Smallest number of American teens and tweens in 25 years are currently using tobacco products.

According to the 2024 National Youth Tobacco Survey, only 8 percent of middle and high school students — or 2.25 million — reported using tobacco products in the past 30 days. By 2019, 23 percent, or just over 6 million, had reported current tobacco use, driven almost entirely by e-cigarette use, at 20 percent.

E-cigarettes are still the most popular choice, used by 6 percent of middle and high school students in 2024, researchers report Oct. 17. Morbidity and Mortality Weekly Report. Nicotine pouches – a product that releases nicotine when placed between the cheek and gum – came in second for the first time at nearly 2 percent, followed by cigarettes, cigars and smokeless tobacco. The National Youth Tobacco Survey began measuring use among college students in 1999.

More middle school students, at 10 percent, reported using any tobacco product in the past 30 days than high school students, at 5.4 percent. Just under 8 percent of high school students reported current use of e-cigarettes in 2024, down from 10 percent in 2023. This drop of 350,000 high school students was a large reason for the decline in current use of each product among all students surveyed.

Disparities in tobacco use among ages and adolescents from different racial and ethnic groups still exist. Past research has found that the tobacco industry has long targeted certain groups through advertising and marketing, including promoting menthol cigarettes in black communities and using tribal icons to target American Indians and Alaska Natives.

Tobacco use most often begins in adolescence, a time when exposure to nicotine, the addictive substance in tobacco, can be particularly harmful to adolescent brain development.SN: 30.6.15). Nicotine affects the ability to learn, remember and pay attention. Tobacco control programs at the federal, state and local levels have contributed to the decline in use, the researchers wrote.

Naloxone has saved thousands of lives by reversing opioid overdoses. But its success depends on someone nearby who can administer the medicine quickly (SN: 5/3/24). Many people are alone when they overdose.

A new implant may one day solve this problem. Inserted under the skin and powered by a battery, the device can detect the onset of an overdose and release naloxone directly into the bloodstream while simultaneously alerting first responders, researchers reported Oct. 23 in Advances in science. The device, called the Naloximeter, has only been tested on animals.

Researchers hope Naloximetry can help some of the highest-risk individuals: Those who are newly sober, either because they sought treatment or were incarcerated. People are 10 to 16 times more likely to die of an overdose in the first months after a period of sobriety, when their body’s tolerance to opioids has decreased, than they are further into recovery.

In 2023, more than 80,000 people in the United States died of opioid overdose (SN: 25.9.2024). “This problem with fentanyl is getting worse,” says Robert Gereau, a neuroscientist at Washington University School of Medicine in St. Louis. “There is a great need for as many harm reduction efforts as possible.”

Common harm reduction techniques have included safe injection centers and hotlines, but new technologies offer promising alternatives when a bystander cannot be present (SN: 14.2.2024). Until now, apps and other devices can only monitor and alert responders. The naloximeter is the first device that can provide treatment—and do so immediately, in the narrow window when overdoses are still reversible. “That’s where this really shines compared to other interventions,” says Monty Ghosh, an addiction researcher at the University of Alberta in Edmonton, Canada, who was not involved in the study.

The Naloximeter sensor works by measuring the loss of oxygen in the blood – specifically, how fast it is falling and to what level. In a human version of this implant, once an overdose is detected, a warning alert will appear on the person’s cell phone so the person can tell if it’s a false alarm; otherwise, naloxone would be released.

Gereau and colleagues tested two different administration methods in rats and pigs. In trials with pigs, they found that the most effective method was an intravenous catheter, similar to a port used to treat cancer, built into the implant. It delivered 0.7 milliliters of naloxone within 60 seconds, which is “enough to start having a lot of effects on the brain,” says Joanna Ciatti, a materials scientist at Northwestern University in Evanston, Ill.

Although it is still a long way from being tested in human clinical trials and sorting out ethical and logistical concerns, the prospect of such a device is exciting, says Ghosh. Its feasibility will depend on the invasiveness of the implant, its cost and, most importantly, whether people with substance abuse concerns, often wary of interventions, will be open to it.

Two towering medieval cities built by mobile herders along Central Asia’s Silk Road trade routes have been hidden in plain sight – until now.

Mountainous regions have traditionally been seen as barriers to trade and communication. But these ancient settlements, located roughly 2,000 meters above sea level, show that herding communities developed a distinct form of urban life where such activities flourished, archaeologist Michael Frachetti and colleagues report Oct. 23. Nature.

“Think of these high-rise cities as nodes in a network that moves power and trade across Asia and Europe,” says Frachetti, of Washington University in St. Louis.

Researchers have discovered buildings and cultural artifacts from only a few ancient settlements located more than 2,000 meters above sea level, such as Peru’s Machu Picchu. Despite the thin air, harsh climate, rugged terrain and limited agricultural land, it now appears that mountainous Central Asia was “an urban area” during the Middle Ages, Frachetti says.

The team focused on two archaeological sites in southeastern Uzbekistan: Tashbulak and Tugunbulak. Centuries of erosion and sediment accumulation have obscured the urban features of both sites, located five kilometers apart, beneath rolling grasslands. Large earthen mounds and pottery shards scattered across the landscape led to the discovery of Tashbulak in 2011 and Tugunbulak in 2015. These finds indicate that Tugunbulak was occupied from the 6th to the 10th centuries. The original inhabitants of Tashbulak arrived in the 8th century.

Using drones equipped with light detection and ranging, or lidar, technology, Frachetti and colleagues mapped the extent and layout of both sites. Lidar laser scans have previously looked through tropical jungles and land cover to reveal ancient urban networks in the Amazon, Central America and Cambodia (SN: 1/11/24; SN: 12/4/23; SN: 29.4.16).

Lidar maps of surface-level ridges on the ground where the walls once stood, augmented by computer reconstructions of those buildings, show that Tugunbulak covered just over a square kilometer. It stood as one of the greatest Central Asian cities of its time, says Frachetti.

The more than 300 structures at Tugunbulak included clusters of buildings with common walls, narrow corridors or roads running between these clusters, walled watchtowers along a ridge, and a central citadel or citadel.

Tugunbulak’s appearance mirrored that of small and large field cities in medieval Asia, researchers say. The hill town citadel, surrounded by a citadel or palace, overlooked a city surrounded by defensive walls.

Tashbulak covered roughly one-eighth of Tugunbulak’s territory, but it was still a vibrant community, Frachetti says. A series of large defensive structures overlooked a wide area of ​​platforms, walls and terraced houses. At least 98 structures identified so far resemble building types discovered at the larger site, researchers say.

Population size is difficult to estimate for both communities. But Frachetti suspects that a relatively constant number of year-round residents periodically swelled during gatherings for special events and commodity exchanges.

Lidar’s discovery of large communities at Tugunbulak and Tashbulak highlights the underappreciated ability of high-altitude cattle groups to band together as early city builders, says archaeologist Michael Fisher of the Max Planck Institute for Geoanthropology in Jena, Germany . The new study shows that “mountain ranges may actually be conduits for cultural and economic transmission, not barriers.”

The mountain ranges present few opportunities for agriculture, however, raising questions about how the populations of Tugunbulak and Tashbulak were fed.

Highland pastures supported herds of cattle, sheep, goats, and horses that could be traded or sold to obtain cultivated foods. Previous excavations at Tashbulak revealed remains of cereals, legumes, nut shells, fruit, fragments of chicken eggshells and cotton seeds. Regular shipments of these foods must have come from field settlements, says Max Planck archaeologist Robert Spengler, who participated in those earlier excavations.

Excavations conducted since 2022 suggest that large-scale iron production occurred at Tugunbulak and Tashbulak, Frachetti says. Iron represented a valuable trade item for the inhabitants of the mountain towns.

These mountain towns may also have provided rest stops for caravans traveling the Silk Road, a set of ancient trade and travel routes that ran from China to Europe. But excavations have not yet confirmed this possibility.

The biggest conundrum in cosmology may be closer to being solved, thanks to the James Webb Space Telescope.

Scientists disagree on the expansion rate of the universe, known as the Hubble constant. There are two main methods for measuring it – one based on exploding stars called supernovae and the other on the universe’s oldest light, the cosmic microwave background. The two techniques have been in conflict for a decade, in what is known as the “Hubble tension” (SN: 21.3.14). If this tension is real and not the result of an error in one of the measurements, it would require a drastic change in the way scientists understand the universe.

New papers published by two of the central players are raising hopes that additional observations by the James Webb Space Telescope, or JWST, of several types of stars and supernovae could settle the question of whether the discrepancy is real, once and for all.

The two teams disagree on whether that tension exists at all. One team says there is no strong evidence for Hubble tension from JWST data. But the other group says the JWST data strengthens the case that the two types of measurements are in conflict. “I’m even more intrigued by the Hubble tension,” says cosmologist Adam Riess of Johns Hopkins University, leader of one of the teams.

The different camps are finally seeing eye to eye on one part of their measurements: the distances to nearby galaxies, which are needed to infer the expansion rate of the universe from supernovae. “This is really new—we’re agreeing on distances, and that’s a real breakthrough,” says cosmologist Wendy Freedman of the University of Chicago, who leads the other team.

“If you had told me 10 years ago that this would all be agreed at this level, I would have just jumped up and down,” says cosmologist Daniel Scolnic of Duke University, a member of Riess’s team.

This agreement gives scientists new confidence that the long-standing dispute is close to being resolved. “I’m very optimistic that in the next couple of years, the questions we’re talking about now, we’ll have solved them,” Freedman says.

Reaching consensus on distances

Scientists’ theory of the universe, called the standard cosmological model, is based largely on unknowns. Dark matter, a substance that adds invisible mass to galaxies, has never been directly detected. And dark energy, a phenomenon that causes the universe’s expansion to accelerate, is also a total question mark. But the model has proved remarkably successful in describing the cosmos.

Starting from the ancient light of the cosmic microwave background, scientists can use the standard cosmological model to determine today’s rate of expansion. This technique reveals that space is expanding at 67 kilometers per second per megaparsec. (A megaparsec is about 3 million light years.)

But supernova measurements by Riess and colleagues peg the number at about 73 km/s/Mpc – putting the two results in direct conflict. This may hint that something is wrong with the standard cosmological model.

To determine the rate of expansion through the supernova technique, cosmologists must measure the distances to many distant supernovae. This requires a technique called a distance scale, to translate close distances to farther ones.

Under special scrutiny is the second rung of this scale, in which scientists observe certain types of stars – most commonly, pulsating stars called Cepheids – to determine the distances to the galaxies where they reside, as well as to the supernovae that occurred in them the same galaxies. Observing these stars with JWST, which has better resolution than the Hubble Space Telescope, could highlight flaws in measurements on that scale.

In addition to Cepheids, Freedman and colleagues used two other types of stars for their distance measurements. Using JWST data for all three, Freedman and colleagues find an expansion rate of about 70 km/s/Mpc. Given the uncertainties in the measurements, this is close enough to the cosmic microwave background number that it does not require physicists to rethink the cosmos, the team reports in a paper submitted Aug. 12 to arXiv.org. But it also does not completely rule out the existence of the Hubble tension. “We need more data to answer the question definitively,” says Freedman.

The three distance measurement techniques were generally in agreement, Freedman says. The Cepheid measurements result in a slightly higher value of the Hubble constant than the other two methods, but not enough to indicate anything wrong with the technique. “There’s a trade-off, but the uncertainties are big enough that you can’t say for sure, ‘This is the way it’s going to turn out,'” Freedman says.

Hubble constant

Despite agreeing on the distances, the teams still differ on Hubble’s constant. This may be due to the small number of measurements made with JWST so far, Riess, Scolnic and colleagues report in a paper submitted to arXiv.org on August 21. If Freedman’s team had chosen different galaxies to observe with JWST, they would have obtained a larger value of the Hubble constant, the team argues. (None of the papers have been peer-reviewed, and results may change under further review.)

Scientists are working only with the first data sets from JWST. To solve the puzzle, “the best thing we can do is use much more JWST time to study the distance scale,” says astronomer John Blakeslee of NOIRLab in Tucson, Ariz., who was not involved in the research. .

Freedman wants to continue looking for unidentified issues known as systematic uncertainties that could artificially push estimates of the Hubble constant higher. One concern is clumping—too many stars clumped together in the same place, throwing off Cepheid measurements. Last year, Riess’ team found no evidence of clumping in the JWST data (SN: 28/9/23). But this effect may be more apparent at greater distances than has been studied so far with JWST, Freedman suggests.

If scientists find that different distance measurements disagree, says cosmologist Saul Perlmutter of the University of California, Berkeley, who was not involved in the research, “then it may suggest that we still have to get to the bottom of the systematic uncertainties first.” before we get to a major problem with the cosmological model.”

But many physicists are satisfied with the Hubble tension. First, various other methods have also found higher-than-expected expansion rates, says cosmologist Eleonora Di Valentino of the University of Sheffield in England, who was not involved in the research. “The Hubble tension is still very strong.”

“I see these results as supporting … the fact that we have this difference between what we expect from our standard cosmological model and what we see from these measurements,” says cosmologist Lloyd Knox of the University of California, Davis, who was not involved. in each team.

The standard cosmological model, he notes, relies on mysterious dark energy and dark matter. “Maybe this is a clue to the dark universe, and we just have to figure out how to interpret it.”

Scientific watchmakers have created a prototype of a nuclear clock, hinting at future possibilities for using atomic nuclei to make precise time measurements and make new tests of fundamental theories of physics.

While the definition of “watch” is scientifically nebulous, the prototype has yet to be used to measure time. So it should technically be called the “frequency standard,” says physicist Jun Ye. But the work brings scientists closer to a nuclear clock than ever before. “For the first time, all the essential ingredients for a working nuclear clock are contained in this work,” says Ye, of JILA in Boulder, Colo.

While atomic clocks measure time based on electrons bouncing between energy levels in atoms, nuclear clocks measure time based on the energy levels of atomic nuclei. A certain frequency of laser light is needed for an atom or an atomic nucleus to make such a jump. The electromagnetic wave motion of that light can be used to tell time.

Nuclear clocks would keep time using a variety of the element thorium, called thorium-229. Most atomic nuclei make energy jumps that are too large to be triggered by a tabletop laser. But thorium-229 has two energy levels that are close enough to each other that the transition between these two levels can serve as a clock.

Now, researchers have pinpointed the frequency of light needed to initiate that jump. It’s 2,020,407,384,335 kilohertz, Ye and colleagues report on Sept. 5. Nature.

Most importantly, measurement has an uncertainty of 2 kilohertz. This is more than a million times the accuracy of the previous best measurement. And it’s more than a billion times the accuracy with which this frequency was known just over a year ago, highlighting multiple successive developments.

The enhancement depends on a component called a frequency comb (SN: 10/5/18). An essential component of many atomic clocks, a frequency comb creates a series of discrete frequencies of light. The use of a thorium-229 frequency comb has been a major research goal for some scientists (SN: 6/4/21). In the new work, Ye and colleagues compared the ticking of the nuclear clock with that of an atomic clock of a known frequency.

“This is something that will be important as a scientific application for tests of fundamental physics,” says physicist Ekkehard Peik of the National Institute of Metrology in Braunschweig, Germany, who was not involved in the new research.

In the future, such comparisons can be used to search for strange physical effects, such as shifting values ​​of fundamental constants (SN: 11/2/16). These are numbers that – as the name implies – are believed to be eternally fixed.

One of the richest biodiversity hotspots in the world is Peru’s Madre de Dios, a region of the Amazon located at the base of the Andes Mountains. When biogeochemist Jacqueline Gerson first traveled there in 2017, she found herself on a boat heading downstream through the forest. As she passed the banks of the river, she noticed a change of scenery.

At first, “it was beautiful, old-growth forest, lots of birds, lots of different wildlife,” says Gerson, a Ph.D. student at Duke University at the time. “Then as I continued downstream … you see these rocks first,” she adds. “As you go along, you see clump after clump after clump and then you start to see some deforestation.”

She witnessed signs of small-scale and artisanal gold mining. Unlike large-scale industrial operations with fleets of dump trucks and excavators, workers here use basic tools or their hands to extract ore. These informal gold mining efforts are so prolific in Madre de Dios that they support at least half of the region’s economy.

But there is a price for this gain. Small-scale miners mix mercury into river bank sediments containing gold particles. This produces a gold-mercury amalgam that can be easily separated from the trash and then burned to isolate the gold. But this combustion also emits mercury fumes into the open air.

For Gerson, now at Cornell University, shedding light on how toxic pollutants flow through the environment is a calling. It studies how human activities contribute to these pollutants and change their pathways.

Globally, humans release more than 2,000 metric tons of mercury into the air each year from coal-burning plants, waste incineration facilities, cement production sites, mining operations, and other sources. Artisanal and small-scale gold mining generates more than 35 percent of these mercury emissions, making it the main anthropogenic source.

In the environment, bacteria convert the element into the more toxic methylmercury, which bioaccumulates more easily in wildlife and humans.SN: 19.6.14). Exposure to large amounts of mercury can wreak havoc on the central nervous system, digestive tract and kidneys, leading to seizures, blindness, sleep loss, memory loss, headaches, muscle weakness or even death.

Much of Gerson’s work focuses on mercury, but she has studied the movements of other dangerous pollutants, such as selenium released from coal mining and sulfur released from agriculture. In most cases, Gerson already has a good idea of ​​where the substances are coming from when she begins her investigation. It’s the rest of the story – where they go, where they end up – that she’s looking for.

Before we can better manage and reduce the risks these pollutants pose to humans, she says, “we first need to understand their fate.”

An Amazon hotspot

Even before her first trip to Madre de Dios, Gerson was aware that signs of mercury exposure had been reported in communities upriver from mining areas. Perhaps people were eating mercury-laden fish that had swum upstream, but Gerson wondered if there might be other routes of exposure. So she and colleagues returned to the region collecting samples during the summer of 2018 and the following winter.

Surprisingly, mercury levels in the air correlate with proximity to mines. But the water shed by leaves in the forest canopy, known as runoff, offered a more complicated picture. The denser the canopy, the more concentrated the mercury is in the stream, with the highest levels occurring in a conservation area called the Los Amigos Biological Concession, Gerson and colleagues reported in 2022 in Nature Communications. Falling mercury levels in Los Amigos are “the highest burdens of any place on the globe,” says Gerson. “That was really surprising [to find] in this area … which we think of as one of the most remote areas in the world.”

What set Los Amigos apart was its pristine, old-growth forest. The large leaves in the mature forest canopy act as mercury collectors, providing ample surfaces for airborne mercury to collect, accumulate and later be washed to the ground by rain, Gerson says. “If you have a mining community surrounded by old-growth forests, you’re going to see really high mercury loads here.”

And it wasn’t just the leaves. Mining also contaminated wildlife. Mercury levels in the feathers of three species of songbirds with different diets were on average two to three times higher at Los Amigos than in another old-growth forest located away from the mines. Runoff and shed leaves send mercury to the soil, where the pollutant is methylated by bacteria and consumed by plants and animals, Gerson explains.

“It’s important to get this information out,” says biogeochemist Mae Gustin of the University of Nevada, Reno, who was not involved in the research. The impact is more widespread than people realize, she says. “Everyone [eco]the system is getting contaminated.”

A spark in Senegal

Gerson’s fascination with mercury did not begin in the Amazon, but rather dates back to a trip to central Senegal. After receiving her undergraduate degree at Colgate University in Hamilton, NY, she went to Senegal as a Peace Corps volunteer.

There, Gerson met another Peace Corps volunteer who had been living in the Kédougou region, a full day’s drive away in southeastern Senegal. “I remember her talking about the need to change communities because [the] The Peace Corps was concerned about her personal exposure to mercury from mining operations there, Gerson says. “It really piqued my interest.”

With Mercury on her mind, Gerson returned to New York and began a master’s program at Syracuse University in 2014. Her master’s advisor, Charles Driscoll, gave her “tremendous flexibility to choose what I wanted to do for my thesis,” Gerson recalls. Over the next several years, she would publish some of her earliest work on how mercury and methylmercury patterns evolved over a decade in a remote area of ​​the Adirondack Mountains, launching a career in search of quicksilver. .

Research eventually drew Gerson back to Senegal. For a study reported in 2023 in Papers of purest productionshe and colleagues worked with local community members—more than 80 percent of whom identified as miners—to spread awareness of the dangers of mercury. The team also distributed locally made devices called retorts that mitigate miners’ exposure to mercury fumes. Surveys showed that the work helped: The share of respondents who reported that they believed mercury was dangerous increased from 83 to 94 percent, and the percentage of individuals who used replicas at least sometimes increased from 3 to 64 percent.

In the United States, polluter movements aren’t the only avenues Gerson is drawing attention to. It is also dedicated to enlightening science entrants. As a Ph.D. student, she co-founded GALS, a free summer science program that organizes overnight camps and backpacking trips for high school girls and gender non-conforming students. And she wrote a 2023 article on Bulletin of the Ecological Society of America entitled “Demystifying the Graduate School Application Process”.

“There’s a lot of hidden agendas going into high school and going into the sciences in general,” Gerson says, that aren’t easily accessible to those who don’t already know the process. “I’m really passionate about trying to make STEM much more inclusive and helping people find their way as well.”

For the first time, scientists have measured a long-sought global electric field in Earth’s atmosphere. This field, called the ambipolar electric field, was predicted to exist decades ago but was never discovered until now.

“That’s the big noise,” says atmospheric scientist Glyn Collinson of NASA’s Goddard Space Flight Center in Greenbelt, Md.

The field is weak, just 0.55 volts — about as strong as a watch battery, Collinson says. But it is strong enough to control the shape and evolution of the upper atmosphere, features that may have implications for our planet’s suitability for life.

“It’s essential to the DNA of our planet,” says Collinson, who reported the new measurement in Nature August 28.

The existence of the ambipolar electric field was first predicted in the 1960s, at the dawn of the space age. Early spacecraft flying over Earth’s poles detected a supersonic outflow of charged particles from the atmosphere, called the polar wind.

The most reasonable thing to explain the fast wind would be an electric field in the atmosphere. The idea is that sunlight can strip electrons from atoms in the upper atmosphere. Those negatively charged electrons are light and energetic enough that they want to float around in space. The positively charged oxygen ions left behind are heavier and tend to sink under Earth’s gravity.

But the atmosphere wants to remain electrically neutral, maintaining an even balance between electrons and ions. The electric field is formed to keep the electrons attached to the ions and prevent them from escaping.

Once established, the field can act as a booster for lighter ions such as hydrogen, giving them enough energy to break free from Earth’s gravity and drift away as the polar wind. It can also pull heavier ions higher into the atmosphere than they would otherwise reach, where other forces can also remove them into space.

That was the hypothesis. But until recently, the technology to detect the field did not exist.

“It really was thought impossible to do,” says Collinson. “[The field] so weak, it was just assumed you would never measure up.”

Collinson realized that this measurement had not been obtained after he and his colleagues tried to measure a similar field on Venus. A search for a paper reporting Earth’s field strength for comparison came up empty.

“It turned out, funny story, it’s never been done,” he says. “We were like, ‘Game on!'”

Collinson and colleagues developed a new instrument called a photoelectron spectrometer specifically to detect the electric field. The team mounted the spectrometer on a rocket called the Endurance, after the ship that carried Ernest Shackleton to explore Antarctica in 1914.

Reaching the launch site in Svalbard, Norway was a journey worthy of the rocket’s name. The team traveled by boat for 17 hours to reach the Svalbard archipelago, located just a few hundred kilometers from the North Pole. Several members of the team contracted COVID-19 along the way. And the war between Russia and Ukraine had started only a few months earlier.

“At the time, there was some nervousness about launching missiles,” says Collinson. “Polar bears were the fewest. We had war and pestilence.”

Two more days of storms kept the Endurance grounded. When the rocket finally launched on May 11, 2022, it went straight into the atmosphere at about 770 kilometers, measuring the energies of the electrons every 10 seconds. The entire flight lasted 19 minutes. In the end, the rocket was thrown into the Greenland Sea.

Endurance measured a difference in electrical potential of 0.55 volts between altitudes of 248 kilometers and 768 kilometers—just enough to explain the polar wind on its own, without any other atmospheric effects.

The measurement is solid and exciting, says planetary scientist David Brain of the University of Colorado Boulder, who was not involved in the new work. But it’s just one data point from a rocket. “I think this result is a really big result that argues that there should be more measurements like this,” he says.

Collinson agrees. He and his colleagues recently won NASA approval for a follow-up rocket—this time called Resolute, for an Arctic exploration ship that launched in 1850.

Because the ambipolar electric field helps control how quickly a planet’s atmosphere escapes into space, it probably plays a role in making a planet hospitable to life, Collinson says. Scientists think Mars was once more like Earth, but lost much of its atmosphere to space over time (SN: 11/27/15). Venus may once have been much wetter than it is today (SN: 8/1/17).

Both of these planets also have ambipolar electric fields, but they may have been better off without them.

“If this process didn’t exist on Venus and Mars, then I think it’s possible that Venus and Mars would have lost less oxygen, and therefore less water,” says Brain.

Earth’s ambipolar electric field helps push its oxygen into space, too. But Earth has one major advantage over Mars and Venus: a global magnetic field to direct charged particles around the planet. “The electric field is the engine that makes the particles move,” says Brain. “The magnetic field is a kind of path along which particles move.” The Earth’s magnetic field means that oxygen can only escape near the poles, and not from every part of the atmosphere. This may help explain why Earth has retained its habitable atmosphere for much longer than Venus or Mars.

“Basically, what makes a planet habitable is going to be a lot of things,” Collinson says. “But I think comparing these different energy fields across different planets is one way to answer the question, why is Earth habitable? Why are we here?”

Quantum entanglement has made its way to the top.

Scientists have measured the strange quantum phenomenon of entanglement in top quarks, the heaviest fundamental subatomic particles known. It is the first detection of entanglement between pairs of quarks – a class of subatomic particles that make up larger particles, including protons and neutrons.

Particles that are entangled have properties that are linked or correlated with each other, causing the two to behave as a unit even when separated by large distances (SN: 15.6.17). Entanglement is usually studied in relatively small laboratory experiments using light particles or photons. In contrast, the new measurement required the world’s most powerful particle accelerator, the Large Hadron Collider at CERN, near Geneva. It is the highest energy detection of entanglement ever.

Using data from proton collisions, scientists with the ATLAS experiment, a particle detector at the Large Hadron Collider, studied the collisions that formed a top quark and its antimatter counterpart, a top antiquark. The two particles become entangled through their spin, a quantum property similar to spin motion. This means that the spins of the two particles are coupled, so measuring one spin will immediately tell you the other.

To detect the entanglement, scientists observed the particles into which the top quark and antiquark decayed. The angles at which those particles were emitted revealed the entanglement, researchers from the ATLAS collaboration report Sept. 18 in Nature. (CMS, another experiment at the Large Hadron Collider, also found evidence of top quark entanglement this year, in a study that has yet to be peer-reviewed.)

As quarks go, top quarks are special. In general, quarks don’t like to be alone, so when they break apart in high-speed collisions, pairs of quarks and antiquarks quickly materialize, morphing together into larger particles. This process, known as hadronization, removes any entanglement. But top quarks and antiquarks decay so fast that hadronization cannot occur, so the particles they decay into can carry the signature of their entanglement.

That is, for the demonstration of entanglement, the top quarks have the upper hand.