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The habitable epoch of the early Universe

Published online by Cambridge University Press:  09 September 2014

Abraham Loeb*
Astronomy Department, Harvard University, 60 Garden Street, Cambridge, MA 02138, USA


In the redshift range 100≲(1+z)≲137, the cosmic microwave background (CMB) had a temperature of 273–373 K (0–100°C), allowing early rocky planets (if any existed) to have liquid water chemistry on their surface and be habitable, irrespective of their distance from a star. In the standard ΛCDM cosmology, the first star-forming halos within our Hubble volume started collapsing at these redshifts, allowing the chemistry of life to possibly begin when the Universe was merely 10–17 million years old. The possibility of life starting when the average matter density was a million times bigger than it is today is not in agreement with the anthropic explanation for the low value of the cosmological constant.

Research Article
Copyright © Cambridge University Press 2014 

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