Reionization is the period in the early universe, several hundred million years after the Big Bang, during which ultraviolet radiation from the first stars and galaxies ionized the neutral hydrogen gas that had filled space since recombination, rendering the universe transparent to that radiation once again. It marks the end of the so-called cosmic dark ages and the beginning of the universe as it appears today, filled with luminous structure. Astronomers study reionization through the redshifted 21-centimeter signal of neutral hydrogen and through the light of the most distant known quasars and galaxies, whose spectra show the fading imprint of the intervening neutral gas.
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Read the Wikipedia article for Reionization in full (raw MediaWiki extract, not a summary); it describes reionization as a cosmological process identified through WMAP and Planck observations from 2003 onward, credits no single proposer, and gives no formulation date distinct from those later observational measurements. Concept Domain Formulated Year Connections
Sources
1. Wikipedia (space and spaceflight articles)
Wikimedia FoundationReionization, Quasars and the Gunn-Peterson trough sectionQuote, Reionization, Quasars and the Gunn-Peterson trough section
One means of studying reionization uses the spectra of distant quasars.
Reionization (Wikipedia)
Wikipedia, Reionization, lead section
In the fields of Big Bang theory and cosmology, reionization is the process that caused electrically neutral atoms in the primordial universe to reionize after the lapse of the "dark ages".
In Group: Big Bang Cosmology and Measurements, Lead sentence
In the fields of Big Bang theory and cosmology, reionization is the process that caused electrically neutral atoms in the primordial universe to reionize after the lapse of the "dark ages".
View the SourceGunn-Peterson trough (Wikipedia)
Gunn-Peterson trough article, lead sectionQuote, Gunn-Peterson trough article, lead section
This effect was originally predicted in 1965 by James E. Gunn and Bruce Peterson, and independently by Peter Scheuer.
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