Falling space debris poses an escalating risk as spacecraft get stronger and more heat resistant

Source: The Conversation – USA – By Matthew Ray, Professor of Chemistry, University of Wisconsin-Stout

Not all space debris burns up in the atmosphere before it makes it back to Earth. PaulFleet/iStock via Getty Images

When it comes to space debris, what goes up is coming down more often – and not safely.

When spacecraft launch, some components, including nonreusable rocket boosters, are jettisoned to decrease weight, leaving them to intentionally burn up as they reenter the atmosphere. Satellites also enter the atmosphere at the end of their life, supposedly burning up. But in many cases, they are not doing so as predicted.

Debris from partially burned-up spacecraft components and satellites reentering Earth’s atmosphere can pose a risk to people and structures on the ground. The surge in launches, driven largely by private players such as SpaceX, is turning a once-remote risk into a growing threat.

Our materials research group at the University of Wisconsin-Stout is studying the materials that allow reentry debris to survive. We look for ways to safely modify their exceptional heat-resistant qualities to make them safer for atmospheric reentry.

Debris landing on Earth

Reentry debris has fallen on both private and public property around the world multiple times since 2021. Some of the most notable events involve pieces from SpaceX Dragon’s carbon fiber trunk, which stays attached to the crewed capsule until just hours before its reentry. These trunks are larger than a 15-passenger van and used for storage.

Trunk debris from the Crew 7 mission to the International Space Station has landed in North Carolina, and fragments from the Crew 1 mission landed in New South Wales, Australia. Similarly, debris from the Axiom 3 mission landed in Saskatchewan, Canada.

A large piece of space debris from a SpaceX Dragon capsule was found by a campsite groundskeeper in North Carolina in 2025.

In addition to trunk debris, carbon fiber components that hold pressurized gases to adjust a spacecraft’s orientation also make up a lot of recovered reentry debris. Some of these most recent recoveries have been in Australia, Argentina and Poland.

Most of the debris that reenters the atmosphere burns up, so why are these pieces making it down to Earth’s surface?

Atmospheric reentry

Satellites such as SpaceX’s Starlink reside in low Earth orbit, typically between 190 and 1,240 miles (300 and 2000 kilometers) above the Earth’s surface. To stay there, they need to move really fast, at about 17,000 miles (27,000 km) per hour. To reach this speed, a rocket with a million pounds of fuel had to accelerate it, and part of this energy is still contained within the satellite’s momentum.

As an object in orbit drifts down, closer to Earth’s upper atmosphere, it starts to collide with air molecules, slowing the object down. The amount of heat generated from this interaction rapidly consumes the satellite, melting metal at over 3,000 degrees Fahrenheit (1,600 degrees Celsius).

More launches

Countries around the world have been launching items into space since the 1950s, so why is reentry a concern now?

Starting in the 1960s, about 100 objects were launched into space every year – or at least that was the case until 2016. Since then, the number has been increasing exponentially. In 2016, 200 objects launched. But in 2025, that number was 4,500, meaning 20% of all objects launched into space since the 1950s were launched last year.

Most of these launches came from companies in the United States, such as SpaceX and Rocket Labs. Companies like these, along with those outside of the U.S., have plans for large satellite constellations composed of hundreds of thousands to a million satellites.

The more objects and payloads launched, the more reentry events occur. Satellite operators are required to remove their decommissioned satellites from orbit after 25 years to comply with regulations set in place by international committees. Groups across the world, including the Federal Communications Commission in the U.S., have pushed to shorten the deorbit window to five years. Because of these guidelines, the full influx of reentry debris events from these recent launches will not be felt for another 10 or more years.

The objects launched and policy decisions made today will have a lasting effect on future safety.

Carbon fiber

As the world has progressed technologically, efficiency for launching items into space has too.

Satellites and spacecraft are becoming lighter, stronger and more heat resistant because of materials such as carbon fiber-reinforced plastics and new metals. These strong materials are sought after because they’re lightweight, but they can also cause deorbiting debris to withstand reentry temperatures.

Carbon fiber, once used exclusively in space technology, is now found in common items such as bicycle frames and racing car bodies. It is still the gold standard for fabricating high-strength, low-weight materials for spacecraft components such as rocket fuselages, interstaging – the protective housing found between the rocket stages – and pressure vessels that experience extreme temperatures and high mechanical stress and strain.

Simple metals such as aluminum and steel melt and burn away, while complex materials such as carbon fiber, which is manufactured at up to 5,000 F (3,000 C), burn away unpredictably, changing the way jettisoned components break up upon reentry.

Since the early 2000s, a majority of recovered space debris contains either carbon fiber-reinforced plastic sections or metal components wrapped with carbon fiber. The carbon fiber can act as an unintentional heat shield for heavier, more harmful debris.

A map showing the world with dots spread across the U.S., South America, the coasts of southern Africa, Australia and Southeast Asia.
This map shows locations where confirmed space debris has been recovered. With the increase in launches, the European Space Agency predicts that future space debris could fall practically anywhere across the world.
European Space Agency

Design For demise

Design for demise is a major area of research focused on mitigating the risk of reentry debris. Instead of relying on controlled and meticulously timed deorbits that send components that survive reentry into the ocean at the end of their lives, spacecraft components are engineered to ensure they completely disintegrate while deorbiting through the atmosphere.

Design for demise can take many forms. These range from changing to more heat-susceptible materials to relocating harder-to-burn components to areas of the spacecraft that will be hotter during reentry, or using linkages that break apart at high temperatures to separate structures into smaller components to help them burn up.

With so much focus historically on spacecraft being made from the lightest, strongest and most heat-resistant materials available, it may seem counterintuitive to intentionally make some materials weaker. The key is making materials smarter, so they maintain their strength during their mission but weaken under the heat of reentry.

The Conversation

Matthew Ray’s lab is developing and working toward patenting a system to decrease risk from future carbon fiber based reentry debris.

Reese Hufnagel conducts research on space debris and is developing ways to make future carbon composites safer for use in orbit.

ref. Falling space debris poses an escalating risk as spacecraft get stronger and more heat resistant – https://theconversation.com/falling-space-debris-poses-an-escalating-risk-as-spacecraft-get-stronger-and-more-heat-resistant-279077

Most people don’t know what they don’t know, but think they do – correcting your metaknowledge can make you a better teacher and learner

Source: The Conversation – USA – By Thomas Blanchard, Research Associate in Cognitive Science, Tufts University

The ability to say ‘I know that I know nothing’ could be considered a sign of wisdom. Nicolas-André Monsiau/Pushkin Museum of Fine Arts via Wikimedia Commons

Do you know what the Apple logo looks like?

Chances are, you think you do. It’s ubiquitous and iconic. How could you not know it?

But when tested, it turns out very few people can remember all the features of the logo. One study of 85 people found that only about half could pick the correct logo out of a lineup of similar ones. And only one person could correctly draw it.

This isn’t an isolated example. A classic study from 1979 found that people similarly couldn’t draw a penny accurately or pick out a correctly drawn penny from incorrect ones.

People aren’t just bad at remembering things they see all the time, but also in actually knowing how they work. In a 2006 study, many people made significant errors when drawing a bicycle, like putting the chain around the front wheel as well as the back wheel. More than just a forgotten detail, putting the chain around both wheels shows a deeper misunderstanding of how a bicycle works. A bicycle with a chain around both wheels wouldn’t be able to turn.

Illustration of bike with different components labeled
Do you truly know how a bicycle works?
Al2/Grandiose via Wikimedia Commons, CC BY-SA

It turns out people’s knowledge of how the world works is often fragmented and sketchy at best. They systematically overestimate their understanding of everyday devices and natural phenomena. People will tend to give themselves high ratings on how well they understand something, such as how bicycles or zippers work. But when they’re asked to actually explain the mechanics of these objects, their ratings of their understanding typically drop.

Just like how your knowledge of the world around you is imperfect, your knowledge about your own knowledge – also called metaknowledge – is often flawed. My field of cognitive science has been uncovering various gaps in human metaknowledge for decades.

If people are systematically overconfident about how well they understand things, why don’t they notice when they don’t understand something? And what can people do to better recognize the limits of their own knowledge?

Why you think you know more than you do

Researchers have identified several factors behind people’s overconfidence in their knowledge.

One is that people confuse environmental support with understanding: The information is out in the world but not actually in your head. With a bicycle or a zipper, all of the parts are visible to you, and you may confuse this transparency for an internal understanding of how they work. But until you go to use that knowledge by attempting to explain how they work, you may not recognize that you don’t understand how those parts interact.

A second factor is confusing different levels of analysis. People can often describe how something works at a very high level. You know that the engine of a car makes the car go, and the brakes slow and stop the vehicle. But confidence in your high-level understanding of the car may bias you to think you also have a good grasp of the finer details, like how the engine pistons and brake pads work.

Additionally, people can be blind to the ways their knowledge shapes their own perception. In one study, researchers had participants tap out the tune to a popular song. On average, the tappers thought listeners would be able to identify the song about 50% of the time. But when listeners had to identify the tapped song, they actually could identify it only 2.5% of the time. The tappers didn’t realize how much their knowledge was making identifying the song seem easy to them.

A teacher talks to a student before a chalkboard wall filled with equations, chemical structures and graphs
Intellectual humility can help you see your expert blind spot.
Vitaly Gariev/Unsplash, CC BY-SA

This disconnect has consequences beyond whether someone else can understand your Morse code version of a song. When teaching people, whether in formal classroom settings or through casual mentorship, you can sometimes have an expert blind spot: the inability to recognize the difficulties beginners face when learning something you have expertise in.

Building expertise often involves internalizing knowledge to the point where it becomes invisible to you. You draw on knowledge you don’t realize you have, making it hard to relate to learners who lack this knowledge – and, of course, hard for learners to relate to your teaching. You might have experienced this when you’ve gotten partway through explaining something, only to realize you’ve been using jargon you forgot isn’t common knowledge and lost your listener.

How to address metaknowledge failures

Your metaknowledge can fail in two directions: You can think you know more than you do, and you can be blind to how much you’re relying on knowledge you do have. Each calls for a different response to correct it.

When you’re overconfident in your knowledge, the remedy is using that knowledge. You’ll quickly realize how much you actually understand and dial down your confidence. Challenging yourself to actually try to walk through how something works is a great exercise in intellectual humility – that is, recognizing that you may be wrong – and can keep you from getting out over your skis.

Building a greater appreciation for what you know is more difficult. You can’t simply unlearn what you’ve internalized. But what this challenge shows is that, to some extent, knowing a subject and knowing how to teach it are two separate skills. Some experts are great teachers, but not simply by virtue of being experts. Recognizing that you have to approach teaching with humility, and that your expertise doesn’t automatically make you a skilled teacher, can go a long way toward making you a better teacher and mentor.

These aren’t easy and quick fixes to failures of metaknowledge. Both require ongoing intellectual humility and a willingness to distrust your own confidence. But acknowledging the fallibility of your own metaknowledge is a good place to start.

The Conversation

Thomas Blanchard does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

ref. Most people don’t know what they don’t know, but think they do – correcting your metaknowledge can make you a better teacher and learner – https://theconversation.com/most-people-dont-know-what-they-dont-know-but-think-they-do-correcting-your-metaknowledge-can-make-you-a-better-teacher-and-learner-280905

Why Trump’s call to pull 5,000 US troops from Germany will hurt America

Source: The Conversation – USA – By Michael A. Allen, Professor of Political Science, Boise State University

The propeller of a ‘raisin bomber’ airplane from World War II is seen in Frankfurt, Germany, in June 2020. AP Photo/Michael Probst

President Donald Trump announced on May 1, 2026, that the United States will withdraw 5,000 U.S. troops from Germany – personnel who had been deployed there as a response to Russia’s invasion of Ukraine.

Germany-U.S. tensions started after the U.S. invasion of Iran. German Chancellor Friedrich Merz refused to support Trump’s war and stated that Iran had humiliated Washington’s leadership by closing the Strait of Hormuz. Trump followed the initial U.S. troop withdrawal announcement with threats to pull more armed forces.

U.S. troops will depart Germany over the next six to 12 months, leaving about 31,000 troops in the country.

The Trump administration’s decision to withdraw personnel comes after weeks of mounting tensions between the U.S. and NATO members. The United Kingdom and Portugal have restricted Washington’s ability to use its bases in those countries for certain activities related to the Iran war.

Trump also threatened to withdraw U.S. troops from Spain and Italy over their opposition to the war and refusal to help the U.S.

“Why shouldn’t I?” Trump said on April 30, 2026, referring to possible U.S. troop withdrawal from the two European countries. “Italy has not been of any help. Spain has been horrible. Absolutely.”

These remarks suggest the Trump administration views U.S. troop withdrawal as punishment for noncompliant European allies. But the reality is more complicated. Although this proposed 5,000-troop reduction is less than 15% of current U.S. forces in Germany, its logic and consequences speak to broader issues of power projection.

As experts in international relations, foreign policy and security cooperation, we have studied the relationship between U.S. military deployments and their host countries for years. While U.S. deployments contribute to the security of the host state, having troops based in Europe and other countries provides the U.S. with significant flexibility for pursuing its own foreign policy goals.

US deployment levels

Europe has historically been one of the regions with the highest concentrations of U.S. military personnel deployed overseas.

Since the end of the Cold War, for example, Italy has hosted between 20,000 and 40,000 personnel, and Spain between 2,000 and 7,000 personnel. Germany has regularly hosted the largest deployments. At the end of the Cold War, the U.S. maintained approximately 227,000 military personnel in Germany. Though Europe remains a significant location for basing U.S. troops, this number fell dramatically in the 1990s, hovering between 50,000 and 75,000 for most years since then.

US power projection

Historians and policymakers often explained U.S. deployments to Europe as a means of deterring the Soviet Union during the Cold War.

Nobel laureate Thomas Schelling described the logic in 1966: Even a small deployment in West Berlin served as a trip wire, ensuring that Soviet incursions would trigger a much larger military response from the U.S. and its European allies.

But a closer look at U.S. foreign policy challenges this view. While U.S. troops stationed in Europe were meant to defend Europe, their utility has extended far beyond that.

U.S. military bases and deployments provide the U.S. with greater flexibility and opportunities to pursue its foreign policy goals. By forward positioning military personnel and assets, the U.S. can reduce response times during crises, as well as the costs of moving its military resources into strategic positions.

A military plane lands on a runway.
A U.S. military aircraft lands at Incirlik Air Base in Adana, Turkey, as part of the operations against ISIS on Aug. 10, 2015.
Volkan Kasik/Anadolu Agency/Getty Images

Foreign deployments can convince countries not to attack countries that host them. During the Cold War, for example, the U.S. deployed nuclear weapons to Incirlik Air Base in Turkey, a NATO ally. Turkey’s close proximity to the Soviet Union increased the U.S.’s ability to challenge its superpower rival with these weapons.

These missiles were famously later withdrawn during the Cuban missile crisis in 1962, giving the U.S. something to bargain with in persuading the Soviets to remove their missiles from Cuba.

Larger military engagements, such as the Vietnam War or the wars in Iraq and Afghanistan, have typically relied on U.S. military facilities in allied states that are closer to the conflict. During the Vietnam War, U.S. bases in Germany, Japan and the Philippines were used as staging areas through which U.S. personnel and equipment moved on their way in or out of Southeast Asia.

U.S. facilities in Germany, such as Ramstein Air Base and Landstuhl Regional Medical Center, have been integral to combat operations, satellite control of drones and treating U.S. personnel wounded in combat. Landstuhl has admitted over 97,000 wounded soldiers since its founding in 1953 and has already treated service members injured during the ongoing Iran war.

Further, military equipment such as radar and interceptor missiles often have limited ranges. Deploying this equipment closer to rival countries can increase the chance of successfully intercepting and destroying incoming missiles.

Humanitarian benefits

Beyond warfare, U.S. humanitarian relief and disaster response operations often benefit from U.S. bases.

For instance, after a large earthquake struck Japan in 2011, U.S. personnel and facilities located in and around Japan enabled the rapid mobilization of relief operations.

A military transport plane takes off from a runway.
A U.S. Air Force C-17 Globemaster transport plane takes off from Ramstein Air Base in Germany on June 23, 2025.
Boris Roessler/Picture Alliance via Getty Images

In 2004, a powerful earthquake in the Indian Ocean triggered large tsunamis, affecting millions of people in nearby countries. U.S. personnel stationed at Yokota Air Base near Tokyo provided relief and supplies to people throughout Southeast Asia and as far as eastern Africa.

Similarly, after an earthquake in Turkey in 2023, U.S. medical personnel relocated from Germany to Incirlik Air Base to help provide relief.

Beyond their humanitarian benefits, these missions can increase favorable views of the U.S. More positive public views of America may also make foreign governments more likely to support U.S. foreign policy goals.

Lower costs for the US

Host states often make direct and indirect contributions to the costs of hosting and sustaining U.S. personnel. These can range from direct financial transfers to construction, tax reductions and subsidies. Japan and South Korea increased the amount they pay to host U.S. troops after Trump demanded they do so in 2019.

U.S. equipment – from tanks and trucks to planes and ships – also often relies on a host country’s infrastructure to operate and move within the host country. Germany, for example, paid over US$1 billion for construction costs and the stationing of U.S. troops in Germany during the 2010s.

Not all countries that host U.S. troops invest as much in their infrastructure as Germany does, and having those troops elsewhere could prove far more costly than having them in Germany.

The Conversation

Michael A. Allen received grant research funding from the Department of Defense’s Minerva Initiative, the US Army Research Laboratory, and the US Army Research Office from 2017 to 2021.

Carla Martinez Machain has received funding from the Department of Defense’s Minerva Initiative, the US Army Research Laboratory, and the US Army Research Office.

Michael E. Flynn has received funding from the Department of Defense’s Minerva Initiative, the US Army Research Laboratory, and the US Army Research Office.

ref. Why Trump’s call to pull 5,000 US troops from Germany will hurt America – https://theconversation.com/why-trumps-call-to-pull-5-000-us-troops-from-germany-will-hurt-america-282116

We tested the new World Cup ball – this is what you need to know about how it will fly, dip and swerve

Source: The Conversation – USA (2) – By John Eric Goff, Professor of Physics, University of Lynchburg

Small variations in the ball can influence how it behaves once it leaves the foot. Robbie Jay Barratt/AMA/Getty Images

Every four years, the men’s World Cup delivers some certainties. The pitch dimensions are tightly regulated, offside is signaled with a flag, and referees end the match with a blast of a whistle. But one key piece of equipment is changed on purpose: the ball.

Adidas, which has supplied World Cup soccer balls since 1970, introduces a new match ball for every tournament, and with that comes fresh aerodynamic calculations for players. How will it fly through the air, weave and dip?

For the past 20 years, my engineering colleagues in Japan and England and I have put the new balls through their paces, investigating soccer ball aerodynamics. Our work begins by putting balls in wind tunnels to measure drag, side and lift forces. We use the measurements from these tests in trajectory simulations that tell us how the ball will behave in a real-game setting.

Putting the 2026 World Cup ball through the wind tunnel test.

That may all sound a little academic, and we do produce an academic paper on our findings. But what our data indicates could mean the difference between a goal or a miss for strikers, a save or a blunder for goalkeepers, and jubilation or heartache for fans.

At the World Cup, the ball is the most important piece of equipment in the biggest tournament of the world’s most popular sport.

This year’s ball, the Trionda, is especially interesting. When FIFA and Adidas unveiled it in fall 2025, the first thing many people noticed was the color and the paneling.

An orange ball and a black and white ball are under a trophy.
Earlier World Cup balls used many panels; modern balls use far fewer.
Manfred Rehm/picture alliance via Getty Images

The ball’s red, blue and green graphics correspond to the three host countries, with maple leaf, star and eagle motifs representing Canada, the United States and Mexico. And for the first time in men’s World Cup history, matches will be played with a four-panel ball.

But with so few panels, has Adidas made the ball too smooth? That is the trap engineers fell into with the Jabulani ball used at the 2010 World Cup in South Africa that became notorious for sudden dips and swerves, which made goalkeepers’ lives far trickier.

You do not want the World Cup ball to feel like the start of a science experiment once it is in the air. And if it behaves strangely, players and goalkeepers notice immediately.

The evolution of soccer balls

World Cup balls have come a long way over the decades. If you go back to 1930, the ball looked very different. The first World Cup final used two different leather balls: Argentina’s Tiento in the first half and Uruguay’s T-Model in the second. Both were hand-sewn, multipaneled balls, inflated through a bladder opening that had to be tied off and tucked back beneath the laces. In damp conditions, the leather absorbed water, making the ball heavier and less predictable in play.

A ball nestles in the top of a goal.
Uruguayan keeper Enrique Ballestrero fails to save a shot from Argentina’s Carlos Peucelle in the final of the first World Cup.
Keystone/Getty Images

By 1994 – when the United States last hosted the men’s tournament – the official ball, Adidas’ Questra, had evolved into a foam-based design. The modern World Cup ball is no longer just stitched leather. It is an engineered aerodynamic surface.

Trionda pushes that evolution further. It has only four panels, the fewest in men’s World Cup history, which have been thermally bonded – melded together using heat and adhesive.

Fewer panels might suggest less total seam length and therefore a smoother ball. And smoothness matters because the thin boundary layer of air clinging to the ball determines where the flow separates, how large a wake forms, and how much drag the ball experiences.

The Trionda has intentionally deep seams, three pronounced grooves on each panel and fine surface texturing.

But will these textures and grooves do the trick? To find that out, my colleagues and I measured the ball’s seam geometry and overall aerodynamic behavior. We compared it with Trionda’s four predecessors: 2022’s Al Rihla, 2018’s Telstar 18, the Brazuca used in 2014 and the Jabulani in 2010.

What the measurements show

In our wind tunnel tests at the
University of Tsukuba, we measured
something called the drag coefficient, which is a way of describing how much air resistance a ball experiences as it moves.

Using this data, we gained insights into how the airflow changes around the ball after it is kicked. The tests helped identify the drag crisis, the speed range in which changes in the boundary layer and flow separation produce a sharp change in drag, which can alter the ball’s acceleration, trajectory and range.

A ball is seen suspended.
The Trionda soccer ball prepares for the wind tunnel.
Goff/Hong/Liu/Asai

We found that the Trionda is effectively rougher than those predecessors.

Trionda reaches its drag crisis at a lower speed, at about 27 mph (43 kph). That is below the roughly 31-40 mph (50-65 kph) range for Al Rihla, Telstar 18 and Brazuca, and far below Jabulani’s roughly 49-60 mph (79-97 kph) range, depending on orientation.

Why does all that matter? Because a ball can feel ordinary off the boot and still behave differently in flight. When the drag crisis occurs in the middle of game-relevant speeds, small changes in launch speed, orientation or spin can shift the ball from one aerodynamic regime to another.

That was Jabulani’s problem. Once kicked with little spin, it had a tendency to slow down too much as it passed through its critical-speed range.

Trionda does not look like that kind of ball. It has a more steady and consistent drag coefficient in the range of speeds associated with corner kicks and free kicks.

But there is a trade-off. Our measurements also showed that once Trionda enters the higher-speed, turbulent-flow regime, its drag coefficients are somewhat larger than those of Brazuca, Telstar 18 and Al Rihla.

In plain language, that suggests a hard-hit long ball may lose a little range.

In our simulations, the difference is not huge. But it is large enough that players may notice long kicks coming up a few meters short.

It is also important to note that we tested a nonspinning ball. As such, our results do not provide a prediction of every pass, clearance or free kick fans will see this summer. Balls in flight often spin due to off-center kicks. That, along with altitude, humidity, temperature and air pressure all influence how a ball flies through the air once kicked.

A ball mounted on a rod.
Close-up of the Trionda ball during wind tunnel testing.
Goff/Hong/Liu/Asai

The big test yet to come

Fewer panels and more texturing aren’t the only differences with the new ball.

Trionda also carries technology that has little to do with its flight and a great deal to do with officiating. Like Al Rihla, Trionda includes “connected-ball technology” that lets computers know when the ball is kicked, helping with offside decisions.

But the architecture has changed. In 2022, the measurement unit was suspended at the center of the ball. With Trionda, it sits in a specially created layer inside one panel, with counterbalancing weights in the other three panels. The chip sends data to the video assistant referee, or VAR, system and the tournament’s semi-automated offside system.

That tweak will help referees, but will the new ball in general help or hinder players?

The evidence from our tests suggests that the ball won’t be behaving in a way that leads to baffling and erratic flight.

But the more intriguing possibilities are subtler and outside the scope of our tests. Will the grooves on Trionda help players generate more backspin on the ball, generating more lift and possibly offsetting Trionda’s somewhat larger high-speed drag coefficient?

That is why I keep studying World Cup balls both in the lab and through their behavior in play. Every four years, a new design offers a fresh way to watch physics enter the game, not in theory, but in the movement of an object in which every player on the soccer field must place their trust.

The Conversation

John Eric Goff currently works as a visitor in the Department of Physics at the University of Puget Sound in Tacoma, Washington. Following the conclusion on 30 June of that one-year appointment, he will start on 1 July as Professor of Engineering Practice in the Weldon School of Biomedical Engineering and the School of Mechanical Engineering at Purdue University.

ref. We tested the new World Cup ball – this is what you need to know about how it will fly, dip and swerve – https://theconversation.com/we-tested-the-new-world-cup-ball-this-is-what-you-need-to-know-about-how-it-will-fly-dip-and-swerve-280781

Immigrant patients often choose doctors with a shared cultural background – what they are seeking isn’t sameness but connection

Source: The Conversation – USA (3) – By Yasamine Salkar, Clinical Assistant Professor of Health Administration, Georgia State University

Patients seek clinical interactions where they feel heard. Evgeniia Siiankovskaia/Moment via Getty Images

At a recent dental appointment, I was unexpectedly seen by a new provider in my longtime dentist’s practice. Early in the visit, he realized we were both Iranian American. Like me, he had been born and raised in the United States. We were both fluent English speakers and fully accustomed to navigating American medical settings.

After we briefly discussed how the war in Iran was affecting our families there, something shifted. The exchange was short, but deeply human. I left feeling an immediate sense of connection, trust and familiarity with a provider I had only just met.

That experience helped me better understand something I had long observed among immigrant families – that immigrant patients often seek out healthcare providers from similar backgrounds. What they are often seeking goes beyond a shared language or cultural familiarity.

I am a health administration professor and lawyer who studies how people navigate health systems. In my work, and through conversations with immigrant families, including my own, I have seen how subtle interactions in clinical settings can shape whether patients feel confident or dismissed and unsure about returning for care. For some, choosing a doctor with a similar background represents their best attempt to feel more understood.

The fact that many patients actively seek out providers who share aspects of their cultural background, even when doing so may require additional effort or limit their options, illustrates that it is not a minor preference, but a meaningful part of how people experience care.

Beyond a shared language

Immigrants make up a growing share of patients in the U.S., accounting for about 15% of the population.

Large national studies suggest that patients often seek providers with whom they share a cultural background. That choice is especially pronounced among racial and ethnic minority patients, those who speak a language other than English at home and those with public insurance.

Even as the U.S. physician workforce becomes more diverse, many patients still report difficulty finding providers who share their cultural or linguistic background. At the same time, some evidence suggests the number of foreign-born physicians may also be declining. In my view, that makes the effort to find such providers all the more noteworthy.

Busy health care waiting room with a doctor discussing treatment plans with mother and daughter and a desk in the background.
Healthcare providers can do a lot to support patients’ sense of trust in their care.
Dragos Condrea/iStock via Getty Images

A shared language may seem like the most obvious explanation for why immigrants seek out doctors from similar backgrounds. And in many cases, it does matter. When patients and clinicians speak the same language, communication improves and medical errors decline, especially for patients who are not fluent in English.

But language alone does not explain experiences like my own.

Narrative research on immigrant patients describes broader issues. For example, a patient might raise a concern about a persistent symptom, only to feel too quickly dismissed, or hear an explanation delivered in a simplified way that does not match their level of knowledge or experience.

These moments can be subtle, but as they accumulate over time, they may contribute to a sense that medical care feels transactional or dismissive rather than responsive to patients’ concerns. Even patients who are fully fluent in English and comfortable navigating the health system may come to expect not to be fully heard.

That expectation can shape where people feel comfortable seeking care.

Why shared background can matter

Sharing a background, whether through race, ethnicity, language or cultural experience, can sometimes help create a sense of connection – especially at the start of a relationship.

But research suggests the relationship is more nuanced than simply matching patients and doctors by identity. The way a doctor communicates, as well as whether they listen carefully, take concerns seriously and involve patients in decisions, also plays a central role.

In one study that examined physician-patient relationships across racial and ethnic groups, patients who felt personally similar to their physician – for example, in how the physician communicated, approached decisions or seemed to understand their concerns – were more likely to trust their doctor, feel satisfied with their care and follow medical advice.

Research on patient-centered care has similarly found that patients value interactions where they feel respected, understood and able to communicate openly.

Together, these studies suggest that while shared backgrounds can sometimes help create trust, communication and interpersonal connection may matter just as much.

More research is needed to understand how much these experiences reflect differences in communication itself versus connection spurred by a common background. But for immigrant patients, it may not be the shared identity itself that matters most, but the expectation that it will help them feel more easily understood. When patients consistently struggle to find that experience, shared background can become one of its few visible signals.

Understanding why immigrant patients make these choices ultimately reveals something more universal: Trust in medicine is shaped not only by clinical expertise, but by everyday human interaction. And patients value this quality so highly that they actively seek out providers who they believe will offer that sense of understanding and connection.

The Conversation

Yasamine Salkar does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

ref. Immigrant patients often choose doctors with a shared cultural background – what they are seeking isn’t sameness but connection – https://theconversation.com/immigrant-patients-often-choose-doctors-with-a-shared-cultural-background-what-they-are-seeking-isnt-sameness-but-connection-271676

How tarot readers are using AI – and what it says about our growing reliance on chatbots for emotional support and advice

Source: The Conversation – USA (3) – By Ziv Epstein, Postdoctoral Associate, Schwarzman College of Computing, Massachusetts Institute of Technology (MIT)

Tarot readings can encourage self-reflection. But what happens when you turn to AI to interpret the cards? Ilya S. Savenok/Getty Images for Sally Hansen

If you’ve ever turned to artificial intelligence to try to figure out how to handle a tricky situation with a friend or colleague, you’re far from alone. For many, AI has become a modern oracle – a source of guidance, emotional support or clarity in moments of uncertainty – though critics worry that they could lead to emotional dependence on the technology.

Of course, the urge to seek answers from forces beyond ourselves is hardly new. For generations, people have turned to psychics, astrology charts or tarot cards for reassurance.

Once fringe, these practices have increasingly become mainstream. According to a 2025 Pew Research survey, nearly 1 in 3 Americans consult tools such as tarot or astrology at least once a year, interest that’s thought to largely be fueled by Gen Z and social media.

Now, we’re seeing these two forces – AI and occult practices – meeting in strange and fascinating ways. An increasing number of tarot readers, from novices to seasoned practitioners, have been turning to AI to help make sense of their tarot readings.

What makes this pairing so striking is that interpretation is the whole point of tarot. And yet AI often brings little knowledge of your history or your unique situation when it dispenses advice.

In a study published in April 2026, we examined which aspects of the practice that tarot readers were delegating to AI, and how the technology was shaping their interpretations.

Watching what happens when readers hand that important interpretive step to AI may offer a glimpse of what helpful AI guidance could look like – and where it could go wrong.

The mainstreaming of occult practices

Tarot cards are experiencing a revival.

Tarot did not start out as a spiritual or fortune-telling tool. It began as a popular card game in the Italian Renaissance, before spreading across Europe.

Over time, readers and occultists layered the cards with mystical symbolism drawn from Kabbalah, Egyptology, numerology and other mystical and symbolic traditions. In the early 20th century, the British publisher William Rider & Son released the Rider-Waite-Smith deck, which became the most popular tarot deck in the English-speaking world.

Whereas only a handful of tarot decks were being published in the early 1970s, today thousands of tarot and oracle decks are in circulation. A standard tarot deck contains 78 cards, each carrying its own symbolic meaning. Practitioners use the cards to sit with hard questions, which can range from difficult relationships to world events: Should I leave my partner? Is this job worth it? What’s going to happen with Donald Trump and the Strait of Hormuz?

After cards are pulled, their meanings are interpreted through the lens of the reader’s question, circumstances and life history.

Someone asking about a relationship and drawing the Tower card, for instance, might read it as impending rupture, or as false assumptions finally giving way. Which reading fits depends on the other cards, the specific question and what the reader already knows about their own situation.

This stands in contrast to AI, which is primed to produce a seemingly definitive answer, even when it’s unaware of the nuances of your situation and context.

The adoption of AI in tarot reading

For our study, we interviewed 12 tarot practitioners about their use of AI in readings they did for themselves.

They generally found themselves pulled in two directions.

On the one hand, they often sought explicit guidance from AI in the process of self-reflection. By using AI to interpret the cards, they could sidestep the frustration of interpreting many cards in light of the question asked.

Say someone drew the Fool and the Ten of Wands for a question about a career change. The Fool points toward a leap into the unknown, while the Ten of Wands speaks to burnout and an unsustainable load.

But do the cards say, “Leave, you’re exhausted and something better awaits”? Or “Leave, and the new job will be just as demanding”?

Rather than sit with that ambiguity, some readers simply ask the AI for the meaning of the reading.

A middle-aged woman wearing glasses smiles and gazes at a large, blue tarot card in her right hand.
An attendee at Google’s 2025 I/O developers conference wears Android XR glasses with Gemini AI, which she’s using to interpret a tarot card.
Camille Cohen/AFP via Getty Images

For more challenging readings, AI’s “yes man energy” helped them feel more confident about their interpretations. This was true for cases where participants both drew physical tarot cards and then interpreted them with AI, or used AI to directly simulate tarot readings.

These uses of AI are seductive. They make the act of self-reflection less demanding. But within the broader tarot community, we found a lot of criticism of AI, and there were concerns about how the sycophantic nature of the technology could undermine people’s intuition and reasoning.

AI as a tool for critical engagement

On the other hand, the tarot readers we interviewed also used AI as a tool to challenge their own biases and assumptions – blind spots in their readings, or what they might be missing in their own interpretation of the cards.

Along these lines, they used AI to generate alternative perspectives so they could compare the different interpretations and see which resonated more. And some even asked for an “objective reading” of the cards, because AI appears to have no skin in the game and be unburdened by personal biases or motives.

Many readers did this when they didn’t want to “bug” or “pester” their friends for help with a reading. Instead, they relied on chatbots in a one-sided relationship that feels supportive – an example of what scholars call parasocial interaction.

Some interviewees even treated bizarre AI-generated outputs or hallucinations as meaningful precisely because they were random and unintended, the same way that a card drawn at random feels like it carries a secret message.

What does this mean for the future of AI?

AI is becoming a powerful new oracle in its own right.

In one recent survey, researchers found that up to 87% of generative AI users are consulting the technology for “personal applications,” which includes advice and emotional support for relationship conflicts and mental health struggles.

Sometimes these chatbots are genuinely helpful. But at the same time, advice seekers can also become emotionally dependent. Some rely on the technology for companionship and guidance instead of friends and family. Chatbots have also been found to nurture delusional beliefs and even lead to self-harm.

Meanwhile, professionals that regularly give guidance are using AI in their practice, from lawyers to therapists and even priests. Pope Leo XIV recently urged priests to resist the temptation to use AI to write sermons.

We think it’s important to make sure the technology isn’t seen as an all-knowing source of truth. It can certainly open up users to new ideas, but it should be a tool to enhance self-reflection, rather than one that serves as a substitute for it.

In some cases, that’s what the tarot readers in our study did. They tapped into their own capacity for reflection by using AI to explicitly challenge their own biases and assumptions. This points to an alternative blueprint for the future of AI – one in which the technology doesn’t simply hand you answers but keeps you actively engaged in the process of finding them.

The Conversation

The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.

ref. How tarot readers are using AI – and what it says about our growing reliance on chatbots for emotional support and advice – https://theconversation.com/how-tarot-readers-are-using-ai-and-what-it-says-about-our-growing-reliance-on-chatbots-for-emotional-support-and-advice-280106

What a list of Black Death survivors reveals about the way people recovered from plague

Source: The Conversation – UK – By Alex Brown, Associate Professor of Medieval History, Durham University

The Dance of Death by John of Kastav (1490). National Gallery of Slovenia

In our research in the British Library’s medieval collections, we have identified a previously unnoticed document that provides fresh insights into the survivors of the outbreak of plague known as the Black Death (1346–53).

The document – a scrap of parchment inserted into an account of the Ramsey Abbey manor of Warboys in Huntingdonshire – records how much time peasants were absent from work when struck down by the plague. It also reveals the names of those who survived and how long their employers believed recovery could take.

Our study sheds new light on a group of 22 tenants who probably contracted plague, languished on their sickbeds for several weeks, and then recovered.

As one of the deadliest pandemics in recorded history, it has been estimated that between a third and two-thirds of the population of medieval Europe died during the Black Death.

Painting of a grim landscape destroyed by plague
The Triumph of Death by Pieter Bruegel the Elder (1562) shows the social upheaval that followed the plague.
Museo del Prado

Given the sheer scale, many historians have focused on discovering details about those who died. Yet this has left the histories of those who contracted plague and recovered largely untold.

Despite the deadliness of the disease, it was possible to recover from plague, and medieval chroniclers mention the possibility – however unlikely – of survival. For example, Geoffrey le Baker, a clerk of Swinbrook in Oxfordshire, wrote in the following decade that he thought recovery depended on people’s symptoms:

People who one day had been full of happiness, on the next were found dead. Some were tormented by boils which broke out suddenly in various parts of the body, and were so hard and dry that when they were lanced hardly any liquid flowed out. Many of these people escaped, by lancing the boils or by long suffering. Other victims had little black pustules scattered over the skin of the whole body. Of these people very few, indeed hardly any, recovered life and health.

But who recovered? Why did so many succumb to the disease when others survived? And just how long was this “long suffering”? Unfortunately, there is remarkably little documentary evidence because most medieval sources record information about mortality rather than ill health.

Unique list of plague survivors

A unique inclusion in the account of the manor of Warboys details a group of people who fell ill between the end of April and the start of August 1349. The monks of Ramsey Abbey wrote a list of their tenants who had fallen sufficiently sick that they could not work on the lord’s lands and detailed the length of time that they were absent.

People were clearly affected differently by their experience of plague.

The quickest recovery was that of Henry Broun who missed just a single week of work. By contrast, John Derworth and Agnes Mold had much more protracted illnesses and were both absent for nine weeks.

The average length of illness was between three and four weeks, with three-quarters of people returning to work in under a month. The speed of their recoveries is all the more surprising given that they were entitled to up to a year and a day of sick leave from work.

This list of survivors includes a preponderance of tenants who occupied larger holdings on the manor. It has long been debated by historians and archaeologists whether the plague killed indiscriminately, with no regard to status, sex or age, or whether the poor and elderly were more vulnerable.

The survival of so many wealthier tenants could indicate that their higher living standards enabled them to recover more readily than their poorer neighbours, perhaps because they were able to stave off secondary infections and complications. We should not read any significance into the fact that 19 out of the 22 people were men: this reflects the gender bias of manorial landholding rather than any sex-selectivity of plague.

Although 22 people may not seem like many, in a regular year during the 1340s, only two or three absences were recorded during the summer months. It, therefore, represents a tenfold increase in regular illnesses on the manor. Put another way, these sick tenants were absent for 91 weeks’ worth of labour services during just a 13-week period.

Medieval drawing of men harvesting wheat
Medieval peasants at work harvesting wheat (circa 1310).
Queen Mary’s Psalter (Ms. Royal 2. B. VII)

Our understanding of the impact of the Black Death has been influenced by the appalling scale of death. Yet it is only when we add those who fell ill and recovered back into the picture that we can truly understand the seismic shock the pandemic had on society. The dead, dying and sick must have considerably outnumbered the living in villages and cities across Europe.

The consequences of this can be seen in medieval accounts and chronicles, one of which records that “there was so great a shortage of servants and labourers that there was no one who knew what needed to be done”. As a result of this combination of high mortality, unprecedented illness and abysmal weather, the two harvests of 1349 and 1350 have been described as the worst experienced in medieval England, worse even than those that caused the great famine of 1315-17.

This archival discovery allows us to write the history of sickness and recovery back into the Black Death, demonstrating that recovery was possible even during one of the worst pandemics in recorded history.

This new evidence reveals the remarkable resilience of medieval peasants. Many of them lay languishing on their sickbeds, exhibiting buboes (the painful, swollen and inflamed lymph nodes on the groin and neck that were typical of the Black Death), vomiting blood and wracked by fevers and not only survived but returned to work in just a few short weeks.

The Conversation

Research for this article was conducted thanks to funding from a Leverhulme Trust research project grant, ‘Modelling the Black Death and Social Connectivity in Medieval England’.

Dr Grace Owen is a postdoctoral research associate on the Leverhulme-Trust funded project, ‘Modelling the Black Death and Social Connectivity in Medieval England’.

ref. What a list of Black Death survivors reveals about the way people recovered from plague – https://theconversation.com/what-a-list-of-black-death-survivors-reveals-about-the-way-people-recovered-from-plague-275622

Ce que les emojis racontent de la biodiversité

Source: The Conversation – France (in French) – By Tatiana Giraud, Directrice de recherches en biologie évolutive, Université Paris-Saclay

Qui n’a jamais agrémenté un message d’une petite fleur ou d’un singe moqueur ? Les emojis font désormais partie de notre quotidien mais que disent-ils de notre rapport au vivant ? C’est la question que nous avons voulu poser à l’académicienne des sciences Tatiana Giraud, chercheuse en biologie évolutive et autrice de La Biodiversité en Infographies, aux Éditions Tana.


The Conversation : Si l’on regarde les 133 émojis disponibles pour représenter les animaux, les plantes, les champignons et les microorganismes sur Emojipedia, peut-on dire qu’ils représentent fidèlement la biodiversité ?


Tatiana Giraud : Non ! On observe en fait dans les émojis les mêmes biais que dans l’imaginaire collectif. C’est une représentation dominée par les vertébrés, et même surtout les mammifères et les oiseaux. Dans les émojis qui existent, on voit également une sur-représentation des animaux domestiqués, comme les chiens, les chats, les poules. Il y a aussi quelques espèces éteintes comme le dodo, plusieurs dinosaures également, et il y a même des espèces imaginaires comme la licorne ou le dragon. C’est d’ailleurs assez amusant, il y a des espèces imaginaires mais il manque plein d’espèces réelles.

Les emojis représentant la faune, la flore et la fonge sur Emojipedia.
Les emojis représentant la faune, la flore et la fonge sur Emojipedia.
Capture d’écran Emojipedia

Qu’est-ce qui manque pour représenter fidèlement la biodiversité ?

Les emojis disponibles pour représenter les « petites bêtes », ou « bugs » en anglais.
Les emojis disponibles pour représenter les « petites bêtes », ou « bugs » en anglais.
Capture d’écran Emojipedia

T. G. : Si l’on voulait que les émojis représentent plus fidèlement la biodiversité, il faudrait qu’il y ait plus d’insectes. Car sur les 2,15 millions d’espèces de plantes, d’animaux et de microorganismes que l’on connaît aujourd’hui, 49 % sont des insectes.

Double page issue de l’ouvrage La Biodiversité en infographies aux Editions Tana
Double page issue de l’ouvrage La Biodiversité en infographies aux Editions Tana.
Tatiana Giraud, Hervé Bouilly et Catherine Huguet pour Tana Editions, Fourni par l’auteur

Si l’on regarde maintenant le poids du vivant, il faudrait beaucoup plus de plantes. Car si l’on s’intéresse à la biomasse, c’est-à-dire à combien pèsent les organismes sur terre, ce sont les plantes qui gagnent haut la main : elles représentent 80 % de la biomasse des êtres vivants.

Double page issue de l’ouvrage La Biodiversité en infographies aux Editions Tana
Double page issue de l’ouvrage La Biodiversité en infographies aux Editions Tana.
Tatiana Giraud, Hervé Bouilly et Catherine Huguet pour Tana Editions, Fourni par l’auteur

Si l’on regarde enfin les branches dans l’arbre généalogique de la vie sur notre planète, il faut avoir en tête qu’il y a beaucoup plus de lignées de microorganismes que d’animaux ou de plantes.

Les microorganismes sont de nature extrêmement variée, on y trouve deux grands groupes de bactéries très différentes, et aussi des microorganismes eucaryotes, dont les champignons mais aussi plein d’autres lignées mal connues…

Double page issue de l’ouvrage La Biodiversité en infographies aux Editions Tana
Double page issue de l’ouvrage La Biodiversité en infographies aux Editions Tana.
Tatiana Giraud, Hervé Bouilly et Catherine Huguet pour Tana Editions, Fourni par l’auteur
Les deux émojis champignons disponibles.
Les deux émojis champignons disponibles.
Capture d’écran Emojipedia

Concernant les champignons, on constate que les deux seuls émojis qui leur sont dédiés représentent des carpophores, c’est-à-dire, la partie aérienne des champignons, soit ce que l’on mange généralement chez les champignons comestibles, qui correspond à leur fructification, l’organe qui produit leurs spores sexuées.

Mais la plupart des champignons vivent surtout sous forme de filaments dans le sol, ou sont des moisissures sur des plantes ou des fruits. C’est sans doute plus difficile à représenter en émojis. Pourtant, cela ne veut pas dire que les champignons se cantonnent à la sphère de l’infiniment petit. Le plus grand organisme vivant sur terre jamais mesuré est un champignon, Armillaria solidipes, identifié dans l’Oregon aux États-Unis, dont le mycélium, soit un ensemble de filaments très fins, s’étend sur presque 10 km2. Son poids est estimé à 35 000 tonnes et il serait âgé de 8650 ans.

Les champignons, c’est justement votre grand domaine de recherche. Est-ce difficile de travailler sur un pan de la biodiversité qui est peu présent dans nos imaginaires ?

T.G. : Oui, à plusieurs niveaux ! Pour attirer des étudiants d’abord. C’est plus difficile quand on leur parle de moisissures ou de champignons que quand on leur dit qu’ils vont travailler sur des tortues, des baleines ou des tigres.

C’est aussi compliqué pour publier des études scientifiques. On doit davantage justifier l’intérêt quand on traite de champignons que quand on travaille sur l’humain ou sur les vertébrés. On note un biais d’intérêt même au sein de la communauté scientifique. Quand on travaille par exemple sur la formation des espèces, on va avoir tendance à citer des exemples de ce phénomène chez les animaux ou les plantes. Mais quand on essaie d’expliquer comment les espèces se forment chez les champignons, cela intéresse tout de suite beaucoup moins de monde.

Quelles stratégies avez-vous du coup mises en place pour faire valoir l’intérêt et l’importance de vos objets de recherche ?

T.G. : Parfois, on insiste sur le fait que les champignons peuvent être de bons modèles pour répondre à des grandes questions qui sont complexes à élucider si l’on se concentre uniquement sur les animaux et les végétaux. Je travaille par exemple sur l’évolution des chromosomes sexuels, afin d’essayer de comprendre pourquoi certains perdent leurs gènes.

Chez les mammifères, et notamment les humains, les chromosomes X et Y sont deux chromosomes sexuels : en général, XX donne un développement femelle et XY un développement mâle. Le chromosome X et Y échangent très peu de morceaux d’ADN entre eux, sauf dans de petites zones à leurs extrémités. Or, les échanges d’ADN aident normalement à réparer les erreurs introduites par mutations sur les chromosomes. Le chromosome Y ne recombine jamais et il manque ainsi ce mécanisme de réparation, ce qui lui a fait perdre progressivement la plupart de ses gènes, et l’a fait rétrécir.

C’est pour cela qu’il est devenu beaucoup plus petit que le X et qu’on dit qu’il s’est « dégénéré ». C’est une réalité qui interpelle : pourquoi est-ce que cela a évolué comme cela ? Le chromosome Y va-t-il disparaître ?

C’est difficile de répondre à cette question si on étudie seulement les mammifères, ils ont déjà tous des vieux chromosomes et ils ont tous les mêmes. Donc si on veut comprendre comment ça a évolué au départ, il faut étudier des situations où ces chromosomes sont encore jeunes. Or, justement, on a montré que chez certains champignons ces chromosomes évoluaient de façons répétées, et pourtant il n’y a même pas de sexes différents : on n’a pas des femelles et des mâles chez les champignons.

C’est très étonnant, car on a longtemps pensé que les chromosomes sexuels devenaient aussi différents parce qu’ils déterminent les sexes mâles et femelles, et qu’il y avait plein de différences entre les mâles et femelles. L’hypothèse était donc qu’il fallait bien arrêter les échanges réguliers de matériel génétique entre le X et le Y pour faire tous ces caractères différents entre mâles et femelles. Mais en fait, on observe exactement la même chose chez les champignons alors qu’il n’y a pas de sexes différents. Ça montre donc bien qu’il y autre chose qui pousse ces chromosomes sexuels à stopper les échanges génétiques. Mais si on étudiait uniquement les mammifères, on ne pourrait pas savoir cela.

Comment expliquer l’évolution des chromosomes sexuels ?

Une autre façon, sinon, d’intéresser les gens aux champignons, c’est d’étudier ceux que les gens aiment bien, par exemple les moisissures qui affinent le camembert ou le roquefort pour essayer de comprendre comment on les a fait évoluer pour faire du bon fromage.

Domestication des champignons du fromage et leur perte de diversité.

Les champignons liés aux maladies émergentes peuvent également susciter l’intérêt. C’est le cas des Cordyceps sur lesquels j’ai pu travailler et qui ont été médiatisés avec le succès de la série The Last of us. Les Cordyceps sont des champignons qui peuvent infecter plusieurs insectes, des fourmis et des chenilles notamment. En les infectant, ils vont changer le comportement de ces insectes en prenant le contrôle de leur cerveau. Mais il reste pour l’instant très improbable d’imaginer que les Cordyceps puissent infecter l’humain, comme cela se passe dans cette série américaine !

The Last of US : faut-il craindre les champignons cordyceps ?

Dans la recherche, certains animaux sont privilégiés par rapport à d’autres. Les oiseaux par exemple, semblent avoir bien plus de succès que les insectes. Si l’on regarde par exemple sur Google Scholar, le moteur de recherches d’articles scientifiques, on constate que, quand on tape birds, on nous propose 7,9 millions publications scientifiques. Quand on tape insects, il n’y en a que 5,8. Comment expliquer que la recherche néglige potentiellement certaines catégories de la biodiversité ?

T. G. : Les oiseaux ont toujours été l’objet de beaucoup d’intérêts, et le plaisir intrinsèque qu’il y a à les regarder n’est sans doute pas étranger aux intérêts scientifiques qu’ils suscitent.

Cet intérêt peut ensuite s’auto-entretenir. Car plus il y a un corpus de données présentes, plus on peut poser de questions poussées. Pour les oiseaux on va avoir des phylogénies complètes permettant de reconstituer l’évolution des organismes vivants. C’est la clef pour répondre à beaucoup de questions. Chez les champignons au contraire, il nous manque plein d’informations pour reconstituer l’évolution des espèces. Mais c’est aussi ce qui me passionne chez les champignons : il y a de ce fait énormément de choses à découvrir, car c’est un champ inexploré, mais c’est sans doute un peu plus risqué.

Les emojis disponibles consacrés aux oiseaux.
Les emojis disponibles consacrés aux oiseaux.
Capture d’écran Emojipedia

C’est cela qui vous a amené à travailler sur les champignons ?

T. G. : À l’origine, c’est plutôt le hasard, je cherchais un sujet de thèse, et l’INRAE en avait publié un sur la pourriture grise de la vigne, causée par le champignon Botrytis cinerea. J’ai donc candidaté et j’ai vite trouvé ça passionnant, car il y avait énormément de choses à défricher pour comprendre l’évolution des champignons pathogènes de plantes, notamment comment il coévoluent avec leurs plantes hôtes.

Les champignons évoluent en effet généralement très vite, car ils produisent des milliards de spores, et donc un grand nombre de mutations différentes chaque génération, et ils peuvent avoir plusieurs générations par an. On observe d’ailleurs que les champignons pathogènes de cultures contournent en général très rapidement les gènes de résistance qu’on introduit dans nos plantes cultivées, en un ou deux ans ils évoluent de nouvelles virulences.

Un autre aspect intéressant des champignons est qu’ils sont très importants écologiquement, ils sont un peu les éboueurs de la nature : ils décomposent la matière organique morte, ce qui permet aux nutriments de retourner dans le sol et d’être à nouveau disponibles pour la croissance des plantes ou des micro-organismes. Les champignons sont aussi assez pratiques à étudier, car ils ont en général de tout petits génomes, qu’on peut donc séquencer assez facilement. On peut aussi les garder vivants à -80 °C pendant des années. C’est d’ailleurs un autre aspect fascinant des champignons : ils ne vieillissent pas, et trente ans plus tard, ils n’ont pas fini de me passionner !

Double page issue de l’ouvrage La Biodiversité en infographies aux Editions Tana
Double page issu de l’ouvrage La Biodiversité en infographies aux Editions Tana.
Tatiana Giraud, Hervé Bouilly et Catherine Huguet pour Tana Editions, Fourni par l’auteur

Les emojis présentent surtout la diversité des espèces, mais la biodiversité, est-ce que ce n’est que cela ? Est-ce qu’il ne faut regarder que le nombre d’espèces pour l’évaluer ?

page issue de l’ouvrage La Biodiversité en infographies aux Editions Tana
page issue de l’ouvrage La Biodiversité en infographies aux Editions Tana.
Tatiana Giraud, Hervé Bouilly et Catherine Huguet pour Tana Editions, Fourni par l’auteur

T. G. : Non, il y a aussi la diversité génétique au sein d’une même espèce. C’est capital, car c’est cela qui permet l’adaptation à de nouveaux environnements ou des conditions changeantes. En effet, l’adaptation se produit par sélection naturelle, qui trie parmi la diversité génétique existante. On connaît bien par exemple la diversité à l’intérieur de l’espèce humaine, avec des variations pour la couleur de la peau, qui est une adaptation à la quantité d’UV à des latitudes données : aux tropiques, trop d’UV induisent des mutations qui peuvent causer des maladies, et la mélanine de la peau protège les humains contre ces UV.

Au contraire, aux hautes latitudes, trop peu d’UV limite notre synthèse de vitamine D, et il vaut mieux ne pas en avoir trop de mélanine dans la peau ; d’autres populations humaines sont adaptées à vivre aux hautes altitude avec peu d’oxygènes, ou à nager en apnée pendant 20 minutes pour pêcher. Dans les émojis on voit que cette diversité génétique n’est présente que chez les chiens ou chez d’autres animaux domestiqués.

The Conversation

Tatiana Giraud ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d’une organisation qui pourrait tirer profit de cet article, et n’a déclaré aucune autre affiliation que son organisme de recherche.

ref. Ce que les emojis racontent de la biodiversité – https://theconversation.com/ce-que-les-emojis-racontent-de-la-biodiversite-282292

Ce que la crise du kérosène signifie pour vos déplacements aériens cet été

Source: The Conversation – in French – By John Gradek, Faculty Lecturer and Academic Program Co-ordinator, Supply Network and Aviation Management, McGill University

Pour de nombreux habitants de l’hémisphère nord, l’arrivée de l’été rime avec les déplacements et les voyages. En famille, entre amis, sur la route, dans les airs ou à l’étranger, les vacances déclenchent chaque année les mêmes grands mouvements de voyageurs.


Pour les Canadiens, les voyages en avion cet été s’annoncent particulièrement mouvementés, sur fond de boycottage des voyages aux États-Unis, amorcé au début 2025, et de crise mondiale du kérosène déclenchée par la fermeture du détroit d’Ormuz.

À quoi pourraient ressembler les voyages en avion cet été, et à quoi les passagers doivent-ils s’attendre lorsqu’ils planifient leurs déplacements ?




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Les Canadiens boycottent toujours les États-Unis

Depuis le début de l’année 2025, les Canadiens boudent les voyages aux États-Unis en réaction aux menaces de droits de douane du président américain Donald Trump et à ses déclarations répétées sur une possible annexion du Canada comme « 51e État ».

Les voyages aller-retour des Canadiens depuis les États-Unis ont baissé de 32 % par rapport à mars 2024, selon Statistique Canada. Les Canadiens ont préféré se tourner vers des destinations nationales ou d’autres destinations internationales.

Le secteur du transport aérien en a pris bonne note. Les compagnies aériennes canadiennes ont réduit de 10 % leur offre de vols vers les États-Unis au premier trimestre, selon la société de données aéronautiques OAG. Air Transat prévoit même de mettre fin à tous ses vols vers les États-Unis d’ici juin.

Air Canada a augmenté le nombre de vols à destination et en provenance du Mexique et a mis en place de nouvelles liaisons aériennes. WestJet a également annoncé de nouvelles liaisons intérieures pour l’été, ainsi que l’ajout de vols supplémentaires entre l’est et l’ouest du Canada.

Qualifier ces projets d’ambitieux serait un euphémisme.

La crise actuelle du carburant

Le 27 février, la campagne militaire américano-israélienne contre l’Iran a débuté. La fermeture consécutive par l’Iran du détroit d’Ormuz – par lequel transite normalement environ un cinquième du pétrole mondial – a fait flamber les prix du kérosène, affectant les approvisionnements destinés à l’Asie et à l’Europe.




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Depuis le début de la guerre, les prix du kérosène ont augmenté de près de 70 %, selon l’indice Platts Global Jet Fuel Index. Les transporteurs aériens ont été contraints de revoir leur offre de vols et de hausser le prix des billets d’avion.

Plusieurs régions du monde sont confrontées à des pénuries imminentes de kérosène. Plusieurs pays d’Asie et d’Europe occidentale ont commencé à rationner les produits pétroliers tels que l’essence, le diesel et le kérosène, à mesure que les réserves locales s’amenuisent.

Certaines compagnies aériennes ont commencé à réduire leurs vols en réponse aux mesures de rationnement, ce qui touche à la fois le nombre d’appareils en service et les effectifs.

La faillite de Spirit, un signal d’alarme

Les difficultés financières sont désormais au centre des discussions dans les conseils d’administration, et de nombreuses initiatives sont envisagées pour préserver les liquidités dans un contexte qui menace la survie de nombreux transporteurs.

L’illustration la plus frappante de cette pression s’est produite le 2 mai, lorsque Spirit Airlines a cessé ses activités. Spirit se classait huitième parmi les compagnies aériennes américaines en termes de sièges proposés en 2025. Sa fermeture a laissé environ 17 000 employés sans emploi et a bloqué des dizaines de milliers de passagers qui détenaient des billets pour des voyages à venir.

Le secrétaire américain aux Transports, Sean Duffy, a déclaré que la compagnie aérienne « était en grande difficulté bien avant la guerre avec l’Iran », mais que la flambée des prix du carburant avait anéanti ses dernières chances de survie. Le PDG de Spirit Airlines, Dave Davis, a pour sa part affirmé au Wall Street Journal que le plan de redressement de la compagnie aurait pu fonctionner sans ce choc pétrolier.

La disparition de Spirit fera disparaître l’une des rares options à très bas prix pour les voyageurs américains et pourrait entraîner une hausse des tarifs dans l’ensemble du secteur.

Sa fermeture a immédiatement attiré l’attention des régulateurs et du grand public sur la crise du kérosène. D’autres transporteurs américains pourraient-ils subir le même sort ? Des compagnies aériennes ailleurs dans le monde sont-elles également menacées ?

Quelles conséquences pour les voyages de l’été 2026

Pour les Canadiens qui voyagent cet été, la situation varie selon qu’il s’agit de vols intérieurs ou internationaux.

Les compagnies aériennes ont augmenté leurs tarifs pour compenser la hausse des coûts du carburant, réduit leurs vols sur les liaisons devenues non rentables et commencé à revoir leurs plans de croissance pour tenir compte des incertitudes géopolitiques.

Pour les voyageurs qui envisagent de voyager à l’étranger cet été, les tarifs aériens ont considérablement augmenté. Les tarifs des vols intérieurs au Canada sont également plus élevés qu’en 2025, bien que l’augmentation soit plus modeste.

La demande sur les liaisons intérieures est restée forte, et les transporteurs n’ont donné aucun signe de ralentissement. La concurrence entre les transporteurs – un facteur clé de la baisse des tarifs aériens – a été au mieux modérée, les compagnies aériennes se concentrant sur la rentabilité et, dans certains cas, sur leur survie.

Comme toutes les crises de ce type, celle du kérosène finira par s’atténuer. Reste à savoir quand, un point encore très incertain. L’Association internationale du transport aérien rappelle que même si le détroit d’Ormuz venait à rouvrir, le retour à un approvisionnement normal en kérosène pourrait prendre des mois.

Pour les voyageurs qui finalisent encore leurs projets d’été, la vraie question est celle du niveau d’incertitude qu’ils sont prêts à accepter. De nouvelles réductions de vols sont possibles, voire probables, et les passagers pourraient n’être prévenus qu’à la dernière minute en cas d’annulation.

Ceux qui souhaitent un voyage simple et sans stress auraient intérêt à privilégier des destinations plus proches et les vols intérieurs. Les voyages internationaux de cet été s’annoncent plus imprévisibles pour ceux qui disposent de davantage de flexibilité.

La Conversation Canada

John Gradek ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d’une organisation qui pourrait tirer profit de cet article, et n’a déclaré aucune autre affiliation que son organisme de recherche.

ref. Ce que la crise du kérosène signifie pour vos déplacements aériens cet été – https://theconversation.com/ce-que-la-crise-du-kerosene-signifie-pour-vos-deplacements-aeriens-cet-ete-282552

Malgré leur pollution numérique considérable, les grandes banques canadiennes divulguent de moins en moins d’informations sur le sujet

Source: The Conversation – in French – By Sylvain Amoros, Adjunct Professor, Department of Marketing, HEC Montréal

Au début de l’année 2025, quelques-unes des plus grandes banques canadiennes, notamment celles qui génèrent le plus d’émissions numériques et qui ont la responsabilité la plus importante, se sont retirées de l’alliance bancaire Net Zéro.

Ces institutions, dont l’empreinte carbone numérique est disproportionnée, ont invoqué la complexité réglementaire et les pressions concurrentielles pour justifier leur choix. Cette décision a suscité de nombreuses interrogations de la part des investisseurs, des décideurs politiques et du grand public quant à l’engagement des banques en faveur du développement durable.

Parallèlement, le projet de loi C-59, adopté fin 2024, a introduit de nouvelles dispositions dans la Loi sur la concurrence afin de renforcer l’imputabilité en matière d’écoblanchiment et d’allégations environnementales trompeuses.

Cette coïncidence est frappante : juste au moment où Ottawa resserre les règles de divulgation, les grandes banques qui dominent les émissions numériques se retirent des engagements climatiques volontaires. Cette tension entre les mesures volontaires et l’imputabilité exigée par le gouvernement fédéral souligne la pression croissante exercée sur les institutions financières pour qu’elles prouvent — plutôt que de simplement promouvoir — leur performance environnementale.

Emprunte carbone numérique

Pendant des décennies, les banques se sont présentées comme des chefs de file en matière de développement durable, grâce au financement d’énergies renouvelables et à des engagements ambitieux sur les plans environnementaux, sociaux et de gouvernance. Pourtant, leur récente sortie des coalitions climatiques, associée à leur empreinte carbone numérique disproportionnée, constitue un revirement alarmant.

Nous avons mené une étude sur l’impact environnemental de neuf banques canadiennes, dont les cinq plus grandes : la CIBC, la Banque TD, la Banque Scotia, la Banque Royale du Canada et la BMO. Notre recherche visait à quantifier leur impact environnemental par le calcul de leur empreinte carbone numérique.

Les banques sont des piliers de notre économie et de notre société. Elles ont le pouvoir et la responsabilité de mener la transition vers une économie plus durable. Cependant, leur récent retrait de l’alliance bancaire Net Zéro, associé aux préoccupations concernant l’écoblanchiment, soulève des questions légitimes quant à leur engagement réel en faveur du développement durable.




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Notre objectif, en tant que chercheurs, est de fournir aux clients des banques et aux institutions financières des informations sur leur incidence environnementale. Il est essentiel de comprendre l’empreinte environnementale des opérations numériques des banques, car cet aspect, souvent négligé, représente une part importante de leur empreinte carbone globale.

Nous avons analysé les données publiques de 2024 afin de mesurer l’impact carbone des pratiques numériques des banques canadiennes. Notre étude s’est concentrée sur deux aspects principaux :

1) l’utilisation des sites Web (l’énergie consommée par le chargement des sites, les transferts de données et l’hébergement), et

2) l’acquisition de trafic, qui englobe l’ensemble des activités marketing visant à attirer des visiteurs sur les sites, qu’il s’agisse de courriels, de publicités payantes, d’optimisation des moteurs de recherche ou de campagnes sur les réseaux sociaux.

Notre objectif était de comparer les émissions de carbone entre les banques, d’évaluer leur efficacité par visite et de fournir des informations transparentes au public. En ciblant les opérations numériques les plus polluantes, nous formulons des recommandations d’amélioration.

Médias sociaux

Notre étude a permis de tirer des conclusions intéressantes sur l’impact environnemental numérique des banques canadiennes. La plus frappante est l’écart de performance entre la banque ayant obtenu le moins bon résultat et la meilleure : la première émet deux fois plus de carbone par visiteur que la seconde. Trois banques sont responsables à elles seules des deux tiers des émissions totales.

Afin de clarifier la suite, le terme « acquisition de trafic » désigne le processus consistant à attirer des visiteurs sur un site, que ce soit par des publicités payantes, des résultats de recherche organiques ou du contenu sur les réseaux sociaux. Le trafic organique provient des internautes qui trouvent naturellement le site d’une banque par le biais de moteurs de recherche, de réseaux sociaux ou de marketing de contenu, tandis que le trafic payant est généré par le placement de publicités.

Les données révèlent que 77 % des émissions numériques sont liées à l’acquisition de trafic, contre seulement 23 % pour l’utilisation des sites Web. Bien qu’il ne représente qu’une petite fraction du trafic total, le trafic payant engendre 95 % des émissions liées au trafic, tandis que le trafic organique n’en représente que 5 %.

Le marketing payant sur les réseaux sociaux est particulièrement problématique : il est responsable de 58 % des émissions, alors qu’il ne constitue que 1 % du trafic total.


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Autrement dit, les publicités sur les réseaux sociaux manquent d’efficacité si on tient compte des émissions de carbone : un visiteur provenant d’une publicité en ligne émet 418 fois plus de dioxyde de carbone qu’un visiteur provenant de sources organiques.

Ces résultats révèlent que la publicité en ligne, en particulier les campagnes sur les réseaux sociaux, représente une source importante de pollution cachée.

Une source de pollution cachée

Nos conclusions montrent à quel point la publicité en ligne, notamment sur les réseaux sociaux, constitue une source importante de pollution numérique. La réalité est claire : chaque clic a un coût carbone.

Les banques peuvent améliorer leur marketing entrant, c’est-à-dire les stratégies qui attirent les utilisateurs de manière organique, en proposant un contenu pertinent, en optimisant les recherches et en bonifiant l’expérience utilisateur, plutôt que d’avoir recours à des publicités payantes.




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La transparence et les pratiques numériques durables sont essentielles pour des services bancaires écologiques qui permettent de réduire les émissions sans sacrifier l’innovation ou la compétitivité.

Après s’être retirées de l’Alliance bancaire Net Zéro et avoir maintenu leurs engagements publics en matière de neutralité carbone, de nombreuses banques continuent de générer des émissions importantes dans le cadre de leurs activités numériques.

Cette situation soulève une question cruciale pour les autorités de réglementation, les investisseurs et les consommateurs : les banques utiliseront-elles leurs ressources considérables pour montrer l’exemple en matière de durabilité, ou retarderont-elles encore la prise de mesures significatives ?

Notre prochaine étude évaluera si ces institutions tiennent leurs engagements ou persistent dans leurs pratiques actuelles, alors que l’urgence climatique ne cesse de croître.


Victor Prouteau, qui était étudiant à la maîtrise à HEC Montréal à l’époque de cette étude, est coauteur de cet article.

La Conversation Canada

Les auteurs ne travaillent pas, ne conseillent pas, ne possèdent pas de parts, ne reçoivent pas de fonds d’une organisation qui pourrait tirer profit de cet article, et n’ont déclaré aucune autre affiliation que leur organisme de recherche.

ref. Malgré leur pollution numérique considérable, les grandes banques canadiennes divulguent de moins en moins d’informations sur le sujet – https://theconversation.com/malgre-leur-pollution-numerique-considerable-les-grandes-banques-canadiennes-divulguent-de-moins-en-moins-dinformations-sur-le-sujet-268924