emission spectrum

The blue glow in water around a nuclear reactor is light born when a charged particle outruns light in that medium. The effect was discovered by Pavel Cherenkov in 1934, with the theory provided by Igor Tamm and Ilya Frank.

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.

A flashlight beam cuts through fog. The denser the fog, the more the light scatters and the later it reaches your eye. A similar principle works with fast radio bursts — mysterious, super-powerful pulses from distant galaxies. As their radio waves travel through space, they interact with free electrons — particles stripped from atoms.

A protein in a cell is not a frozen sculpture. It is constantly in motion: bending, breathing, jittering. This motion, its dynamics, determines how the protein works. But peering directly into the dance is hard, and computer simulations often demand enormous computing power. A new approach, named DynaMode, views protein motion as a musical piece.

When an electric charge moves with acceleration, it emits electromagnetic radiation, i.e., light — a familiar phenomenon in physics. However, researchers have found that when moving along a specially chosen trajectory, the radiation acquires unusual properties.

When many excited atoms are gathered together, they often fire light in concert, like a crowd clapping in rhythm. This well-known phenomenon is called Dicke superradiance. But the authors of the new study asked: what happens if the atoms are not identical and each one feels its neighbors?

Two quantum dots are like two tiny pockets in a piece of silicon where an electron can sit, like a ball in a cup. When the pockets are far apart, each electron lives on its own, and its energy resembles the levels of a solitary atom.

The light an atom emits is not just a flash. It carries an imprint of the atom's state at the moment of emission. Physicists took a superconducting qubit, an artificial atom the size of a microchip, and made it glow into an open waveguide, like a bulb in a long corridor.

Cosmic dust isn't dirt: it's tiny grains, like soot from a campfire, scattered between the stars. Some of them spin at breakneck speeds, millions of times per second, emitting faint radio waves. Astronomers call this anomalous microwave emission: it interferes with studies of the early universe, but it's also a mystery in its own right.