electric current

A superconductor is a material in which electricity flows without loss, like water through a perfectly smooth pipe. But if you squeeze it slightly, like a spring, its properties change. Scientists have long wanted to measure how much heat such a compressed material absorbs, but instruments couldn't fit into the cramped setup. Now they've devised a way around this obstacle.

In 1994–1995, the LEP accelerator collided electrons and positrons, producing Z bosons that promptly decayed into showers of particles. The DELPHI detector recorded these events, and now, decades later, a new pattern has been found in that data: the electric charge within particle jets is not distributed randomly but follows a simple sine curve.

In the quantum world, particles sometimes behave like acrobats on invisible tightropes. An instanton field is a brief vortex that appears and vanishes in an instant. When a fermion (a particle like an electron) enters such a vortex, its energy does not stay put. Instead, it smoothly slides from one level to another, like a ball rolling down a hill.

In 1976, physicists predicted that an electron could do more than just fly past a nucleus: it could slam into it, transferring energy and making the nucleus 'shudder.' They called this effect NEEC — nuclear excitation by electron capture. But for nearly fifty years, no one has managed to observe it in an experiment.

Electric charge is a slippery thing. You can measure how much there is in the entire universe or in a single particle, but try to point your finger and say, 'Right here, in this cubic centimeter, there is exactly this much charge right now,' and you hit a fundamental wall. The issue is that total charge, which physicists denote by the letter Q, is nonlocal.

The river splits in two. One branch is wide and fast, with water flowing smoothly, but as temperature rises, the flow slows: eddies and waves appear. The second branch is narrow, with rapids, where water leaps from rock to rock. This flow, on the contrary, becomes more lively with warming.

The brain self-cleans its waste: cerebrospinal fluid flows through narrow channels surrounding arteries. The channel walls are soft and ripple with each pulse, and the tissue is porous like a sponge. Every heartbeat turns arteries into tiny pumps, driving fluid through the pores.

In a water supply system, water sometimes flows not as a continuous stream but in separate identical portions, as if the tap opens and closes, letting through exactly one drop each time. This is roughly how electric current behaves in superconducting contacts called Josephson junctions.

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.

In the world of superconductors, electrons don't like to be alone. They typically pair up into Cooper pairs and move without resistance, like figure skaters holding hands. But you can make them dance in fours. The authors of this work propose a scheme where Cooper quartets, groups of four electrons exchanging partners in a rapid rhythm, are born.

In a thin semiconductor channel, electrons behave not like lone runners but like a crowd at rush hour. They constantly bump into each other, and these collisions determine how easily heat and electric current pass through the material.

In the cold heart of a pure crystal, electrons flow like a viscous fluid — an idea predicted by Lev Landau. But the vortices of this fluid remained invisible, like a painting inferred from the noise of a crowd. Now scientists have created a nanostring: a semiconductor tuning fork with a circular cavity.

Electric current in a superconductor is like a crowd running down a frictionless corridor. But in type-II superconductors there are obstacles, tiny vortices of magnetic field, that the current shoves out of place. Once a vortex moves, resistance appears and the current drops.

Current flowing through a wire is never perfectly smooth. If you listen closely enough, you hear a rustle — shot noise. It arises because charge is not carried as a continuous stream but in discrete portions, like raindrops on a roof. From the character of this noise, you can tell how much charge each 'drop' carries.

A quantum dot is like a tiny island where one or a few electrons can settle. In this new work, such an island was connected to two 'seas' of electrons: one flat like a pancake, the other bulky like an ocean. Electrons can hop from the island to the seas and back, and this hop depends on the shape of the electron's wave on the island.

A metal is a sea of electrons that move almost freely, colliding only occasionally. But in some materials, this sea suddenly becomes viscous and unpredictable: electrons stop behaving like independent particles. Physicists call this state 'non-Fermi liquid,' and it remains a puzzle.

Neutrinos are tiny particles that zip through Earth, barely noticing it. In the MicroBooNE experiment, they are caught in a tank of liquid argon. When a neutrino strikes an argon nucleus, it produces an electron and protons, like splashes from a stone thrown into water.

Since the days of Galileo, it was believed that in a vacuum all bodies fall identically. Einstein elevated this to a principle: gravity travels at the speed of light and is the curvature of spacetime.

Run a current through a wire, and the wire heats up. Anyone who has ever touched a phone charger knows this. Physicists call this heating Joule heating, after James Joule, who in the mid-19th century measured how much heat electricity produces. Since then, the formula has been simple: the greater the resistance and the current, the hotter the wire.

Measured dipole moment of tantalum-181: 3.39 × 10⁻³² e·cm — like spotting a one-atom shift across the entire Solar System. An ordinary atomic nucleus is perfectly balanced, like a spinning top. In tantalum, that balance is broken: the positive and negative charges are slightly offset from each other.