This page tells the story of matter from the beginning of the universe to today in nine chapters: how quarks built protons, protons built atoms, and atoms built stars, planets, living things and you. As you scroll, the drawing beside the text rebuilds each chapter's scene from the same particles.
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A single point of light flickering in the dark.
Chapter 1 · 13.8 billion years ago, and before
State of matter: unknown
This story begins: “At first there was nothing.” But here science has to be honest: we don't know what came before the Big Bang. There is a threshold where time, space and matter as we know them begin, and we cannot yet see beyond it.
What we do know is this: everything you see today, the stars, the oceans, iron mines, trees and you, was once packed into an unimaginably small, hot and dense state.
Chapter 2 · 13.8 billion years ago
State of matter: a boiling soup of quarks, electrons and light
Then the universe began to expand. We call it the Big Bang, but it did not go off in one place like a bomb: space itself began to grow, everywhere at once.
In the first moments the temperature was far above billions of degrees. There were no atoms yet, not even protons. The universe was a boiling soup of elementary particles: quarks, electrons and particles of light (photons).
Chapter 3 · From the first second to 380,000 years
State of matter: hydrogen and helium atoms
As the universe expanded, it cooled. Within a millionth of a second, quarks joined in threes: protons and neutrons were born. The first building blocks of matter had been assembled from subatomic particles.
In the first few minutes, protons and neutrons fused into helium nuclei. But the electrons were still too fast to hold on to them.
About 380,000 years later the universe had cooled enough. Electrons settled around the nuclei and the first true atoms formed: three quarters hydrogen and one quarter helium by mass. The nuclei of the hydrogen atoms in your body date from those days.
Chapter 4 · 13.6 to 13 billion years ago
State of matter: gas clouds, the first stars, galaxies
Then came a long darkness. There was not a single star, only slowly cooling hydrogen and helium gas. But the gas was not exactly equally dense everywhere.
Slightly denser regions pulled in the gas around them through gravity. Gas clouds collapsed, their centres heated up and the first stars ignited. Stars gathered into clusters, clusters merged, and galaxies were born.
Our own galaxy, the Milky Way, formed this way. Today it holds more than 100 billion stars, its spinning arms hanging in space like a giant whirlpool.
Chapter 5 · Over billions of years
State of matter: atoms fuse into heavier atoms
Every star is a furnace. At its centre, hydrogen nuclei fuse into helium, and that fusion gives off light and heat. It is the reason the Sun shines.
Big stars go further: helium into carbon, carbon into oxygen, then neon, magnesium, silicon and finally iron. Atoms were fusing into heavier atoms, and matter was becoming more varied.
At iron, the furnace goes out. A giant star whose core fills with iron collapses and explodes as a supernova, scattering the elements it made over its lifetime into space. Even heavier elements, such as gold, were probably made mostly in collisions of neutron stars.
Chapter 6 · 4.6 billion years ago
State of matter: gas and dust, then the Sun and seeds of planets
In one arm of the Milky Way, a cloud of gas and dust carrying the ashes of earlier generations of stars began to collapse under its own weight.
As the cloud spun, it flattened into a disc. At the centre, matter was squeezed so tightly that hydrogen began to burn: the Sun was born.
The dust grains left in the disc stuck together. Dust became pebbles, pebbles became rocks, and rocks became seeds of planets kilometres across.
Chapter 7 · 4.54 billion years ago
State of matter: rock, metal, water and air
For tens of millions of years the seeds of planets collided and merged. One of the planets born this way was the young Earth, third from the Sun.
The young Earth was like a molten ball. Heavy iron and nickel sank to the centre and lighter rock rose to the surface. Today most of Earth's mass is made of four elements: iron, oxygen, silicon and magnesium. The impact of a Mars-sized body also created the Moon.
As Earth cooled, water vapour fell as rain and the oceans filled. Atoms had now built a planet in the form of minerals, rocks, water and air.
Chapter 8 · At least 3.5 billion years ago
State of matter: atoms → molecules → cells → living things
In the oceans, atoms of carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur joined and split apart in countless ways. At some point, some molecules became able to make copies of themselves. Exactly how this happened is still one of science's big open questions.
Self-copying molecules were wrapped in a thin membrane: the first cell. Atoms were no longer just combining; they were keeping an order, using energy and multiplying. Today the recipe for that order is written in DNA.
Over billions of years, cells filled the air with oxygen, learned to live together and became multicellular life. They left the seas for the land; dinosaurs came and went, and mammals spread.
Chapter 9 · From 300,000 years ago to today
State of matter: an arrangement that thinks: you
And at last, we arrived. Homo sapiens, who appeared in Africa about 300,000 years ago, is one of the newest links in this long chain.
Your body holds about 7 × 10²⁷ atoms. Your hydrogen comes from the Big Bang, your carbon and oxygen from inside stars, your iron from exploding stars. You are an arrangement made from the ashes of stars, now reading this story.
One day your atoms will scatter again and become part of other things: soil, air, perhaps a new living being. Atoms don't vanish; they just join new arrangements. The story goes on.
Each chapter goes deeper elsewhere on Atom: dates in the 38-stop journey, sizes on the ladder of scales, your ancestors in “What were you?”, and the stories of iron and steel under Matter.
About 13.8 billion years. The figure comes from measurements of the first light released 380,000 years after the Big Bang (the cosmic microwave background).
Hydrogen comes from the Big Bang; elements such as carbon, nitrogen, oxygen, calcium and iron come from inside stars and their explosions. That is why “we are stardust” is not a metaphor but literally true.
An atom is the smallest unit that still has the properties of an element. It has a tiny nucleus of protons and neutrons at its centre, surrounded by electrons. An atom is about 0.1 nanometres across: ten million atoms side by side make just 1 millimetre. Protons and neutrons are themselves made of quarks.
Almost all the atoms in your body are stable and can last unchanged for billions of years. When a living thing dies, its atoms do not disappear; they pass into soil, air and other living things and join new arrangements.