transmission

Light born when a fast electron enters a material is usually assumed to be the same in all directions. But in crystals where optical properties depend on direction, that's not the case. Run your hand over velvet: one way it's smooth and shiny, the other — dark and rough. Similarly, a crystal responds differently to light depending on how it's oriented.

Radio waves, high-frequency electromagnetic oscillations, are powerless against the Earth's bulk: they attenuate, being almost completely absorbed within a couple of meters of depth. But a low-frequency magnetic field, governed by the equations of electrodynamics, behaves differently.

A beam of light enters frosted glass and fades — nothing unusual. But physicists have long known how to make light pass through without losing a single photon. This trick is called electromagnetically induced transparency: two light waves cancel each other at the right point, and absorption disappears. Now a similar feat has been pulled off with atoms.

In the quantum world, light and matter constantly exchange energy. Previously, they were described statically, like frozen poses. The new approach follows the dance itself: the transitions between states, like a continuous sequence of movements.

When light swings past a massive body like a black hole, its path warps — an effect predicted by Einstein. New research has taken into account that near such objects, clouds of hadrons often swirl — the very particles we know from protons and neutrons in atomic nuclei.

Each vowel sound is a distinct shape of the mouth, tongue, and throat. When you say 'ah,' 'ee,' or 'oo,' not only does the air inside your head change, but so does the way radio waves pass through it. Researchers peered into this process using MRI scans taken right during speech and built a precise computer model of the head — from bones to soft tissues.

An ordinary lens always refracts light the same way. Its properties are frozen in glass forever. But now there's a surface that changes the game on the fly. Scientists made an ultrathin film with resonant elements and infused it with liquid crystals — the same stuff used in phone screens.

A flashlight beam in fog breaks into thousands of faint specks. Each speck is light that has bounced off countless water droplets before reaching your eye. To make sense of this mess, physicists construct a special table — the scattering matrix. It records how each incoming ray turns into a set of outgoing ones.

A thermos of liquid xenon cooled to minus 100 degrees Celsius. Inside are sensitive sensors that catch rare signals from dark matter particles. To bring these signals out, copper cables are usually used. But over the long haul, the signal weakens, and adjacent cables start 'cross-talking' — that's called crosstalk.

A stone drops into a pond — ripples spread across the water. Do short waves outrun long ones? No, in deep water it's the opposite: long waves overtake short ones. In metal, sound of one pitch travels at one speed, another pitch at another.

Sound in a thin plate behaves like ripples on water: it travels, reflects off edges, and changes shape. But sound has a peculiar trait: it can pass through places where waves are forbidden to exist. It's as if ripples on a pond suddenly vanished before a stone barrier and reappeared on the other side, without going around it.

When light passes through biological tissue or frosted glass, it scatters and loses the image. Researchers at the Paris Institute of Nanosciences have shown that a scattering medium can be tuned to transmit images encoded in the correlations of entangled photons while remaining opaque to classical light.

Shine a flashlight through a narrow slit, and the beam doesn't stay a thin stripe; it spreads out sideways. Light has a habit of bending around obstacles, and because of that, the smallest spot you can get with an ordinary lens is no smaller than half a wavelength.