Ubiquitous Antiquity...

Life on other planets could have been warmed by the afterglow of the Big Bang.
L. CALÇADA/ESO

Aliens might have existed during the Universe’s infancy. A set of calculations suggests that liquid water — a pre­requisite for life — could have formed on rocky planets just 15 million years after the Big Bang.

Abraham Loeb, an astrophysicist at Harvard University in Cambridge, Massachusetts, has realized that in the early Universe, the energy required to keep water liquid could have come from the cosmic microwave background, the afterglow of the Big Bang, rather than from host stars. Today, the temperature of this relic radiation is just 2.7 kelvin, but at an age of around 15 million years it would have kept the entire Universe at a balmy 300 kelvin, says Loeb, who posted his calculations to the arXiv preprint server this month.

Loeb says that rocky planets could have existed at that time, in pockets of the Universe where matter was exceptionally dense, leading to the formation of massive, short-lived stars that would have enriched these pockets in the heavier elements needed to make planets. He suggests that there would have been a habitable epoch of 2 million or 3 million years during which all rocky planets would have been able to maintain liquid water, regardless of their distance from a star. “The whole Universe was once an incubator for life,” he says.

Nature: Life possible in the early Universe
Physics arXiv: The Habitable Epoch of the Early Universe, Abraham Loeb