exotic phase transitions

The map of dense nuclear matter resembles a road map: lines of phase transitions cross at critical points, like highways at intersections. Until now, only two intersections were known on such a map: the nuclear liquid-gas and deconfinement, where hadrons dissolve into quarks.

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.

In a binary star system, one star pulls matter from its companion. Over centuries, this material settles onto the surface of a neutron star — the ultra-dense remnant of a dead star. This process, called accretion, usually proceeds smoothly. Gravity behaves as general relativity predicts, without surprises.

When two black holes merge, ripples spread across the fabric of spacetime — gravitational waves. But what if one of them isn't a run-of-the-mill black hole but something else — an exotic compact object?

Water turns to ice at zero degrees — sharply, with no intermediate states. Something similar happens to complexity when we take a random quantum state of an entire system and look only at a part of it. As long as that part occupies less than half the system, its complexity grows smoothly. But as soon as the fraction crosses 50%, a jump occurs.

Since the late 20th century, astronomers have known that the recession of galaxies is accelerating, as if pushed by an invisible tailwind.

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.

Drop a pebble into a pond, and ripples spread across the water. Strike a bell, and it rings at its own frequency. When a black hole collides with another, it too 'rings'—except instead of sound, it's the trembling of space itself.

A vast hall with a thousand doors, and only one leads to the stars. The rest are locked, and the keys aren't just hidden: they're wrapped in other keys and tangled into a knot. That's the Great Filter in a new reading: not a chain of failures but a tangled hierarchy where each step depends on the previous one nonlinearly.

Strike a bell, and it responds with its own note. Likewise, a black hole disturbed by the fall of a star or another black hole begins to 'ring,' emitting gravitational waves. But instead of sound, it's the trembling of space itself, and instead of a single note, a whole set of decaying frequencies. These are called quasinormal modes.

A stone falls into a pond, and ripples spread across the water. But if the stone is very small and the water is not quite ordinary, the ripples pass right through it, as if it weren't there.

An orchestra without a conductor is playing, and suddenly, without any visible cue, the violins grow louder and the woodwinds shift slightly in time. From the outside, nothing seems to have changed, but inside the ensemble, a regrouping has occurred. This is roughly how small physical systems behave during so-called third-order pseudotransitions.

Water in a kettle, as it boils, clearly separates into liquid and steam. But under enormous pressure, the boundary vanishes: the substance enters a supercritical state — neither one nor the other, but something in between. Black holes can do this too.

In the quantum world, there are rules that seem to be broken. One of them is the conservation law: if in classical physics symmetry guarantees the conservation of charge, then in the quantum description this guarantee can disappear. This phenomenon is called a quantum anomaly.

A stack of identical pancakes on a plate is just a stack. But if you arrange them with a certain order, something new suddenly appears: for example, a pattern that was not visible in each pancake individually. Physicists have performed a similar trick with thin layers of materials.

Black holes are cosmic drains, gravitational funnels that pull in matter from their surroundings. This process, called accretion, doesn't always go smoothly: some of the infalling gas can be ejected back as narrow relativistic jets — jets.

In the ocean, sometimes a huge solitary wave appears out of nowhere and then vanishes. Such rogue waves are rare but dangerous. Similar rare and intense spikes occur in other systems, from financial markets to lasers. The problem is that they are hard to predict, let alone trigger on demand.

Physicists built a chain of Rydberg atoms — atoms with electrons in enormous orbits, comparable to planetary paths. These giant atoms feel their neighbors intensely, turning the chain into a quantum analog of a string.

Time crystals are an exotic phase of matter that exhibits periodic motion not in space but in time, even while in its ground, unexcited state. This idea, reminiscent of a perpetual clock that never needs winding, was first proposed by Frank Wilczek.

The trace of a short-lived particle is like a signature left in the detector. The particle is born and decays in an instant, but from its trace you can reconstruct its character — whether it's compact like a stone or fluffy like a snowball. That's exactly what this work is about: the authors propose a new way to read such signatures. They noticed that each particle has an angle that links its mass and lifetime.

The hunt for exomoons — the search for satellites around planets of other stars — resembles watching shadows in a theater where the spotlight keeps fading and flaring. The planet Kepler-167e, a gas giant near a scorching star, was discovered by William Borucki and his team.

In a chain of cold spins stretched along a single line, order and disorder can intertwine into a pattern that defies the usual rules. Two states of matter, two kinds of "order," are separated by a crossroads where the roads do not converge but diverge.