polarization measurement

Eight sky maps taken by different detectors of the Planck telescope resemble eight road atlases of the same city drawn by different cartographers. Each atlas is rotated by its own angle: one cartographer held the tablet slightly tilted, another slightly turned. If you overlay the atlases, the streets won't align. But if you know how each atlas is rotated, you can align them perfectly.

A thin section of eucalyptus lies under the microscope objective, and white light, passing through two polarizing filters, turns the wood into a mosaic of purple, yellow, and blue patches. These colors are not random: like letters on a map, they show the direction of the invisible cellulose threads inside the cell walls.

Radio waves from a distant pulsar travel through the interstellar medium, encountering invisible magnetic structures the size of the distance from the Sun to Earth. One such structure is a current sheet, where the magnetic field abruptly changes direction, like a compass needle flipping from north to south.

A laser hits an atom, and tears out an electron. The brighter the light, the stronger the kick, and the faster the electron flies away. That's how the familiar picture works, where light is a smooth wave. But what if the light isn't smooth but 'squeezed,' with quantum fluctuations, like the trembling of a string?

The universe sometimes resembles an old fabric: after rapid cooling, wrinkles could have remained — thin, almost invisible threads of monstrous density. They are called cosmic strings. Usually, at the center of such a string hides a singularity — a point where the laws of physics lose their meaning.

On the wall: light and dark fringes. That’s what light looks like when it cancels itself out. Way back in the 17th century, Christiaan Huygens suggested that light is a wave.

Light from the very beginning of the cosmos has been traveling toward us for 13.8 billion years. During that time, its polarization, the direction of its oscillations, might have been twisted, like a compass needle that someone quietly nudged. Physicists call this phenomenon cosmic birefringence.

May 2022. The space polarimeter IXPE, the spectroscope NuSTAR, and the monitor NICER simultaneously stared at one spot in the sky — at the black hole in the Cygnus X-1 system, where it orbits a blue supergiant in a close binary system with a period of 5.6 days.

A black hole is not just a dark silhouette against the stars. Its shadow is surrounded by a thin glowing ring of photons that loop around the event horizon before escaping to an observer.

In a close binary system, the hot star, like a searchlight, illuminates its cooler companion. Some of the light scatters off free electrons in its atmosphere — this is Thomson scattering — and acquires linear polarization. As the stars orbit each other, this polarization rotates, like the hand of a peculiar cosmic metronome.

An ordinary microscope is powerless when you need to examine a single virus in detail. It's too small. But there's a tool that fires flashes billions of times brighter than sunlight — an X-ray free-electron laser. It's designed to 'photograph' a particle before the beam vaporizes it.

Red giants are swollen, aging stars. Deep inside, an ocean of plasma churns: heat forces its way from the core to the surface, generating waves like a mighty surf. The star's magnetic field acts like an invisible seabed – it steers these waves, changing their height and speed.

Around an invisible fire, glowing gas swirls. The fire itself is hidden, but its outline can be guessed from the way the flames dance. That's roughly how astronomers 'see' black holes — not the object itself, but the superheated matter that, before plunging into the abyss, accelerates to enormous speeds and shines.

When two black holes merge, they shake the very fabric of spacetime. The newborn giant doesn't settle instantly (it rings like a cosmic bell, emitting a characteristic pattern of damped gravitational waves) the so-called ringdown.

The universe is not emptiness, but a vast crystalline sphere, threaded with invisible boundaries — domain walls frozen after phase transitions.

Light from a distant star is not just a steady stream. It oscillates like a wave and can vibrate in different directions. Usually these oscillations are indistinguishable, but a magnetar can sort them out.

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.

A distant orchestra plays a symphony, but the recording is full of noise. The melody is written for two instruments, yet a third voice seems to break through the static — quiet and unfamiliar. This is how astrophysicists listen to gravitational waves, trying to catch the slightest deviations from Einstein's predictions.

The neutron star 4U 1735-44 is gobbling up matter from a companion star. The matter spirals into a flat disk, like water going down a bathtub drain. But this disk shines in X-rays, and astronomers have for the first time measured how "combed" those rays are: that is, how polarized.

When particles collide at enormous speeds, they produce a shower of new particles. Among them are antiprotons — twins of ordinary protons but with the opposite charge. Each of these particles has its own spin, like a tennis ball sent with a twist. But whether antiprotons are actually spun up at birth has never been checked.

In the crystal HfTe5, electrons behave almost like light: their mass is so small that they obey the laws of relativity. If you place such a crystal in a strong magnetic field, the electrons start to circle in tiny orbits. Their energy then changes not smoothly but in steps, like floors in a building.

You can make a light beam look like a flower with several petals. If you send such a beam through a cloud of cold rubidium atoms and switch on a magnetic field, the petals start to rotate. The angle of rotation is directly linked to the field's strength.

Entangled photons are like two couriers marching in lockstep: their quantum states, particularly polarization, are synchronized so that measuring one instantly determines the state of the other, even at a distance. In a material, this synchronization gets disrupted.

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.

Laser light is like a perfectly aligned row of soldiers on parade: all waves oscillate in the same plane. Such light is called polarized. In a new study, physicists have for the first time produced polarized gamma rays by colliding electrons with a powerful laser pulse.

In particle scattering experiments, the target is often polarized: nuclei are aligned so that their spins point predominantly in one direction. The degree of this alignment affects the collision outcomes.

A neutron star the size of a city spins thirty times per second. Its magnetic field is trillions of times stronger than Earth's. Such conditions could spawn a cloud of axions around the star — light particles that no detector has caught yet, but which neatly explain the hidden mass of the Universe.

Light is a stream of photons, and ordinarily a photon has no magnetic moment: it doesn't deflect in a magnetic field like iron filings.

The Sun is not a calm sphere. Waves constantly ripple through its interior, like a bell after being struck. These oscillations reach the surface and reveal what's happening on the far, invisible side. Astronomers have long been able to 'listen' to this ringing and find large sunspot groups there.

The X-ray pulsar Centaurus X-3 is a neutron star that spins rapidly and emits pulses of X-ray light like a lighthouse. Scientists pointed three space telescopes at it and studied the polarization of its emission — how the electric field of the light wave oscillates.

The black hole GS 1354-64 in the constellation Musca woke up in 2025 and began greedily pulling matter from its companion star. The orbiting X-ray telescope IXPE caught it at a rare moment: the outburst had already subsided, but the system had not yet settled down.

In a giant particle accelerator, where protons traveling at nearly the speed of light smash into a neon target, charmed baryons are born — particles that live for less than a billionth of a second.

On a silicon wafer the size of a dinner plate, you can place not just one substance but an entire map of thousands of different compositions. A laser knocks atoms off targets and deposits them in thin layers, varying the proportions from point to point. The result is a materials library: more of one metal here, more of another there, and all combinations visible at once.

Light from the star HD 163296 passes through the surrounding gas-and-dust disk like a flashlight beam through murky water. The disk's particles scatter the light, giving it a special property — polarization: the waves begin to oscillate in a single plane, like a rope shaken strictly up and down.

A flashlight in thick fog is useless: the beam scatters, and the reflected light drowns in noise. But if you tie two photons with an invisible thread, one can pass through the fog and come back, while the other stays safe. This connection is called quantum entanglement — when two particles behave as a single whole, even when far apart.

Terahertz radiation sits between microwaves and infrared light. It passes through clothing, paper, and plastic but is blocked by water and metal. That's why these waves are used in security scanners and for quality control of materials.

Terahertz radiation sits between microwaves and infrared light. It passes through clothing, paper, and plastic, but not through metal or water. That's why it's used in security scanners and medical imaging. To see the polarization of such radiation, you need a detector.

Light traveling through an optical fiber is like a runner in a narrow corridor: it can run straight, or it can weave from side to side. The direction of these "weaves" is polarization. Physicists have learned to keep the runner on a straight path: they constantly check its trajectory and gently correct it, not letting it veer off.

Neutron stars are ultra-dense remnants of supernovae the size of a city. In the 1930s, Fritz Zwicky hypothesized their existence, and later Jocelyn Bell Burnell discovered pulsars — rapidly rotating neutron stars.

In the binary system Cyg X-2, a neutron star pulls matter from a normal companion star. The infalling gas spirals in, heats up to millions of degrees, and shines brightly in X-rays. Astronomers pointed two space telescopes, IXPE and NuSTAR, at this object and, for the first time, measured in detail how polarized that light is.