Birds use a variety of navigational strategies, including the geomagnetic field, especially when other cues are not available, such as under overcast or nocturnal conditions. Magnetite particles in the beak, cryptochromes in the eye, cellular ion-channel alterations, and changes in the vestibular system have been proposed to explain magnetoreception, but the exact mechanisms remain debated. Here, we used physical, morphological, functional, and genomic assays to identify the presence of superparamagnetic macrophages in the liver. We found that after macrophage depletion, pigeons flying under overcast conditions lacked their usual orientation capabilities. Orientation was unimpaired in birds without macrophages when the sun was visible, suggesting that this was their primary cue.
Using a “bootstrap” approach, researchers show that a small set of assumptions may naturally lead to a string-theory description of certain high-energy processes.
String theory has been a remarkably influential conceptual framework for modern theoretical physics. While its description of nature in terms of tiny strings captures the imagination, the string framework has had profound impact in a broad range of subfields, going well beyond its lead role as a viable theory of quantum gravity. For instance, it has led to deeper understanding of black holes and their relation to entanglement and quantum information [1], and it has provided theoretical benchmarks for explaining quark–gluon plasma observations in quantum chromodynamics [2]. As a complement to direct calculations, theoretical physicists would like to understand string theory as emerging from a set of fundamental principles that any theory of nature must respect. Consistency with these bedrock conditions, so goes the idea, could perhaps make string theory inevitable.
The U.S. Department of Energy’s (DOE) Brookhaven National Laboratory has reached a key early milestone in developing radiofrequency control systems for the Electron-Ion Collider (EIC)—a next-generation research facility that will collide electrons with ions to reveal how the building blocks of matter are held together.
At the heart of any particle accelerator are radiofrequency (RF) systems, which use electromagnetic waves to accelerate particle beams to near-light speed and keep them tightly controlled. The system tested here—known as low-level radiofrequency (LLRF)—acts as the “brain,” precisely controlling those RF fields to ensure stable and accurate operation.
This milestone marks the first successful test of the newly built EIC common platform-based LLRF electronics on a real accelerator cavity. The common platform is a shared hardware and control system for accelerator operations, allowing teams to use the same technology rather than create separate electronics for each system.
Researchers at the University of Twente and Utrecht University have packed rigid, rod-shaped particles into soft lipid containers the size of a living cell and watched the container and its contents reshape each other. The vesicle’s form determines how the rods line up; the tightly packed rods, in turn, bend the container into new shapes. This provides a minimal model for how physical coupling between a soft boundary and internal filaments can help cellular structures organize from within. The paper is published in the Proceedings of the National Academy of Sciences.
Living cells are crowded with filaments. These threadlike scaffolds hold a cell in shape, push it forward when it moves and pull it apart when it divides, all inside a soft membrane that bends and flows around them. The filaments shape the membrane, and the membrane in turn constrains the filaments.
Physicists understand one half of that exchange, but mostly for rigid containers. Pack enough rod-shaped particles into a fixed box and they switch from a disordered jumble to neat alignment, much like matches settling when you shake the box. What happens when the container can give way had barely been tested. A flexible wall can deform to make room for its contents, so the familiar rules no longer hold.
Physicists from Heinrich Heine University Düsseldorf (HHU) have examined a fundamental property of quantum mechanics in collaboration with the German Aerospace Center (DLR). In an article published in the journal Physical Review Letters, they show that this theory does not necessarily need to be formulated with imaginary numbers—real numbers can, in fact, also be used.
The physical theory of quantum mechanics describes the world of atomic and subatomic particles. Its development began in the 1900s with physicists such as Max Planck, Niels Bohr, Werner Heisenberg and Erwin Schrödinger.
Quantum mechanics can effectively describe phenomena at microscopic scales, including, for example, the diffraction of particles at a double slit —which shows that particles also exhibit wave-like behavior—and the quantum tunneling effect, in which a certain probability exists that particles can penetrate a barrier even if they have insufficient energy to do so. Particularly important phenomena today include entanglement and coherence, which are key for applications such as quantum computers and communication.
Superfluids are intriguing states of matter in which particles behave like a giant collective wave, allowing them to flow without any friction. When this fluid flows past a fixed obstacle at a velocity below a specific threshold, it moves around it without slowing down or exerting any drag. Above this critical velocity, however, the superfluid state starts to break down, and the energy from the flow dissipates in the form of ripples and vortices in the fluid.
Researchers at Sorbonne University, the University of Porto, Côte d’Azur University and Paris-Saclay University recently investigated this phenomenon in a superfluid of light, a system in which light behaves like a superfluid. Their paper, published in Physical Review Letters, shows that under specific conditions, a mobile obstacle in a superfluid of light can start swimming against the flow.
“Our project naturally came about as a collaborative effort to bridge theory and experiment, sparked during joint discussions when Pierre-Élie Larré, now at LPTMS in Paris-Saclay, visited our lab in 2022,” Quentin Glorieux, co-senior author of the paper, told Phys.org.
An international research team from Tohoku University, Tokyo University of Science, Vanderbilt University and the University of Adelaide has discovered a novel, exceptionally simple method to precisely synthesize extremely small iridium nanoclusters in ambient air. Such a feat was previously considered highly challenging. In addition, the nanoclusters outperform conventional, commercially available iridium catalysts by 1.5 times in mass activity, while maintaining sustained operational stability without degradation for more than 20 hours.
This breakthrough could result in improved production of green hydrogen, which is considered the ultimate clean fuel. The findings were published in the Journal of the American Chemical Society.
The Oxygen Evolution Reaction (OER) can create green hydrogen, but the reaction requires so much energy that producing green hydrogen efficiently is a huge challenge. Furthermore, because the reaction takes place in a highly corrosive, strongly acidic environment, iridium (Ir) is virtually the only rare and expensive catalyst capable of enduring it.
I think this was one of my most enjoyable dialogues in our What’s new series. Maybe Sabine and I are getting more used to each other’s cadence and interests or maybe it was the subject matter. Either way, I think you will find this to be a fascinating and provocative discussion of science at the forefront, and at the not-so-forefront, because that science is interesting too! We began our discussion describing a new finding of a Giant Ring of galaxies billions of light years across in the sky. The key questions are: Is it real? And is it surprising? We both have slightly different takes on this. Next we described a new measurement of the strength of gravity on scales from 80 to 800 million light years in distance. And guess what? Gravity falls off just like Newton predicted! This may seem like a big yawn, but one of the most popular models that claims to do away with dark matter would imply that Gravity would fall off differently on these scales. Does this new result kill that idea? Stay tuned. Microsoft, which has cried wolf a number of times so far when it comes to something called Majorana qubits as the basis of a new viable quantum computer just published a new paper claiming they finally have it. Sabine and I discuss why we are both still skeptical, but why the effort is worth it. Next, CERN, the large European particle physics laboratory, and the world particle physics community seem to have converged on plans for building a huge new accelerator in the current CERN site… this time involving an underground ring 91 km in circumference, in which electrons and positrons would collide to explore the detailed properties of the Higgs particle. Is the effort worth it? Again, Sabine and I have slightly different takes on this. Fusion power, which we have talked about in a number of earlier episodes, continues to tempt humanity with the promise of unlimited energy. Many people, myself included, have tended to argue that fusion seems to be 25 years in the future, and may always be 25 years in the future. But many new efforts are underway, so who knows. Unfortunately, a group of economists has analyzed fusion in the context of other large energy programs and have argued that even if we can achieve it, it may not be as economically viable as many claim. Finally, one day Richard Feynman went to a Thai restaurant with his young companion Ralph Leighton, and wondered what he should order. Should it be the same old dish he loved or something new. An equation filled napkin later, and he had the answer. Fifty years later some cognitive scientists resurrected Feynman’s napkin and explained it, and argued it might have important implications in other social situations. Such is the power of science. Consider supporting the podcast and the Origins Project Foundation at https://www.originsproject.org/ To see commercial-free, full HD video episodes, join us at lawrence krauss.substack.com Thank you for your support! iTunes: https://podcasts.apple.com/us/podcast… https://TheOriginsPodcast.com Twitter: / theoriginspod Instagram: / theoriginspod Facebook: / theoriginspod The Origins Podcast, a production of The Origins Project Foundation, features in-depth conversations with some of the most interesting people in the world about the issues that impact all of us in the 21st century. Host, theoretical physicist, lecturer, and author, Lawrence M. Krauss, will be joined by guests from a wide range of fields, including science, the arts, and journalism. The topics discussed on The Origins Podcast reflect the full range of the human experience — exploring science and culture in a way that seeks to entertain, educate, and inspire. Full Episodes Playlist: • Ricky Gervais — The Origins Podcast with L…
