Dark Ages Chronology of the universe

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before decoupling occurred, of photons in universe interacting electrons , protons in photon-baryon fluid. universe opaque or foggy result. there light not light can observe through telescopes - since then, has been red-shifted visible red (corresponding ~3000 k) radio waves in microwave range (corresponding temperature of 3 k). baryonic matter in universe consisted of ionized plasma, , became neutral when gained free electrons during recombination , thereby releasing photons, creating cmb. when photons released (or decoupled) universe became transparent. @ point, additional radiation emitted 21 cm spin line of neutral hydrogen. there observational effort underway detect faint radiation, in principle more powerful tool cosmic microwave background studying universe.


the dark ages thought have been present around 380 thousand 150 million years after big bang. transitioned , ended around 1 billion years after big bang. october 2010 discovery of udfy-38135539, first observed galaxy have existed during following reionization epoch, gives window these times. galaxy earliest in period observed , distant galaxy ever observed on record of leiden university s richard j. bouwens , garth d. illingsworth uc observatories/lick observatory. found galaxy udfj-39546284 @ time 480 million years after big bang or halfway through cosmic dark ages @ distance of 13.2 billion light-years. more recently, udfy-38135539, egsy8p7 , gn-z11 galaxies found around 380–550 million years after big bang , @ distance of around 13.4 billion light-years.


habitable epoch

ca. 10-17 million years after big bang

the dark ages span period during temperature of cosmic background radiation cooled 4000 k down 60 k. background temperature between 373 k , 273 k, allowing possibility of liquid water, during period of 6.6 million years, 10 17 million after big bang (redshift 137–100). loeb (2014) speculated primitive life might in principle have appeared during window, called habitable epoch of universe .








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