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Category: physics

Ripples in fire-ant collectives suggest motions are driven by neighbor alignments

Researchers in Spain have discovered that in collectives of moving fire ants, rippling “waves” of density and activity are likely triggered by local regions where ants collectively travel in the same direction as their neighbors.

Described in a new paper published in Journal of Applied Physics, Alberto Fernandez-Nieves and colleagues at the University of Barcelona are hopeful that their predictions could be confirmed in future experiments—potentially leading to deeper insights into the complex motions of active materials.

Astrophysicists strike black gold with treasure trove of gravitational wave detections

Researchers from the University of Glasgow’s Institute for Gravitational Research are celebrating the publication of a vast new treasure trove of gravitational wave detections, hailed as a milestone marking the coming of age of gravitational astronomy.

The Gravitational Wave Transient Catalogue-5.0, or GWTC-5, is released online, with corresponding scientific papers submitted to Astrophysical Journal and Astrophysical Journal Letters.

This latest update details a total of 161 new signals from colliding black holes detected between April 2024 and the end of January 2025 by the gravitational wave detectors LIGO in the United States, Virgo in Italy, and KAGRA in Japan, known as the LVK collaboration. The publication brings the total number of gravitational wave signals detected to date to 390.

Surface design transforms thermal management and enables frictionless systems

A research team led by Professor Steven Wang, Associate Vice President (Resources Planning) and Associate Professor in the Department of Mechanical Engineering and School of Energy and Environment, has designed a revolutionary capillary structure that can trigger the Leidenfrost effect, offering a practical solution for the temperature-regulated Leidenfrost effect without requiring complex surface engineering.

The study, titled “Capillary Leidenfrost Effect”, was recently published in the journal Nature Physics.

The Leidenfrost effect is a physical phenomenon discovered in 1756. It occurs when a liquid droplet touches a surface much hotter than its boiling point, forming a vapor layer that makes it levitate and hover, slowing down evaporation. A simple example is water on a very hot pan: the drops sizzle and disappear quickly, but once it reaches the Leidenfrost point, they bead up, skate and dance around on a steam barrier, and last much longer before evaporating. This effect is ubiquitous in a wide range of laboratory and industrial applications.

Imaginary-time technique speeds X-ray scattering simulations by 50-fold for extreme matter

Researchers at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) have developed a new procedure, enabling them to speed up elaborate computer simulations that analyze matter under extreme conditions. In particular, this work improves the evaluation of experiments at large-scale research facilities like the European XFEL—and should facilitate substantial progress, among others, in fusion research and laboratory astrophysics.

The team presented the results in the journal npj Computational Materials.

Sometimes, matter is present in extreme states—such as in stars or in the interior of gas giants where enormous pressures and temperatures prevail. Such conditions can also be produced in the lab, in laser fusion experiments, for instance. In order to understand precisely what happens, researchers use X-ray scattering—as at the European XFEL near Hamburg.

The 2024 Oppenheimer Lecture featuring Andrea Liu

Physical systems that can learn by themselves.

Brains learn and perform an enormous variety of tasks on their own, using relatively little energy. Brains are able to accomplish this without an external computer because their analog constituent parts (neurons) update their connections without knowing what all the other neurons are doing using local rules. We have developed an approach to learning that shares the property that analog constituent parts update their properties via a local rule, but does not otherwise emulate the brain. Instead, we exploit physics to learn in a far simpler way. Our collaborators have implemented this approach in the lab, developing physical systems that learn and perform machine learning tasks on their own with little energy cost. These systems should open up the opportunity to study how many more is different within a new paradigm for scalable learning.

Physicists figure out how to reduce formation of ‘viscous fingers’

When they reach the bottom of a soap dispenser, frugal handwashers might try adding water to the bottle to push out the last bit of soap. But usually, the water drills right through the soap and jets out an only slightly sudsy splash.

This happens because when you push a less viscous fluid like water into a more viscous fluid like soap in a confined space, the place where the two fluids meet can be unstable, and the runnier liquid might find a path of least resistance.

If you look very closely, you might see tiny protuberances form at the place where the fluids touch, in a phenomenon physicists call “viscous fingering.” In certain types of confined spaces, the fingers form a branching pattern.

Using pulsars as ultra-precise gravitational probes to ‘weigh’ neighboring galaxies

Researchers at The University of Alabama in Huntsville (UAH), a part of The University of Alabama System, have identified a promising new method for measuring the mass of galaxies orbiting the Milky Way by using pulsars, some of the universe’s most precise natural clocks, to detect tiny gravitational effects across our galaxy.

The work, published on the arXiv preprint server, offers a novel approach for studying the hidden dark matter contained within nearby satellite galaxies. The findings could have broad implications for astrophysics and cosmology.

The study was authored by UAH astrophysicists Dr. Thomas Donlon, postdoctoral research assistant II, and Dr. Sukanya Chakrabarti, a professor and Pei-Ling Chan Endowed Chair in the College of Science, in collaboration with Dr. Jason A. S. Hunt, an astrophysicist at the University of Surrey, U.K. The research examines how the gravitational pull of neighboring dwarf galaxies subtly disturbs the Milky Way.

Better helium reporting to improve fission and fusion materials modeling

Standardizing calculations of the helium byproducts generated in advanced fission and fusion energy system materials can increase reactor safety and longevity, according to a study led by University of Michigan Engineering with collaborators at Oak Ridge National Laboratory and its management contractor UT-Battelle.

Through a series of simulations, the researchers found that modeling assumptions and key alloy elements—like carbon, nitrogen and nickel—significantly influence helium generation predictions. If left unaddressed, excess helium in real-world reactors could lead to faster component failure as materials swell and become brittle.

“If used, our reporting methods will improve the experimental and modeling fidelity of the nuclear materials databases being generated both domestically and internationally, driving the rapid deployment of advanced nuclear,” said Kevin Field, a professor of nuclear engineering and radiological sciences at U-M and corresponding author of the study published in the Journal of Physics: Energy.

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