They hide a vast chemical arsenal that researchers are mining for pain, diabetes, and brain disease therapies.This horrid disease has been with us for much longer than we thought.Stuck between life and death, this foot consumes nutrients, heals itself, and grows, but doesn’t turn into a whole new organism.One of fusion energy’s biggest selling points is that it is supposed to be different from traditional nuclear power.
Unlike today’s fission reactors, which rely on uranium fuel and produce materials that can be linked to nuclear weapons programs, fusion machines are often portrayed as a cleaner and safer alternative.
However, as governments and companies pour billions of dollars into making fusion commercially viable, some researchers are asking a burning question: How will anyone ensure that future fusion plants are being used exactly as advertised?
This is important because “fusion power systems can in principle be used to make significant amounts of fissile material,” researchers note.
A new study suggests antineutrinos, tiny particles produced in nuclear reactions, could act as independent witnesses to what is happening inside a fusion reactor. If this idea works as expected, future inspectors may be able to spot attempts to produce weapons-related materials without opening up the reactor or interrupting its operation.
Most fusion designs under development rely on a reaction between two forms of hydrogen called deuterium and tritium. When these atomic nuclei merge, they release enormous amounts of energy.
They also release fast-moving neutrons, which are essential for extracting that energy and converting it into electricity. Those neutrons, however, do not care how they are used.
If uranium-238 were placed near the fusion reaction, some of the neutrons could be absorbed by the uranium. Through a sequence of nuclear transformations, the uranium could eventually become plutonium-239, one of the materials that can be used in nuclear weapons.
This possibility does not mean that fusion reactors are secret weapons factories. Producing plutonium in this way would require deliberate action. Yet regulators generally prefer to design safeguards before a technology becomes widespread rather than after.
“Demonstrating methods to assure the timely detection of such a misuse scenario would be extremely valuable as part of the efforts to guarantee the peaceful use of fusion energy systems,” the study authors said.
The challenge has been finding a monitoring method that can reliably reveal what is happening inside a reactor without becoming intrusive or technically impractical.
The study authors investigated whether antineutrinos could provide that monitoring capability.
Antineutrinos are among the most elusive particles known to science.
Trillions pass through the human body every second without leaving a trace. Since they interact so weakly with matter, they cannot realistically be blocked by walls, shielding, or other barriers.
That property turns them into a unique source of information. If plutonium production were taking place inside a fusion reactor, the nuclear reactions involved would generate a characteristic antineutrino signal. In principle, that signal could reveal activity that operators might otherwise try to conceal.
The researchers used computer simulations to test whether such a signal would be detectable in practice. They modeled the antineutrinos expected from plutonium-producing reactions and compared them with other sources of background noise, including signals generated during normal reactor operation and particles arriving from space.
Their results indicate that the difference should be measurable. According to the study, a relatively compact detector could detect the production of only a few kilograms of plutonium over about 30 days.
In one benchmark scenario examined by the researchers, the production of 8 kilograms of plutonium in a month generated a strong and easily detectable antineutrino signal. This is a small enough amount to provide an early warning that something unusual is happening.
“Our results confirm that even a modestly-sized antineutrino detector should be able to detect the presence of fertile material during operation in a reliable and timely manner,” the study authors added.
Equally important, the detector would not need to sit inside the reactor complex. This is because antineutrinos travel through matter almost unhindered; the monitoring system could operate from outside the facility, making it less disruptive for reactor operators.
No commercial deuterium-tritium fusion power plants exist today, which means there is currently no facility where the approach can be tested under full operating conditions. The researchers therefore relied on simulations rather than real-world measurements.
That limitation also highlights why the study matters now. Fusion developers are still working to prove that their reactors can generate electricity economically.
If they succeed, governments and international agencies will eventually need a framework for monitoring the technology. Creating such safeguards after hundreds of reactors are already operating would be far more difficult.
The new work does not solve every question surrounding fusion security, but it does offer a practical way to verify that future reactors are doing only what they are supposed to do.
The study is published in the journal Physical Review Applied.
For more than three centuries, physicists have believed in Isaac Newton’s third law—every action has an equal and opposite reaction. However, many real-world collective systems appear to ignore this rule.
For example, a bird in a flock pays attention mainly to birds in front of it, not those behind. Cells moving through tissue respond to some neighbors but not others. Swarming bacteria and even human crowds often behave in similarly one-sided ways.
These nonreciprocal interactions have long posed a challenge because many of the mathematical tools physicists use assume that action and reaction are balanced.
Now, a new study presents a framework that effectively restores access to those powerful tools without changing the underlying physics. This work could make it much easier to study flocking animals, active matter, biological tissues, and potentially even exotic quantum systems.
“We have developed and proven a theory that makes much of what we teach our students applicable to nonreciprocal systems as well,” said Marin Bukov, one of the study authors and a researcher at the Max Planck Institute for the Physics of Complex Systems.
These systems, where Newton’s third law does not apply, can now finally be described exactly and simulated precisely—even using established methods. This is exactly the kind of tool that has been missing in recent years,” Bukov added.
In conventional systems, interactions can be described by an energy function, allowing researchers to use well-established methods from statistical mechanics and many-body physics.
Nonreciprocal systems are different. If one bird responds to another but not vice versa, there is no single interaction energy that describes the pair. Without that energy landscape, many standard analytical and computational approaches become unavailable.
Scientists could still simulate the systems directly, but the calculations were often slower, less flexible, and harder to interpret. A general framework capable of handling nonreciprocal interactions while preserving the advantages of traditional physics had remained elusive.
The researchers solved the problem by introducing what they call auxiliary degrees of freedom. In simple terms, every real component in a nonreciprocal system is paired with an artificial counterpart that exists only in mathematics.
The key idea is surprisingly simple. Instead of changing the physics, the researchers add mathematical partners to every real component in the system.
“The trick behind the new theory is that it constructs a partner for each component of the system—a fictitious partner that doesn’t exist in nature,” Ricard Alert, one of the study authors and a biophysicist at the Max Planck Institute, said.
Imagine a flock of birds. Instead of modeling only the real birds, the framework adds a second set of fictional birds. These imaginary birds are carefully defined so that the originally one-way interactions can be rewritten as ordinary two-way interactions between real and auxiliary partners.
The resulting enlarged system obeys the reciprocal rules that physicists know how to handle. Once a specific constraint is imposed, the mathematical model reproduces the exact behavior of the original nonreciprocal flock.
The idea resembles a common strategy in theoretical physics, where extra variables are introduced to simplify difficult problems.
What makes this work different is that the auxiliary variables provide a general recipe for translating nonreciprocal interactions into a form compatible with Hamiltonian mechanics—a mathematical framework physicists use to predict how complex systems evolve over time.
To demonstrate the approach, the team studied a model known as the vision-cone XY model. In this system, each element interacts only with neighbors that fall within a specific field of view, much like birds paying attention only to those ahead of them.
Since one bird can see another without being seen in return, the interaction is inherently nonreciprocal. The researchers showed that by adding an auxiliary partner for every element and enforcing a mirror-like relationship between the two, the original dynamics emerge exactly from a Hamiltonian description.
The payoff was immediate. The team proved that Monte Carlo simulations based on the new Hamiltonian framework reproduced both steady and changing states of the original nonreciprocal system.
This means scientists can now apply computational techniques that were previously reserved for conventional reciprocal systems. In practice, researchers may be able to analyze much larger systems more efficiently and explore behaviors that were previously difficult to access.
The framework also unlocked another powerful tool, Floquet engineering, a technique that uses periodic driving to manipulate interactions.
Using their new formulation, the researchers showed how a periodically driven nonreciprocal spin system could effectively be transformed from a two-dimensional network into behavior resembling a collection of one-dimensional chains. Such control would have been difficult to analyze without a Hamiltonian description.
“Overall, our construction paves the way towards extending statistical mechanics and Hamiltonian dynamics to non-reciprocal systems,” the study authors note.
The framework gives physicists a new way to study nonreciprocal systems using many of the established tools developed for conventional physics. Beyond flocking birds and moving cells, it could help researchers analyze a wide range of systems where interactions are one-sided.
Currently, the approach applies to pairwise interactions and introduces an auxiliary partner for every real component, making more complex systems a challenge for future work.
Looking ahead, the study authors want to explore whether nonreciprocal interactions can produce entirely new forms of collective quantum behavior.
If so, the framework could open a new window into how complex matter organizes itself when the usual action-reaction symmetry breaks down.
The study is published in the journal Nature Physics.
For centuries, the Arctic has remained one of the most dangerous places on Earth to explore. Beneath what looks like solid snow can lie hidden pools of icy water capable of swallowing people, vehicles, and scientific equipment without warning.
These risks make collecting data from polar regions slow, expensive, and often dangerous. Now, a small four-legged robot promises to change this.
A modified version of Lynx S10, an autonomous robot developed by China-based DEEP Robotics, has become the first quadruped platform to walk on Arctic Ocean ice floes. It successfully demonstrates that autonomous machines may one day perform some of the most hazardous fieldwork in places where human access is limited.
“The Lynx S10 enables autonomous path planning and intelligent obstacle avoidance,” the DEEP Robotics team notes.
The achievement is significant not because a robot survived the cold, but because it showed that compact autonomous systems can navigate unpredictable ice, snow, and water-filled terrain that even experienced researchers approach with extreme caution.
The Arctic expedition was designed as a real-world stress test for the Lynx S10, a compact quadruped robot that weighs less than 20 kilograms even with its battery installed.
Unlike larger robotic platforms that require extensive transport and setup, the machine can be carried and deployed by a single person. “Its compact body allows single-person portability and rapid deployment, enhancing operational mobility,” the DEEP Robotics team claims.
Despite its small size, it is equipped with sixteen precision joints that allow it to bend, twist, and maneuver through spaces that would be inaccessible to bulkier robots.
The standard version of the robot is already highly capable. According to its creators, “Equipped with a next-generation AI motion control and gait algorithm, the Lynx S10 performs a variety of extreme maneuvers.”
For instance, it can travel at speeds of up to 8 m/s on flat ground, climb over obstacles as tall as 50 centimeters, and switch between wheeled and legged movement depending on the terrain.
When necessary, it can even rise into a bipedal stance to gain additional height and visibility.
To operate independently, the robot relies on an advanced perception system.
Four ultra-wide-angle cameras equipped with high-dynamic-range lenses continuously monitor its surroundings, while front and rear LiDAR sensors generate detailed three-dimensional maps. This allows the machine to identify obstacles, plan routes, and navigate without constant human control.
Its rugged design also enables operation in harsh environments. The standard platform is rated IP66 against dust and water intrusion, functions in temperatures from minus 20 to 55 degrees Celsius, carries payloads exceeding 8 kilograms, and can automatically locate and travel to a charging station when battery levels become low.
However, Arctic ice presented challenges that went far beyond the robot’s original design specifications.
Engineers therefore modified the platform before deployment. The standard wheels were replaced with large biomimetic paws inspired by the broad feet of polar bears. These custom feet spread the robot’s weight across a larger surface area, helping prevent it from sinking into soft snow.
Anti-slip textures improved grip on slick surfaces, while integrated crampons provided extra traction on hard ice. The robot’s sealing was also upgraded from IP66 to IP67 for greater protection against water intrusion.
Researchers introduced another unusual modification for environments where ice and water mixed together. By increasing the effective surface area of the limbs, the robot’s legs could function almost like paddles, allowing it to move through slushy conditions that would challenge conventional wheeled systems.
The Arctic tests quickly revealed why such adaptations were necessary. In several locations, snow concealed dangerous meltwater pools beneath the surface. The robot encountered terrain that appeared stable but actually floated above hidden pockets of water.
Thanks to its redesigned feet and traction system, it maintained stability while traversing these deceptive surfaces. In one instance, it successfully glided across an area that looked like solid ice but concealed water underneath.
Later tests pushed the machine into regions where ice and water were intermixed, and the modified limbs enabled it to continue moving through the difficult terrain.
More importantly, this was not a finished commercial product being showcased under controlled conditions. The Arctic vehicle was still an alpha-stage prototype.
The broader significance of the project extends well beyond a single expedition. Environmental researchers and emergency responders often need to operate in locations that are dangerous, remote, or impossible for humans to access safely.
Lynx S10 “confidently handles challenging environments such as dusty sites, heavy rain, and humid/foggy conditions,” the researchers at DEEP Robotics added.
This lightweight autonomous robot is capable of crossing unstable ice and moving through mixed ice-water environments. Therefore, it could help collect environmental data, monitor climate-related changes, and support search-and-rescue operations without exposing people to the same risks.
Researchers are now using the performance data gathered during the mission to further improve the design. Hopefully, future versions will be even more capable of handling unpredictable natural environments.
You can read more about Lynx S10 here.
For decades, nuclear clocks have existed as one of physics’ most tempting promises. A device that could keep time even more accurately than today’s best atomic clocks. Now, two independent research teams have turned this idea into reality.
Researchers in China and Europe have demonstrated working nuclear clocks based on the nucleus of thorium-229, a rare isotope whose unique properties have long made it the leading candidate for next-generation timekeeping.
The achievement represents much more than a new kind of clock. Since a nucleus is far better shielded from environmental disturbances than the electrons used in atomic clocks, nuclear clocks could eventually become the most precise timekeepers ever built.
Plus, this breakthrough could improve navigation, gravitational sensing, and tests of the laws governing the universe.
As the researchers note, “by making a laser-addressed atomic nucleus an operational clock reference, this work extends quantum metrology from electronic to nuclear transitions, and opens a new platform for compact clocks, solid-state nuclear quantum sensors and precision tests of fundamental physics.”
Modern atomic clocks keep time by measuring the frequency of light absorbed or emitted when electrons jump between specific energy levels inside an atom.
As these frequencies are extremely stable, counting their oscillations provides an exceptionally accurate way to measure time. Physicists have long envisioned building a clock using a nucleus instead of electrons. The idea is attractive because atomic nuclei are much smaller and more isolated from the outside world.
Stray electric and magnetic fields that can slightly disturb electrons have far less influence on the nucleus. In principle, that should allow a nuclear clock to achieve even greater stability and precision.
“Such a nuclear clock might rival or outperform current optical clocks based on electron-shell transitions in atoms or ions, is expected to be more robust against external perturbations, and provides enhanced sensitivity in clock-based tests of fundamental principles of physics,” the researchers explained.
However, the problem is that almost all nuclear energy transitions are far too energetic to be controlled with lasers. They typically require high-energy gamma rays rather than ordinary laser light.
Thorium-229 is a remarkable exception. Its nucleus possesses an unusually low-energy excited state that can be reached using ultraviolet laser light. For years, physicists recognized that this made thorium-229 the only known realistic candidate for a nuclear clock.
Even so, the task remained extraordinarily difficult. The required transition occurs at a wavelength of roughly 148 nanometers, deep in the vacuum ultraviolet region of the electromagnetic spectrum.
Producing stable laser light at this wavelength and precisely matching it to the nuclear transition pushed existing technology to its limits.
The two groups solved the problem using broadly similar strategies. One team, led by researchers at Tsinghua University, and another from the Vienna Center for Quantum Science and Technology, embedded thorium-229 atoms inside calcium fluoride crystals.
“Here, we implement a thorium-229 nuclear clock by stabilizing a continuous-wave laser to the 148 nm nuclear transition with rapid feedback based on continuous absorption spectroscopy,” the researchers from the Vienna Center note.
The crystal acts as a solid host that holds large numbers of thorium nuclei in place while allowing laser light to interact with them. Both groups then illuminated the crystals with highly specialized continuous-wave vacuum ultraviolet lasers tuned near the thorium nuclear transition.
Although the overall concept was similar, the teams optimized different parts of the experiment. The Chinese researchers relied on a more powerful laser system to drive the nuclear transition. The European team instead used crystals containing a higher concentration of thorium nuclei, increasing the number of nuclei available for measurement.
Once they had successfully excited the nuclei, the researchers needed to demonstrate that the system could function as a true clock rather than simply detecting the transition.
The Chinese team locked the frequency of their vacuum ultraviolet laser directly to the nuclear resonance. In effect, the thorium nucleus became a frequency reference that continuously corrected the laser.
The researchers reported a fractional frequency instability approaching one part in 10 trillion after a day of operation, showing that the nuclear transition could serve as a stable timekeeping signal.
The European team chose a different test. Instead of focusing solely on clock performance, they used their nuclear clock as a scientific probe.
The researchers searched for ultralight dark matter, a hypothetical form of matter that could subtly alter the energy levels inside atomic nuclei. If such particles existed, they might produce tiny periodic shifts in the thorium transition frequency.
“We use the nuclear clock to constrain models of ultralight dark matter by searching for periodic fluctuations and slow drifts in the nuclear transition energy, on time scales between 20 sec and one day,” the Vienna team said.
No evidence of dark matter was detected. However, the experiment demonstrated that the nuclear clock was sensitive enough to rival or exceed the capabilities of the world’s best atomic clocks when searching for such effects.
Together, the two studies provide the strongest evidence yet that practical nuclear clocks are no longer a theoretical concept but an operational technology.
While these first-generation devices are still laboratory systems, they mark the beginning of a new era in precision measurement.
Future nuclear clocks could outperform today’s most advanced atomic clocks because the thorium nucleus is naturally protected from many sources of noise that limit current technologies.
According to the researchers, such clocks could eventually improve satellite navigation, provide more precise gravitational measurements, and enable new tests of fundamental physics.
The next major goal is to refine the technology, reduce its size and complexity, and compare multiple nuclear clocks against one another.
Scientists found evidence that Chicxulub remained hydrothermally active four times longer than earlier estimates.A wearable lens used the retina to reach mood circuits deep in the brain and reverse depression-like changes in mice.
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