The Universe:
A History.
From before the Big Bang to the galaxies, stars, planets, and life present in our modern day Universe.
The Early Universe
When the hot Big Bang first occurred, the Universe reached a maximum temperature never recreated since. What was it like back then?
Some 13.8 billion years ago, the Universe became hot, dense, and filled with high-energy quanta all at once. Here’s what it was like.
Cosmic inflation is the state that preceded and set up the hot Big Bang. Here’s what the Universe was like during that time period.
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50-200 Million Years | The First Stars Form
The Big Bang’s hot glow faded away after only a few million years, leaving the Universe dark until the first stars formed. Oh, the changes!
Atomic nuclei form in minutes. Atoms form in hundreds of thousands of years. But the “dark ages” rule thereafter, until stars finally form.
The first elements in the Universe formed just minutes after the Big Bang, but it took hundreds of thousands of years before atoms formed.
In the early stages of the hot Big Bang, there were only free protons and neutrons: no atomic nuclei. How did the first elements form from them?
In the early stages of the hot Big Bang, matter and antimatter were (almost) balanced. After a brief while, matter won out. Here’s how.
For a substantial fraction of a second after the Big Bang, there was only a quark-gluon plasma. Here’s how protons and neutrons arose.
In the very early Universe, practically all particles were massless. Then the Higgs symmetry broke, and suddenly everything was different.
In the earliest stages of the hot Big Bang, equal amounts of matter and antimatter should have existed. Why aren’t they equal today?
250-550 Million Years | The First Galaxies Form
In the early stages of our Solar System, there were three life-friendly planets: Venus, Earth, and Mars. Only Earth thrived. Here’s why.
The Earth that exists today wasn’t formed simultaneously with the Sun and the other planets. In some ways, we’re quite a latecomer.
It took 9.2 billion years of cosmic evolution before our Sun and Solar System even began to form. Such a small event has led to so much.
Early on, only matter and radiation were important for the expanding Universe. After a few billion years, dark energy changed everything.
Our own galaxy, the Milky Way, is both completely normal and absolutely remarkable in a number of ways. Here’s the story of our cosmic home.
On the largest cosmic scales, galaxies line up along filaments, with great clusters forming at their intersection. Here’s how it took shape.
Life became a possibility in the Universe as soon as the raw ingredients were present. But living, inhabited worlds required a bit more.
Today, the star-formation rate across the Universe is a mere trickle: just 3% of what it was at its peak. Here’s what it was like back then.
As early as we’ve been able to identify them, the youngest galaxies seem to have large supermassive black holes. Here’s how they were made.
For 550 million years, neutral atoms blocked the light made in stars from traveling freely through the Universe. Here’s how it then changed.
Even after the first stars form, those overdense regions gravitationally attract matter and also merge. Here’s how they grow into galaxies.
The first stars in the Universe were made of pristine material: hydrogen and helium alone. Once they die, nothing escapes their pollution.
The first stars took tens or even hundreds of millions of years to form, and then died in the cosmic blink of an eye. Here’s how.
13.8 Billion Years | The Modern Universe
Although mammals may be the dominant form of life today, we’re relative newcomers on planet Earth. Here’s our place in natural history.
For billions of years on Earth, life was limited to simple unicellular, non-differentiated organisms. In a mere flash, that changed forever.
Known as the Great Oxygenation Event, Earth froze over as oxygen accumulated in our atmosphere, nearly driving all life extinct.
Although early Earth was a molten hellscape, once it cooled, life arose almost immediately. That original chain of life remains unbroken.
Keep Exploring
A deep dive into the chaotic journey of star formation.
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Lord Kelvin is thought to have said there was nothing new to discover in physics. His real view was the opposite.
Dr. Thomas Hughes is a UK-based scientist and science communicator who makes complex topics accessible to readers. His articles explore breakthroughs in various scientific disciplines, from space exploration to cutting-edge research.
