'Tis the season for many holiday traditions, including the Ugly Christmas Sweater—you know, those 1950s-style heavy knits featuring some kind of cartoonish seasonal decoration, like snowflakes, Santa Claus, or—in the case of Mark Darcy from Bridget Jones' Diary (2001)—Rudolph the Red-Nosed Reindeer. "It’s obnoxious and tacky, but also fuzzy and kind of wholesome—the fashion equivalent of a Hallmark Christmas movie (with a healthy dose of tongue-in-cheek)," as CNN's Marianna Cerini recently observed.

Fashion (or lack thereof) aside, sweaters and other knitted fabric are also fascinating to physicists and mathematicians. Case in point: a recent paper published in the journal Physical Review Letters examining the complex mechanics behind the many resting shapes a good Jersey knit can form while at rest.

Knitted fabrics are part of a class of intertwined materials—which also includes birds' nests, surgical knots, knotted shoelaces, and even the degradation of paper fibers in ancient manuscripts. Knitted fabrics are technically a type of metamaterial: an engineered material that gets its properties not from the base materials but from their designed structures. The elasticity (aka, stretchiness) of knitted fabrics is an emergent property: the whole is more than the sum of its parts. How those components (strands of yarn) are arranged at an intermediate scale (the structure) determines the macro scale properties of the resulting fabric.

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There are thousands of YouTube videos in which DIY science enthusiasts cut grapes in half—leaving just a thin bit of skin connecting them—and put the grapes in the microwave, just to marvel at the sparks and plume of ionized gas (plasma) that the grapes produce. This quirky property of grapes might help make more efficient quantum sensors, according to a new paper published in the journal Physical Review Applied.

The plasma-inducing grape effect was first observed in 1994, per the authors. As previously reported, the usual explanation for the generation of plasmas is that grapes are so small that the irradiating microwaves become highly concentrated in the grape tissue, ripping some the molecules apart to generate charged ions (adding to the electrolytes already present in the grapes). The electromagnetic field that forms causes ions to flow from one grape half to the other via the connecting skin—at least at first. That's when you get the initial sparks. Eventually, the ions start passing through the surrounding air as well, ionizing it to produce that hot plume of plasma.

But in 2019, Trent University scientists showed that explanation isn't quite right. The skin bridge isn't necessary for the effect to occur. Rather, the plasma is generated by an electromagnetic "hot spot." The grapes have the right refractive index and size to "trap" microwaves, so putting two of them close together leads to the generation of a hot spot between them. The trick also works with gooseberries, large blackberries, and quail eggs, as well as hydrogel beads—plastic beads soaked in water. ("Many microwaves were in fact harmed during the experiments," co-author Hamza Khattak admitted at the time.)

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When you want to move an object from one place to another, you usually grab it with your hands or a robotic arm. But what if you want to move something you cannot touch without damaging or disrupting it, like a droplet of liquid? A solution proposed by a team of scientists at the North Carolina State University is a metamaterial that can change shape in response to magnetic fields.

This material had to be easily deformable to change shape, yet at the same time stiff enough to bear loads. “That seemed contradictory—how do you make something that is stiff and deformable at once?” says Jie Yin, a mechanical metamaterials researcher at NC State. His team did it with ferromagnetic elastomers, kirigami cuts, balloons, and magnets.

Refreshable Braille display

“There is not much research on using magnets to manipulate non-magnetic objects. It is very, very hard,” says Yinding Chi, another NC State researcher and lead author of the study. The idea Chi and his colleagues came up with could be compared to a refreshable Braille display. They imagined a surface dotted with domes that could rise, turn, or depress on demand, allowing it to dynamically form relief-like images or move in a pattern similar to waves in the ocean. Objects would then move on these surfaces like they were carried by waves. “This way, you can move various objects without using grippers,” Yin says.

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There is now a genetic excuse not to bother cutting carbs. Humans have genetically adapted to eating starchy foods, and our ancestors may have been carb-ivores even before modern Homo sapiens emerged.

The salivary amylase gene, known as AMY1, is already known to have helped us adapt to eating carbs. It encodes amylase, an enzyme that breaks starches found in pasta and bread down to glucose—and may have given us a taste preference for them. Humans have multiple copies of the gene, which may help us produce high levels of the enzyme.

Researchers from the University of Buffalo and the Jackson Laboratory have now found that, while most copies of this gene arose with the advent of farming, modern humans and our closest relatives had accumulated extra copies long before agriculture.

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Flu season is ramping up across the US, but Louisiana—the state that has reportedly barred its health department from promoting flu shots, as well as COVID-19 and mpox vaccines—is leading the country with an early and strong surge.

Louisiana's flu activity has reached the "Very High" category set by the Centers for Disease Control and Prevention, according to the latest data. The 13-category scale is based on the percentage of doctor's visits that were for influenza-like illnesses (ILIs) in the previous week. Louisiana is at the first of three "Very High" levels. Oregon is the only other state to have reached this level. The rest of the country spans the scale, with 13 jurisdictions at "High," including New York City and Washington, DC. There are 11 at "Moderate," 10 at "Low," and 19 at "Minimal."

Map of ILI activity by state Credit: CDC

Last week, NPR, KFF Health News, and New Orleans Public Radio WWNO reported that the state had forbidden the health department and its workers from promoting annual flu shots, as well as vaccines for COVID-19 and mpox. The policy was explicitly kept quiet and officials have avoided putting it in writing.

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Charlotte, a green sea turtle, was hit by a boat back in 2008. This left it with an affliction colloquially referred to as the “bubble butt,” a kind of floating syndrome that makes it impossible for a turtle to dive. Most sea turtles suffering from issues like this simply die at sea, since the condition leaves them stranded at the surface where they can’t forage, sleep, and avoid predators like sharks. But fate had other plans for Charlotte.

Charlotte didn’t end up as a shark’s lunch and didn’t starve to death floating helplessly in the ocean. Instead, it got rescued shortly after the boat accident and eventually found a home at Mystic Aquarium in Stonington, Connecticut, where it received professional care. That was the first time Charlotte got lucky. The second time came when a collaboration formed: Adia, a company specializing in 3D-printing solutions; Formlabs, one of the world’s leading manufacturers of 3D printers; and New Balance Athletic, a sportswear giant based in Boston. This team chose Charlotte as a technology showcase, which basically turned the turtle into an Oscar Pistorius of the sea—just without the criminal conviction.

Weights and diet

Sea turtles are marine reptiles, which means they don’t have gills like fish—they need air to breathe. The lungs also play a key role in their buoyancy regulation system, which allows them to rest for extended periods of time at the sea floor or float at a precisely chosen depth. A sea turtle can precisely choose the depth at which it achieves neutral buoyancy by inhaling the exactly right volume of air.

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On May 2, 2008, the Chaitén volcano in Chile awoke with unexpected fury after more than 9,000 years of dormancy. The eruption blasted rocks and ash a dozen miles into the air, and then heavy rainfall swept the fallen debris up in immense mudflows. A river of rubble carved a destructive path through the nearby town of Chaitén before surging into the sea. The town, practically split in two by the torrent that cut through its middle, was evacuated as ash blanketed over 200,000 square kilometers of surrounding land.

While the terrestrial aftermath was plain to see, captured by both the local media and satellites, the impact on the sea was unknown.

Mists shroud the hillsides at the entrance to Chaitén Bay, as seen from aboard the Schmidt Ocean Institute’s <em>Falkor (too)</em> research vessel. Credit: Alex Ingle / Schmidt Ocean Institute

The eruption released over 750 billion liters of lava—enough to fill more than 300,000 Olympic-sized swimming pools—mainly in the form of rock fragments. The debris flowed through rivers into the Northern Patagonian Sea, just six miles away.

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Welcome to Edition 7.24 of the Rocket Report! This is the last Rocket Report of the year, and what a year it's been. So far, there have been 244 rocket launches to successfully reach orbit this year, a record for annual launch activity. And there are still a couple of weeks to go before the calendar turns to 2025. Time is running out for Blue Origin to launch its first heavy-lift New Glenn rocket this year, but if it flies before January 1, it will certainly be one of the top space stories of 2024.

As always, we welcome reader submissions. If you don't want to miss an issue, please subscribe using the box below (the form will not appear on AMP-enabled versions of the site). Each report will include information on small-, medium-, and heavy-lift rockets as well as a quick look ahead at the next three launches on the calendar.

Corkscrew in the sky. A Japanese space startup said its second attempt to launch a rocket carrying small satellites into orbit had been terminated minutes after liftoff Wednesday and destroyed itself again, nine months after the company’s first launch attempt in an explosion, the Associated Press reports. The startup that developed the rocket, named Space One, launched the Kairos rocket from a privately owned coastal spaceport in Japan's Kansai region. Company executive and space engineer Mamoru Endo said an abnormality in the first stage engine nozzle or its control system is likely to have caused an unstable flight of the rocket, which started spiraling in mid-flight and eventually destroyed itself about three minutes after liftoff, using its autonomous safety mechanism.

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Louisiana's health department has been barred from advertising or promoting vaccines for flu, COVID-19, and mpox, according to reporting by NPR, KFF Health News, and New Orleans Public Radio WWNO.

Their investigative report—based on interviews with multiple health department employees who spoke on the condition of anonymity for fear of retaliation—revealed that employees were told of the startling policy change in meetings in October and November and that the policy would be implemented quietly and not put into writing.

Ars Technica has contacted the health department for comment and will update this post with any new information.

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The publisher of a high-profile, now-corrected study on black plastics has been removed from a critical index of academic journals after failing to meet quality criteria, according to a report by Retraction Watch.

On December 16, Clarivate—a scholarly publication analytics company—removed the journal Chemosphere from its platform, the Web of Science, which is a key index for academic journals. The indexing platform tracks citations and calculates journal "impact factors," a proxy for relevance in its field. It's a critical metric not only for the journals but for the academic authors of the journal's articles, who use the score in their pursuit of promotions and research funding.

To be included in the Web of Science, Clarivate requires journals to follow editorial quality criteria. In an email to Ars Technica, Clarivate confirmed that Chemosphere was removed for "not meeting one or more of the quality criteria." According to Retraction Watch, Chemosphere has retracted eight articles this month and published 60 expressions of concern since April.

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When the Sun is blazing and the wind is blowing, Germany’s solar and wind power plants swing into high gear. For nine days in July 2023, renewables produced more than 70 percent of the electricity generated in the country; there are times when wind turbines even need to be turned off to avoid overloading the grid.

But on other days, clouds mute solar energy down to a flicker and wind turbines languish. For nearly a week in January 2023, renewable energy generation fell to less than 30 percent of the nation’s total, and gas-, oil- and coal-powered plants revved up to pick up the slack.

Germans call these periods Dunkelflauten, meaning “dark doldrums,” and they can last for a week or longer. They’re a major concern for doldrum-afflicted places like Germany and parts of the United States as nations increasingly push renewable-energy development. Solar and wind combined contribute 40 percent of overall energy generation in Germany and 15 percent in the US and, as of December 2024, both countries have goals of becoming 100 percent clean-energy-powered by 2035.

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The Louisiana resident infected with H5N1 bird flu is hospitalized in critical condition and suffering from severe respiratory symptoms, the Louisiana health department revealed Wednesday.

The health department had reported the presumptive positive case on Friday and noted the person was hospitalized, as Ars reported. But a spokesperson had, at the time, declined to provide Ars with the patient's condition or further details, citing patient confidentiality and an ongoing public health investigation.

This morning, the Centers for Disease Control and Prevention announced that it had confirmed the state's H5N1 testing and determined that the case "marks the first instance of severe illness linked to the virus in the United States."

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We think of squirrels as adorably harmless creatures, admiring their bushy tails and twitchy little noses and the way they cram their cheeks with nuts or seeds to bring back to their nests for later. But the rodents turn out to be a bit more bloodthirsty than we thought. According to a new paper published in the Journal of Ethology, California ground squirrels have been caught in the act—many times over—of chasing, killing, and eating voles.

Co-author Jennifer Smith, a biologist at the University of Wisconsin, Eau Claire, described the behavior as "shocking," given the sheer number of times they watched squirrels do this. “We had never seen this behavior before," she said. "Squirrels are one of the most familiar animals to people. We see them right outside our windows; we interact with them regularly. Yet here’s this never-before-encountered-in-science behavior that sheds light on the fact that there’s so much more to learn about the natural history of the world around us.”

Squirrels mainly consume acorns, seeds, nuts, and fruits, but they have been known to supplement that diet with insects and, occasionally, by stealing eggs or young hatchlings from nests. And back in 1993, biologist J.R Callahan caused a stir by reporting that as many as 30 species of squirrel could be preying on smaller creatures: namely, fish, amphibians, reptiles, birds, and the occasional small mammal.

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Teen drug use continued to fall in 2024, extending a dramatic decline spurred by the COVID-19 pandemic that experts expected would reverse now that the acute phase of the global crisis is well over.

But, according to data released Tuesday, the number of eighth, 10th, and 12th graders who collectively abstained from the use of alcohol, marijuana, or nicotine hit a new high this year. Use of illicit drugs also fell on the whole and use of non-heroin narcotics (Vicodin, OxyContin, Percocet) hit an all-time low.

"Many experts in the field had anticipated that drug use would resurge as the pandemic receded and social distancing restrictions were lifted," Richard Miech, team lead of the Monitoring the Future survey at the University of Michigan, said in a statement. "As it turns out, the declines have not only lasted but have dropped further."

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The first batch of Internet satellites for China's Guowang megaconstellation launched Monday on the country's heavy-lift Long March 5B rocket.

The satellites are the first of up to 13,000 spacecraft a consortium of Chinese companies plans to build and launch over the next decade. The Guowang fleet will beam low-latency high-speed Internet signals in an architecture similar to SpaceX's Starlink network, although Chinese officials haven't laid out any specifics, such as target markets, service specifications, or user terminals.

The Long March 5B rocket took off from Wenchang Space Launch Site on Hainan Island, China's southernmost province, at 5:00 am EST (10:00 UTC) Monday. Ten liquid-fueled engines powered the rocket off the ground with 2.4 million pounds of thrust, steering the Long March 5B on a course south from Wenchang into a polar orbit.

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Editors of the environmental chemistry journal Chemosphere have posted an eye-catching correction to a study reporting toxic flame retardants from electronics wind up in some household products made of black plastic, including kitchen utensils. The study sparked a flurry of media reports a few weeks ago that urgently implored people to ditch their kitchen spatulas and spoons. Wirecutter even offered a buying guide for what to replace them with.

The correction, posted Sunday, will likely take some heat off the beleaguered utensils. The authors made a math error that put the estimated risk from kitchen utensils off by an order of magnitude.

Specifically, the authors estimated that if a kitchen utensil contained middling levels of a key toxic flame retardant (BDE-209), the utensil would transfer 34,700 nanograms of the contaminant a day based on regular use while cooking and serving hot food. The authors then compared that estimate to a reference level of BDE-209 considered safe by the Environmental Protection Agency. The EPA's safe level is 7,000 ng—per kilogram of body weight—per day, and the authors used 60 kg as the adult weight (about 132 pounds) for their estimate. So, the safe EPA limit would be 7,000 multiplied by 60, yielding 420,000 ng per day. That's 12 times more than the estimated exposure of 34,700 ng per day.

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A person in Louisiana is hospitalized with H5N1 bird flu after having contact with sick and dying birds suspected of carrying the virus, state health officials announced Friday.

It is the first human H5N1 case detected in Louisiana. For now, the case is considered a "presumptive" positive until testing is confirmed by the Centers for Disease Control and Prevention. Health officials say that the risk to the public is low but caution people to stay away from any sick or dead birds. A spokesperson for Louisiana's health department told Ars that the hospitalized patient had contact with both backyard and wild birds.

Although the person has been hospitalized, their condition was not reported. The spokesperson said the department would not comment on the patient's condition due to patient confidentiality and an ongoing public health investigation.

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The gap of time between how long Americans live and how much of that time is spent in good health only grew wider in the last two decades, according to a new study published in JAMA Network Open.

The study, which looked at global health data between 2000 and 2019—prior to the COVID-19 pandemic—found the US stood out for its years of suffering. By 2019, Americans had a gap between their lifespan and their healthspan of 12.4 years, the largest gap of any of the 183 countries included in the study. The second largest gap was Australia's, at 12.1 years, followed by New Zealand at 11.8 years and the UK at 11.3 years.

America also stood out for having the largest burden of noncommunicable diseases in the world, as calculated by the years lived with disease or disability per 100,000 people.

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ORLANDO, Florida—Earlier this year, officials at US Space Command released a list of priorities and needs, and among the routine recitation of things like cyber defense, communications, and surveillance was a relatively new term: "integrated space fires."

This is a new phrase in the esoteric terminology the military uses to describe its activities. Essentially, "fires" are offensive or defensive actions against an adversary. The Army defines fires as "the use of weapon systems to create specific lethal and nonlethal effects on a target."

The inclusion of this term in a Space Command planning document was another signal that Pentagon leaders, long hesitant to even mention the possibility of putting offensive weapons in space for fear of stirring up a cosmic arms race, see the taboo of talking about space warfare as a thing of the past.

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