Calculations explain curious properties of some 2D materials
Category: physics – Page 6
Archaeology, Anthropology, and Interstellar Communication
Addressing a field that has been dominated by astronomers, physicists, engineers, and computer scientists, the contributors to this collection raise questions that may have been overlooked by physical scientists about the ease of establishing meaningful communication with an extraterrestrial intelligence. These scholars are grappling with some of the enormous challenges that will face humanity if an information-rich signal emanating from another world is detected. By drawing on issues at the core of contemporary archaeology and anthropology, we can be much better prepared for contact with an extraterrestrial civilization, should that day ever come.
NASA SP-2013–4413
Temporal anti-parity–time symmetry offers new way to steer energy through systems
The movement of waves, patterns that carry sound, light or heat, through materials has been widely studied by physicists, as it has implications for the development of numerous modern technologies. In several materials, the movement of waves depends on a physical property known as parity-time (PT) symmetry, which combines mirror-like spatial symmetry with a symmetry in a system’s behavior when time runs forward and backwards.
Systems with PT symmetry can suddenly alter their behavior when they pass specific thresholds known as phase transitions, where they shift from balanced to unbalanced states. So far, systems exhibiting PT symmetry are mostly static, meaning that they exhibit fixed properties over time.
In Nature Physics, researchers at University of Shanghai for Science and Technology, Fudan University and National University of Singapore introduce a new concept called temporal anti-parity–time (APT) symmetry, which delineates more clearly both where and when a phase transition happens in a non-Hermitian system, a system that exchanges energy with its surroundings.
Physics of foam strangely resembles AI training
Foams are everywhere: soap suds, shaving cream, whipped toppings and food emulsions like mayonnaise. For decades, scientists believed that foams behave like glass, their microscopic components trapped in static, disordered configurations.
Now, engineers at the University of Pennsylvania have found that foams actually flow ceaselessly inside while holding their external shape. More strangely, from a mathematical perspective, this internal motion resembles the process of deep learning, the method typically used to train modern AI systems.
The discovery could hint that learning, in a broad mathematical sense, may be a common organizing principle across physical, biological and computational systems, and provide a conceptual foundation for future efforts to design adaptive materials. The insight could also shed new light on biological structures that continuously rearrange themselves, like the scaffolding in living cells.
This crystal sings back: Study sheds light on magnetochiral instability
Researchers from The Grainger College of Engineering at the University of Illinois Urbana-Champaign have reported the first observation of a dynamic magnetochiral instability in a solid-state material. Their findings, published in Nature Physics, bridge ideas from nuclear and high-energy physics with materials science and condensed matter physics to explain how the interplay between symmetry and magnetism can amplify electromagnetic waves.
A material’s behavior is heavily influenced by its symmetries. One unique symmetry of interest to many physicists is chirality. Chiral materials have non-superimposable mirror images, like a right and left hand. For physicists like Fahad Mahmood, Rafael Fernandes and Jorge Noronha, the nonlinear interaction between chiral materials and light is of particular interest. How do these materials respond when light triggers effects beyond the straightforward, linear response?
“If I have a shiny crystal and I put a red laser on it, I’ll get red light back; that’s a linear response, as the frequencies—or colors—of the incoming and outgoing light are the same,” Mahmood said. “You can go a little further and try to excite some frequency so that it sends back a different color: you put red light on something, and it shines back as green, blue or yellow. That’s nonlinear response.”
A dry surface thanks to fluid physics: Contact-free method gently remove liquids from delicate microstructures
Researchers at the University of Konstanz have developed a gentle, contact-free method to collect liquids and remove them from microscopic surface structures. The method uses vapor condensation to generate surface currents that transport droplets off surfaces.
Many modern technologies rely on microscopic elements, such as microchips in smartphones. The manufacturing process for these elements requires their surfaces to be exposed to different types of liquids that must be completely removed afterward.
A research team led by Stefan Karpitschka from the University of Konstanz has now developed a new method that uses surface tension to efficiently transport these liquids off the finished product. The work is published in the journal Proceedings of the National Academy of Sciences.
Tiny Mars’s big impact on Earth’s climate: How the red planet’s pull shapes ice ages
At half the size of Earth and one-tenth its mass, Mars is a featherweight as far as planets go. Yet new research reveals the extent to which Mars is quietly tugging on Earth’s orbit and shaping the cycles that drive long-term climate patterns here, including ice ages.
The study is published in the journal Publications of the Astronomical Society of the Pacific.
Stephen Kane, a professor of planetary astrophysics at UC Riverside, began this project with doubts about recent studies tying Earth’s ancient climate patterns to gravitational nudges from Mars. These studies suggest that sediment layers on the ocean floor reflect climate cycles influenced by the red planet despite its distance from Earth and small size.
Physicists create resilient 3D solitons in the lab
For the first time, physicists in Italy have created a ‘lump soliton’: an extremely stable packet of light waves which can travel through 3D space, and even interact with other solitons without losing its shape.
Led by Ludovica Dieli at Sapienza University of Rome, the team achieved their result using a specially engineered crystal, whose responses to incoming light beams could be tightly controlled using an external voltage. Their study appears in Physical Review Letters.