Is there life out there?

CETI

We present a cosmic perspective on the search for life and examine the likely number of Communicating Extra-Terrestrial Intelligent civilizations (CETI) in our Galaxy by utilizing the latest astrophysical information. Our calculation involves Galactic star-formation histories, metallicity distributions, and the likelihood of stars hosting Earth-like planets in Habitable Zones, under specific assumptions which we describe as the Astrobiological Copernican Weak and Strong conditions. These assumptions are based on the one situation in which intelligent, communicative life is known to exist – on our own planet.