Physics Magazine

A Scaling Law for Tours A simple model can reproduce the distribution of tour lengths harvested by a social media app used by thousands of visitors to Los Angeles and New York.

Researchers were given access to thousands of circular trips logged by the social network app Foursquare. From that trove, they built a simple model that could account for the distribution of trip lengths.

Mimicking Lightning in a Dielectric Electrons accelerated to relativistic speeds in a dielectric material can produce bursts of x rays, similar to a phenomenon found in thunderstorms.

Thunderstorms can cause 100-meter-scale regions in the atmosphere to generate bursts of gamma rays via cascades of relativistic electrons. Now theorists have predicted that a similar mechanism could work in centimeter-scale regions in dielectric solids.

Launching an Alert System for the Changing Sky With the debut of a public alert stream, the Rubin Observatory demonstrates the ability to report transient signals—from supernovae, variable stars, active galactic nuclei and asteroids—in near real t...

The Rubin Observatory has released its first set of identifications of transient events in the night sky. Compiled over a single day, the dataset contains 800,000 events.

Gravitational Collapse Primes Galactic Magnetism A coordinate transformation devised for an expanding universe leads to new insights into how a collapsing protogalaxy acquires a large magnetic field.

The magnetic fields of the Milky Way and other mature galaxies are sustained by their disks’ rotation and turbulence. That dynamo takes too long to establish itself to account for the fields of young galaxies. Now researchers have found a new faster-acting dynamo powered by a galaxy’s formation.

Isolating the Effect of Dimensions on Electrons A new layered material enabled researchers to document a dramatic change in metallic electron behavior as the material goes from 3D to 2D.

Theorists expect Anderson localization to set in more readily in two dimensions than in three. Now researchers have demonstrated that tendency directly by progressively removing a crystal's atomic layers until only one remained.

Neutrons Illuminate the Magnetic Dance of Chiral Phonons Neutron scattering has provided a new and broader view of the twirling collective atomic vibrations in a magnetic crystal.

Researchers have used neutron scattering to enrich our understanding of chiral phonons. Like regular phonons, chiral phonons convey sound and heat, but they are also magnetic, thanks to the twirling motions they acquire from the symmetries of their host lattice.

How To Build Your Own Quantum Computer A group of physicists are developing a quantum computer that’s entirely open source, from hardware to software

Two physicists tell Physics Magazine about their plan to build a 30-qubit trapped-ion quantum computer. Once complete, the computer and its software will be freely available to anyone.

Fluid Flows Prevent Microswimmer Clumps Contrary to previous suggestions, hydrodynamic interactions impede the clustering of tiny biological and artificial swimmers.

Groups of self-propelled microscopic swimmers can sometimes spontaneously form dense clumps, leaving dilute regions between them. Now researchers have shown that the clumping is more difficult when swimmers interact with one another through flows in the fluid.

Exoplanet Observations Sharpen Picture of Planetary Formation Two investigations underscore the role of orbital instabilities in accounting for the diversity of planetary systems.

A rogue planet whose mass is close to Saturn's has been discovered through gravitational lensing. It was likely kicked out of its host system via an orbital instability.

Viewing Neural Networks Through a Statistical-Physics Lens Statistical physics is shedding light on how network architecture and data structure shape the effectiveness of neural-network learning.

Despite the practical success of neural networks, how they learn remains poorly understood. New research in statistical physics is exploring central questions in machine-learning theory, clarifying how learning depends on NN architecture and on the statistics of training data.

Algal Swimming Patterns Change with Light Intensity In response to changes in illumination, a swimming microorganism reverses the direction of its circular trajectory by tilting its flagella’s planes of motion.

Researchers have discovered a new navigation strategy used by certain green algae. The microorganisms swim in wide circles when illuminated and switch from counterclockwise (CCW) to clockwise (CW) swimming when the light intensity exceeds a threshold.

When the Cosmic Web Spins

Listen to science journalist Paul Adepoju recount how astronomers discovered that one of the largest structures in the universe—a cosmic filament—is spinning on its axis.

Why Wildfire Smoke Drives One-Way Swirling New modeling explains why smoke-filled vortices in the upper atmosphere have all been observed rotating in a single direction.

Smoke from summer wildfires rises into the stratosphere and coalesces into swirling blobs, which rotate, puzzlingly, in only one direction. Researchers now explain why, using a model that includes heating effects and wind shear.

Cosmic Inflation Confronts Dueling Data An apparent shift in the value of an important inflation parameter may be an artifact of differences between cosmological datasets.

Last year, two teams reported values of an important cosmological parameter that exceeded previous estimates, disfavoring several popular inflation models. Now researchers have shown that the discrepancy is mainly caused by differences in the underlying datasets.

Entangled Ions Measure Time Faster An optical clock based on a pair of calcium ions achieves a given precision more quickly when the ions are entangled.

For some applications of atomic clocks—in satellite navigation systems, for example—the answer must be prompt as well as precise. Researchers have now demonstrated a way to use quantum entanglement to halve the measurement time of an ion-based optical clock without compromising its precision.

Explaining the Conductivity of Ionic Liquids Researchers have used molecular dynamics simulations to study changes in the charge-transport properties of a room-temperature ionic liquid under a strong electric field.

Researchers have simulated ion transport under strong electric fields in an ionic liquid known as [BMIM][TFSI]. Their findings could help to improve water-electrolysis propulsion systems, which are used as thrusters to maneuver CubeSats.

Bilayer Graphene Reveals Hidden Topology Small rotations of a graphene layer relative to its neighboring layer expose previously unseen topological phases.

Twisted bilayer graphene exhibits a rich array of electronic phenomena, which arise mostly from the material’s flat energy bands. Now researchers have studied how higher-energy bands influence those phenomena and introduce new ones.

Quantum Gravity Tests Coming Soon Before determining the correct quantum theory of gravity, researchers need to know if gravity is actually quantized. Experiments testing that assumption are now being developed.

The standoff between quantum mechanics and general relativity has persisted for many decades, prompting some physicists to propose that quantum mechanics needs to be superseded. New experiments could point the way forward.

A Laser Built for Nuclear Timekeeping Researchers have designed and demonstrated an ultraviolet laser that removes a major bottleneck in the development of a nuclear clock.

The nuclear transitions that underlie nuclear clocks are difficult to drive controllably using existing laser technology. Now researchers have tested a new intense single-frequency ultraviolet laser that can achieve such driving for thorium-229 nuclei.

A New Model for Particle Charging A statistical approach yields a fast, flexible model for how particles in a powder acquire electric charge from each other and their surroundings.

The microphysics of contact charging is an active area of research, as is the quest to understand the phenomenon as it plays out on larger scales in processing plants. Now researchers have developed a contact-charging model that can cope with particles and walls made of different materials.

AI Discovers Geophysical Turbulence Model Researchers have used an artificial-intelligence tool to reveal long-sought equations that describe small-scale features in 2D turbulent systems.

To incorporate turbulence at scales shorter than the resolution of their models, climate scientists resort to so-called closure models. A new AI-based closure model not only improves performance. It also illustrates that AI-generated models need not be black boxes.

Galaxies Wind Around a Cosmic Filament Galaxies can collect in large filamentary structures that have—until now—been considered rigid. A new study suggests one filament may be rotating.

Cosmic filaments are typically regarded as rigid. But new observations of 14 galaxies in the same filament indicate that the entire filament is rotating about its axis. If similar rotation is detected in other structures, it could serve as a test of cosmological models.

Seeing the Quantum Butterfly Effect A combined experimental and theoretical study reveals the emergence of quantum chaos in a complex system, suggesting that it can be described with a universal theoretical framework.

With the help of scramblon theory, researchers have successfully separated genuine quantum chaos from the imperfections of time reversal in a macroscopic solid-state sample manipulated with NMR.

Solitons Take Their Lumps in Two Dimensions Experiments with structured light beams provide the first observation of “lump” solitons, shape-preserving solitary waves in a 2D setting.

Solitons have primarily been observed in settings where the underlying physics is 1D, such as narrow water channels. Now researchers have used a structured light beam to become the first to produce a lump soliton, a mathematically exact soliton in 2D.

A Novelist Derives Physics–Crime Duality Nova Jacobs reflects on how she came to write murder mysteries set in the world of physics.

How did an aspiring Hollywood screenwriter become a novelist who sets her murder mysteries in the world of physics?

When Two Superconductors Become One By exploiting defects in a superconductor, scientists have observed the switching of a material’s two superconducting states into one.

Most superconductors have more than one energy band where electrons can pair up to flow without resistance. Scattering off crystal defects enables electrons to jump between bands, frustrating the study of multi-band superconductivity—until now.

Electronic Chirality Without Structural Chirality A crystal whose arrangement of atoms lacks chirality can nevertheless host a chiral electronic state.

Theorists have predicted that the intermetallic compound uranium rhodium stannide, whose structure lacks handedness, could harbor an electronic state that does exhibit handedness. They call the state purely electronic chirality or PEC.

Building Better Bridges on Quantum Chips Fabricating some structures using niobium instead of aluminum could lead to more resilient superconducting quantum computers.

Researchers have demonstrated a new way to fabricate waveguides, capacitors, and other qubit components above the rest of the chip. The elevated arrangement will make it easier to scale up superconducting quantum computers.

Science Fiction as a Science Driver Can scenarios inspired by science fiction help anticipate the effects of future technologies?

This week marks the debut of a new editorial column in Physics Magazine. Written in a personal voice by one of our editors, the column offers reflections on contemporary ideas filtered through a physicist’s way of seeing things.

Exposing Nuclear Magic Calculations show how the mysterious “magic numbers” that stabilize nuclear structures emerge naturally from nuclear forces—once these are described with appropriate spatial resolution.

Nuclei containing specific "magic" numbers of protons and neutrons (2, 8, 20, 28, 50, 82 . . . ) are unexpectedly stable. Now researchers have shown how magic numbers emerge from the underlying interactions between protons and neutrons.