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?