Matter–Radiation Equality

≈ 50,000 years · Radiation Era

Temperature (K): 9300
When: ≈ 50,000 years
Redshift: z ≈ 3400
Era: Radiation Era
Seconds After Big Bang: 1577846500000

What Happened

Matter density overtakes radiation density. Gravity can finally begin assembling structure, because until now radiation pressure smoothed out every clump as fast as it formed.

Researchers

Julien Lesgourgues James Peebles

Equations

First Friedmann Equation Cosmological Equation of State Linear Perturbation Growth Cosmological Fluid Equation

Theories

Dark Matter Big Bang Cosmology

Referenced by

equation

Cosmological Equation of State Cosmological Fluid Equation First Friedmann Equation Linear Perturbation Growth

researcher

James Peebles Julien Lesgourgues

theory

Big Bang Cosmology Dark Matter

Open on the Timeline of the Universe shelf — the interactive card, the filters, and everything alongside it.

From the Cosmic Timeline database in Notion, last edited 2026-08-16. This page is the row, rendered by the build; nothing on it is written by hand.