The forces separate
At a hundredth of a billionth of a second, one force becomes two and particles acquire mass.
- When
- Known to
- ± 20 million years
- Era
- Primordial
Around 10⁻¹¹ seconds, with the universe at some 10¹⁵ kelvin, the unified electroweak force splits into electromagnetism and the weak nuclear force. The Higgs field settles into its present value in the process, and particles that had been massless acquire mass. This is the earliest epoch whose physics can be reproduced experimentally — it is the energy scale the Large Hadron Collider was built to reach.