Stage 1 · 5.4×10−44 → 10−36 seconds
Where physics runs out
The first sliver of time, where gravity and quantum physics meet and no tested theory can follow.
No tested physics describes this era. Everything in this scene is an artistic metaphor, not a simulation.
At the smallest scales, space and time may not be smooth at all. Here they churn like a foam.
Many physicists suspect the forces of nature began as a single force. Here it appears as one bright field.
Gravity is thought to split off first, right at the start of this era. Here it peels away as a darker layer.
In grand unified theories, the strong force breaks away next, around 10−36 seconds. It will later hold atomic nuclei together.
Stage 2 · 10−36 → 10−32 seconds
The great stretch
In a tiny fraction of a second, space grows at least 1026 times, and quantum jitters become the seeds of all later structure.
Start with a patch of space far smaller than an atom, filled with a uniform energy that physicists call the inflaton field.
That energy makes space stretch exponentially, doubling in size again and again.
By the end it has grown at least 1026 times, like an atom swelling to a light-year across.
Space now expands faster than light can cross it, so neighbouring regions lose contact. The soft boundary marks how far light can reach.
Tiny quantum jitters are stretched to vast sizes and freeze in place as faint ripples. They are the seeds of every future galaxy.
Stage 3 · 10−32 → 10−6 seconds
Quark soup
A plasma of free quarks and gluons cools, the Higgs field gives particles mass, and matter turns out to have a tiny edge over antimatter.
Inflation is over. Its energy has turned into a hot, dense soup of particles and light.
Quarks carry a property called colour charge, drawn here as red, green and blue. The streaks are gluons, which carry the strong force between quarks.
Electromagnetism and the weak force are still one electroweak force. The particles have no mass yet and move at the speed of light.
10−12 s: The Higgs field switches on. Quarks and electrons gain mass, so they slow down.
In the same change, the electroweak force splits into electromagnetism and the weak nuclear force.
For every billion antiquarks there are about a billion and one quarks, and nobody yet knows why. The extra matter is exaggerated here so you can see it.
Stage 4 · 10−6 → 1 second
Matter's narrow escape
Quarks lock into protons and neutrons, matter and antimatter annihilate, and a one-in-a-billion remnant survives.
10−5 s: The soup cools to a few trillion degrees. Quarks can no longer roam free, and they snap into groups.
Three quarks make a proton or a neutron. A quark and an antiquark make a short-lived particle called a meson.
1 ms: Matter meets antimatter. Protons and antiprotons, neutrons and antineutrons annihilate in flashes of light.
When the flashes fade, only about one proton or neutron in a billion is left. The scene shows roughly 1 in 50 so you can see them.
Those few survivors are the protons and neutrons in every atom that exists today.
Stage 5 · 1 second → 3 minutes
Neutrinos break free
Neutrinos stop interacting and stream away, while electrons and positrons annihilate and heat the light.
About one second in, neutrinos stop interacting with other matter and stream away freely. Over 300 of them still fill every cubic centimetre of space.
Electrons and their antimatter twins, positrons, are still being made from pure energy and destroyed in pairs.
10 s: The universe is now too cool to make new pairs. Electrons and positrons annihilate, turning into light.
That energy heats the light. Photons end up about 40% hotter than the neutrinos, which left before the flash.
A small excess of electrons survives, just enough to balance the charge of the protons. These are the electrons in every atom today.
Meanwhile, free neutrons slowly decay into protons, with a half-life of about ten minutes. The first nuclei will have to form fast.
Stage 6 · 3 → 20 minutes
The first nuclei
Protons and neutrons fuse into the first atomic nuclei, leaving a universe of about 75% hydrogen and 25% helium by mass.
Protons and neutrons collide and pair up as deuterium. At first, the heat breaks most pairs apart as fast as they form.
4.5 min: The universe cools enough for deuterium to survive. The deuterium bottleneck breaks.
Deuterium is rapidly built up into helium-4, two protons and two neutrons bound tightly together. Almost every free neutron ends up inside one.
6 min: There was about one neutron for every seven protons. Pairing them up inside helium makes helium about a quarter of the mass.
A trace of lithium forms too: about one atom for every two billion hydrogen atoms.
Space is now too cool and thin for fusion, and it stops. The final mix by mass is about 75% hydrogen and 25% helium, plus traces of deuterium and lithium.
Stage 7 · 20 minutes → 250,000 years
The glowing fog
For hundreds of thousands of years the universe is an opaque, cooling fog of nuclei, electrons and light, until matter overtakes radiation.
With the first nuclei made, a long, quiet era begins. Space is a glowing fog of nuclei, electrons and light.
Light can't get far. Each photon, a particle of light, bounces off free electrons again and again, so the fog is opaque.
Space keeps expanding, and the fog cools from tens of millions of degrees toward a few thousand.
Gravity pulls matter together while the pressure of light pushes back, so the fog rings with sound waves. Their pattern will be frozen into the oldest light we can see.
50,000 yr: Matter now outweighs radiation. Dark matter, which ignores the fog, begins to clump.
Stage 8 · 250,000 → 380,000 years
The universe turns transparent
As the fog cools to about 3,000 kelvin, electrons join nuclei to form atoms, and the light set free becomes the cosmic microwave background.
The fog has cooled to about 3,600 kelvin and glows orange.
Electrons begin to settle onto nuclei and stay, forming the first atoms, mostly hydrogen.
It took this long because light outnumbers atoms more than a billion to one. Until now, there was always a photon energetic enough to knock an electron loose.
With fewer free electrons to bounce off, light travels farther and the fog starts to thin.
The ripples from inflation are imprinted on the glow as tiny hot and cold spots, differences of a few parts in 100,000.
370,000 yr: Light scatters for the last time and streams free. Stretched into microwaves by expansion, it is the cosmic microwave background, shown here as Planck mapped it.
Stage 9 · 380,000 → 150 million years
The dark ages
With no stars yet, dark matter quietly pulls the ripples from inflation into a vast cosmic web.
The fog has cleared. Space is filled with neutral hydrogen and helium gas, and there are no stars yet.
2 Myr: The afterglow cools below 1,000 kelvin and slides into the infrared. To human eyes, the universe is now dark.
From here on, the colours show density, not light. Nothing in this scene would be visible to the eye.
Dark matter doesn't need light. Its gravity pulls on the faint ripples left by inflation, and dense regions grow denser.
Matter drains out of empty voids into sheets and filaments. Where filaments cross, it gathers into clumps called halos.
This is the cosmic web, the scaffolding for every galaxy to come. Gas settles into the deepest halos.
Stage 10 · 150 → 500 million years
The first stars
Gas collapses in the densest dark-matter halos, and the first stars ignite, then explode and seed space with heavier elements.
Gas sinks into the densest dark-matter halos. Where it cools enough, it collapses.
The first stars ignite. Made only of hydrogen and helium, they are probably giants, burning blue-white at around 100,000 degrees.
Their ultraviolet light strips electrons from the surrounding hydrogen, and the gas glows. The red is the same hydrogen light seen in nebulae today.
Stars this massive live only a few million years. Then they explode as supernovae.
The blasts scatter carbon, oxygen, iron and other new elements into space.
Enriched gas forms the next stars, smaller and longer-lived, gathered into the first small galaxies.
Stage 11 · 500 million → 1 billion years
Galaxies light up space
Ultraviolet light from young galaxies and quasars strips the electrons from the hydrogen between galaxies, bubble by bubble.
Ultraviolet light from young galaxies strips electrons off the hydrogen around them, carving out glowing bubbles.
These first galaxies are small and clumpy, far smaller than the Milky Way today, but they make stars quickly.
670 Myr: About half of the hydrogen between galaxies has now lost its electrons.
Some galaxies already hold black holes over a billion times the Sun's mass. Gas falling in makes them blaze as quasars, some with jets.
The bubbles grow and merge. The gas between galaxies is ionised again, as it was before atoms formed, hence the name reionization.
1 Gyr: By about one billion years, almost all the hydrogen between galaxies is ionised, and ultraviolet light travels freely.
Stage 12 · 1 → 7.8 billion years
Cosmic noon
Galaxies merge and blaze with new stars, peaking about 3.5 billion years in, while a spiral like our Milky Way takes shape.
Galaxies have grown and multiplied along the cosmic web. They often collide and merge.
Collisions and fresh gas set off bursts of star formation. The curve shows how many stars the universe makes each year.
3.5 Gyr: Cosmic noon: star formation peaks at about nine times today's rate.
After the peak, star formation slowly winds down as galaxies use up or lose their gas.
Zoom in on one young spiral galaxy, still growing by swallowing smaller neighbours.
A galaxy like this becomes our Milky Way. Its disk settles and its spiral arms take shape.
Stage 13 · 7.8 → 9.2 billion years
Expansion speeds up
Dark energy overcomes the pull of matter, and the expansion of space begins to accelerate.
For billions of years, gravity slowed the expansion of space. Now the expansion has started to speed up.
The cosmic web keeps its shape. Only the spacing changes: during this chapter, distances between galaxy clusters grow by about 14%.
The cause is called dark energy. It behaves like an energy of empty space itself, and nobody knows what it is.
As space grows, matter thins out but dark energy doesn't, so its share of the total keeps rising.
The gauge shows the shift: dark energy climbs from about a third of the total to over 40%.
Dark energy overtakes matter later, about 3.5 billion years ago. Today it makes up about 68% of the universe.
Stage 14 · 4.6 → 4.4 billion years ago
Sun and Earth
A cloud enriched by earlier stars collapses into the Sun, a disk of dust builds the planets, and a giant impact makes the Moon.
4.57 Gyr ago: A cloud of gas and dust, enriched by earlier stars, collapses. A young Sun forms at its centre.
The leftover material flattens into a spinning disk. Inner parts orbit faster than outer ones, and dust clumps into ever larger rocks.
4.54 Gyr ago: In the inner disk, rocky bodies collide and merge. Earth grows to nearly its full size.
4.5 Gyr ago: A body about the size of Mars strikes the young Earth. Debris thrown into orbit gathers into the Moon.
Earth's surface is an ocean of molten rock. Slowly it cools, and a thin crust forms.
Steam in the air will condense into rain. The stage is set for the first oceans.
Stage 15 · 4.4 billion → 540 million years ago
Life takes hold
For almost four billion years life is microscopic, yet it fills the air with oxygen and invents the complex cell.
3.8 Gyr ago: Single-celled microbes appear in the oceans. Exactly when is debated, somewhere between 3.5 and 4.1 billion years ago.
Some microbes learn to harvest sunlight and split water, releasing oxygen as waste. At first, iron in the seas and rocks soaks it up.
2.4 Gyr ago: Oxygen builds up in the air for the first time: the Great Oxidation Event. It changes the chemistry of the oceans, the rocks and the sky.
1.8 Gyr ago: Complex cells appear, with a nucleus and mitochondria. They likely began when one microbe engulfed another and the two lived on together.
1 Gyr ago: Cells start to team up into larger bodies. Among the first are simple red seaweeds.
Stage 16 · 540 million → 10,000 years ago
The age of animals
From the Cambrian explosion to the fall of the dinosaurs and the first humans, complex life spreads across sea and land.
Dinosaurs dominate life on land. The first ones appeared about 230 million years ago.
66 Myr ago: An asteroid about 10 km wide hits what is now Mexico. All dinosaurs except birds die out, and mammals spread and diversify.
Mammals now fill the world the dinosaurs left. Whales swim the oceans and apes live in the forests.
2.6 Myr ago: Earth cools into a cycle of ice ages. Ice sheets advance and retreat again and again.
300,000 yr ago: Our own species, Homo sapiens, appears in Africa.
Modern humans spread out of Africa and, over tens of thousands of years, reach every continent except Antarctica.
Stage 17 · 10,000 years ago → today
Here and now
From Earth out to the edge of the observable universe, a last look at where 13.8 billion years have led.
Start at Earth, one of eight planets circling an ordinary star.
The Sun is one of a few hundred billion stars in the Milky Way, a disk about 100,000 light-years across.
The Milky Way belongs to the Local Group, a few dozen galaxies led by Andromeda and our own.
Farther out, galaxies trace the cosmic web, grown from the ripples of inflation.
At the edge of what we can see is the cosmic microwave background, light set free 380,000 years after the Big Bang. The place it came from is now about 45 billion light-years away.
Today the universe is about 5% ordinary matter, 27% dark matter and 68% dark energy. Every star, planet and person is made from that 5%.