In physical cosmology, the photon epoch was the period in the evolution of the early universe in which photons dominated the energy of the universe. The photon epoch started after most leptons and anti-leptons were annihilated at the end of the lepton epoch, about 10 seconds after the Big Bang.[1] Atomic nuclei were created in the process of nucleosynthesis, which occurred during the first few minutes of the photon epoch. For the remainder of the photon epoch, the universe contained a hot dense plasma of nuclei, electrons and photons.[2]
At the start of this period, many photons had sufficient energy to photodissociatedeuterium, 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 cosmic microwave background radiation was created and then structure formation took place. This is referred to as the surface of last scattering, as it corresponds to a virtual outer surface of the spherical observable universe.[4]
^Narison, S. (2015). Particles and the Universe, From the Ionian School to the Higgs Boson and Beyond. World Scientific Publishing Company Pte Limited. p. 219. ISBN9789814644709.
^Boesgaard, A. M.; Steigman, G. (1985). "Big Bang nucleosynthesis: theories and observations". Annual Review of Astronomy and Astrophysics. 23: 319–378. Bibcode:1985ARA&A..23..319B. doi:10.1146/annurev.aa.23.090185.001535.
^Sazhina, O. S.; et al. (May 2008). "Cosmic microwave background anisotropy induced by a moving straight cosmic string". Journal of Experimental and Theoretical Physics. 106 (5): 878–887. arXiv:0809.0992. Bibcode:2008JETP..106..878S. doi:10.1134/S1063776108050051. S2CID 15260246.
Further reading
Allday, Jonathan (2002). Quarks, Leptons and the Big Bang (Second ed.). Institute of Physics Publishing. ISBN978-0-7503-0806-9.
This physical cosmology-related article is a stub. You can help Wikipedia by expanding it.
photon, epoch, physical, cosmology, photon, epoch, period, evolution, early, universe, which, photons, dominated, energy, universe, photon, epoch, started, after, most, leptons, anti, leptons, were, annihilated, lepton, epoch, about, seconds, after, bang, atom. In physical cosmology the photon epoch was the period in the evolution of the early universe in which photons dominated the energy of the universe The photon epoch started after most leptons and anti leptons were annihilated at the end of the lepton epoch about 10 seconds after the Big Bang 1 Atomic nuclei were created in the process of nucleosynthesis which occurred during the first few minutes of the photon epoch For the remainder of the photon epoch the universe contained a hot dense plasma of nuclei electrons and photons 2 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 cosmic microwave background radiation was created and then structure formation took place This is referred to as the surface of last scattering as it corresponds to a virtual outer surface of the spherical observable universe 4 See also EditBig Bang nucleosynthesis Timeline of the Big BangReferences Edit The Timescale of Creation Archived 2009 07 28 at the Wayback Machine Narison S 2015 Particles and the Universe From the Ionian School to the Higgs Boson and Beyond World Scientific Publishing Company Pte Limited p 219 ISBN 9789814644709 Boesgaard A M Steigman G 1985 Big Bang nucleosynthesis theories and observations Annual Review of Astronomy and Astrophysics 23 319 378 Bibcode 1985ARA amp A 23 319B doi 10 1146 annurev aa 23 090185 001535 Sazhina O S et al May 2008 Cosmic microwave background anisotropy induced by a moving straight cosmic string Journal of Experimental and Theoretical Physics 106 5 878 887 arXiv 0809 0992 Bibcode 2008JETP 106 878S doi 10 1134 S1063776108050051 S2CID 15260246 Further reading EditAllday 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 vte Retrieved from https en wikipedia org w index php title Photon epoch amp oldid 1114087795, wikipedia, wiki, book, books, library,
