Astronomy
Big Bang Nucleosynthesis
Quick fact
In the first three minutes of the universe, the temperature was a billion degrees—enough to fuse protons and neutrons into helium, but too short-lived to form stable elements beyond lithium.
Why this is interesting
Every atom of hydrogen in your body was forged in the first minutes after the Big Bang. But how did simple particles become the building blocks of all matter, and why did the process stop before making elements like carbon or oxygen?