Science – Page 5

LLMs’ impact on science: Booming publications, stagnating quality

AI, LLMs, Science, scientific publications / Kris Guyer / December 18, 2025

This effect was likely to be most pronounced in people that weren’t native speakers of English. If the researchers limited the analysis to people with Asian names working at institutions in Asia, their rate of submissions to bioRxiv and SSRN nearly doubled once they started using AI and rose by over 40 percent at the arXiv. This suggests that people who may not have the strongest English skills are using LLMs to overcome a major bottleneck: producing compelling text.

Quantity vs. quality

The value of producing compelling text should not be underestimated. “Papers with clear but complex language are perceived to be stronger and are cited more frequently,” the researchers note, suggesting that we may use the quality of writing as a proxy for the quality of the research it’s describing. And they found some indication of that here, as non-LLM-assisted papers were more likely to be published in the peer reviewed literature if they used complex language (the abstracts were scored for language complexity using a couple of standard measures).

But the dynamic was completely different for LLM-produced papers. The complexity of language in papers written with an LLM was generally higher than for those using natural language. But they were less likely to end up being published. “For LLM-assisted manuscripts,” the researchers write, “the positive correlation between linguistic complexity and scientific merit not only disappears, it inverts.”

But not all of the differences were bleak. When the researchers checked the references being used in AI-assisted papers, they found that the LLMs weren’t just citing the same papers that everyone else did. They instead cited a broader range of sources, and were more likely to cite books and recent papers. So, there’s a chance that AI use could ultimately diversify the published research that other researchers consider (assuming they check their own references, which they clearly should).

What does this tell us?

There are a couple of cautions for interpreting these results. One, acknowledged by the researchers, is that people may be using AI to produce initial text that’s then heavily edited, and that may be mislabeled as human-produced text here. So, the overall prevalence of AI use is likely to be higher. The other is that some manuscripts may take a while to get published, so their use of that as a standard for scientific quality may penalize more recent drafts—which are more likely to involve AI use. These may ultimately bias some of the results, but the effects the authors saw were so large that they’re unlikely to go away entirely.

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NASA will soon find out if the Perseverance rover can really persevere on Mars

Mars, Mars 2020, Mars Perseverance, Mars Sample Return, NASA, planetary science, Science, solar system, Space / Mike M. / December 18, 2025

Engineers at JPL are certifying the Perseverance rover to drive up to 100 kilometers.

The Perseverance rover looks back on its tracks on the floor of Jezero Crater in 2022. Credit: NASA/JPL

When the Perseverance rover arrived on Mars nearly five years ago, NASA officials thought the next American lander to take aim on the red planet would be taking shape by now.

At the time, the leaders of the space agency expected this next lander could be ready for launch as soon as 2026—or more likely in 2028. Its mission would have been to retrieve Martian rock specimens collected by the Perseverance rover, then billed as the first leg of a multilaunch, multibillion-dollar Mars Sample Return campaign.

Here we are on the verge of 2026, and there’s no sample retrieval mission nearing the launch pad. In fact, no one is building such a lander at all. NASA’s strategy for a Mars Sample Return, or MSR, mission remains undecided after the projected cost of the original plan ballooned to $11 billion. If MSR happens at all, it’s now unlikely to launch until the 2030s.

That means the Perseverance rover, which might have to hand off the samples to a future retrieval lander in some circumstances, must continue weathering the harsh, cold, dusty environment of Mars. The good news is that the robot, about the size of a small SUV, is in excellent health, according to Steve Lee, Perseverance’s deputy project manager at NASA’s Jet Propulsion Laboratory (JPL).

“Perseverance is approaching five years of exploration on Mars,” Lee said in a press briefing Wednesday at the American Geophysical Union’s annual fall meeting. “Perseverance is really in excellent shape. All the systems onboard are operational and performing very, very well. All the redundant systems onboard are available still, and the rover is capable of supporting this mission for many, many years to come.”

The rover’s operators at JPL are counting on sustaining Perseverance’s good health. The rover’s six wheels have carried it a distance of about 25 miles, or 40 kilometers, since landing inside the 28-mile-wide (45-kilometer) Jezero Crater in February 2021. That is double the original certification for the rover’s mobility system and farther than any vehicle has traveled on the surface of another world.

This enhanced-color mosaic is made from three separate images taken on September 8, 2025, each of which was acquired using the Perseverance rover’s Mastcam-Z instrument. The images were processed to improve visual contrast and enhance color differences. The view shows a location known as “Mont Musard” and another region named “Lac de Charmes,” where the rover’s team will be looking for more rock core samples to collect in the year ahead. The mountains in the distance are approximately 52 miles (84 kilometers) away.

Going for 100

Now, engineers are asking Perseverance to perform well beyond expectations. An evaluation of the rover’s health concluded it can operate until at least 2031. The rover uses a radioactive plutonium power source, so it’s not in danger of running out of electricity or fuel any time soon. The Curiosity rover, which uses a similar design, has surpassed 13 years of operations on Mars.

There are two systems that are most likely to limit the rover’s useful lifetime. One is the robotic arm, which is necessary to collect samples, and the other is the rover’s six wheels and the drive train that powers them.

“To make sure we can continue operations and continue driving for a long, long way, up to 100 kilometers (62 miles), we are doing some additional testing,” Lee said. “We’ve successfully completed a rotary actuator life test that has now certified the rotary system to 100 kilometers for driving, and we have similar testing going on for the brakes. That is going well, and we should finish those early part of next year.”

Ars asked Lee why JPL decided on 100 kilometers, which is roughly the same distance as the average width of Lake Michigan. Since its arrival in 2021, Perseverance has climbed out of Jezero Crater and is currently exploring the crater’s rugged rim. If NASA sends a lander to pick up samples from Perseverance, the rover will have to drive back to a safe landing zone for a handoff.

“We actually had laid out a traverse path exploring the crater rim, much more of the crater rim than we have so far, and then be able to return to a rendezvous site,” Lee said. “So we did an estimate of the total mission drive duration to complete that mission, added margin for science exploration, added margin in case we need the rendezvous at a different site… and it just turned out to add up to a nice, even 100 kilometers.”

The time-lapse video embedded below shows the Perseverance rover’s record-breaking 1,351-foot (412-meter) drive on June 19, 2025.

Despite the disquiet on the future of MSR, the Perseverance rover has dutifully collected specimens and placed them in 33 titanium sample tubes since arriving on Mars. Perseverance deposited some of the sealed tubes on the surface of Mars in late 2022 and early 2023 and has held onto the remaining containers while continuing to drive toward the rim of Jezero.

The dual-depot approach preserves the option for future MSR mission planners to go after either batch of samples.

Scientists selected Jezero as the target for the Perseverance mission because they suspected it was the site of an ancient dried-up river delta with a surplus of clay-rich minerals. The rover’s instruments confirmed this hypothesis, finding sediments in the crater floor that were deposited at the bottom of a lake of liquid water billions of years ago, including sandstones and mudstones known to preserve fossilized life in comparable environments on Earth.

A research team published findings in the journal Nature in September describing the discovery of chemical signatures and structures in a rock that could have been formed by ancient microbial life. Perseverance lacks the bulky, sprawling instrumentation to know for sure, so ground teams ordered the rover to collect a pulverized specimen from the rock in question and seal it for eventual return to Earth.

Fill but don’t seal

Lee said Perseverance will continue filling sample tubes in the expectation that they will eventually come back to Earth.

“We do expect to continue some sampling,” Lee said. “We have six open sample tubes, unused sample tubes, onboard. We actually have two that we took samples and didn’t seal yet. So we have options of maybe replacing them if we’re finding that there’s even better areas that we want to collect from.”

The rover’s management team at JPL is finalizing the plan for Perseverance through 2028. Lee expects the rover will remain at Jezero’s rim for a while. “There are quite a number of very prime, juicy targets we would love to go explore,” he said.

In the meantime, if Perseverance runs across an alluring rock, scientists will break out the rover’s coring drill and fill more tubes.

“We certainly have more than enough to keep us busy, and we are not expecting a major perturbation to our science explorations in the next two and a half years as a result of sample return uncertainty,” Lee said.

Perseverance has its own suite of sophisticated instruments. The instruments can’t do what labs on Earth can, but the rover can scan rocks to determine what they’re made of, search for life-supporting organic molecules, map underground geology, and capture startling vistas that inspire and inform.

This photo montage shows sample tubes shortly after they were deposited onto the surface by NASA’s Perseverance Mars rover in late 2022 and early 2023. Credit: NASA/JPL-Caltech/MSSS

The rover’s sojourn along the Jezero Crater rim is taking it through different geological eras, from the time Jezero harbored a lake to its formation at an even earlier point in Martian history. Fundamentally, researchers are asking the question “What was it like if you were a microbe living on the surface of Mars?” said Briony Horgan, a mission scientist at Purdue University.

Along the way, the rover will stop and do a sample collection if something piques the science team’s interest.

“We are adopting a strategy, in many cases, to fill a tube, and we have the option to not seal it,” Lee said. “Most of our tubes are sealed, but we have the option to not seal it, and that gives us a flexibility downstream to replace the sample if there’s one that we find would make an even stronger representative of the diversity we are discovering.”

An indefinite wait

Planetary scientists have carefully curated the specimens cached by the Perseverance rover. The samples are sorted for their discovery potential, with an emphasis on the search for ancient microbial life. That’s why Perseverance was sent to Jezero in the first place.

China is preparing its own sample-return mission, Tianwen-3, for launch as early as 2028, aiming to deliver Mars rocks back to Earth by 2031. If the Tianwen-3 mission keeps to this schedule—and is successful—China will almost certainly be first to pull off the achievement. Officials have not announced the landing site for Tianwen-3, so the jury is still out on the scientific value of the rocks China aims to bring back.

NASA’s original costly architecture for Mars Sample Return would have used a lander built by JPL and a small solid-fueled rocket to launch the rock samples back into space after collecting them from the Perseverance rover. The capsule containing the Mars rocks would then transfer them to another spacecraft in orbit around Mars. Once Earth and Mars reached the proper orbital alignment, the return spacecraft would begin the journey home. All told, the sample return campaign would last several years.

NASA asked commercial companies to develop their own ideas for Mars Sample Return in 2024. SpaceX, Blue Origin, Lockheed Martin, and Rocket Lab submitted their lower-cost commercial concepts to NASA, but progress stalled there. NASA’s former administrator, Bill Nelson, punted on a decision on what to do next with Mars Sample Return in the final weeks of the Biden administration.

A few months later, the new Trump administration proposed outright canceling the Mars Sample Return mission. Mars Sample Return, known as MSR, was ranked as the top priority for planetary science in a National Academies decadal survey. Researchers say they could learn much more about Mars and the possibilities of past life there by bringing samples back to Earth for analysis.

Budget writers in the House of Representatives voted to restore funding for Mars Sample Return over the summer, but the Senate didn’t explicitly weigh in on the mission. NASA is now operating under a stopgap budget passed by Congress last month, and MSR remains in limbo.

There are good arguments for going with a commercial sample-return mission, using a similar approach to the one NASA used to buy commercial cargo and crew transportation services for the International Space Station. NASA might also offer prizes or decide to wait for a human expedition to Mars for astronauts to scoop up samples by hand.

Eric Berger, senior space editor at Ars, discussed these options a few months ago. After nearly a year of revolving-door leadership, NASA finally got a Senate-confirmed administrator this week. It will now be up to the new NASA chief, Jared Isaacman, to chart a new course for Mars Sample Return.

Stephen Clark is a space reporter at Ars Technica, covering private space companies and the world’s space agencies. Stephen writes about the nexus of technology, science, policy, and business on and off the planet.

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Physicists 3D-printed a Christmas tree of ice

3D printing, evaporative cooling, Physics, Science / Rejus Almole / December 17, 2025

Physicists at the University of Amsterdam came up with a really cool bit of Christmas decor: a miniature 3D-printed Christmas tree, a mere 8 centimeters tall, made of ice, without any refrigeration equipment or other freezing technology, and at minimal cost. The secret is evaporative cooling, according to a preprint posted to the physics arXiv.

Evaporative cooling is a well-known phenomenon; mammals use it to regulate body temperature. You can see it in your morning cup of hot coffee: the hotter atoms rise to the top of the magnetic trap and “jump out” as steam. It also plays a role (along with shock wave dynamics and various other factors) in the formation of “wine tears.” It’s a key step in creating Bose-Einstein condensates.

And evaporative cooling is also the main culprit behind the infamous “stall” that so frequently plagues aspiring BBQ pit masters eager to make a successful pork butt. The meat sweats as it cooks, releasing the moisture within, and that moisture evaporates and cools the meat, effectively canceling out the heat from the BBQ. That’s why a growing number of competitive pit masters wrap their meat in tinfoil after the first few hours (usually when the internal temperature hits 170° F).

Ice-printing methods usually rely on cryogenics or on cooled substrates. Per the authors, this is the first time evaporative cooling principles have been applied to 3D printing. The trick was to house the 3D printing inside a vacuum chamber using a jet nozzle as the printing head—something they discovered serendipitously when they were trying to get rid of air drag by spraying water in a vacuum chamber. “The printer’s motion control guides the water jet layer-by-layer, building geometry on demand,” the authors wrote in a blog post for Nature, adding:

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Trump admin threatens to break up major climate research center

atmospheric science, climate change, Earth science, NCAR, NSF, research, Science / Paul Patrick / December 17, 2025

UCAR, for its part, has issued a statement indicating that the USA Today article was the first it has heard of the matter.

In many cases where the administration has attempted to take drastic actions like this, courts have ruled that they run afoul of a legal prohibition against “arbitrary and capricious” federal actions. That said, courtroom losses haven’t inhibited the administration’s willingness to try, and the time spent waiting for legal certainty can often accomplish many of its aims, such as disrupting research on politically disfavored subjects and forcing scientists to look elsewhere for career stability.

Scientists, meanwhile, are reacting with dismay. “Dismantling NCAR is like taking a sledgehammer to the keystone holding up our scientific understanding of the planet,” said Texas Tech climate researcher Katharine Hayhoe. “Everyone who works in climate and weather has passed through its doors and benefited from its incredible resources.”

Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, called NCAR a “unique and valuable asset” and emphasized the wide range of research conducted there.

Obviously, shutting down one source of information about climate change won’t alter what’s happening—greenhouse gases will continue to behave as physics dictates, raising global temperatures. But the Trump administration seemingly views everything through the lens of ideology. It has concluded that scientists are its ideological opponents and thus that its own ideologically driven conclusions are equal to the facts produced by science. Because of that perspective, it has been willing to harm scientists, even if the cost will eventually be felt by the public that Trump ostensibly represents.

Story was updated on Dec. 17 to reflect a recently issued statement by the NSF.

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The $4.3 billion space telescope Trump tried to cancel is now complete

astronomy, dark energy, exoplanets, goddard space flight center, NASA, roman space telescope, Science, Space / Paul Patrick / December 16, 2025

“We’re going to be making 3D movies of what is going on in the Milky Way galaxy.”

Artist’s concept of the Nancy Grace Roman Space Telescope. Credit: NASA Goddard Space Flight Center Scientific Visualization Studio

A few weeks ago, technicians inside a cavernous clean room in Maryland made the final connection to complete assembly of NASA’s Nancy Grace Roman Space Telescope.

Parts of this new observatory, named for NASA’s first chief astronomer, recently completed a spate of tests to ensure it can survive the shaking and intense sound of a rocket launch. Engineers placed the core of the telescope inside a thermal vacuum chamber, where it withstood the airless conditions and extreme temperature swings it will see in space.

Then, on November 25, teams at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, joined the inner and outer portions of the Roman Space Telescope. With this milestone, NASA declared the observatory complete and on track for launch as soon as fall 2026.

“The team is ecstatic,” said Jackie Townsend, the observatory’s deputy project manager at Goddard, in a recent interview with Ars. “It has been a long road, but filled with lots of successes and an ordinary amount of challenges, I would say. It’s just so rewarding to get to this spot.”

An ordinary amount of challenges is not something you usually hear a NASA official say about a one-of-a-kind space mission. NASA does hard things, and they usually take more time than originally predicted. Astronomers endured more than 10 years of delays, fixes, and setbacks before the James Webb Space Telescope finally launched in 2021.

Webb is the largest telescope ever put into space. After launch, Webb had to perform a sequence of more than 50 major deployment steps, with 178 release mechanisms that had to work perfectly. Any one of the more than 300 single points of failure could have doomed the mission. In the end, Webb unfolded its giant segmented mirror and delicate sunshield without issue. After a quarter-century of development and more than $11 billion spent, the observatory is finally delivering images and science results. And they’re undeniably spectacular.

The completed Nancy Grace Roman Space Telescope, seen here with its solar panels deployed inside a clean room at NASA’s Goddard Space Flight Center in Maryland. Credit: NASA/Jolearra Tshiteya

Seeing far and wide

Roman is far less complex, with a 7.9-foot (2.4-meter) primary mirror that is nearly three times smaller than Webb’s. While it lacks Webb’s deep vision, Roman will see wider swaths of the sky, enabling a cosmic census of billions of stars and galaxies near and far (on the scale of the Universe). This broad vision will support research into dark matter and dark energy, which are thought to make up about 95 percent of the Universe. The rest of the Universe is made of regular atoms and molecules that we can see and touch.

It is also illustrative to compare Roman with the Hubble Space Telescope, which has primary mirrors of the same size. This means Roman will produce images with similar resolution to Hubble. The distinction lies deep inside Roman, where technicians have delicately laid an array of detectors to register the faint infrared light coming through the telescope’s aperture.

“Things like night vision goggles will use the same basic detector device, just tuned to a different wavelength,” Townsend said.

These detectors are located in Roman’s Wide Field Instrument, the mission’s primary imaging camera. There are 18 of them, each 4,096×4,096 pixels wide, combining to form a roughly 300-megapixel camera sensitive to visible and near-infrared light. Teledyne, the company that produced the detectors, says this is the largest infrared focal plane ever made.

The near-infrared channel on Hubble’s Wide Field Camera 3, which covers much the same part of the spectrum as Roman, has a single 1,024-pixel detector.

“That’s how you get to a much higher field-of-view for the Roman Space Telescope, and it was one of the key enabling technologies,” Townsend told Ars. “That was one place where Roman invested significant dollars, even before we started as a mission, to mature that technology so that it was ready to infuse into this mission.”

With these detectors in its bag, Roman will cover much more cosmic real estate than Hubble. For example, Roman will be able to re-create Hubble’s famous Ultra Deep Field image with the same sharpness, but expand it to show countless stars and galaxies over an area of the sky at least 100 times larger.

This infographic illustrates the differences between the sizes of the primary mirrors and detectors on the Hubble, Roman, and Webb telescopes. Credit: NASA

Roman has a second instrument, the Roman Coronagraph, with masks, filters, and adaptive optics to block out the glare from stars and reveal the faint glow from objects around them. It is designed to photograph planets 100 million times fainter than their stars, or 100 to 1,000 times better than similar instruments on Webb and Hubble. Roman can also detect exoplanets using the tried-and-true transit method, but scientists expect the new telescope will find a lot more than past space missions, thanks to its wider vision.

“With Roman’s construction complete, we are poised at the brink of unfathomable scientific discovery,” said Julie McEnery, Roman’s senior project scientist at NASA Goddard, in a press release. “In the mission’s first five years, it’s expected to unveil more than 100,000 distant worlds, hundreds of millions of stars, and billions of galaxies. We stand to learn a tremendous amount of new information about the universe very rapidly after Roman launches.”

Big numbers are crucial for learning how the Universe works, and Roman will feed vast volumes of data down to astronomers on Earth. “So much of what physics is trying to understand about the nature of the Universe today needs large number statistics in order to understand,” Townsend said.

In one of Roman’s planned sky surveys, the telescope will cover in nine months what would take Hubble between 1,000 and 2,000 years. In another survey, Roman will cover an area equivalent to 3,455 full moons in about three weeks, then go back and observe a smaller portion of that area repeatedly over five-and-a-half days—jobs that Hubble and Webb can’t do.

“We will do fundamentally different science,” Townsend said. “In some subset of our observations, we’re going to be making 3D movies of what is going on in the Milky Way galaxy and in distant galaxies. That is just something that’s never happened before.”

Getting here and getting there

Roman’s promised scientific bounty will come at a cost of $4.3 billion, including expenses for development, manufacturing, launch, and five years of operations.

This is about $300 million more than NASA expected when it formally approved Roman for development in 2020, an overrun the agency blamed on complications related to the coronavirus pandemic. Otherwise, Roman’s budget has been stable since NASA officials finalized the mission’s architecture in 2017, when it was still known by a bulky acronym: WFIRST, the Wide Field InfraRed Survey Telescope.

At that time, the agency reclassified the Roman Coronagraph as a technology demonstration, allowing managers to relax their requirements for the instrument and stave off concerns about cost growth.

Roman survived multiple attempts by the first Trump administration to cancel the mission. Each time, Congress restored funding to keep the observatory on track for launch in the mid-2020s. With Donald Trump back in the White House, the administration’s budget office earlier this year again wanted to cancel Roman. Eventually, the Trump administration released its fiscal year 2026 budget request in May, calling for a drastic cut to Roman, but not total cancellation.

Once again, both houses of Congress signaled their opposition to the cuts, and the mission remains on track for launch next year, perhaps as soon as September. This is eight months ahead of the schedule NASA has publicized for Roman for the last few years.

Townsend told Ars the mission escaped the kind of crippling cost overruns and delays that afflicted Webb through careful planning and execution. “Roman was under a cost cap, and we operated to that,” she said. “We went through reasonable efforts to preclude those kinds of highly complex deployments that lead you to having trouble in integration and test.”

The outer barrel section of the Roman Space Telescope inside a thermal vacuum chamber at NASA’s Goddard Space Flight Center, Maryland. Credit: NASA/Sydney Rohde

There are only a handful of mechanisms that must work after Roman’s launch. They include a deployable cover designed to shield the telescope’s mirror during launch and solar array wings that will unfold once Roman is in space. The observatory will head to an observing post about a million miles (1.5 million kilometers) from Earth.

“We don’t have moments of terror for the deployment,” Townsend said. “Obviously, launch is always a risk, the tip-off rates that you have when you separate from the launch vehicle… Then, obviously, getting the aperture door open so that it’s deployed is another one. But these feel like normal aerospace risks, not unusual, harrowing moments for Roman.”

It also helps that Roman will use a primary mirror gifted to NASA by the National Reconnaissance Office, the US government’s spy satellite agency. The NRO originally ordered the mirror for a telescope that would peer down on the Earth, but the spy agency no longer needed it. Before NASA got its hands on the surplus mirror in 2012, scientists working on the preliminary design for what became Roman were thinking of a smaller telescope.

The larger telescope will make Roman a more powerful tool for science, and the NRO’s donation eliminated the risk of a problem or delay manufacturing a new mirror. But the upside meant NASA had to build a more massive spacecraft and use a bigger rocket to accommodate it, adding to the observatory’s cost.

Tests of Roman’s components have gone well this year. Work on Roman continued at Goddard through the government shutdown in the fall. On Webb, engineers uncovered one problem after another as they tried to verify the observatory would perform as intended in space. There were leaky valves, tears in the Webb’s sunshield, a damaged transducer, and loose screws. With Roman, engineers so far have found no “significant surprises” during ground testing, Townsend said.

“What we always hope when you’re doing this final round of environmental tests is that you’ve wrung out the hardware at lower levels of assembly, and it looks like, in Roman’s case, we did a spectacular job at the lower level,” she said.

With Roman now fully assembled, attention at Goddard will turn to an end-to-end functional test of the observatory early next year, followed by electromagnetic interference testing, and another round of acoustic and vibration tests. Then, perhaps around June of next year, NASA will ship the observatory to Kennedy Space Center, Florida, to prepare for launch on a SpaceX Falcon Heavy rocket.

“We’re really down to the last stretch of environmental testing for the system,” Townsend said. “It’s definitely already seen the worst environment until we get to launch.”

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Utah leaders hinder efforts to develop solar energy supply

Policy, Science, solar cells, Solar energy, syndication, Utah / Paul Patrick / December 16, 2025

Solar power accounts for two-thirds of the new projects waiting to connect to the state’s power grid.

Utah Gov. Spencer Cox believes his state needs more power—a lot more. By some estimates, Utah will require as much electricity in the next five years as it generated all last century to meet the demands of a growing population as well as chase data centers and AI developers to fuel its economy.

To that end, Cox announced Operation Gigawatt last year, declaring the state would double energy production in the next decade. Although the announcement was short on details, Cox, a Republican, promised his administration would take an “any of the above” approach, which aims to expand all sources of energy production.

Despite that goal, the Utah Legislature’s Republican supermajority, with Cox’s acquiescence, has taken a hard turn against solar power—which has been coming online faster than any other source in Utah and accounts for two-thirds of the new projects waiting to connect to the state’s power grid.

Cox signed a pair of bills passed this year that will make it more difficult and expensive to develop and produce solar energy in Utah by ending solar development tax credits and imposing a hefty new tax on solar generation. A third bill aimed at limiting solar development on farmland narrowly missed the deadline for passage but is expected to return next year.

While Operation Gigawatt emphasizes nuclear and geothermal as Cox’s preferred sources, the legislative broadside, and Cox’s willingness to go along with it, caught many in the solar industry off guard. The three bills, in their original form, could have brought solar development to a halt if not for solar industry lobbyists negotiating a lower tax rate and protecting existing projects as well as those under construction from the brunt of the impact.

“It took every dollar of political capital from all the major solar developers just to get to something tolerable, so that anything they have under development will get built and they can move on to greener pastures,” said one industry insider, indicating that solar developers will likely pursue projects in more politically friendly states. ProPublica spoke with three industry insiders—energy developers and lobbyists—all of whom asked to remain anonymous for fear of antagonizing lawmakers who, next month, will again consider legislation affecting the industry.

The Utah Legislature’s pivot away from solar mirrors President Donald Trump taking a more hostile approach to the industry than his predecessor. Trump has ordered the phaseout of lucrative federal tax incentives for solar and other renewable energy, which expanded under the Biden administration. The loss of federal incentives is a bigger hit to solar companies than the reductions to Utah’s tax incentives, industry insiders acknowledged. The administration has also canceled large wind and solar projects, which Trump has lamented as “the scam of the century.” He described solar as “farmer killing.”

Yet Cox criticized the Trump administration’s decision to kill a massive solar project in neighboring Nevada. Known as a governor who advocates for a return to more civil political discourse, Cox doesn’t often pick fights. But he didn’t pull punches with the decision to halt the Esmeralda 7 project planned on 62,300 acres of federal land. The central Nevada project was expected to produce 6.2 gigawatts of power—enough to supply nearly eight times the number of households in Las Vegas. (Although the Trump administration canceled the environmental review of the joint project proposed by multiple developers, it has the potential to move forward as individual projects.)

“This is how we lose the AI/energy arms race with China,” Cox wrote on X when news surfaced of the project’s cancellation. “Our country needs an all-of-the-above approach to energy (like Utah).”

But he didn’t take on his own Legislature, at least publicly.

Many of Utah’s Republican legislators have been skeptical of solar for years, criticizing its footprint on the landscape and viewing it as an unreliable energy source, while lamenting the retirement of coal-generated power plants. The economies of several rural counties rely on mining coal. But lawmakers’ skepticism hadn’t coalesced into successful anti-solar legislation—until this year. When Utah lawmakers convened at the start of 2025, they took advantage of the political moment to go after solar.

“This is a sentiment sweeping through red states, and it’s very disconcerting and very disturbing,” said Steve Handy, Utah director of The Western Way, which describes itself as a conservative organization advocating for an all-of-the-above approach to energy development.

The shift in sentiment against solar energy has created a difficult climate for an all-of-the-above approach. Solar projects can be built quickly on Utah’s vast, sun-drenched land, while nuclear is a long game with projects expected to take a decade or more to come online under optimistic scenarios.

Cox generally supports solar, “in the right places,” especially when the captured energy can be stored in large batteries for distribution on cloudy days and after the sun goes down.

Cox said that instead of vetoing the anti-solar bills, he spent his political capital to moderate the legislation’s impact. “I think you’ll see where our fingerprints were,” he told ProPublica. He didn’t detail specific changes for which he advocated but said the bills’ earlier iterations would have “been a lot worse.”

“We will continue to see solar in Utah.”

Cox’s any-of-the-above approach to energy generation draws from a decades-old Republican push similarly titled “all of the above.” The GOP policy’s aim was as much about preserving and expanding reliance on fossil fuels (indeed, the phrase may have been coined by petroleum lobbyists) as it was turning to cleaner energy sources such as solar, wind, and geothermal.

As governor of a coal-producing state, Cox hasn’t shown interest in reducing reliance on such legacy fuels. But as he slowly rolls out Operation Gigawatt, his focus has been on geothermal and nuclear power. Last month, he announced plans for a manufacturing hub for small modular reactors in the northern Utah community of Brigham City, which he hopes will become a nuclear supply chain for Utah and beyond. And on a recent trade mission to New Zealand, he signed an agreement to collaborate with the country on geothermal energy development.

Meanwhile, the bills Cox signed into law already appear to be slowing solar development in Utah. Since May, when the laws took effect, 51 planned solar projects withdrew their applications to connect to the state’s grid—representing more than a quarter of all projects in Utah’s transmission connection queue. Although projects drop out for many reasons, some industry insiders theorize the anti-solar legislation could be at play.

Caught in the political squeeze over power are Utah customers, who are footing higher electricity bills. Earlier this year, the state’s utility, Rocky Mountain Power, asked regulators to approve a 30 percent hike to fund increased fuel and wholesale energy costs, as well as upgrades to the grid. In response to outrage from lawmakers, the utility knocked the request down to 18 percent. Regulators eventually awarded the utility a 4.7 percent increase—a decision the utility promptly appealed to the state Supreme Court.

Juliet Carlisle, a University of Utah political science professor focusing on environmental policy, said the new solar tax could signal to large solar developers that Utah energy policy is “becoming more unpredictable,” prompting them to build elsewhere. This, in turn, could undermine Cox’s efforts to quickly double Utah’s electricity supply.

Operation Gigawatt “relies on rapid deployment across multiple energy sources, including renewables,” she said. “If renewable growth slows—especially utility-scale solar, which is currently the fastest-deploying resource—the state may face challenges meeting demand growth timelines.”

Rep. Kay Christofferson, R-Lehi, had sponsored legislation to end the solar industry’s state tax credits for several legislative sessions, but this was the first time the proposal succeeded.

Christofferson agrees Utah is facing unprecedented demand for power, and he supports Cox’s any-of-the-above approach. But he doesn’t think solar deserves the advantages of tax credits. Despite improving battery technology, he still considers it an intermittent source and thinks overreliance on it would work against Utah’s energy goals.

In testimony on his bill, Christofferson said he believed the tax incentives had served their purpose of getting a new industry off the ground—16 percent of Utah’s power generation now comes from solar, ranking it 16th in the nation for solar capacity.

Christofferson’s bill was the least concerning to the industry, largely because it negotiated a lengthy wind-down of the subsidies. Initially it would have ended the tax credit after Jan. 1, 2032. But after negotiations with the solar industry, he extended the deadline to 2035.

The bill passed the House, but when it reached the Senate floor, Sen. Brady Brammer, R-Pleasant Grove, moved the end of the incentives to 2028. He told ProPublica he believes solar is already established and no longer needs the subsidy. Christofferson tried to defend his compromise but ultimately voted with the legislative majority.

Unlike Christofferson’s bill, which wasn’t born of an antipathy for renewable energy, Rep. Casey Snider, R-Paradise, made it clear in public statements and behind closed doors to industry lobbyists that the goal of his bill was to make solar pay.

The bill imposes a tax on all solar production. The proceeds will substantially increase the state’s endangered species fund, which Utah paradoxically uses to fight federal efforts to list threatened animals for protection. Snider cast his bill as pro-environment, arguing the money could also go to habitat protection.

As initially written, the bill would have taxed not only future projects, but also those already producing power and, more worrisome for the industry, projects under construction or in development with financing in place. The margins on such projects are thin, and the unanticipated tax could kill projects already in the works, one solar industry executive testified.

“Companies like ours are being effectively punished for investing in the state,” testified another.

The pushback drew attacks from Snider, who accused solar companies of hypocrisy on the environment.

Industry lobbyists who spoke to ProPublica said Snider wasn’t as willing to negotiate as Christofferson. However, they succeeded in reducing the tax rate on future developments and negotiated a smaller, flat fee for existing projects.

“Everyone sort of decided collectively to save the existing projects and let it go for future projects,” said one lobbyist.

Snider told ProPublica, “My goal was never to run anybody out of business. If we wanted to make it more heavy-handed, we could have. Utah is a conservative state, and I would have had all the support.”

Snider said, like the governor, he favors an any-of-the-above approach to energy generation and doesn’t “want to take down any particular industry or source.” But he believes utility-scale solar farms need to pay to mitigate their impact on the environment. He likened his bill to federal law that requires royalties from oil and gas companies to be used for conservation. He hopes federal lawmakers will use his bill as a model for federal legislation that would apply to solar projects nationwide.

“This industry needs to give back to the environment that they claim very heavily they are going to protect,” he said. “I do believe there’s a tinge of hypocrisy to this whole movement. You can’t say you’re good for the environment and not offset your impacts.”

One of the more emotional debates over solar is set to return next year, after a bill that would end tax incentives for solar development on agricultural land failed to get a vote in the final minutes of this year’s session. Sponsored by Rep. Colin Jack, R-St. George, the bill has been fast-tracked in the next session, which begins in January.

Jack said he was driven to act by ranchers who were concerned that solar companies were outbidding them for land they had been leasing to graze cows. Solar companies pay substantially higher rates than ranchers can. His bill initially had a slew of land use restrictions—such as mandating the distance between projects and residential property and creeks, minimum lot sizes and 4-mile “green zones” between projects—that solar lobbyists said would have strangled their industry. After negotiating with solar developers, Jack eliminated the land use restrictions while preserving provisions to prohibit tax incentives for solar farms on private agricultural land and to create standards for decommissioning projects.

Many in rural Utah recoil at rows of black panels disrupting the landscape and fear solar farms will displace the ranching and farming way of life. Indeed, some wondered whether Cox, who grew up on a farm in central Utah, would have been as critical of Trump scuttling a 62,300-acre solar farm in his own state as he was of the Nevada project’s cancellation.

Peter Greathouse, a rancher in western Utah’s Millard County, said he is worried about solar farms taking up grazing land in his county. “Twelve and a half percent is privately owned, and a lot of that is not farmable. So if you bring in these solar places that start to eat up the farmland, it can’t be replaced,” he said.

Utah is losing about 500,000 acres of agricultural land every 10 years, most of it to housing. A report by The Western Way estimated solar farms use 0.1 percent of the United States’ total land mass. That number is expected to grow to 0.46 percent by 2050—a tiny fraction of what is used by agriculture. Of the land managed by the Utah Trust Lands Administration, less than 3,000 of the 2.9 million acres devoted to grazing have been converted to solar farms.

Other ranchers told ProPublica they’ve been able to stay on their land and preserve their way of life by leasing to solar. Landon Kesler’s family, which raises cattle for team roping competitions, has leased land to solar for more than a decade. The revenue has allowed the family to almost double its land holdings, providing more room to ranch, Kesler said.

“I’m going to be quite honest, it’s absurd,” Kesler said of efforts to limit solar on agricultural land. “Solar very directly helped us tie up other property to be used for cattle and ranching. It didn’t run us out; it actually helped our agricultural business thrive.”

Solar lobbyists and executives have been working to bolster the industry’s image with lawmakers ahead of the next legislative session. They’re arguing solar is a good neighbor.

“We don’t use water, we don’t need sidewalks, we don’t create noise, and we don’t create light,” said Amanda Smith, vice president of external affairs for AES, which has one solar project operating in Utah and a second in development. “So we just sort of sit out there and produce energy.”

Solar pays private landowners in Utah $17 million a year to lease their land. And, more important, solar developers argue, it’s critical to powering data centers the state is working to attract.

“We are eager to be part of a diversified electricity portfolio, and we think we bring a lot of values that will benefit communities, keep rates low and stable, and help keep the lights on,” Rikki Seguin, executive director of Interwest Energy Alliance, a western trade organization that advocates for utility-scale renewable energy projects, told an interim committee of lawmakers this summer.

The message didn’t get a positive reception from some lawmakers on the committee. Rep. Carl Albrecht, R-Richfield, who represents three rural Utah counties and was among solar’s critics last session, said the biggest complaint he hears from constituents is about “that ugly solar facility” in his district.

“Why, Rep. Albrecht, did you allow that solar field to be built? It’s black. It looks like the Dead Sea when you drive by it,” Albrecht said.

This story was originally published by ProPublica.

Utah leaders hinder efforts to develop solar energy supply Read More »

Sharks and rays gain landmark protections as nations move to curb international trade

inside climate news, rays, Science, sharks, syndication / Mike M. / December 13, 2025

Gov’ts agree to ban or restrict international trade in shark meat, fins, and other products.

For the first time, global governments have agreed to widespread international trade bans and restrictions for sharks and rays being driven to extinction.

Last week, more than 70 shark and ray species, including oceanic whitetip sharks, whale sharks, and manta rays, received new safeguards under the Convention on International Trade in Endangered Species of Wild Fauna and Flora. The convention, known as CITES, is a United Nations treaty that requires countries to regulate or prohibit international trade in species whose survival is threatened.

Sharks and rays are closely related species that play similar roles as apex predators in the ocean, helping to maintain healthy marine ecosystems. They have been caught and traded for decades, contributing to a global market worth nearly $1 billion annually, according to Luke Warwick, director of shark and ray conservation at Wildlife Conservation Society (WCS), an international nonprofit dedicated to preserving animals and their habitats.

The sweeping conservation measures were adopted as the treaty’s 20th Conference of the Parties (COP20) concluded in Samarkand, Uzbekistan, signaling a landmark global commitment to stop or regulate the demand for shark meat, fins, and other products derived from the animals.

“These new protections are a powerful step toward ensuring these species have a real chance at recovery,” said Diego Cardeñosa, an assistant professor at Florida International University and lead scientist at the school’s Predator Ecology and Conservation Lab, which is developing new technologies to combat the illegal trade of sharks.

More than a third of shark and ray species are now threatened with extinction. Pelagic shark populations that live in the open ocean have declined by more than 70 percent over the last 50 years. Reef sharks have all but vanished from one in five coral reefs worldwide. “We’re in the middle of an extinction crisis for the species and it’s kind of a silent crisis,” said Warwick. “It’s only in the last decade or so we’ve really, really started to notice that this is happening, and the major driver of it is actually overfishing.”

Unlike tuna and other commercially valuable fish that have been tightly regulated for decades, sharks have long lacked comparable controls on their trade and have often been treated as if they were another fast-reproducing seafood commodity.

“People treat sharks and rays, or have done over the last 50 years, as if they’re like other fish,” Warwick said. But unlike many fish that produce millions of eggs a year, sharks and rays take much longer to mature and produce significantly fewer young. Manta rays, for instance, may only give birth to seven live pups in their lifetime. “But we’ve been catching and killing them, just like other fish, and that, sadly, has led to these catastrophic declines.”

Manta rays are targeted primarily for their large gill plates, which are used in some traditional medicines in Asia aimed at detoxifying the body and boosting immunity, though there is no scientific evidence to support these claims. Their meat is sometimes turned into animal feed or consumed locally.

Shark fins remain a delicacy in luxury Chinese cuisine, prized in expensive dishes like shark fin soup. Shark meat is increasingly sold as a low-cost source of protein. It’s also a common ingredient in cat and dog food.

The livers of deep-water species like gulper sharks are also harvested for their oil, which is used to produce squalene, a staple component of topical skincare products and makeup. Years of unregulated trade of the species have driven population declines of more than 80 percent in some regions.

“The cosmetic industry, really, in a way, is driving the trade of the sharks,” said Gabriel Vianna, a shark researcher from the Charles Darwin Foundation, an international nonprofit dedicated to conserving the Galapagos Islands. In recent years, squalene has also been increasingly used in pharmaceuticals and even COVID-19 vaccines. “We should be using synthetic options and not exploiting these species,” Vianna said.

But until last week, there were no international controls in place to regulate trade in these species despite growing demand for their livers.

That has now changed through the latest decisions adopted at CITES, which Warwick said mark a turning point in marine conservation.

For much of its 50-year history, the convention focused on protecting iconic land species like elephants, rhinos, primates, and parrots, or charismatic marine species like sea turtles, Warwick said. By 1981, CITES had imposed an international ban on all international trade of sea turtles, which Warwick credited for helping some species make remarkable comebacks in the last few decades. Only in the last 10 years, Warwick said, has the convention slowly begun recognizing sharks and rays with similar urgency.

This year at COP20, all proposed protections for sharks and rays were adopted, largely with unanimous support from CITES’ 185 member countries and the European Union, which Warwick said had never happened before.

The European Union is one of the top suppliers of shark meat to Southeast and East Asian markets, with its imports and exports adding up to more than 20 percent of global shark meat trade, according to the World Wildlife Fund.

Gulper sharks, targeted for their livers, as well as smoothhound and tope sharks, which are primarily fished for their meat, were listed under CITES’ Appendix II. Each listing covers multiple species—20 species of gulper sharks and 30 species of smoothhounds—grouped together because their products cannot be reliably distinguished in trade.

The listing requires all CITES parties to strictly regulate international trade of the species and demonstrate if it is traceable and biologically sustainable. Some species, including wedgefish and giant guitarfish—large shark-like rays targeted for their highly valuable fins—are now protected by a temporary suspension of trade.

Others, such as oceanic whitetips, whale sharks, manta, and devil rays, can no longer be traded internationally at all. Under the new protections, CITES now lists them as Appendix I species, meaning they face a real extinction risk due to trade and are afforded the treaty’s highest level of protection.

“If you find an oceanic whitetip fin being traded, 90 days from here onwards, that’s an illegal product,” he said.

For many shark advocates, the new listings are bittersweet.

“We are very happy but we are very sad at the same time,” said Vianna. “We shouldn’t be happy about this species being listed. We should actually be really worried that there’s such a problem with them.” Meaningful implementation of the new protections will be critical to the survival of many of these species, he said.

Research published in November by Cardeñosa and Warwick found that fins from several shark and ray species, such as oceanic white tip sharks, which were previously listed under Appendix II, were frequently found in Hong Kong—the world’s largest shark fin market—between 2015 and 2021. Appendix II allows for regulated trade, but little to no legal trade in species like the oceanic white tip has been reported since CITES began regulating it in 2014, revealing a significant gap in the amount of sharks being traded and what is being legally documented. For example, genetic analysis of shark fins in Hong Kong detected more than 70 times the number of oceanic whitetip shark fins reported in official CITES records, indicating that more than 90 percent of the trade is illegal.

“This tells us that enforcement gaps remain, especially in large, complex supply chains,” Cardeñosa said in an email.

Now that the oceanic whitetip shark has been uplisted to Appendix I, which prohibits any international trade, Cardeñosa hopes loopholes that previously allowed the protected species and others to slip through will be closed.

“The new listings will not eliminate illegal trade overnight, but they will significantly strengthen the ability of countries to inspect, detect, and prosecute illegal shipments,” Cardeñosa said. “Parties must invest in identification tools, capacity building, and routine monitoring if these protections are to translate into real reductions in illegal trade.”

ProPublica is a Pulitzer Prize-winning investigative newsroom. Sign up for The Big Story newsletter to receive stories like this one in your inbox.

This article originally appeared on Inside Climate News, a nonprofit, non-partisan news organization that covers climate, energy and the environment. Sign up for their newsletter here.

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Investors commit quarter-billion dollars to startup designing “Giga” satellites

Commercial space, k2, satellites, Science, Space / Paul Patrick / December 13, 2025

A startup established three years ago to churn out a new class of high-power satellites has raised $250 million to ramp up production at its Southern California factory.

The company, named K2, announced the cash infusion on Thursday. K2’s Series C fundraising round was led by Redpoint Ventures, with additional funding from investment firms in the United States, the United Kingdom, and Germany. K2 has now raised more than $400 million since its founding in 2022 and is on track to launch its first major demonstration mission next year, officials said.

K2 aims to take advantage of a coming abundance of heavy- and super-heavy-lift launch capacity, with SpaceX’s Starship expected to begin deploying satellites as soon as next year. Blue Origin’s New Glenn rocket launched twice this year and will fly more in 2026 while engineers develop an even larger New Glenn with additional engines and more lift capability.

Underscoring this trend toward big rockets are other launchers like SpaceX’s Falcon 9 and Falcon Heavy, United Launch Alliance’s Vulcan, and new vehicles from companies like Rocket Lab, Relativity Space, and Firefly Aerospace. K2’s founders believe satellites will follow a similar progression, reversing a trend toward smaller spacecraft in recent years, to address emerging markets like in-space computing and data processing.

Mega, then Giga

K2 is designing two classes of satellites—Mega and Giga—that it will build at an 180,000-square-foot factory in Torrance, California. The company’s first “Mega Class” satellite is named Gravitas. It is scheduled to launch in March 2026 on a Falcon 9 rocket. Once in orbit, Gravitas will test several systems that are fundamental to K2’s growth strategy. One is a 2o-kilowatt Hall-effect thruster that K2 says will be four times more powerful than any such thruster flown to date. Gravitas will also deploy twin solar arrays capable of generating 20 kilowatts of power.

“Gravitas brings our full stack together for the first time,” said Karan Kunjur, K2’s co-founder and CEO, in a company press release. “We are validating the architecture in space, from high-voltage power and large solar arrays to our guidance and control algorithms, and a 20 kW Hall thruster, and we will scale based on measured performance.”

Investors commit quarter-billion dollars to startup designing “Giga” satellites Read More »

Scientists built an AI co-pilot for prosthetic bionic hands

AI, prosthetics, robotic hands, robotics, Science, sensors / Paul Patrick / December 12, 2025

To test their AI-powered hand, the team asked intact and amputee participants to manipulate fragile objects: pick up a paper cup and drink from it, or take an egg from a plate and put it down somewhere else. Without the AI, they could succeed roughly one or two times in 10 attempts. With the AI assistant turned on, their success rate jumped to 80 or 90 percent. The AI also decreased the participants’ cognitive burden, meaning they had to focus less on making the hand work.

But we’re still a long way away from seamlessly integrating machines with the human body.

Into the wild

“The next step is to really take this system into the real world and have someone use it in their home setting,” Trout says. So far, the performance of the AI bionic hand was assessed under controlled laboratory conditions, working with settings and objects the team specifically chose or designed.

“I want to make a caveat here that this hand is not as dexterous or easy to control as a natural, intact limb,” George cautions. He thinks that every little increment that we make in prosthetics is allowing amputees to do more tasks in their daily life. Still, to get to the Star Wars or Cyberpunk technology level where bionic prostheses are just as good or better than natural limbs, we’re going to need more than just incremental changes.

Trout says we’re almost there as far as robotics go. “These prostheses are really dexterous, with high degrees of freedom,” Trout says, “but there’s no good way to control them.” This in part comes down to the challenge of getting the information in and out of users themselves. “Skin surface electromyography is very noisy, so improving this interface with things like internal electromyography or using neural implants can really improve the algorithms we already have,” Trout argued. This is why the team is currently working on neural interface technologies and looking for industry partners.

“The goal is to combine all these approaches in one device,” George says. “We want to build an AI-powered robotic hand with a neural interface working with a company that would take it to the market in larger clinical trials.”

Nature Communications, 2025. DOI: 10.1038/s41467-025-65965-9

Scientists built an AI co-pilot for prosthetic bionic hands Read More »

Ars Live: 3 former CDC leaders detail impacts of RFK Jr.’s anti-science agenda

Ars Live Chat, CDC, health, Science / Tim Belzer / December 11, 2025

The Centers for Disease Control and Prevention is in critical condition. This year, the premier public health agency had its funding brutally cut and staff gutted, its mission sabotaged, and its headquarters riddled with literal bullets. The over 500 rounds fired were meant for its scientists and public health experts, who endured only to be sidelined, ignored, and overruled by Health Secretary Robert F. Kennedy Jr., an anti-vaccine activist hellbent on warping the agency to fit his anti-science agenda.

Then, on August 27, Kennedy fired CDC Director Susan Monarez just weeks after she was confirmed by the Senate. She had refused to blindly approve vaccine recommendations from a panel of vaccine skeptics and contrarians that he had hand-selected. The agency descended into chaos, and Monarez wasn’t the only one to leave the agency that day.

Three top leaders had reached their breaking point and coordinated their resignations upon the dramatic ouster: Drs. Demetre Daskalakis, Debra Houry, and Daniel Jernigan walked out of the agency as their colleagues rallied around them.

Dr. Daskalakis was the director of the CDC National Center for Immunization and Respiratory Diseases. He managed national responses to mpox, measles, seasonal flu, bird flu, COVID-19, and RSV.

Ars Live: 3 former CDC leaders detail impacts of RFK Jr.’s anti-science agenda Read More »

No sterile neutrinos after all, say MicroBooNE physicists

MicroBooNE, neutrinos, particle physics, Physics, Science, sterile neutrinos / Rejus Almole / December 11, 2025

Since the 1990s, physicists have pondered the tantalizing possibility of an exotic fourth type of neutrino, dubbed the “sterile” neutrino, that doesn’t interact with regular matter at all, apart from its fellow neutrinos, perhaps. But definitive experimental evidence for sterile neutrinos has remained elusive. Now it looks like the latest results from Fermilab’s MiniBooNE experiment have ruled out the sterile neutrino entirely, according to a paper published in the journal Nature.

How did the possibility of sterile neutrinos even become a thing? It all dates back to the so-called “solar neutrino problem.” Physicists detected the first solar neutrinos from the Sun in 1966. The only problem was that there were far fewer solar neutrinos being detected than predicted by theory, a conundrum that became known as the solar neutrino problem. In 1962, physicists discovered a second type (“flavor”) of neutrino, the muon neutrino. This was followed by the discovery of a third flavor, the tau neutrino, in 2000.

Physicists already suspected that neutrinos might be able to switch from one flavor to another. In 2002, scientists at the Sudbury Neutrino Observatory (or SNO) announced that they had solved the solar neutrino problem. The missing solar (electron) neutrinos were just in disguise, having changed into a different flavor on the long journey between the Sun and the Earth. If neutrinos oscillate, then they must have a teensy bit of mass after all. That posed another knotty neutrino-related problem. There are three neutrino flavors, but none of them has a well-defined mass. Rather, different kinds of “mass states” mix together in various ways to produce electron, muon, and tau neutrinos. That’s quantum weirdness for you.

And there was another conundrum, thanks to results from Los Alamos’ LSND experiment and Fermilab’s MiniBooNE (MicroBooNE’s predecessor). Both found evidence of muon neutrinos oscillating into electron neutrinos in a way that shouldn’t be possible if there were just three neutrino flavors. So physicists suggested there might be a fourth flavor: the sterile neutrino, so named because unlike the other three, it does not couple to a charged counterpart via the electroweak force. Its existence would also have big implications for the nature of dark matter. But despite the odd tantalizing hint, sterile neutrinos have proven to be maddeningly elusive.

No sterile neutrinos after all, say MicroBooNE physicists Read More »

This is the oldest evidence of people starting fires

Archaeology, firestarting, hominins, making fire, Neanderthals, Science / Kris Guyer / December 10, 2025

We didn’t start the fire. (Neanderthals did, at least 400,000 years ago.)

This artist’s impression shows what the fire at Barnham might have looked like. Credit: Craig Williams, The Trustees of the British Museum

Heat-reddened clay, fire-cracked stone, and fragments of pyrite mark where Neanderthals gathered around a campfire 400,000 years ago in what’s now Suffolk, England.

Based on chemical analysis of the sediment at the site, along with the telltale presence of pyrite, a mineral not naturally found nearby but very handy for striking sparks with flint, British Museum archaeologist Rob Davis and his colleagues say the Neanderthals probably started the fire themselves. That makes the abandoned English clay pit at Barnham the oldest evidence in the world that people (Neanderthal people, in this case) had learned to not only use fire, but also create it and control it.

A cozy Neanderthal campfire

Today, the Barnham site is part of an abandoned clay pit where workers first discovered stone tools in the early 1900s. But 400,000 years ago, it would have been a picturesque little spot at the edge of a stream-fed pond, surrounded by a mix of forest and grassland. There are no hominin fossils here, but archaeologists unearthed a Neanderthal skull about 100 kilometers to the south, so the hominins at Barnham were probably also Neanderthals. The place would have have offered a group of Neanderthals a relatively quiet, sheltered place to set up camp, according to Davis and his colleagues.

The cozy domesticity of that camp apparently centered on a hearth about the size of a small campfire. What’s left of that hearth today is a patch of clayey silt baked to a rusty red color by a series of fires; it stands out sharply against the yellowish clay that makes up the rest of the site. When ancient hearth fires heated that iron-rich yellow clay, it formed tiny grains of hematite that turned the baked clay a telltale red. Near the edge of the hearth, the archaeologists unearthed a handful of flint handaxes shattered by heat, alongside a scattering of other heat-cracked flint flakes.

And glinting against the dull clay lay two small pieces of a shiny sulfide mineral, aptly named pyrite—a key piece of Stone Age firestarting kits. Long before people struck flint and steel together to make fire, they struck flint and pyrite. Altogether, the evidence at Barnham suggests that Neanderthals were building and lighting their own fires 400,000 years ago.

Fire: the way of the future

Lighting a fire sounds like a simple thing, but once upon a time, it took cutting-edge technology. Working out how to start a fire on purpose—and then how to control its size and temperature—was the breakthrough that made nearly everything else possible: hafted stone weapons, cooked food, metalworking, and ultimately microprocessors and heavy-lift rockets.

“Something else that fire provides is additional time. The campfire becomes a social hub,” said Davis during a recent press conference. “Having fire… provides this kind of intense socialization time after dusk.” It may have been around fires like the one at Barnham, huddled together against the dark Pleistocene evening, that hominins began developing language, storytelling, and mythologies. And those things, Davis suggested, could have “played a critical part in maintaining social relationships over bigger distances or within more complex social groups.” Fire, in other words, helped make us more fully human and may have helped us connect in the same way that bonding over TV shows does today.

Archaeologists have worked for decades to try to pinpoint exactly when that breakthrough happened (although most now agree that it probably happened multiple times in different places). But evidence of fire is hard to find because it’s ephemeral by its very nature. The small patch of baked clay at Barnham hasn’t seen a fire in half a million years, but its light is still pushing back the shadows.

an artist's impression of a person's hands holding a piece of flint and a piece of pyrite, striking them together to make sparks — This was the first step toward the Internet. We could have turned back. Credit: Craig Williams, The Trustees of the British Museum

A million-year history of fire

Archaeologists suspect that the first hominins to use fire took advantage of nearby wildfires: Picture a Homo erectus lighting a branch on a nearby wildfire (which must have taken serious guts), then carefully carrying that torch back to camp to cook or make it easier to ward off predators for a night. Evidence of that sort of thing—using fire, but not necessarily being able to summon it on command—dates back more than a million years at sites like Koobi Fora in Kenya and Swartkrans in South Africa.

Learning to start a fire whenever you want one is harder, but it’s essential if you want to cook your food regularly without having to wait for the next lightning strike to spark a brushfire. It can also help maintain the careful control of temperature needed to make birch tar adhesives, “The advantage of fire-making lies in its predictability,” as Davis and his colleagues wrote in their paper. Knowing how to strike a light changed fire from an occasional luxury item to a staple of hominin life.

There are hints that Neanderthals in Europe were using fire by around 400,000 years ago, based on traces of long-cold hearths at sites in France, Portugal, Spain, the UK, and Ukraine. (The UK site, Beeches Pit, is just 10 kilometers southwest of Barnham.) But none of those sites offer evidence that Neanderthals were making fire rather than just taking advantage of its natural appearance. That kind of evidence doesn’t show up in the archaeological record until 50,000 years ago, when groups of Neanderthals in France used pyrite and bifaces (multi-purpose flint tools with two worked faces, sharp edges, and a surprisingly ergonomic shape) to light their own hearth-fires; marks left on the bifaces tell the tale.

Barnham pushes that date back dramatically, but there’s probably even older evidence out there. Davis and his colleagues say the Barnham Neanderthals probably didn’t invent firestarting; they likely brought the knowledge with them from mainland Europe.

“It’s certainly possible that Homo sapiens in Africa had the ability to make fire, but it can’t be proven yet from the evidence. We only have the evidence at this date from Barnham,” said Natural History Museum London anthropologist Chris Stringer, a coauthor of the study, in the press conference.

a person holds a tiny fragment of pyrite between a thumb and forefinger — The two pyrite fragments at the side may have broken off a larger nodule when it was struck against a piece of flint. Credit: Jordan Mansfield, Pathways to Ancient Britain Project.

Digging into the details

Several types of evidence at the site point to Neanderthals starting their own fire, not borrowing from a local wildfire. Ancient wildfires leave traces in sediment that can last hundreds of thousands of years or more—microscopic bits of charcoal and ash. But the area that’s now Suffolk wasn’t in the middle of wildfire season when the Barnham hearth was in use. Chemical evidence, like the presence of heavy hydrocarbon molecules in the sediment around the hearth, suggests this fire was homemade (wildfires usually scatter lighter ones across several square kilometers of landscape).

But the key piece of evidence at Barnham—the kind of clue that arson investigators probably dream about—is the pyrite. Pyrite isn’t a naturally common mineral in the area around Barnham; Neanderthals would have had to venture at least 12 kilometers southeast to find any. And although few hominins can resist the allure of picking up a shiny rock, it’s likely that these bits of pyrite had a more practical purpose.

To figure out what sort of fire might have produced the reddened clay, Davis and his colleagues did some experiments (which involved setting a bunch of fires atop clay taken from near the site). The archaeologists compared the baked clay from Barnham to the clay from beneath their experimental fires. The grain size and chemical makeup of the clay from the ancient Neanderthal hearth looked almost exactly like “12 or more heating events, each lasting 4 hours at temperatures of 400º Celsius or 600º Celsius,” as Davis and his colleagues wrote.

In other words, the hearth at Barnham hints at the rhythms of daily life for one group of Neanderthals 400,000 years ago. For starters, it seems that they kindled their campfire in the same spot over and over and left it burning for hours at a time. Flakes of flint nearby conjure up images of Neanderthals sitting around the fire, knapping stone tools as they told each other stories long into the night.

Nature, 2025 DOI: 10.1038/s41586-025-09855-6 About DOIs).

Kiona is a freelance science journalist and resident archaeology nerd at Ars Technica.

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