supersymmetry

In the quantum world, particles fall into two irreconcilable camps: bosons love to pile into the same state (like light in a laser), while fermions are individualists that never occupy the same spot. You'd think one neural network couldn't learn both personalities at once.

An invisible scaffold holds galaxies together, keeping them from flying apart. This is dark matter — matter that doesn't shine and barely interacts with ordinary stuff. Astrophysicists have long debated what it's made of.

A translator gets distracted by every rustle in the hall, and a one-hour meeting stretches into two. A single wrong intonation changes the meaning beyond recognition. That's roughly how a particle with spin 3/2—the gravitino — behaves. It cannot exist in isolation: its "speech" must be perfectly coordinated with its surroundings, or the whole structure falls apart.

The wind carries pollen, and each grain moves as if on its own. But once the air swirls into a vortex, the pollen trajectories can no longer be separated: they are tangled. This is roughly how electrons behave in a strange metal: their motion is so strongly coupled to soft fluctuations of the medium that the usual particle carriers disappear.

The Standard Model of particle physics is a catalog of all known building blocks of the universe: electrons, quarks, and others. But it is silent about dark matter and doesn't get along with gravity.

Since Saul Perlmutter and his colleagues discovered the accelerated expansion of the universe, physicists have been scratching their heads over the nature of dark energy.

A geometer runs a finger along an invisible surface, and by how the geodesics bend, lifts its fingerprint. That fingerprint can be the maximum normal curvature κ(F): the largest curvature among all geodesics passing through a point of the immersed manifold.

The early universe was a restless place. Space trembled with gravitational waves — ripples in the very fabric of reality. In this churning cauldron, dark matter is thought to have been born. But the newborn particles had no mass: it had to come from somewhere. Usually, the Higgs field is responsible for mass.

The quantum world is full of transformations. Sometimes a system made of one type of particle starts behaving as if it harbors completely different ones. For example, in a chain of bosons, sociable particles that like to crowd into the same state, fermions from the Standard Model may unexpectedly appear, even though they usually keep to themselves.

Two clouds of ultracold atoms, almost frozen at temperatures of a few nanokelvins, mix in a trap. One cloud consists of light atoms, the other of heavy ones. They push each other differently. Physicists have long been able to describe such mixtures with simple equations, but those work only if the atoms are perfectly identical.

A lump of dark matter drifts through the void — invisible, almost intangible. No one knows what it's made of, but a new study suggests viewing it as a drop of quantum liquid. Two kinds of fermion particles — call them "heavy" (ψ) and "light" (χ)—exchange signals via a third mediator particle (φ), like floats tied to a single line.

A stone thrown into water leaves ripples. A satellite orbiting Earth also leaves a trace — not on water, but in the laws of physics. Its orbit is not a frozen line: it slowly rotates, like the hand of a giant clock.

In the world of elementary particles, there's a long-standing puzzle: why are the masses of the electron, muon, and tau particle so vastly different? And why are quarks, the building blocks of protons and neutrons, also split into three generations with sharp jumps in mass?

In the first moments after the Big Bang, matter and antimatter should have been created in equal amounts. But today we see only matter — stars, planets, ourselves. Where did the antimatter go? One clue hides in nearly elusive particles: right-handed neutrinos. The usual story is that their decays create a slight bias in favor of matter.

The end of the Universe is not just the fading of light. If dark energy, the mysterious substance accelerating cosmic expansion, tears it apart in a Big Rip scenario, or if expansion reverses into a contraction that pulls everything back to a point like a big bang in reverse, a…

When a car on cruise control hits a bump, the speed jumps for a moment, but the engine runs smoothly. Something similar was recently noticed with dark energy — the force that makes the Universe expand faster and faster.

In the very beginning, moments after the Big Bang, the universe was ridiculously symmetric: particles and antiparticles in equal measure. But a tiny imbalance occurred, like one extra grain of sugar in a kilogram, and the entire familiar world, stars, planets, people, arose from that surplus. How nature created this imbalance remains a mystery.

A translator gets distracted by every rustle in the hall, and a one-hour meeting stretches into two. That's roughly how ordinary quantum mechanics works: a particle evolves in time, while space serves as the stage. But what if we swapped their roles? Then the particle 'moves' through space, and time becomes a static backdrop.

A coffee whirlpool can span two spots in a cup — a blur of swirling liquid. Quantum particles behave similarly: a spacetime whirlpool where they exist in two places at once. But gravity acts as the spoon that stirs the fabric of space and time.

After the Big Bang, the Universe resembled a tightly inflated balloon: pressure prevented matter from clumping together. But hypothetical superheavy particles — sort of ‘heavyweights’ of the microcosm — momentarily made the balloon less stiff. Matter easily clumped, giving birth to black holes with masses from a billion to a billion billion tons.

In the kitchen, there's a bucket of water and an identical bucket of sand. Pour the sand into the water, and you get a mixture where there's exactly five times more sand than water. That's roughly how our universe is arranged: one part ordinary matter — the stuff stars, planets, and we ourselves are made of — and five parts elusive dark matter.

A handful of coins drops onto a table. While they spin, each can land heads or tails: that's quantum uncertainty. But once they settle, the picture becomes definite, classical. That's roughly how noise destroys quantum order, turning it into ordinary disorder.

In a pot of boiling water, bubbles of steam are born and pop, but the water itself remains a liquid. Something similar happens in an ultracold atomic gas: atoms constantly form pairs and then fly apart again, even though superfluidity has not yet set in.

In nuclear transitions of beryllium-8, helium-4, and carbon-12, physicists from the ATOMKI collaboration have been seeing extra events since 2020—as if, when an excited nucleus decays, something else is sometimes born besides the usual photons. The energy of this "something" is always the same: about 17 million electron-volts.

Dark matter makes up 85% of the matter in the Universe, yet remains invisible. It only reveals itself through gravity. We can catch it by its cosmic 'hum' — a faint vibration that permeates space. A single detector is powerless here: the signal is too quiet. Physicists turn many sensors into a quantum ensemble.

Dark matter is the invisible scaffold of the cosmos, its existence betrayed by whirls of galaxies to Fritz Zwicky and Vera Rubin. What it is made of remained a mystery for half a century. A new hypothesis paints an unusual picture.

Predicted by Wolfgang Pauli and named by Enrico Fermi, neutrinos are nearly elusive particles. Inside dying supernova giants and merging neutron stars, an immense number are born. Each particle has a flavor that can change.

Matter is like a house. In some rooms, there is the strict order of a crystal, where every atom is in its place. In others, the chaos of superfluid helium, where atoms forget about their neighbors.

In general relativity, a black hole has long been regarded as a perfect mirror: no matter what fields fall onto it, it does not deform. The tidal Love numbers, which measure how a body deforms under an external tidal field, turned out to be zero for scalar, electromagnetic, and gravitational perturbations.

Quantum entanglement is a fragile resource. Heat a system, and thermal fluctuations will tear the delicate threads of correlations: at a sufficiently high but finite temperature, the Gibbs state of a local Hamiltonian becomes separable, that is, representable as a probabilistic mixture of products of local states.

Two telescopes look at the same Universe and see different expansion rates. Local measurements from supernovae give 73.04 ± 1.04 km/s/Mpc, while cosmic microwave background data within the standard model predict 67.36 ± 0.54.

At the edge of spacetime, where all light rays end, live symmetries that physicists have debated for half a century. They are called superrotations, transformations of the celestial sphere that diverge at isolated points, like vortices in superfluid helium.

In the boiling broth of the newborn Universe, all particles lost their distinctions, like vegetables at hellish temperatures. Recovering that simple recipe is the goal of modern physics. The SO(10) theory — an extension of the Standard Model — offers such a recipe. It unifies all forces and links the masses of any particles with a single formula.

Two actors on the same stage. One is a fermion, finicky and demanding, hard to make follow the rules of a quantum simulator. The other is a boson, easygoing and undemanding, ready to take any role. The director hopes the audience won't notice the substitution.