atomic units

Miners took canaries underground not for their songs. The bird would fall off its perch before the miner noticed carbon monoxide. In ultrahigh vacuum, the canary's role is played by a cloud of one hundred thousand lithium or rubidium atoms.

An electron leaves a molecule like a tenant leaving the top floor: to get out, you have to climb the energy steps. But in the quantum staircase, the steps are not empty: other electrons crowd on them, and the crowding changes the height of the climb. The standard ADC(3) method does not notice this crowding; it assumes each electron climbs an empty staircase.

Water in a glass looks continuous, but it's actually a dance of trillions of molecules constantly breaking and forming bonds. Seeing this dance in full detail was previously impossible: accurate calculations that account for the quantum properties of electrons could only handle tiny droplets of a few hundred atoms. The new model UBio-MolFM changes the game.

If you accelerate an observer to near-light speed, the emptiness around them stops being cold. A thermal glow emerges — an effect predicted in 1976 and named after William Unruh. For earthly accelerations, this glow is vanishingly faint, like a whisper at a rock concert.

A palm hovering over a hot stove feels the heat even when the surrounding air seems cool. Something similar happens to electrons in the Aharonov–Bohm effect: the particle senses an electric voltage even though it enters a region where the field has already been switched off.

To uncover the proton's true size, physicists swapped the electron in a hydrogen atom for its heavy copy — the muon. Acting like a magnifying glass with thousandfold power, the muon gets right up against the nucleus and 'probes' the proton with unprecedented precision.

According to ordinary mechanics, an electron in an atom should spiral into the nucleus and crash into it, like a surfer losing speed and falling off the board. But atoms live for billions of years. Because space isn’t empty. Even in absolute vacuum, an invisible electromagnetic sea ripples — the zero-point field. Its waves continuously nudge the electron.

The hydrogen atom is like a tiny clock, ticking with a precision engineers can only dream of. When an electron jumps between orbits, it absorbs or emits light at a strictly defined frequency: that's the 'tick.' In the new work, physicists caught one such transition, between the 2S and 6P states, and measured its frequency with an…

The helium atom is like a tiny solar system: electrons orbit the nucleus, but their orbits are governed by strict rules. Scientists have learned to observe these motions with incredible precision.

At Hungary's Institute for Nuclear Research, ATOMKI, physicists noticed something odd: in the decays of excited atomic nuclei, pairs of electrons and positrons sometimes fly apart at an unusual angle. It's as if an invisible mediator particle briefly appears and disappears between them.

Like long-distance runners, atomic nuclei, from light helium to heavy iron, race toward us across the Galaxy. At the finish line, in a detector on a high-altitude balloon, we see that heavy nuclei arrive a bit more exhausted than light ones. The difference is small, but it repeats from flight to flight.

High above Earth, a satellite flies, and inside it is an instrument the size of a small wardrobe. It catches particles that have been racing through the galaxy for billions of years and finally slam into the detector. Such particles are called cosmic rays, and they bring news of distant stellar explosions.

High above the Antarctic ice sheet, a balloon with a detector floated for twenty days. It caught tiny particles that had been traveling toward us for millions of years from distant stellar explosions. Now scientists have sorted through the catch and reported how much energy the protons and nuclei of different elements carried.