multi field inflation

In a pot of boiling soup, light fat droplets rise to the top, while heavy vegetable chunks sink to the bottom. Particles in the tenuous hot gas around the Sun and other stars behave much the same way — except instead of broth, there's a mixture of charged particles: electrons, protons, and alpha particles.

In the first fraction of a second after the Big Bang, the universe expanded at an unimaginable rate. The engine behind this expansion could have been a field that behaves like a slowly rolling ball — the axion. What makes the axion special is that, like a conductor, it can drive electromagnetic waves, creating them literally out of nothing.

The early universe resembled an overheated cauldron, seething with quantum fluctuations (random bursts of energy). In this chaos, like steam over boiling water, a special field, the scalar field, condensed. It became the 'engine' that made space expand at an incredible rate. This process is called inflation.

The neutron, one of the building blocks of the atomic nucleus, could, according to the equations, have a noticeable electric dipole moment: that is, behave like a tiny magnet. In reality, however, this effect is almost absent, creating a puzzle known as the strong CP problem.

In the first moments after the Big Bang, the universe expanded at an incredible rate — a phase known as inflation. Even the vacuum was restless back then: quantum jitters shook the fields like wind rustling through a wheat field.

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.

$$10^{-35}$$ seconds. A tiny instant during which the Universe manages to expand by a factor of $$10^{26}$$. Immediately after, it goes through thousands of rapid transformations — like a ball bouncing along a chain of tunnels. This cascade is the essence of chain inflation, first proposed by Alan Guth.

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.

In 1929, Edwin Hubble pointed his telescope at distant galaxies and discovered they were receding. Ninety years later, two measurements of this recession rate, from ancient light and from nearby stars, stubbornly disagree. A 9% discrepancy cannot be chalked up to error. It is as if the Universe in its youth and in its maturity runs on different clocks.

In the first 10⁻³⁵ seconds after the big bang, the most rapid part unfolded. Space expanded faster than light — that's expansion of the universe (inflation). Almost the entire score was performed by a single field, the inflaton, conducting the tempo and key.

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.

In the first moments after its birth, the universe expanded faster than a match lights. This process is called inflation. It explains why today's cosmos is so homogeneous and flat. But what happened before it? Perhaps the laws of quantum gravity were at work then, and their traces can be found in the data.

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.

10⁻¹²⁰. That's not just a small number: it's a chasm. That's the ratio of dark energy density to the Planck density, the natural scale of quantum gravity. The colossal difference of 120 orders of magnitude has long seemed an unsolvable puzzle. But the answer might lie in a drama played out at the dawn 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 early universe expanded at a breakneck pace: this phase is called inflation. But how exactly did it do it? Some models describe the expansion as a steep exponential surge, others as a more gentle power-law motion.

When the cooling cosmos, in the aftermath of the Big Bang, lost its primordial symmetry, tensions arose in the fields, like microcracks forming in solidifying glass. Global monopoles, predicted by Gerard 't Hooft and Polyakov, became such “scars” on the fabric of the universe. Each monopole is a tiny but incredibly massive knot of field.

In the first moments after the Big Bang, the universe underwent a rapid expansion — inflation. Like a balloon inflated not uniformly but with tiny pulsations, it stretched billions of times over a fraction of a second. These pulsations froze into density ripples, from which galaxies later grew.

In the first moments after the Big Bang, the Universe was not a silent void but a seething cauldron of plasma, threaded with sound waves. As the temperature dropped, the cosmos underwent phase transitions — spontaneous reorganizations that gave birth to bubbles of a new phase.

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.

A tiny star spirals around a giant rotating black hole. Slowly, it moves closer in a spiral, and this dance lasts thousands of years. All the while, waves ripple through space, like ripples on water, but these are gravitational waves. They can be "heard" with special detectors.

In the first moments, the universe expanded at an unimaginable rate — a phase called inflation. It is thought that particles of dark matter, the invisible substance that holds galaxies together, could have been born from the vacuum during this time. But what determines exactly how many are produced? The authors considered a model with two fields.

Inflation is the ultra-fast expansion of the universe in its first moments. It was driven by a field resembling a ball rolling down a hill. But there could have been a second, almost imperceptible ball nearby. The authors of this work considered exactly that scenario: a light spectator field (the axion), frozen at the top of its potential.

A sunspot cools, and above it a dark filament, a prominence, hangs for weeks. Inside it, like a compressed spring, hides the magnetic field. It can be laid out in neat arches, or it can be twisted into a tight rope.

The oldest light in the universe has been traveling toward us for nearly 14 billion years. It was born when the cosmos first became transparent, and since then its plane of oscillation has been rotating ever so slightly. The cause is an invisible ocean permeating all of space: the dark energy field that makes the universe expand faster and faster.

Quantum noise, like the hiss of an untuned radio, filled the infant Universe. Alan Guth showed that superfast expansion (inflation) caused this ripple to freeze, giving rise to clumps of matter — the seeds of galaxies. A new method extends this picture to any theory of gravity.

Astronomers build maps of galaxies and listen to the radio whisper of neutral hydrogen. The signal is so faint that even a working TV would drown it out, but sensitive antennas pick it up from the depths of the Universe.

A giant drum has just taken a hit. Its membrane is still trembling, but besides the main boom, a fine ripple spreads across it — someone ran a finger over the taut skin. In much the same way, in the first moments after the Big Bang, spacetime vibrated not only with the "roar" of expansion but also with the tension of suddenly emerging magnetic fields.

The Universe was born in the Big Bang and almost instantly passed through a phase of inflation — an ultra-fast expansion that blew up microscopic regions to cosmological scales.

A magnet with only one pole — north, but no south. Split it in half, and instead of two ordinary magnets, you get two more one-pole magnets. In our world, no such particle has been found, although many theories predict their existence. These hypothetical objects are called magnetic monopoles. The authors of the study noticed a curious connection.

Baking bread starts with nearly homogeneous dough, in which tiny gas bubbles are already hidden. They grow, and the rate of their growth determines the future structure of the crumb. In cosmology, the role of such bubbles is played by the seeds of galaxies — barely noticeable density enhancements in the hot 'soup' of the early universe.

Right after the Big Bang, space swelled at an unimaginable speed — that's inflation. Now expansion has slowed, but galaxies are moving apart faster and faster. The culprit behind the acceleration has been named dark energy.

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 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.

The Universe performs a symphony in two contrasting tempos. The first explosive accelerando (inflation, conceived by Alan Guth) sent spacetime soaring in the first trillionth of a second. The second acceleration, slow but relentless, began five billion years ago.

Tuning a radio is a delicate business: one knob turns easily, another resists. In the physics of the early Universe, there are also 'knobs'—parameters that determine what we see today. One of them is the strength of the coupling between a special field (the one that drove the rapid expansion of the Universe) and the geometry of space.

A balloon is being inflated faster and faster. At first, it stretches smoothly, but at some point, the pump stutters — the speed drops, then picks up again. During this brief respite, tiny bubbles appear on the rubber. As inflation resumes, they turn into dense knots. Something similar happened to the universe itself right after the Big Bang.

Immediately after the Big Bang, the Universe underwent ultra-fast expansion, an idea proposed by Alan Guth and developed by Andrei Linde. When the expansion stopped, the field-energy began to oscillate like a giant swing.