Photon epoch

In

At the start of this period, many photons had sufficient energy to photodissociate deuterium, so those atomic nuclei that formed were quickly separated back into protons and neutrons. By the ten second mark, ever fewer high energy photons were available to photodissociate deuterium, and thus the abundance of these nuclei began to increase. Heavier atoms began to form through nuclear fusion processes: tritium, helium-3, and helium-4. Finally, trace amounts of lithium and beryllium began to appear. Once the thermal energy dropped below 0.03 MeV, nucleosynthesis effectively came to an end. Primordial abundances were now set, with the measured amounts in the modern epoch providing checks on the physical models of this period.^[3]

370,000 years after the Big Bang, the temperature of the universe fell to the point where nuclei could combine with electrons to create neutral atoms. As a result, photons no longer interacted frequently with matter, the universe became transparent and the

• Timeline of the early universe
• Big Bang nucleosynthesis
• Timeline of the Big Bang

References

Further reading

• Allday, Jonathan (2002). Quarks, Leptons and the Big Bang (Second ed.). Institute of Physics Publishing.
  ISBN 978-0-7503-0806-9
  .

This physical cosmology-related article is a stub. You can help Wikipedia by expanding it.

• v
• t
• e