“Clearly, enriching the cosmos with heavy elements takes a while. So there's inevitably an interval between the sterile aftermath of the Big Bang and a time when the cosmic chemistry set had enough ingredients to make rocky planets (and squishy biology).”

American astronomer and author

G. Seth Shostak is an American astronomer and author, best known as the senior astronomer for the SETI Institute. He has spent his career working in astronomy and public discussion of the search for life beyond Earth. His work at SETI places him at the center of research and outreach on extraterrestrial intelligence. As an author and scientist, he often writes and speaks about astronomy, the search for signals from other civilizations, and related questions about the universe.