cosmic inflation

In the first moments, the Universe expanded at an enormous rate. This process is called inflation, and its driving force is the inflaton field. Its energy pushed space apart, like yeast raising dough. But physicists suspect that the dough might have left 'bubbles'—superheavy particles born from the expansion itself.

The universe is a vast, dark ocean. We see only the glowing foam on its surface — stars and galaxies. But hidden in the depths are two invisible forces: dark matter, which with its gravity keeps galaxies from flying apart, and dark energy, which, on the contrary, pushes space itself apart, making the universe expand faster and faster.

The early universe underwent rapid expansion — inflation. According to one theory, the driving force of this process (the inflaton) behaved like an axion — a particle interacting with a gauge field through a special coupling (an analog of the Chern–Simons effect).

0.965—a number that split cosmologists into 'before' and 'after'. That's the value of the spectral index ns measured by the ACT telescope as it stared into the cosmic microwave background — the cooled light of the Big Bang.

In the first fractions of a second after the Big Bang, the Universe underwent inflation — a monstrously rapid expansion that smoothed out all irregularities. But amid this cosmic smoothness, one "wrong" note could have been hidden: quantum fluctuations of the axion field.

Eight hundred million years after the Big Bang, and at the heart of a young galaxy a monstrous engine is already throbbing. A black hole with a mass of ten billion suns devours matter so greedily that its radiation should outshine everything around it. But outside, silence.

2.1 × 10⁻⁹ — that's the temperature variation across the sky, about the same as measuring ripples a fraction of a millimeter high on the ocean surface. This microscopic non-uniformity is imprinted in the cosmic microwave background and tells the story of the very beginning of time.

In the first moments after the Big Bang, the Universe underwent a rapid expansion, inflation, blowing up quantum fluctuations to scales visible today in the cosmic microwave background.

The cosmological principle – the notion that the Universe is homogeneous and isotropic on large scales – has guarded our understanding of the world since the time of Edwin Hubble and Georges Lemaître, whose ideas formed the basis of the Big Bang model.

The Universe is an orchestra playing the symphony of the Big Bang. For a long time, the conductor was thought to be dark energy — an unwavering metronome setting the pace of expansion.

The cosmic microwave background is the petrified light of the first moments. Shortly after the Big Bang, microscopic quantum fluctuations were stretched by inflation to the scales of galactic superclusters.

The very first moments of the Universe's life resemble tuning a complex musical instrument. Quantum fluctuations, stretched by rapid inflation, became the 'notes' from which galaxies later formed. In the new work, physicists considered an unusual opening chord — a superoscillating state.

A translator hears not just words, but intonation, pauses, the tremor in a voice. Ordinary entropy analysis of cosmic perturbations is like meeting minutes: it records facts but loses the nuances. Pseudoentropy entropy is a new tool that captures the hidden "music" of the early universe.

The origin of the hot Big Bang is one of the greatest mysteries. The familiar picture: after inflation, the inflaton field transfers energy to ordinary particles, reheating the Universe. Yet dark matter and dark energy hint that nature has hidden sectors.

Ancient light, traveling 14 billion years, reaches us from all directions. At first glance, it looks perfectly smooth, but if you look closely, tiny fluctuations appear, like ripples on a still pond. Those ripples aren't random noise; they're an encoded history of the universe.

The birth of the universe resembles not an explosion, but a traffic jam. At first, a tiny fraction of a second after the Big Bang, space expanded sluggishly, like cars stuck in gridlock. Then came a sharp surge — accelerated expansion, which cosmologists call inflation.

It all started with a tiny clump that grew faster than light could cross it. Inside this inflating bubble, our future Universe, reigned unimaginable heat. But one field, called the inflaton (the engine of inflation), behaved like a conductor: it controlled both the expansion and how other particles behaved.

The classic story of the Universe’s birth from a blazing point called the Big Bang raises uncomfortable questions: why is the cosmos so homogeneous, and what was before the singularity?

The mystery of the missing antimatter has haunted physics since the mid-20th century. The Big Bang should have created equal amounts of matter and antimatter, yet today's world is almost entirely matter. The Standard Model is powerless to explain this baryon asymmetry — we need new particles and mechanisms beyond it.

You are pacing a huge hall in complete darkness. You walk from wall to wall, counting your steps, and suddenly realize that the distances don't add up as they should. It seems as if the floor is not flat but bulging like a hump or hollowed like a bowl. That's roughly what astronomers found when studying distant galaxies and sound waves frozen in the early Universe.

The birth of the universe is often compared to inflating a balloon: in the first moments, it stretched rapidly. But the very "rubber" of this balloon was probably not perfectly smooth — rather, it was covered with the finest ripples.

The night sky looks as smooth as the surface of a calm lake. But if you look at gamma-ray bursts (brief, blinding explosions visible across the entire universe) you'll find ripples in that smoothness. Scientists took a catalog of such bursts and divided the sky into two hemispheres. In the southern one, they found a tiny group: 4–5 bursts huddled together.

After the Big Bang, the Universe simmered as a fiery 'soup' of fundamental particles. Expanding and cooling, the soup gradually 'solidified' into protons and neutrons — much like crystallization. Had the solidifying been instantaneous, like a lake cracking in a deep freeze, the fabric of spacetime would have convulsed.

The universe wasn't born alone — alongside it came a mirror twin where everything is reversed: left and right are swapped and time flows from future to past. After the Big Bang, the world, according to Alan Guth's idea of superfast inflation, should have contained equal amounts of matter and antimatter.

Light born at the moment of the Big Bang has traveled to us for almost 14 billion years. But along the way, it passed through the gravitational fields of galaxies and clumps of dark matter, which bent its rays. To an observer, this looks like an image stretched and smudged by an old window pane.

In one hospital ward it's +40°C, in another +10°C, and on average it's +25°C. If temperature affected something nonlinearly (say, the rate of bacterial growth) the average would give a wrong prediction. The same problem arises when cosmologists describe a universe where galaxies are packed into clusters and voids yawn between them.

Gas clouds in the Milky Way give birth to stars, and the heaviest among them are true giants. Previously, it was thought that such a star ignites almost instantly, like a light bulb. But new research shows that a star grows gradually, like a snowball rolling down a mountain: the longer it rolls, the bigger it gets. The authors compared two catalogs: bright gas clouds around young stars and the stars themselves.

In the first moments after the Big Bang, the cosmos was like a pot of boiling broth. In it, like lumps of flour, dense clumps of energy — oscillons — curdled and swelled. They grew, gained strength, and soon took over the expansion of the Universe.