tritium

Inside the steel of a future fusion reactor, tiny helium bubbles form, and on their walls a chemical drama unfolds. Chromium and tantalum atoms, like sentinels, take positions at the cavity boundary and change the rules of the game for hydrogen.

In the cold cloud TMC-1, where the temperature never rises above ten degrees above absolute zero, molecules rarely encounter one another. But every so often a helium atom whizzes past, and that brief touch is enough to alter the molecule's rotation. Such collisions dictate what radiation we see from Earth.

Triton's icy shell is like a locked door to a basement where water sloshes behind the wall. We can't open it, but we can press our ear to it and listen for echoes of footsteps: how Neptune's magnetic field responds within the moon's interior, how the ice trembles from distant impacts.

In the depths of sub-Neptunes, the most common type of planet in the Galaxy, though not one you could stand on, silicate magma and hydrogen mix into a single supercritical cocktail. Previously, it was thought that beneath the dense hydrogen atmosphere lay a sharp boundary with molten silicate, like oil on water.

The helium atom is like a tightly stretched string: every note it plays is strictly predicted by theory. But in recent years, precise measurements of one such "note"—the energy needed to strip an electron from an excited helium atom — have started to sound slightly higher than they should.

Atomic batteries powered by plutonium decay have been running pacemakers and space probes for over sixty years. But the raw material is scarce: worldwide, only a few kilograms of plutonium-238 are produced each year, barely enough for the most critical missions.

In dark interstellar clouds where new stars are born, chemistry starts with a tiny particle — the trihydrogen ion (H₃⁺). It collides with other atoms and sets off a cascade of reactions that build ever more complex molecules. For a long time, it was thought that the main reaction producing it, H₂⁺ colliding with H₂, only happens in the gas phase.

In 1946, proposed a method that revolutionized archaeology: determining age by the decay of radiocarbon. The clock ticks: every 5730 years, half of the atoms vanish. But why so slowly? For a light nucleus, this is an anomaly — typical lifetimes are millions of times shorter. The mystery held for seven decades.

Two pendulums on a shared string trade motion: push one, and the second starts swinging, and a moment later the first gets a push back. In a thorium-229 atom, energy flows nearly loss-free between the electron shell and the nucleus.

A sub-Neptune is a planet that falls between Earth and Neptune in size. These worlds are abundant in our galaxy, but their internal structure has been hotly debated. New research shows that in their youth, these planets behave like a sponge soaked with water.

A planet the size of Neptune, but glowing white-hot. Beneath the clouds lies an ocean of magma capable of absorbing an entire hydrogen atmosphere. The new SEAMIST model is the first to trace how such dissolution changes a planet's fate from birth to old age. The big surprise is the mechanism of catastrophic boiling.

Two guitar strings are stretched on the same neck. They are almost identical, but one is slightly shorter — and they sound different. That's roughly how the two isomers of ethanimine work: molecules with the same set of atoms but rotated differently in space. Astronomers spotted this molecule in the dense clouds near the center of our Galaxy.

The most precise modern clocks count time by the oscillations of electrons in atoms. But their rhythm can be thrown off, like a mechanical watch's spring gets jolted by shaking. Physicists found a more reliable pendulum: the atomic nucleus.

Atomic nuclei are wrapped in fluffy electron coats — in such attire, they can't get close enough to embrace. But swap the light coat for a heavy one: a muon, a particle from the standard model, shrinks the cloud by nearly 200 times.

A steel cylinder that has held hydrogen for a long time sometimes breaks not along the usual grain boundaries but right through the crystal grains, leaving a strange pattern, as if the crack chose the wrong road. For a long time, people looked at this and wondered: why?

In a crystal of water and caustic cesium, oxygen and cesium atoms sit in place like beads in a rigid lattice. Hydrogen atoms behave differently: they are like passengers constantly changing seats. In this layered material, each oxygen is linked to three neighbors via hydrogen bridges, forming a honeycomb-like pattern.

A ball rolls up a hill, but it doesn't have enough energy, so it rolls back down. That's classical mechanics for you. But in the quantum world, a tiny particle can sometimes pass right through the hill, as if the barrier weren't there. This trick, tunneling, is business as usual for a light atom like hydrogen.

Fusion, the merging of a proton with a boron-11 nucleus, promises a near-perfect energy source: no dangerous neutron flux, just a stream of charged particles that can be directly converted into electric current. But there's a fundamental problem: the Coulomb barrier.

Neutrinos are almost elusive particles: they zip through planets without noticing atoms. So every catch is a stroke of luck. Recently, the underwater detector KM3NeT snagged a neutrino with energy millions of times greater than Earth's most powerful accelerators can produce.

Inside every atom lives a proton. For a long time, it was considered as eternal as matter itself. But theories that unify all forces of nature predict that, sooner or later, the proton will decay. The only question is how long we have to wait. In the Japanese detector Super-Kamiokande — a giant tank of ultra-pure water — physicists searched for signs of such a decay.

Neutrinos are tiny particles that pass through the planet's bulk like light through a windowpane. Every second, billions of them fly through your pinky fingernail, but catching even one is no easy feat. To do it, scientists dug a two-kilometer-deep mine in Canada and installed the SNO+ detector.

In the first minutes of the Big Bang, the universe whipped up a cocktail of hydrogen, helium, and a pinch of lithium.

An ordinary nuclear reactor is like a boiler where fuel burns evenly throughout the volume. Here the picture is different: a fission wave, a narrow zone where atoms split and release heat, slowly creeps along a cylindrical rod of uranium carbide. Ahead of the wave, the fuel is untouched; behind, it is already spent. So fire runs along a candle wick, leaving wax behind.

Comet 3I/ATLAS was spotted when it entered the Solar System from interstellar space. The James Webb Telescope split the light from its gas cloud into a rainbow, a spectrum, and in this pattern, the lines of rare molecules with deuterium (heavy hydrogen) appeared.

A membrane for water electrolysis is like a sponge soaked with water. Inside it, hydroxide ions, particles that carry electric charge, must move freely. But exactly how they move has long been a mystery: tracking each ion in an experiment is too difficult.

A high-speed collision knocked a neutron out of a helium-8 nucleus, and for an instant a helium-7 nucleus appeared, like an overloaded shelf shedding three books at once. This fleeting 'sound' of decay was captured for the first time: three neutrons flew apart, leaving behind an ordinary helium-4 nucleus.

A customs officer can't take a suitcase apart to see what's inside. They shine X-rays through it and, from the shadows on the screen, tell: here's metal, here's organic matter. In much the same way, an inspector for future nuclear disarmament treaties should be able to check a warhead — without opening it or seeing its secret internals. Neutrons are better suited for this than X-rays.

A semiconductor film just one atom thick is like a communal apartment: it houses negatively charged electrons and positively charged 'holes.' When light hits such a film, an electron and a hole can pair up into an exciton — a bound state of an electron and a hole, akin to a hydrogen atom.

An atomic nucleus usually follows its own rules: its decay doesn't care about temperature, pressure, or molecular neighbors. But the uranium-235m isotope is a striking exception. This nucleus sits in an excited state, like a tightly coiled spring, and sooner or later it releases the extra energy.

Every time deuterium and tritium fuse in a fusion reactor, a fast neutron flies out. It can turn one substance into another — for example, create valuable isotopes for medicine. Today such neutrons cost a fortune, because there are few experimental facilities and they rarely operate.

Inside a future fusion reactor, a magnet weighing as much as a small car will float. It holds the superheated plasma like an invisible hand holding a cloud. Previously, such a magnet was considered unsuitable for deuterium-tritium fuel: neutron fluxes would quickly destroy it.

When a star like the Sun runs out of hydrogen, it swells into a red giant, and helium piles up in its core. At some point, the helium ignites — in a few seconds, it releases as much energy as the star had radiated over thousands of years. This is a helium flash.

Light in semiconductors is born from pairs of charges, an electron and a hole, that attract each other like a magnet to a fridge. Such a pair is called an exciton. If you add one more charge to the pair, you get a trion — a trio of three particles.

Chemistry has two worlds: in one, the catalyst is a solid particle and the reaction happens on its surface; in the other, it's a dissolved molecule where everything occurs around a single metal center. These worlds rarely meet. But in a new study, they collide. The researchers took iron oxide, a black powder used in magnetic tapes, and scattered single rhodium atoms across its surface.

In the first minutes after the Big Bang, the Universe was like a blazing hot stove. On it, according to the 'recipe' of the standard theory, hydrogen, helium, and a bit of lithium were supposed to cook. But telescopes see only a third of the lithium that this recipe calls for.

A magnetic compass in a test tube sounds like a magic trick, but it's pure physics. In a solution of fumarate (a salt of malic acid), carbon-13 nuclei behave like tiny spinning tops.

A piece of chromium exposed to air gets covered in invisible armor, an oxide film, within a minute. That film protects the metal from rust, but for a battery it's a disaster: the film blocks chromium ions, so no current flows. Scientists mixed five metals — chromium, bismuth, copper, tin, and nickel.

A cosmic dust grain is covered in ice, and on this ice, like in a tiny kitchen, molecules are cooked. One of them is methanol, an alcohol that serves as a building block for more complex compounds in space. Previously, it was thought that methanol only forms when hydrogen atoms stick one by one to a carbon monoxide molecule.

In a silicon crystal, the stuff of microchips, there sometimes sits a foreign atom, like magnesium. It behaves like a tiny magnet with several 'pointer positions.' If you illuminate such a crystal with a short flash of light, the atom momentarily gets excited, then returns to its ground state.

For two atomic nuclei to fuse, they must overcome their fierce electric repulsion — like trying to bring two angry bulls together. Normally, only monstrous energy does the trick, as in stellar cores, where Hans Bethe explained fusion back in the 1930s.