As a physics reporter and lover of mathematics, I won’t be celebrating Pi Day this year. That’s because pi is wrong.

I don’t mean that the value is incorrect. Pi, known by the symbol π, is the number you get when you divide a circle’s circumference by its diameter: 3.14159… and so on without end. But, as some mathematicians have argued, the mathematical constant was poorly chosen, and students worldwide continue to suffer as a result.

A longtime fixture of high school math classes, pi has inspired books, art (SN Online: 5/4/06) and enthusiasts who memorize it to tens of thousands of decimal places (SN: 4/7/12, p. 12). But some contend that replacing pi with a different mathematical constant could make trigonometry and other math subjects easier to learn. These critics — including myself — advocate for an arguably more elegant number equal to 2π: 6.28318…. Sometimes known as tau, or the symbol τ, the quantity is equal to a circle’s circumference divided by its radius, not its diameter.

This idea is not new. In 2001, mathematician Bob Palais of the University of Utah in Salt Lake City published an article in the Mathematical Intelligencer titled “ π is wrong!” The topic gained more attention in 2010 with The Tau Manifesto, posted online by author and educator Michael Hartl. But the debate tends to reignite every year on March 14, which is celebrated as Pi Day for its digits: 3/14.
The simplest way to see the failure of pi is to consider angles, which in mathematics are typically measured in radians. Pi is the number of radians in half a circle, not a whole circle. That makes things confusing: For example, the angle at the tip of a slice of pizza — an eighth of a pie — isn’t π/8, but π/4. In contrast, using tau, the pizza-slice angle is simply τ/8. Put another way, tau is the number of radians in a full circle.

That factor of two is a big deal. Trigonometry — the study of the angles and lines found in shapes such as triangles — can be a confusing whirlwind for students, full of blindly plugging numbers into calculators. That’s especially true when it comes to sine and cosine, two important functions in trigonometry. Many trigonometry problems involve calculating the sine or cosine of an angle. When graphed, the two functions look like a series of wiggles, shaped a bit like an “S” on its side, that repeat the same values every 2π. That means pi covers only half of an S. Tau, on the other hand, covers the full wiggle, a more intuitive measure.

Pi has become so embedded in mathematics that it could be hard to excise. A more practical approach may be to introduce tau as a teaching tool alongside pi, rather than a replacement. Education is where tau’s impact is most likely to be felt: Professional scientists and mathematicians can comfortably handle the factors of two that crop up with pi in equations.

You might argue that multiplying by two isn’t that hard, even for students. But it isn’t the arithmetic that concerns me. Trigonometry is notorious for creating a divide between the math-fluent and math-phobic. But helping more people understand and enjoy mathematics isn’t some pie-in-the-sky fantasy. Everyone is capable of doing math. We just need to work smarter, and speak more clearly, to help those who struggle.

So here’s to June 28 — Tau Day.

17th century scientist Christiaan Huygens set his sights on faraway Saturn, but he may have been nearsighted.

Huygens is known, in part, for discovering Saturn’s largest moon, Titan, and deducing the shape of the planet’s rings. But by some accounts, the Dutch scientist’s telescopes produced fuzzier views than others of the time despite having well-crafted lenses.

That may be because Huygens needed glasses, astronomer Alexander Pietrow proposes March 1 in Notes and Records: the Royal Society Journal of the History of Science.
To make his telescopes, Huygens combined two lenses, an objective and an eyepiece, positioned at either end of the telescope. Huygens experimented with different lenses to find combinations that, to his eye, created a sharp image, eventually creating a table to keep track of which combinations to use to obtain a given magnification. But when compared with modern-day knowledge of optics, Huygens’ calculations were a bit off, says Pietrow, of the Leibniz Institute for Astrophysics Potsdam in Germany.

One possible explanation: Huygens selected lenses based on his flawed vision. Historical records indicate that Huygens’ father was nearsighted, so it wouldn’t be surprising if Christiaan Huygens also suffered from the often-hereditary affliction.

Assuming that’s the reason for the mismatch, Pietrow calculates that Huygens had 20/70 vision: What someone with normal vision could read from 70 feet away, Huygens could read only from 20 feet. If so, that could be why Huygens’ telescopes never quite reached their potential.

Sea otters restocked in old home

When the [Atomic Energy Commission] first cast its eye on the island of Amchitka as a possible site for the testing of underground nuclear explosions, howls of anguish went up; the island is part of the Aleutians National Wildlife Refuge, created to preserve the colonies of nesting birds and some 2,500 sea otters that live there…— Science News, November 9, 1968

Update
The commission said underground nuclear testing would not harm the otters, but the fears of conservationists were well-founded: A test in 1971 killed more than 900 otters on the Aleutian island.
Some otters remained around Amchitka, but 602 otters were relocated in 1965–1972 to Oregon, southeast Alaska, Washington and British Columbia — areas where hunting had wiped them out. All but the Oregon population thrived, and today more than 25,000 otters live near the coastal shores where once they were extinct.

“They were sitting on the precipice,” says James Bodkin, who is a coastal ecologist at the U.S. Geological Survey. “It’s been a great conservation story.”

THE WOODLANDS, TEXAS — Martian dirt may have all the necessary nutrients for growing rice, one of humankind’s most important foods, planetary scientist Abhilash Ramachandran reported March 13 at the Lunar and Planetary Science Conference. However, the plant may need a bit of help to survive amid perchlorate, a chemical that can be toxic to plants and has been detected on Mars’ surface (SN: 11/18/20).

“We want to send humans to Mars … but we cannot take everything there. It’s going to be expensive,” says Ramachandran, of the University of Arkansas in Fayetteville. Growing rice there would be ideal, because it’s easy to prepare, he says. “You just peel off the husk and start boiling.”
Ramachandran and his colleagues grew rice plants in a Martian soil simulant made of Mojave Desert basalt. They also grew rice in pure potting mix as well as several mixtures of the potting mix and soil simulant. All pots were watered once or twice a day.

Rice plants did grow in the synthetic Mars dirt, the team found. However, the plants developed slighter shoots and wispier roots than the plants that sprouted from the potting mix and hybrid soils. Even replacing just 25 percent of the simulant with potting mix helped heaps, they found.

The researchers also tried growing rice in soil with added perchlorate. They sourced one wild rice variety and two cultivars with a genetic mutation — modified for resilience against environmental stressors like drought — and grew them in Mars-like dirt with and without perchlorate (SN: 9/24/21).

No rice plants grew amid a concentration of 3 grams of perchlorate per kilogram of soil. But when the concentration was just 1 gram per kilogram, one of the mutant lines grew both a shoot and a root, while the wild variety managed to grow a root.

The findings suggest that by tinkering with the successful mutant’s modified gene, SnRK1a, humans might eventually be able to develop a rice cultivar suitable for Mars.

SAN DIEGO — Labs growing replicas of snakes’ venom glands may one day replace snake farms.

Researchers in the Netherlands have succeeded in growing mimics of venom-producing glands from multiple species of snakes. Stem cell biologist Hans Clevers of the Hubrecht Institute in Utrecht, the Netherlands, reported the creation of these organoids on December 10 at a joint meeting of the American Society for Cell Biology and the European Molecular Biology Organization.

If scientists can extract venom from the lab-grown glands, that venom might be used to create new drugs and antidotes for bites including from snakes that aren’t currently raised on farms.

Up to 2.7 million people worldwide are estimated to be bitten by venomous snakes each year. Between about 81,000 to 138,000 people die as a result of the bite, and as many as roughly 400,000 may lose limbs or have other disabilities, according to the World Health Organization.
Antivenoms are made using venom collected from snakes usually raised on farms. Venom is injected into other animals that make antibodies to the toxins. Purified versions of those antibodies can help a bitten person recover, but must be specific to the species of snake that made the bite. “If it’s a fairly rare or local snake, chances are there would be no antidote,” Clevers says.

Three postdoctoral researchers in Clevers’ lab wanted to know if they could make organoids — tissues grown from stem cells to have properties of the organs they mimic — from snakes and other nonmammalian species. The researchers started with Cape coral snakes (Aspidelaps lubricus) that were dissected from eggs just before hatching. Stem cells taken from the unhatched snakes grew into several different types of organoids, including some that make venom closely resembling the snake’s normal venom, Clevers reported at the meeting.

His team has produced venom-gland organoids from at least seven species of snakes. The organoids have survived in the lab for up to two years so far.

Clevers and colleagues hope to harvest venom from the organoids, which produce more highly concentrated venom than snakes usually make. “It’s probably going to be easier than milking a snake,” he says.

Satellites may be a more accurate way to track smog-producing ammonia.

It’s notoriously tricky to pinpoint accurate numbers for ammonia gas emissions from sources such as animal feedlots and fertilizer plants. But new maps, generated from infrared radiation measurements gathered by satellites, reveal global ammonia hot spots in greater detail than before. The new data suggest that previous estimates underestimate the magnitude of these emissions, researchers report December 5 in Nature.

In the atmosphere, ammonia, which contains nitrogen, can help form tiny particles that worsen air quality and harm human health. The research could help keep tabs on who’s emitting how much, to make sure that factories and farms are meeting environmental standards.
Emissions are usually estimated by adding up output from individual known sources of activity, but those calculations are only as good as the data that go into them. Ammonia sticks around only hours to a few days in the atmosphere, so on-the-ground measurements vary a lot even in the same place, says coauthor Martin Van Damme, an atmospheric scientist at the Université Libre de Bruxelles in Belgium.

“There’s so much uncertainty in ammonia emissions,” says Daven Henze, a mechanical engineer at the University of Colorado Boulder who wasn’t part of the research. Other scientists, including his research group, have estimated ammonia releases using satellite data before. But these new maps rely on a more detailed dataset and have substantially better resolution, Henze says — fine enough that the study authors were able to link areas of high emissions to specific factories or farms.
The new maps show 248 nitrogen emission hot spots across the globe at a resolution of about a kilometer. Eighty-three of those hot spots arose from agricultural activity that involved high numbers of cows, pigs and chickens, such as a site in Colorado that overlapped on satellite imagery maps with two big cattle feedlots. Ammonia emissions from feedlots come largely from livestock waste. Another 158 sites were affected by industrial emissions — mostly from sites that produced ammonia-based fertilizer, such as in Marvdasht, Iran. Six hot spots couldn’t be pinned to specific activity.
Ammonia is also emitted naturally, from volcanoes or seabird colonies. But most of those sources were too weak or not concentrated enough to show up as hot spots in the data. Lake Natron in Tanzania is the one exception — its mud flats show up as an ammonia-releasing hot spot, perhaps due to decaying algae. But it’s not clear why other lakes with similar mud flats didn’t. Some natural sources may have gone undetected because of where they were located — in places with heavy cloud cover that obscured the data, or where turbulent air dissipated ammonia especially quickly, Van Damme suggests.

Some areas with particularly high overall ammonia emissions from biomass burning or fertilizer, such as West Africa and the Indus Valley in Pakistan and northern India, didn’t reveal specific hot spots, either, the researchers report.

Since people in the United States began dying in the fentanyl-related drug overdose epidemic, whites have been hit the hardest. But new data released March 21 by the Centers for Disease Control and Prevention show that African-Americans and Hispanics are catching up.

Non-Hispanic whites still experience the majority of deaths involving fentanyl, a synthetic opioid. But among African-Americans and Hispanics, death rates rose faster from 2011 to 2016. Whites experienced a 61 percent annual increase, on average, while the rate rose 140.6 percent annually for blacks and 118.3 percent per year for Hispanics. No reliable data were available for other racial groups.
Overall, the number of U.S. fentanyl-related deaths in 2011 and 2012 hovered just above 1,600. A sharp increase began in 2013, reaching 18,335 deaths in 2016. That’s up from 0.5 deaths per 100,000 people in 2011 to 5.9 per 100,000 in 2016.

In the first three years of the data, men and women died from fentanyl-related overdoses at similar rates, around 0.5 per 100,000. But in 2013, those paths diverged, and by 2016, the death rate among men was 8.6 per 100,000; for women it was 3.1 per 100,000. Overdose death rates rose most sharply along the East Coast, including in New England and the middle Atlantic, and in the Great Lakes region.

One of the most powerful opioids, fentanyl has been around for decades and is still prescribed to fight pain. But it has emerged as a street drug that is cheap to make and is found mixed into other drugs. In 2013, fentanyl was the ninth most common drug involved in overdose deaths, according to the CDC report; in 2016, it was number one. Just a little bit can do a lot of damage: The drug can quickly kill a person by overwhelming several systems in the body (SN: 9/3/2016, p. 14).

Unusual virus is valuable tool —

Viruses, which cannot reproduce on their own, infect cells and usurp their genetic machinery for use in making new viruses…. But just how viruses use the cell machinery is unknown.… Some answers may come from work with an unusual virus, called M13, that has a particularly compatible relationship with … [E. coli] bacteria. — Science News, April 5, 1969

Update
M13 did help unlock secrets of viral replication. Some bacteria-infecting viruses, called bacteriophages or simply phages, kill the host cell after hijacking the cell’s machinery to make copies of themselves. Other phages, including M13, leave the cell intact. Scientists are using phage replication to develop drugs and technologies, such as virus-powered batteries (SN: 4/25/09, p. 12). Adding genetic instructions to phage DNA for making certain molecules lets some phages produce antibodies against diseases such as lupus and cancer. The technique, called phage display, garnered an American-British duo the 2018 Nobel Prize in chemistry (SN: 10/27/18, p. 16).

My youngest child, now just over a year old, has started to talk. Even though I’ve experienced this process with my older two, it’s absolutely thrilling. He is putting words to the thoughts that swirl around in his sweet little head, making his mind a little less mysterious to the rest of us.

But these early words may not mean what we think they mean, a new study hints. Unsurprisingly, when 2-year-olds were asked a series of “this or that” questions, the toddlers showed strong preferences — but not for the reasons you’d think. Overwhelmingly, the toddlers answered the questions with the last choice given.
That bias, described in PLOS ONE on June 12, suggests that young children’s answers to these sorts of questions don’t actually reflect their desires. Instead, kids may simply be echoing the last thing they heard.

This verbal quirk can be used by parents to great effect, as the researchers point out in the title of their paper: “Cake or broccoli?” More fundamentally, the results raise questions about what sort of information a verbal answer actually pulls out of a young child’s mind. This murkiness is especially troublesome when it comes to questions whose answers call for adult action, such as: “Did you hit your sister on purpose or on accident?”

In the first series of experiments, researchers led by Emily Sumner at the University of California, Irvine, asked 24 1- and 2-year-olds a bunch of two-choice questions, some of which involved a polar bear named Rori or a grizzly bear named Quinn. One question, for example, was, “Does Rori live in an igloo or a tepee?” Later, the researchers switched the bear and the order of the options, asking, for example, “Does Quinn live in a tepee or an igloo?”

The toddlers could answer either verbally or, for reluctant speakers, by pointing at one of two stickers that showed the choices. When the children answered the questions by pointing, they chose the second option about half the time, right around chance. But when the toddlers spoke their answers, they chose the second option 85 percent of the time, regardless of the bear.
SECOND BEST A toddler taking part in a study selects the second option in three either-or questions. This tendency, called the recency bias, may reflect kids’ inability to juggle several choices in their minds simultaneously. Credit: E. Sumner et al/PLOS ONE 2019

This abundance of second options selected — a habit known as the recency bias — might be due to the fact that young children have trouble holding the first option in mind, the researchers suspect. Other experiments showed that children’s tendency toward the second option got stronger when the words got longer.

Adults actually have the opposite tendency: We’re more inclined to choose the first option we’re given (the primacy bias). To see when this shift from last to first occurs, the researchers studied transcripts of conversations held between adults and children ages 1.5 to 4. In these natural conversations, 2-year-olds were more likely to choose the second option. But 3- and 4-year-olds didn’t show this bias, suggesting that the window closes around then.

The results hold a multitude of delightful parenting hacks: “Would you like to jump on the bed all night, or go to sleep?” But more importantly, the study serves as a reminder that the utterances of small children, while fascinating, may not carry the same meanings as those that come from more mature speakers. If you really want a straight answer, consider showing the two options to the toddler. But if you go that route, be prepared to hand over the cake.

For the first time, researchers have harnessed the body’s own chemistry to “grow” electrodes inside the tissues of living fish, blurring the boundary between biology and machines.

The technique uses the body’s sugars to turn an injected gel into a flexible electrode without damaging tissues, experiments show. Zebrafish with these electrodes grown in their brains, hearts and tail fins showed no signs of ill effects, and ones tested in leeches successfully stimulated a nerve, researchers report in the Feb. 24 Science.
Someday, these electrodes could be useful for applications ranging from studying how biological systems work to improving human-machine interfaces. They also could be used in “bioelectronic medicine,” such as brain stimulation therapies for depression, Parkinson’s disease and other conditions (SN: 2/10/19).

Soft electronics aim to bridge the gap between soft, curvy biology and electronic hardware. But these electronics typically still must carry certain parts that can be prone to cracks and other issues, and inserting these devices inevitably causes damage to tissues.

“All the devices we have made, even though we have made them flexible, to make them more soft, when we introduce them, there will still be a scar. It’s like sticking a knife into the organ,” says Magnus Berggren, a materials scientist at Linköping University in Sweden. That scarring and inflammation can degrade electrode performance over time.

Previous efforts to grow soft electronics inside tissues have drawbacks. One approach uses electrical or chemical signals to power the transformation from chemical soup to conducting electrodes, but these zaps also cause damage. A 2020 study got around this problem by genetically modifying cells in worms to produce an engineered enzyme that does the job, but the new method achieves its results without genetic alterations.

Berggren and colleagues’ electrodes instead exploit a natural energy source already present in the body: sugars. The gel cocktail contains molecules called oxidases that react with the sugars — glucose or lactate — to produce hydrogen peroxide. That then activates another ingredient in the cocktail, an enzyme called hydrogen peroxidase, which is the catalyst needed to transform the gel into a conducting electrode.

“The approach leverages elegant chemistry to overcome many of the technical challenges,” says biomedical engineer Christopher Bettinger of Carnegie Mellon University in Pittsburgh, who was not involved in the study.

To test the technique, the researchers injected the cocktail into the brains, hearts and tail fins of transparent zebrafish. The gel turns blue when it becomes conductive, giving a visual readout of its success.
“The beautiful thing is you can see it: The zebrafishes’ tail changes color, and we know that blue indicates a conducting polymer,” says materials scientist Xenofon Strakosas, also of Linköping University. “The first time I saw it, I thought ‘Wow, it’s really working!’”

The fish appeared to suffer no ill effects, and the researchers saw no evidence of tissue damage. In partially dissected leeches, the team showed that delivering a current to a nerve via a soft electrode could induce muscle contractions. Ultimately, devices like this could be paired with various wireless technologies in development.

Long-term implant performance remains to be determined, however. “The demonstrations are impressive,” Bettinger says. “What remains to be seen is the stability of the electrode.” Over time, substances in the body could react with the electrode materials, degrading it or even producing toxic substances.

The team still needs to refine how precisely the electrodes can stimulate nerves, says chemical engineer Zhenan Bao of Stanford University, who was not involved in the work. She and colleagues developed the way to “grow” electrical components using genetic modifications. Ensuring stimulation is concentrated where it’s needed for a treatment, while preventing the leakage of current to unwanted regions will be important, she says.

In the new study, the relative abundance of different sugars in different tissues determines exactly where electrodes form. But in the future, a component of the main ingredient could be swapped out for elements that attach to specific bits of biology to make targeting much more precise, Berggren says. “We’re conducting experiments right now where we’re trying to bind these materials directly on individual cells.” Notes Strakosas: “There are some applications where precision is really important; that’s where we have to invest effort.”