quark core

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.

Deep inside a neutron star, where matter is compressed to the density of an atomic nucleus, neutrons form a superfluid and protons form a superconductor. A neutron vortex is a quantized vortex in the superfluid, akin to a miniature whirlpool that cannot stop spinning.

At the center of a neutron star, matter is compressed so tightly that a teaspoon weighs a billion tons. You'd think there's no better place to look for signs of quantum gravity. But between the laboratory and the fundamental scale lies a chasm of 10⁸⁰ in density. Three doors lead into this room.

A neutron star is what remains after a massive star explodes. Its matter is compressed so tightly that a teaspoonful would weigh billions of tons. Under such conditions, protons and neutrons can rearrange, and new particles (hyperons, similar to neutrons but containing a 'strange' quark) can appear.

An interpreter gets distracted by every rustle in the hall, and a one-hour meeting stretches into two. A neutron star compresses a solar mass into a sphere the size of a city, and the matter in its core is denser than an atomic nucleus. Physicists cannot probe its structure in the lab: the required pressures are unattainable.

A white dwarf is the former core of a star like the Sun, squeezed down to the size of Earth. A teaspoon of its material would weigh several tons. A neutron star is an even denser remnant: a city the size of Manhattan, but with more mass than the Sun.

A star's radius drops by a thousand kilometers. Not because its mass increased, but because its own magnetic field squeezed the crust like an invisible corset.

A handful of sand in your fist: the grains press against each other, and your hand can't squeeze any further. Ordinary matter behaves similarly. But in a neutron star, compression is billions of times stronger — atoms are crushed, electrons are squeezed into protons, and nearly all space is filled with neutrons.

At the centers of many galaxies, not only supermassive black holes lurk, but also vast clouds of invisible matter. If this matter consists of ultralight particles, it can gather into dense clumps — a kind of 'star' made of dark matter.

A heaping teaspoon, and the scale reads a billion tons. That's roughly what a teaspoon of neutron star matter would weigh if you could scoop it up and put it on a scale. Such objects are born after a supernova explosion: the star's core collapses into a sphere the size of a city, and the density exceeds that of an atomic nucleus.

An old factory where instead of machines there are atomic nuclei, and neutrino radiation seethes all around. When a massive star exhausts its fuel, its core compresses a hundredfold, and the temperature skyrockets to billions of degrees.

The interiors of neutron stars are a realm of degenerate matter. Here, protons condense into a superconducting condensate, threaded by quantum vortices. Imagine tiny magnetic tops: each carries a quantum of magnetic flux and glides through the electron fluid.

Neutron stars — remnants of supernovae — are among the densest objects in the Universe. Their central density exceeds nuclear density many times over, and gravity is surpassed only by black holes.

In nuclear physics, the belief long reigned that two neutrons cannot form a bound state — they attract too weakly and immediately fly apart. However, on the surface of neutron-rich nuclei, where the matter density drops to a thousandth of normal nuclear density, the situation changes dramatically.

The hot broth of the early universe cooled unevenly. At some point, bubbles of a new phase began to pop within it, like steam bubbles in boiling water. But these bubbles weren't made of steam; they were made of a new state of matter in which particles of the dark sector clumped into larger lumps. That's how dark matter could have been born.

In the microscopic world of the strong interaction, nature's most powerful glue, quarks never wander alone. Over large distances, they stick together into the protons and neutrons we know. But under extreme compression, like in the depths of a neutron star, this glue creates far more exotic forms of matter.

A neutron star is a gravitational lens that focuses our attempts to glimpse dark matter. Through its ultra-dense matter, like exotic glass, we search for the axion — an elusive particle that could explain the hidden mass of the universe.

Neutron stars are cosmic 'ice cubes' of unimaginable density: a tablespoon of their material would outweigh Mount Everest. It was a mystery what lay in their cores: ordinary neutron matter (a giant atomic nucleus) or exotic quark matter, where particles are not bound into neutrons.

In the depths of a massive neutron star, where a teaspoon of matter weighs as much as a mountain, quarks are squeezed to unimaginable proximity.

Imagine a spinning top the size of a city, weighing more than the Sun and making hundreds of revolutions per second. That's a neutron star — the remnant of an exploded star. Occasionally, its rotation suddenly speeds up, as if something inside has switched. Astronomers call these jumps glitches and suspect that invisible vortices in the star's superfluid interior are to blame.

Neutron stars are super-dense spheres of the remnants of exploded stars. Some of them we see as pulsars — cosmic lighthouses sending out radio bursts. What's inside them long remained a mystery. Physicists assumed that hidden fields could affect their structure, but it was believed that if the field is short-range, its effect is negligible.

Imagine a packed dance floor where dancers glide without any friction — passing through each other without a touch. That's a superfluid. In a neutron star's crust, neutrons could behave this way, but a rigid lattice of ions gets in the way, like suddenly sticking the dance floor full of pillars.

In the standard picture, black holes are the undisputed density champions: all their matter is squeezed into a single point. Imagine the entire mass of Mount Everest packed into a grain of salt. But physicists have found a theoretical trick.

The core of a neutron star can be likened to a taut string of super-nuclear density. Sound traveling along it is the oscillation of pressure, whose speed $$c_s$$ betrays the stiffness of matter. New research shows that this cosmic string does not hum monotonically.

An atomic nucleus is like a droplet with a thin coating — a neutron 'skin.' Inside the droplet, protons and neutrons are mixed evenly, but on the outside, like the froth on milk, a layer forms where neutrons are noticeably more abundant.

The outer crust of a neutron star is like a layered cake, where each layer is a strictly defined filling. It's a crystalline lattice of atomic nuclei immersed in a sea of electrons. The deeper you go, the stronger the pressure, and the heavier the nuclei that can exist there without falling apart.

A neutron star is the collapsed core of a massive star, squeezed to the size of a city. In its heart, matter is packed so densely that atoms cease to exist, and protons and neutrons dissolve into a sea of quarks.

The crust of a neutron star is not just a solid shell. Under pressures of billions of tons per square centimeter, atoms lose their electrons, and the remaining nuclei arrange into a rigid crystal lattice, reminiscent of a honeycomb, but made of matter a trillion times denser than steel.

Inside a neutron star, the density doesn't change smoothly but drops abruptly at sharp cliffs — density staircases. At these steps, the void suddenly births pairs: neutrinos and antineutrinos.

A neutron star is a spinning top with the mass of the Sun, crushed to the size of a city. It's born in the fire of a supernova and usually only slows its spin. But sometimes, for no apparent reason, it suddenly speeds up — such a jerk is called a glitch.

A pot of soup simmering with three ingredients. The chef adjusts the proportions on the fly, and the progress is tracked by the position of a point on a triangular scale. That's roughly how physicists tackle neutrinos from a supernova explosion.

When a heavy atomic nucleus splits, it doesn't break into even halves. First, two fragments form that look like pears pressed together at their narrow ends. Then the junction begins to smooth out, like two droplets merging and the surface quickly leveling. In that brief moment, the surface moves inward, and particles inside the nucleus can bounce off it, like a ball off an oncoming wall.

If an atomic nucleus is a family, then in an ordinary helium house live two protons and two neutrons, holding hands tightly. Now imagine that one family member is an oddball who loves to wander far from home.

In a gas cloud left after a star exploded (called a supernova remnant), astronomers noticed a giant glowing letter S. It was drawn by two jets of superheated material ejected during the cataclysm. These jets didn't just shoot straight out — they slowly spun like a top, which bent their path into curves.

When a massive star runs out of fuel, its core collapses and a shock wave races outward. But even before the star tears apart, particles that barely interact with ordinary matter may be born in its depths. If they decay into light, that energy leaks into the dense gas around the star. This gas, like a blanket, wraps the star.

A neutron star is the remnant of an exploded star, compressed to the size of a city. In its core, matter is packed so densely that a teaspoon of such material would weigh as much as a mountain. At such densities, as predicted by the theory of strong interactions, particles acquire 'twins'—parity partners.

Long before that, Fritz Zwicky predicted that a supernova explosion gives birth to a tiny neutron star. Years later, Jocelyn Bell Burnell caught its pulses, discovering pulsars.

At the heart of a neutron star, matter is squeezed so tightly that protons and neutrons transform into heavier particles — hyperons. These particles resemble neutrons but contain a strange quark. For a long time, physicists couldn't understand how a star with hyperons inside could be as heavy as observations show.

The neutron is the particle that makes up most of a neutron star. On its own, it is unstable: a free neutron lives for about fifteen minutes, then decays into a proton, an electron, and an antineutrino.

Just as in a crowded room each new person sharply increases the pressure on the walls, in a neutron star increasing density leads to a rise in internal resistance. But even this resistance has an absolute ceiling.