social commentary. Aired in the fall of 1961, the episode “The Shelter” showed how quickly civilization (epitomized by a suburban middle-class family and their friends) broke down over decisions about who would be saved and who would not. Meanwhile, President John F. Kennedy had started to shift the national strategy from individual shelters to community shelters. At his instruction, the U.S. Army Corps of Engineers began surveying existing buildings suitable for public shelters. Post offices, especially ones with basements capable of housing at least 50 people, were a natural fit. Each postmaster general was designated as the local shelter manager and granted complete authority to operate the shelter, including determining who would be admitted or excluded. The Handbook for Fallout Shelter Management gave guidance for everything from sleeping arrangements to sanitation standards. Shelters were stocked with food and water, medicine, and, of course, radiological survey instruments. What to do in case of a nuclear attack These community fallout shelters were issued a standard kit for radiation detection. The kit came in a cardboard box that contained two radiation monitors, the CD V-700 (a Geiger counter, pictured at top) and the CD V-715 (a simple ion chamber survey meter); two cigar-size CD V-742 dosimeters, to measure a person’s total exposure while wearing the device; and a charger for the dosimeters. Also included was the Handbook for Radiological Monitors, which provided instructions on how to use the equipment and report the results. Post office fallout shelters were issued standard kits for measuring radioactivity after a nuclear attack.National Postal Museum/Smithsonian Institution The shelter radiation kit included two radiation monitors, two cigar-size dosimeters, and a charger for the dosimeters. Photoquest/Getty Images In the event of an attack, the operator would take readings with the CD V-715 at selected locations in the shelter. Then, within three minutes of finishing the indoor measurements, he would go outside and take a reading at least 25 feet (7.6 meters) from the building. If the radiation level outside was high, there were procedures for decontamination upon returning to the shelter. The “protection factor” of the shelter was calculated by dividing the outside reading by the inside reading. (Today the Federal Emergency Management Agency, FEMA, recommends a PF of at least 40 for a fallout shelter.) Operators were directed to retake the measurements and recalculate the protective factor at least once every 24 hours, or more frequently if the radiation levels changed rapidly. The CD V-700 was intended for detecting beta and gamma radiation during cleanup and decontamination operations, and also for detecting any radioactive contamination of food, water, and personnel. RELATED: DIY Gamma-Ray Spectroscopy With a Raspberry Pi Pico Each station would report their dose rates to a regional control center, so that the civil defense organization could determine when people could leave their shelter, where they could go, what routes to take, and what facilities needed decontamination. But if you’ve lived through a natural or manmade disaster, you’ll know that in the immediate aftermath, communications don’t always work so well. Indeed, the Handbook for Radiological Monitors acknowledged that a nuclear attack might disrupt communications. Luckily, the U.S. Post Office Department had a backup plan. In May 1958, Postmaster General Arthur E. Summerfield made an appeal to all postal employees who happened to be licensed amateur radio operators, to form an informal network that would provide emergency communications in the event of the collapse of telephone and telegraph networks and commercial broadcasting. The result was Post Office Net (PON), a voluntary group of ham radio operators; by 1962, about 1,500 postal employees in 43 states had signed on. That year, PON was opened up to nonemployees who had the necessary license. RELATED: The Uncertain Future of Ham Radio Although PON was never activated due to a nuclear threat, it did transmit messages during other emergencies. For example, in January 1967, after an epic blizzard blanketed Illinois and Michigan with heavy snow, the Michigan PON went into action, setting up liaisons with county weather services and relaying emergency requests, such as rescuing people stranded in vehicles on Interstate 94. A 1954 civil defense fair featured a display of amateur radios. The U.S. Post Office recruited about 1,500 employees to operate a ham radio network in the event that regular communications went down. National Archives The post office retired the network on 30 June 1974 as part of its shift away from civil defense preparedness. (A volunteer civil emergency-response ham radio network still exists, under the auspices of the American Radio Relay League.) And by 1977, laboratory tests indicated that most of the food and medicine stockpiled in post office basements was no longer fit for human consumption. In 1972 the Office of Civil Defense was replaced by the Defense Civil Preparedness Agency, which was eventually folded into FEMA. And with the end of the Cold War, the civil defense program officially ended in 1994, fortunately without ever being needed for a nuclear attack. Do we still need civil defense? The idea for this column came to me last fall, when I was doing research at the Linda Hall Library, in Kansas City, Mo., and I kept coming across articles about civil defense in magazines and journals from the 1950s and ’60s. I knew that the Smithsonian’s National Postal Museum, in Washington, D.C., had several civil defense artifacts (including the CD V-700 and a great “In Time of Emergency” public service announcement record album). As a child of the late Cold War, I remember being worried by the prospect of nuclear war. But then the Cold War ended, and so did my fears. I envisioned this month’s column capturing the intriguing history of civil defense and the earnest preparations of the era. That chapter of history, I assumed, was closed. Little did I imagine that by the time I began to write this, the prospect of a nuclear attack, if not an all-out war, would suddenly become much more real. These days, I understand the complexities and nuances of nuclear weapons much better than when I was a child. But I’m just as concerned that a nuclear conflict is imminent. Here’s hoping that history repeats itself, and it does not come to that. Part of a continuing series looking at historical artifacts that embrace the boundless potential of technology. An abridged version of this article appears in the August 2025 print issue. References The November 1951 issue of Electrical Engineering summarized a civil defense conference held at the General Electric Co.’s Electronics Park in Syracuse, N.Y., earlier that year. Two hundred eighty federal, state, county, and city officials from across the United States and Canada attended, which got me thinking about the topic. Many of the government’s civil defense handbooks are available through the Internet Archive. The U.S. Postal Bulletins have also been digitized, and the USPS historian’s office wrote a great account, “The Postal Service’s Role in Civil Defense During the Cold War.” Although I’ve highlighted artifacts from the National Postal Museum, the Smithsonian Institution has many other objects across multiple museums. Eric Green has been collecting civil defense material since 1978 and has made much of it available through his virtual Civil Defense Museum. Alex Wellerstein, a historian of nuclear technology at the Stevens Institute of Technology, writes the Substack newsletter Doomsday Machines, where he gives thoughtful commentary on how we think about the end of times, in both fiction and reality. His interactive Nukemap is informative and scary.
After finding the homeschooling life confining, the teen petitioned her way into a graduate class at Berkeley, where she ended up disproving a 40-year-old conjecture. The post At 17, Hannah Cairo Solved a Major Math Mystery first appeared on Quanta Magazine
The Titanic lies about 12,500 feet under the ocean. The pressure down there is so immense that even submersibles supposedly built for those conditions can, as we know, tragically fail. Now imagine taking a sub nearly three times deeper. Read more on E360 →
The next section of Chapter 3 of Stewart Brand’s Maintenance on Books in Progress
The Japan Atomic Energy Agency reported earlier this year that is has developed and tested a battery with depleted uranium as the active material of the negative electrode. Why would they do this, and what role could such a battery play? First let’s look at the details (which are sparse). The battery uses depleted uranium […] The post Depleted Uranium Batteries first appeared on NeuroLogica Blog.
