The interactive reference to the beginning and evolution of the universe.
The Big Bang is the leading scientific explanation for the origin of the universe, describing how it expanded from an extremely hot, dense state about 13.8 billion years ago. This comprehensive guide walks through the sequence of cosmic epochs—from the Planck epoch to the present day—covering the formation of particles, atoms, stars, and galaxies, and the evidence that supports this model.
Explore the Big Bang model, from the Planck epoch to the formation of stars and galaxies. Learn about cosmic inflation, the cosmic microwave background, and the evidence supporting our modern understanding of the universe’s origin.
The hadron epoch was a critical phase in the early universe when quarks first bound into protons and neutrons. This article explains its place in cosmic history, its key processes, and why it matters for understanding the matter we see today.
Explore the question of whether time began with the Big Bang, and journey through the major cosmic epochs—from the Planck epoch to the formation of stars and galaxies—guided by the standard Lambda-CDM model of cosmology.
The cosmic microwave background (CMB) is the oldest light in the universe, a relic of the hot Big Bang. This article explains how astronomers measure it from Earth, what it reveals about cosmic history, and why it anchors our modern understanding of the cosmos.
From the Planck epoch’s unimaginable heat to the cool darkness of the cosmic microwave background, the early universe underwent a dramatic cooling as it expanded. This guide traces the temperature milestones that shaped matter, light, and structure.
The universe was not infinitely small at the Big Bang. Cosmic inflation stretched space to a finite, macroscopic size before the hot Big Bang began. This article traces the universe’s evolution from the Planck epoch to today, explaining key epochs, the cosmic microwave background, and the formation of structure.
The universe is 13.8 billion years old. This definitive guide explains how astronomers measure the age of the cosmos using the cosmic microwave background, stellar evolution, and the expansion rate, and traces the universe’s evolution from the Planck epoch to the present day.
The lepton epoch was a brief but pivotal period roughly 1–10 seconds after the Big Bang, when electrons, positrons, and neutrinos dominated the universe. It set the stage for neutrino decoupling, the annihilation of electron-positron pairs, and the primordial conditions that led to Big Bang nucleosynthesis.
One second after the Big Bang, the universe had expanded and cooled enough for neutrinos to decouple, ending the quark–hadron transition and setting the stage for nucleosynthesis. This article traces the entire cosmic timeline from the Planck epoch to structure formation, explaining inflation, recombination, the cosmic microwave background, and the emergence of stars and galaxies.
