temperature difference

A piston in a cylinder with gas usually moves when the gas pushes on it. But there is a piston that moves when the space in front of it is empty. Every five seconds, it checks the space near its wall, and if no one is there, it takes a step inward, compressing the gas without direct mechanical force.

A particle sits in an energy pit like a pea in a dimple. To get out, it needs to go over the barrier, and usually this is rare: the higher the barrier, the longer the wait. The Arrhenius law says the waiting time grows exponentially, meaning doubling the barrier height increases the time by hundreds of times.

A regular battery releases heat smoothly: what you store is what you get. The power is fixed once and for all, like a faucet that pours water in a single stream. But sometimes you don't need a steady flow; you need a short, powerful burst: to instantly heat a part, trigger a reaction, or dump excess heat.

Microwave plasma in a vortex is like a kitchen mixer that simultaneously heats and stirs the gas. In the reactor, the gas is swirled, and microwaves heat it to thousands of degrees, tearing carbon dioxide molecules apart. Scientists created a computer model of such a reactor to understand how pressure affects the process.

Inside an ultracold chamber, two atomic clouds collide: a few dozen cesium atoms acting as the working fluid, and thousands of rubidium atoms serving as the heat reservoir.

The solar wind is a continuous stream of charged particles flowing from the Sun. It has two main components: protons (hydrogen nuclei) and alpha particles (helium nuclei, four times heavier).

A conventional computer computes by shuttling electric charges along wires. But can you compute with heat? A network of pipes carrying hot and cold water can perform simple logic operations if the pipes are connected in the right order.

Drop a pebble into a pond, and ripples spread across the water. In much the same way, any body, even the tiniest, perturbs the gravitational field around it. In empty, cold space, these perturbations, like ripples on a calm surface, make two nearby objects always repel each other.

In a crystal, heat travels on waves. Atoms vibrate, and these vibrations, called phonons, carry energy from the hot edge to the cold one. For a long time, it was believed that if phonons hit resonance (their frequencies exactly match) and can exchange energy, heat would flow like an avalanche. It turns out that's not the case.

The Kerr-NUT black hole is not just a cosmic vacuum cleaner. It's a solution to Einstein's equations where the hole has mass, rotation, and a strange NUT parameter. This parameter behaves like a magnetic charge for gravity: seemingly invisible, yet it alters the properties of surrounding space.

Hot tea cools down, and ice cream melts — heat always flows from warm to cold, and this law seemed unbreakable. But in the quantum world, even familiar rules can be rewritten. Physicists placed a tiny mechanical resonator (a vibrating bridge the size of a microbe) in an optical cavity between two mirrors.

In a glass of water, oil gathers into droplets: that's equilibrium separation dictated by chemistry. But there are systems where order arises not from rest but from a constant flow of energy.

Inside every cell, logistics is in full swing: tiny protein motors, like couriers, haul cargo along a network of microtubules. One of the main workhorses is kinesin, which steps using the energy of ATP (the cell's main energy currency). For a long time, researchers tried to evaluate it like a car: how much fuel it burns, how fast it gets there.

In classical thermodynamics, heat engines are like a virtuoso musician on stage: the closer to perfection in performance (Carnot efficiency), the slower the tempo (power).

Imagine water as a ballroom, where each molecule is a dancer, constantly forming fleeting partnerships. These hydrogen bonds give rise to local patterns: some resemble a stiff waltz — an ordered network with cavities (low-density structure), others a wild jitterbug, where partners crowd into chaotic dense clusters.

Imagine a steam engine where instead of a steel piston there is an event horizon, and the cylinder is curved space itself. This metaphor has gained mathematical flesh: physicists have for the first time constructed a complete set of reversible heat cycles with a Schwarzschild black hole confined in a spherical cavity.

Heat a nail in a fire, and it will lengthen — everyone knows that. But heat only the tip and leave the other end cold, and the nail doesn't just get longer: it bends, because hot metal expands more than cold metal. It's this very bending, but at the atomic level, that physicists have turned into electricity.

A heat engine doesn't have to be made of iron. In the microworld, a single electron can play the role of a piston, and the measurement process itself can serve as fuel. Two neighboring 'pockets' for electrons are connected by a narrow bridge.

A lithium-ion battery is like a multi-story building where lithium ions live on every floor. When you charge the battery, the ions move from floor to floor, and the whole building warms up a bit. Usually, this heat dissipates evenly, like from underfloor heating. But sometimes one spot gets too hot, and then the whole building can go up in flames.

A kettle cools on the table. Heat escapes into the air, and is wasted. Yet you could squeeze a bit of electricity out of it. Devices that can do this are called thermomagnetic generators. Inside them, there are no pistons or turbines — only a material that changes its magnetic properties when heated and cooled.

A piece of metal heated at one end produces a weak electric current: this has been known for nearly two hundred years. But what if, instead of a simple metal, you take a layered "sandwich": a superconductor, a thin insulator, and a flat layer of electrons?

Usually, current in a metal acts like boiling water on ice: it heats the material and destroys magnetic order. But in a layered structure of tungsten ditelluride and the ferromagnet Fe3GeTe2, current behaves differently.

A droplet of liquid metal glides along a narrow channel like mercury from a broken thermometer. It needs no motor — the fuel is a chemical reaction with the surrounding liquid. But what happens when the droplet hits a wall? Previously, such machines were studied in open spaces, and in tight channels they behave differently.

An ordinary heat engine is like a mill between the hot and cold banks of a river: the greater the drop, the stronger the current. Here, the drop is tiny, just one or two degrees, but water can still turn the wheel. The secret is that water is made to boil not by heating but by a sudden drop in pressure, so steam bursts out even from barely warm liquid.

A black hole isn't completely black. From its horizon, a faint thermal glow constantly seeps out, like steam rising from a cooling cup of tea. The temperature of this glow depends on the strength of gravity at the surface.

Every machine, whether a car engine or a tiny nanocooler, runs with a jitter. Fuel burns unevenly, electrons slip through contacts off schedule, and the power needle on your instruments vibrates slightly. These vibrations are called fluctuations. They are not just noise: they tell you how stable a device is and how much energy it wastes.

Uranus and Neptune have long puzzled scientists: their magnetic fields are heavily tilted and tangled, nothing like Earth's. The answer lay in an exotic form of water — superionic ice, which fills their interiors.

The idea of a expanding universe, proposed by Georges Lemaître, finds an unexpected analogy. Space behaves like a piston in a cylinder: dark energy pushes it, much like steam. The relationship between pressure and volume in this 'engine' is strikingly similar to that of a steam boiler.

Water in a glass cools, ice melts, and a kettle heats the stove: that's how the world works: heat always flows from hot to cold. This is the second law of thermodynamics, a law that has never been broken.

The James Webb Space Telescope is watching TRAPPIST-1—a tiny red dwarf with seven Earth-sized planets in orbit. And it sees something unusual: bright flares on this star barely reach 3500–4000 degrees. For comparison, a typical solar flare heats up to 9000–10000 degrees.

A regular motor burns fuel and wastes a ton of energy as heat — that's dictated by the laws of thermodynamics. A quantum engine does it differently: its fuel isn’t heat, but a perfect rhythm. Physicists call this rhythmic precision quantum coherence.

Water always flows downhill, and heat from hot to cold. That's what энтропия dictates. But the quantum world finds loopholes. Physicists made light particles interact with hot and cold environments in an uncertain sequence — like a flipped coin that hasn't landed yet.

Atoms, like a swarm of fireflies, shine in unison. When they flash together, the light multiplies — a hundred atoms shine ten thousand times brighter than one. Physicists have turned this trick into a heat engine. A typical motor needs both a hot and a cold source, but here the atoms operate with just a cold one.

A heat engine is like a sailboat: to move forward, it needs a difference. Usually that means a temperature difference between hot and cold reservoirs. But what if the reservoir itself starts moving? The wind that fills the sails is created not only by a pressure difference but also by the motion of air masses.

Two qubits, quantum bits, two-level systems, glide through hot and cold thermal baths. One moves at 0.8 times the speed of light. At that moment, familiar thermodynamics cracks: a moving qubit senses temperature differently than a stationary one. For it, the cold bath can feel hotter, and the hot bath colder.