phase diagram

In a mountain range, there are trails that can be contracted to a point if you walk through a flat valley. But there are also loop routes that cannot be shrunk without crossing a ridge.

Two dancers on one stage: the triangle and the stripe. In a quantum gas of dysprosium atoms cooled to 62 nanokelvin, these two spatial structures have met for the first time in a single experiment. The gas is held in a trap shaped like a surfboard, and its atoms are among the most magnetic in the periodic table.

Earth's magnetic field is like an invisible shield that protects us from cosmic radiation. But if you look closely at its long-term averaged pattern, you'll notice that this shield isn't perfectly smooth: it has its own "seams" and "patches." New research using computer simulations of the geodynamo shows that…

Imagine a slide with three dips: the deepest one is a stable position for a ball, the middle one is precarious. A slight push and the ball rolls down. Yet, constant vibration of the right strength can hold it in the middle hollow for a long time. In the 1950s, physicists Lee and Yang discovered that all states of matter are separated by invisible points in the world of imaginary numbers.

Time crystals are quantum phases of matter that spontaneously oscillate, like a tuning fork with an infinitely decaying echo. If an ordinary spatial crystal repeats an atomic pattern in space, breaking translational symmetry, a time crystal exhibits periodicity in time, breaking time translation symmetry.

If you drop an ice cube into a glass of water, it will float until it melts. But if you cool the water slowly, at some point it all freezes at once: that's a first-order phase transition: abrupt, with a clear boundary.

Strike a tuning fork, and it rings with a single pure note. But if the fork is trembling and people are chattering nearby, the sound won't be perfect. Same with molecules: each one absorbs light of a specific color, but due to its own vibrations and the jostling of neighbors, that color gets smeared out. The authors of the paper figured out how to show this to students without complex formulas.

Inside each tiny particle that makes up the cathode of a sodium-ion battery, sodium is unevenly distributed — like sugar clumping in tea. This reduces the battery's capacity and lifespan. To see this hidden landscape, scientists used X-ray microscopy and trained artificial intelligence to interpret the data.

Drop a stone into a calm pond — the ripples spread evenly. Drop it into a churning stream — the water swirls unpredictably. Scientists have long wrestled with a similar question: how can you tell from a single particle's path whether its motion is chaotic? Previously, this meant comparing the particle's path with neighboring ones, which is complicated and time-consuming.

Matter is like a house. In some rooms, there is the strict order of a crystal, where every atom is in its place. In others, the chaos of superfluid helium, where atoms forget about their neighbors.