Math Puzzle: How Many Handshakes?
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Scientific American
12-07-2025
- Scientific American
Math Puzzle: How Many Handshakes?
Leila and Sahar are attending a dinner party with four other couples. Each attendee knows their partner, but they may or may not know anyone else there. Before the five couples sit down to eat, anyone who doesn't know each other shakes hands. After everyone sits, Leila makes an observation to the table: 'I just noticed that no two of you shook hands the same number of times.' How many hands did Leila and Sahar each shake? (Martin Gardner previously included a variation of this puzzle, attributed to mathematician Lars Bertil Owe, in his Mathematical Games column in the May 1973 issue of Scientific American.)
Scientific American
11-07-2025
- Scientific American
Your Garbage Has a 'Wild Afterlife' on the International Black Market
Sorting your trash and recycling is common practice: break down the cardboard boxes, separate the compostable material and plastics and put them into the correct containers, put the trash on the curb, and you're done. But what happens next is where the story gets interesting. A billion-dollar industry exists around moving countless tons of waste from wealthy countries to poorer ones. For two years journalist Alexander Clapp lived out of a backpack and visited the smelliest parts of the most beautiful places on Earth—looking for hidden dump sites in the Venezuelan jungle and scaling mountains of trash in Ghana—for his new book Waste Wars: The Wild Afterlife of Your Trash. He tracks the massive scope of waste management, from top-level international relations to underground whisper networks, and reveals the dirty underbelly of what happens to our trash. Scientific American spoke with Clapp about the people who break apart and sort our trash all over the world, the growth of the global waste economy and the future of waste management. [ An edited transcript of the interview follows.] On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. Can you tell me where our exported garbage and not-quite-recyclable goods end up? It would depend what type of trash we're talking about, when we're talking about it or from which country it's being discarded. But a lot of global trash over the last 30 to 40 years has been going to poor countries under the guise that it's being recycled. That trash will get broken down, or someone will attempt to make some use out of it—to extract some profit from it—and that's an extremely dangerous and often lethal process where all sorts of contaminants and forever chemicals enter local ecosystems. They go into the air, they go into the water, and they do huge amounts of damage—damage to, disproportionately, the most vulnerable populations in the world. Why would one country ever, under any circumstances, buy the garbage from another country? Is someone getting scammed, or is there a legitimate reason to buy boatloads of biological, technological or toxic waste? That is one of the reasons why I got interested in this topic. We send our waste to the very countries that cannot handle their own domestic waste outputs. I think the dichotomy that's worth keeping in mind with the waste trade is that it's not necessarily rich countries versus poor countries; within poor countries, you have importers who are actually buying the waste for pennies, and they are very much part of the problem. The most important thing to understand about the waste trade is that in the 1980s many poor countries felt that they had no option other than to import waste from the so-called global north. They were heavily indebted; they were desperate for factories, ports, industry of any kind. And so I think there's a really insipid, disturbing history of how and why the waste trade began. Which leads to the question—how much money is actually involved in this global waste economy? Let's say it costs $140 to put a ton of old plastic in a landfill. A waste broker would actually have to pay the landfill in order to bury that plastic. But what if instead you could sell that plastic to an importer in Malaysia for a few dollars? Then you're not paying $140; you're actually making $2 or $3. That said, a lot of the waste trade, by nature, is operating underground. If you're sending waste to another country, you're not calling it trash on any export document—you're calling it recyclable material. One thing that I hope my book encourages or leads people to question is how much of our waste is actually moving around the world. What are you most interested in regarding the future of this waste economy and of waste management on a global scale? I think what's really interesting about the global waste trade is that in many ways it's like the global drug trade. You see organized crime groups that are getting more and more involved in the waste trade because, frankly, the supply of this stuff is endless. The punishment if you get caught moving waste is negligible. I think the future of waste export and waste movement is organized crime. I think they're going to see this as a monumentally lucrative opportunity. What was the most shocking story you uncovered while researching for this book? The most shocking story probably was with the cruise ship-dismantling industry in Türkiye. On the Aegean coast of Türkiye, there's a [town] called Aliağa where American cruise ship companies disproportionately send a lot of their ships to be dismantled. And you would think that the process of deconstructing a cruise ship would be mechanically refined, but it's actually kind of this maniacal process done almost entirely by hand where you have armies of helmeted men filing into these cruise ships and breaking this stuff up. One thing that I found was that most of the men who get recruited into doing this work have little idea of what they're doing. They've never seen the ocean before. They were recruited from the middle of Türkiye and given a week's worth of training. It's absolutely excruciating. What was the most surprisingly common occurrence across all of your research? In terms of the most common story that I would hear, it's the extent to which in poor countries trash, and especially plastic, is just regarded as another commodity. Generally [the people I encountered didn't] think about this stuff as a potentially toxic substance. That was shocking to me. In places such as Java and [other parts of] Indonesia, hundreds of tons of Western plastic are imported every week and used as fuel in tofu factories, and then that tofu gets exported around the world's most populous island [Java]. I was just struck by how kind of pedestrian it seems to just burn plastic in places to get rid of it or to find some use for it.
Newsweek
07-07-2025
- Newsweek
Labrador Gets Soft Crate, Owners Instantly Regret Their 'Good Idea'
Based on facts, either observed and verified firsthand by the reporter, or reported and verified from knowledgeable sources. Newsweek AI is in beta. Translations may contain inaccuracies—please refer to the original content. The owners of a Labrador retriever named Leila thought it was a good idea to buy their pup a soft crate, but immediately changed their mind once she stepped foot into it. In a viral Instagram video shared in April under the username @sugarrushtails, the posters recall "that time we thought a soft crate for a Lab [Labrador retriever] puppy was a good idea..." as their pup Leila is seen rolling on the floor with her crate non-stop. "This will never be old," the caption says. The American Kennel Club (AKC) explains that crate training can make life a lot easier for both dogs and their owners, and should be carried out as soon as you get your pup home. Crates help dogs deal with stress during emergencies. They are a great self-soothing tool for dogs who deal with anxiety, or for pups who become distressed during events like thunderstorms, constructions or fireworks. They are also just a great place to escape when life gets too chaotic or scary, and they can be a comforting place to sleep when your pup is confronted with a challenging situation like the arrival of a baby or a new pet. There are different kinds of dog crates available and which one you should buy depends on your dog's physical characteristics as well as their personality. Plastic crates are cheap, lightweight and easy to carry around, but they are also low on airflow and that can cause a dog to overheat in hot weather. Metal ones have high airflow, and allow your pup to see around them, making them feel more comfortable, but they can also rust, or damage your pup's teeth if they have the bad habit of chewing things off. Soft-sided crates like the one in the clip are lightweight and easy to travel with, but they are not durable, and are very easy to escape. A stock image shows a chocolate Labrador retriever puppy inside a crate. A stock image shows a chocolate Labrador retriever puppy inside a crate. getty images The video quickly went viral on social media and it has so far received over 13 million views and 559,529 likes. One user, Iambrandilokey, commented: "I actually used to put my husky in one of these when she wanted to go outside and I was doing stuff she's a runner so when she's out she has to be on a leash and I put her in that she can't run she just rolls around the yard." Jennyu_repay said: "Ma'am that's a college student's laundry basket." Livingluxewithlauren added: "Gentle parenting is for gentle children." Newsweek reached out to @sugarrushtails for comment via Instagram chat. We could not verify the details of the case. Do you have funny and adorable videos or pictures of your pet you want to share? Send them to life@ with some details about your best friend and they could appear in our Pet of the Week lineup.
