Big Bang Nucleosynthesis

• 2 minutes

  • It’s cool enough (1.5 billion K) for protons and neutrons to form deuterium nuclei

• 3 minutes

  • It’s cool enough (1 billion K) for some helium and some beryllium and lithium to form.
  • No heavier elements than lithium could form

• 30 minutes

  • The density and temperature have dropped to where nuclear reactions stop occurring.

• The abundance of deuterium and helium is set by the temperature and density of normal matter between 2 and 30 minutes after the big bang

Notes: