In 1961, famed astronomer Frank Drake created a formula for estimating the number of extra-terrestrial intelligences (ETIs) that could exist within our galaxy. Known as the “Drake Equation“, this formula demonstrated that even by the most conservative estimates, our galaxy was likely to host at least a few advanced civilizations at any given time. About a decade later, NASA officially kicked of its search for extra-terrestrial intelligence (SETI) program.
Despite an observable universe sprinkled with several trillion galaxies, each stuffed with a trillion planets, we see no evidence of anyone. No signals, no megastructures, no interstellar rockets. While astronomers routinely uncover puzzling objects in the sky, these always turn out to be manifestations of natural phenomena.