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Big Bang nucleosynthesis
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Formation of light elements in the first minutes.
In the first 3 minutes protons and neutrons fused into about 75% hydrogen, 25% helium-4 by mass, with traces of deuterium and lithium. Predictions match observed abundances.
Neutron-to-proton ratio of 1:7.
Lithium is a puzzle.
In more detail
Big Bang nucleosynthesis produced light nuclei such as hydrogen, helium and lithium in the first few minutes after the Big Bang. The predicted abundances match observations.
Real-world uses
- It provides a test of the Big Bang model.
- It constrains the number of neutrino types and the density of baryons.
- Cosmologists predict the abundances of hydrogen, helium and lithium from the first few minutes of the universe.
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Frequently asked questions
What elements were formed?
Mostly hydrogen and helium, with small amounts of lithium and deuterium.
Why not heavier elements?
The universe expanded and cooled too quickly for fusion to produce them.
Why is there so much helium?
Helium was produced in large amounts during the early universe, before stars had time to form it.
Related topics in Particle Physics & Cosmology
Expansion of the universe · Big Bang theory · Cosmic microwave background · Inflation · Dark matter · Dark energy