The Cradles of Life

Abstract

The process of star and planet formation provides the most likely opportunity for life as we know it to take hold in the universe. Life as we know it wouldn’t form inside a star, and it wouldn’t form in the emptiness of intergalactic space, as these are respectively too hot and too cold. One might think that the early stages of the reionization epoch may have been possible when there were large quantities of raw material (gas) everywhere. But there were no heavy elements at that time – a requirement for life as we know it. At the other extreme one might think that billions of years from now an old and sterile planet could still acquire life, long, long after it had formed. Panspermia (the dispersal of life) between planets would be a possibility, but that just transfers the problem to another planet.