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Maoz 2016, pp. 251–252: "Going forward in time now, the temperature declined, and at T ~ 3000 K, few of the photons in the radiation field, even in its high-energy tail, had the energy required to ionize a hydrogen atom. Most of the electrons and protons then recombined. Once this happened, at a time trec = 380,000 yr after the Big Bang, the major source of opacity disappeared, and the Universe became transparent to radiation of most frequencies." Maoz, Dan (2016). Astrophysics in a Nutshell (2nd ed.). Princeton, New Jersey; Oxford, UK: Princeton University Press. ISBN978-0-691-16479-3. LCCN2015956047. OCLC950932058.
Maoz 2016, pp. 251–252: "Going forward in time now, the temperature declined, and at T ~ 3000 K, few of the photons in the radiation field, even in its high-energy tail, had the energy required to ionize a hydrogen atom. Most of the electrons and protons then recombined. Once this happened, at a time trec = 380,000 yr after the Big Bang, the major source of opacity disappeared, and the Universe became transparent to radiation of most frequencies." Maoz, Dan (2016). Astrophysics in a Nutshell (2nd ed.). Princeton, New Jersey; Oxford, UK: Princeton University Press. ISBN978-0-691-16479-3. LCCN2015956047. OCLC950932058.
Maoz 2016, pp. 251–252: "Going forward in time now, the temperature declined, and at T ~ 3000 K, few of the photons in the radiation field, even in its high-energy tail, had the energy required to ionize a hydrogen atom. Most of the electrons and protons then recombined. Once this happened, at a time trec = 380,000 yr after the Big Bang, the major source of opacity disappeared, and the Universe became transparent to radiation of most frequencies." Maoz, Dan (2016). Astrophysics in a Nutshell (2nd ed.). Princeton, New Jersey; Oxford, UK: Princeton University Press. ISBN978-0-691-16479-3. LCCN2015956047. OCLC950932058.
