Electroweak epoch

Lore & Background

In physical cosmology, the electroweak epoch occurred after the strong force separated from the electronuclear interaction, but while the universe remained hot enough for the electroweak interaction to persist. Some cosmologists place its start at the beginning of the inflationary epoch, about 10⁻³⁶ seconds after the Big Bang; others place it at about 10⁻³² seconds, when the inflaton field's energy was released, creating a dense quark–gluon plasma. During this phase, particle interactions were energetic enough to produce large numbers of W and Z bosons and Higgs bosons.

Reader's Guide

The electroweak epoch is a critical transitional period in the early universe's thermal history. Its significance lies in the fact that it directly preceded the quark epoch and involved the last unification of two fundamental forces—electromagnetism and the weak interaction—before they separated. This means no observable gravitational wave background peaking in the mHz range or electroweak baryogenesis occurs within the Standard Model, though extensions such as supersymmetry may still allow a first-order transition. The epoch thus constrains models of baryogenesis and early-universe physics.

Did You Know?

• The electroweak epoch ended when the universe was about 10⁻¹² seconds old, after which W and Z bosons ceased to be created at observable rates.
• Extensions to the Standard Model such as supersymmetry and the two-Higgs-doublet model can have a first-order electroweak phase transition but require additional CP violation.