magnetism

Two dancers on one stage: one pulls the partner in one direction, the other in the opposite. In the crystal Cu2(OH)3Br, known as botallackite, copper atoms form chains where the spins (magnetic moments) of neighboring ions align either parallel, as in a ferromagnet, or antiparallel, as in an antiferromagnet.

Inside a solar flare, magnetic field lines snap like stretched rubber bands and reconnect — releasing in minutes enough energy to power humanity for millions of years. In the lab, this process, magnetic reconnection, could long be triggered but not stopped. Now physicists have a switch.

A magnetic field usually acts like a strict traffic cop: for heat to turn into electricity, it must stand across the road. If the field lies along the heat flow, the effect disappears, or so it was believed for decades. Scientists took an ultra-thin film of a magnetic oxide — a material where electron spins are aligned in a plane, like compass needles on a table.

A black hole is not a vacuum cleaner. By itself, it doesn't pull everything in more strongly than an ordinary star of the same mass. But if there's a magnetic field nearby and charged particles flying around, an interesting game begins.

A magnetic mirror is a tube open at both ends. The magnetic field inside is arranged so that hot plasma doesn't leak out: at the ends, the field lines bunch up like a cork in a bottle. Plasma particles flying toward the exit are repelled by these "corks" and bounce back. But some still escape: that's the classic "loss cone" argument.

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.

Ion current through a membrane is like a queue at a turnstile. Sometimes the turnstile is free — ions pass through quickly. Sometimes it gets stuck — the flow drops. A weak magnetic field, it turns out, doesn't push ions from behind; it simply changes the number of open turnstiles.

An inflatable balloon with magnetic field lines drawn on it with a marker is a simple model of how a weak magnetic field behaves in an expanding universe. While the balloon is small, the lines lie obediently on the rubber and don't hinder its stretching. That's roughly how a field fills ready-made space without arguing with its geometry.

The flash lasts a thousandth of a second, but in that instant it releases as much energy as the Sun emits in a day. Such signals, fast radio bursts, have been caught by telescopes since 2007, and their source remains a mystery. A new study offers an elegant answer: it's all about a cosmic amplifier.

In the vast clouds of rarefied gas that fill the space between stars, something is always churning. Supernova explosions, colliding streams — all of it shakes the plasma. And in this rippling, as it turns out, hides the mechanism that gives birth to magnetic fields. Plasma is a gas in which electrons are stripped from atoms.

Space is threaded with magnetic fields. They exist around galaxies, stars, and even in nearly empty voids — the vast empty spaces between galaxy clusters. It's usually thought that fields are amplified from weak 'seed' fields by turbulence, much like a dynamo. But the origin of the seed fields themselves has remained a puzzle.

Red giants are swollen, aging stars. Deep inside, an ocean of plasma churns: heat forces its way from the core to the surface, generating waves like a mighty surf. The star's magnetic field acts like an invisible seabed – it steers these waves, changing their height and speed.

Two neutron stars whirl in their final dance. If their spin aligns with their orbital motion, the partners merge neatly, launching a narrow jet of superheated matter. If they spin in opposite directions, the dance breaks apart, scattering a thick shroud of debris.

Inside a neutron star, matter is compressed so intensely that atomic nuclei fuse into long strands and flat sheets. Astrophysicists call these structures nuclear pasta. At their surface, the density of matter plummets to nearly zero, like diving out of thick jelly into thin air. It's this sharp transition that creates the unusual effect.

A neutron star is a sphere the size of a city but with the mass of an entire Sun. Its magnetic field can tear atoms apart from thousands of kilometers away. Yet until now, it was a mystery how this field is arranged inside: whether it is twisted into tight ropes or more like neat lines radiating from the poles.

In the first moments after the Big Bang, the universe was a boiling cauldron. But then, according to a new hypothesis, it suddenly cooled dramatically — far more than previously thought. In this icy world, dark matter particles, like tiny pendulums, froze and did not begin their oscillations.

An ordinary magnet always carries two poles — north and south. Split it in half, and each piece immediately grows its own pair. But deep in particle theory lives a strange notion: the monopole — a particle carrying just one magnetic charge, a lone pole without a partner.

In the orchestra of atoms, each instrument has its own score. But sometimes two musicians start playing in unison, and the sound amplifies many times over. In the quantum world, this 'harmony' is called a Feshbach resonance. It allows you to control atomic interactions with jeweler-like precision.

A thick rubber band is twisted tighter and tighter. At some point, it can't take it anymore — it snaps and whips around, releasing the stored energy. That's roughly how magnetic fields inside neutron stars — the ultra-dense remnants of exploded stars — behave.

A comb rubbed through your hair picks up scraps of paper. Physicists decided to apply this simple trick at the microscopic level — to control magnetic vortices called skyrmions. A skyrmion is like a tiny tornado in a sea of magnetization: at its center, compass arrows point up, while at the edges they twist downward.

The La3Ni2O7 crystal resembles a layered pie, where the filling of nickel and oxygen atoms alternates with lanthanum layers. At ambient pressure, it does not conduct without resistance, but squeeze it or grow it as a thin film, and high-temperature superconductivity emerges.

A juggler tosses clubs while sitting on a spinning chair. If he starts spinning the clubs all in one direction, the chair will rotate the opposite way — otherwise, the conservation of angular momentum would be violated.

A spinning top whirls so fast it's about to fly apart. Add to it a super-strong magnet — one that, if placed on the Moon, would wipe data from every credit card on Earth. That's a magnetar: an ultra-dense remnant of an exploded star, a lump of matter where a teaspoon weighs as much as a mountain.

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.

A vast, dark cloud of gas stretched across the young universe. Inside it, like invisible fingers, magnetic field lines left over from the very birth of the cosmos threaded through. These fields act on charged particles, pushing them together, like a gentle breeze gathering fallen leaves into piles.

When a massive star explodes as a supernova, its outer layers are blasted into space at thousands of kilometers per second. A shock wave forms — a giant invisible bulldozer that sweeps up interstellar gas and dust. In this maelstrom, particles can be accelerated to energies comparable to that of a flying tennis ball compressed into a single proton.

Gas falls onto a neutron star — the ultra-dense remnant of an exploded star. This gas accumulates at the magnetic poles and forms a mountain. But a mountain on a neutron star is not like one on Earth: it is held not by rock but by magnetic field lines, like iron filings on a magnet. When there is too much gas, the mountain begins to break apart.

A fridge magnet stays put because the tiny atomic arrows inside it all point in the same direction. But when those arrows start to argue (some pulling left, others right, and some spinning like tops) you get magnetic frustration. That disorder gives rise to whimsical patterns: stripes, spirals, vortices.

In a large gas cloud where stars are born, the magnetic field lines are roughly aligned in one direction, like the fibers in a piece of felt. But look inside, into the dense clumps that will eventually become stars, and the picture changes: there the lines are twisted every which way, like a ball of yarn after a kitten has played with it.

The star GJ 436 is a dim red dwarf, and orbiting it is a Neptune-sized planet on a nearly vertical, tilted orbit. Astronomers spent 18 years taking spectra of this star to track its spots and flares. Suddenly, a rhythm emerged in the data that matched neither the star's rotation nor its 8-year activity cycle. This rhythm exactly followed the planet's orbit.

About 380,000 years after the Big Bang, the universe cooled enough for electrons and protons to finally combine into neutral hydrogen. Although this event is called recombination, it was actually their first meeting — the heat had kept them from sticking together until then.

Magnetic moments in a crystal are like compass needles fixed at lattice sites. In the normal state, they line up in neat order, but if an electromagnetic wave strikes the crystal, the needles start to sway, like wheat stalks in the wind. These oscillations are called magnons, and they carry energy without the atoms themselves moving.

Two stars orbit so closely that their outer layers merge into a shared envelope. Matter flows from one to the other, like water spilling from an overfull cup into its neighbor. In this cosmic dance, where stars literally touch each other, astronomers have for the first time detected magnetic fields in large numbers.

Dark matter is invisible, but according to calculations, it holds galaxies together. Catching its particles is like hearing a whisper in a noisy room. You need a material that responds loudly and noticeably to the slightest nudge. Molecular magnets could be such a material — substances where each molecule acts as an independent tiny magnet.

Without the invisible framework of dark matter, galaxies would fly apart. Astronomer Vera Rubin proved back in the 1970s that stars rotate as if held by an unseen mass. But new research shows it's not just passive ballast.