velocity distribution

In a ring-shaped channel between two toothed rings, microspheres are suspended: some with a radius of 8 micrometers, others 14. The discharge is switched on, and the particles start moving. The small ones go one way, the large ones the other. It is like a shopping mall where escalators for people of different heights run in opposite directions.

An airplane wing, like a skier on a ski jump, remembers its acceleration. Change the angle of attack sharply, and the lift does not immediately reach its new value. It builds up gradually, as if the wing is not yet sure the maneuver is for real. This effect was discovered by engineer Herbert Wagner in 1925.

If you push water in a narrow channel too fast, a steep wave forms and breaks into foam. In the world of ultracold atoms, cooled to near absolute zero, quantum laws prevent such a wave from breaking. Physicists took a cloud of rubidium atoms stretched into a thin thread and sharply compressed it from one end with a movable wall of light.

On a steep mountain slope, a single falling rock sometimes triggers an avalanche, and sometimes gets stuck. It all depends on the state of the slope.

Picture a pot of boiling soup, but every grain in it is not just a point but a tiny top spinning around its own axis. That's the world of spin-1 particles. For example, some short-lived mesons born in accelerator collisions.

Space is full of invisible sprinters — particles racing nearly at the speed of light. They are caught in the solar wind, near neutron stars, and even in the intergalactic void between galaxies. But what accelerates them where there are no shock waves or magnetic reconnections?

If you pour sand into a glass, it settles in a flat layer. But instead of sand, take the tiniest particles of gas: in a gravitational field they don't just fall: each particle races along its own trajectory, collides with neighbors, and all this commotion creates pressure.

A giant cauldron of simmering soup stretches across millions of light-years. This is the atmosphere of the Perseus galaxy cluster — a cloud of scorching gas held together by gravity. Until recently, astronomers thought that in the center of this cauldron, the gas was calmly cooling, ready to condense into new stars.

A stream of electrons enters plasma like a jet of water hitting a calm pond. The jet disturbs the surface, giving rise to waves that grow quickly and mix the water. In plasma, this process is called the Buneman instability: the electron beam excites oscillations that then scatter its energy.

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.

Near black holes and neutron stars, plasma churns like water in a boiling kettle. But this 'kettle' has no walls — only magnetic fields that twist and tear. At the tears, thin sheets form where magnetic field lines reconnect, giving particles a kick like a surfer catching a wave.

Interstellar space is not empty: it is filled with tenuous gas, which is warm in some places and cold in others. The boundaries between such regions resemble the walls between soap bubbles.

In helium cooled to near absolute zero, the liquid stops rubbing against itself and begins to flow without any resistance.

A living cell is like a bustling city: cargo moves continuously along its streets, and traffic flows are regulated so that everything needed arrives on time. But while you can watch a city from a helicopter, the cell's interior has long been observable only through a narrow slit — the microscope showed just a flat picture.

A pot of boiling water sits on the stove: the higher the heat, the hotter the water and the more steam escapes. Hot gas in galaxy clusters behaves much the same way. But in small galaxy groups, this "steam" leaks out faster than you'd expect from the temperature alone.

A cell is a city with gates. Each gate is a protein channel in the membrane: through it, ions, sugars, and signaling molecules pass in and out. Some gates are almost always open, while others open and close randomly, like subway doors that let a passenger through one moment and slam shut in their face the next.

Fluid flows in the narrow gaps between brain cells. It doesn't stay still: each heartbeat pushes it forward, and breathing adds its own waves. This was seen in images ten years ago, but only now have researchers calculated how this pulsing accelerates molecules. If you drop ink into a stream, it drifts with the current. But if the stream speeds up and slows down, the ink spreads wider.

In the 19th century, James Clerk Maxwell imagined a tiny demon. It knows the speed of every gas molecule and opens a door: fast ones to the left, slow ones to the right. This creates a temperature difference without expending energy, seemingly violating the laws of physics.

A blazar is a distant galaxy with a plasma jet shooting from its center, aimed almost directly at us. Inside this jet, particles are accelerated to near-light speeds and emit powerful radiation.

The diffusion equation, a mathematical tool describing how particles spread out in space, has long painted a paradoxical picture: a disturbance, like ripples on Water, instantly engulfs the entire universe. This challenged the theory of relativity, which holds that nothing can move faster than light.

When water churns behind a boat, the energy of motion is converted into heat through a cascade of vortices. Measuring how quickly this happens directly is difficult: you'd need to track all the vortices at once. So scientists use a simplification: they look at only one velocity component at a single point.

In the mountains, an echo repeats any shout, and you can't immediately tell who shouted: a person or the wind. That's roughly how climate scientists work when they try to understand why an unusual heat wave or drought happened. They look for a human fingerprint in a weather disaster, but nature has its own voices that can sound similar.