The Colonization of the Galaxy -- A Key Concept in the Search for Extraterrestrial Intelligence

Abstract

The Drake Equation, which precludes stellar colonization and assumes an independent origin for each stellar civilization, predicts, according to most of its backers, a number N = 10⁵ −10⁶ of advanced technological civilizations in the Galaxy, i.e., roughly one per million stars. The concept, on the other hand, of the colonization of the Galaxy predicts, either N = 10¹⁰−10¹¹ if the colonization has already occurred, with space colonies in orbit around every well behaved star of the Galaxy, or N = 10⁻¹ −10⁰ if the colonization has not yet taken place, because the reason it has not yet occurred must simply be that throughout the long history of the Galaxy there were too few civilizations capable of initiating the colonization process. These conditions simplify considerably the search for extraterrestrial intelligence because we now need to investigate only a small number of stars in our own, vicinity, rather than millions of faraway stars as required by the Drake equation. If a systematic astronomical search in our own solar system, and in particular in the asteroid belt, as well as in 10–20 of our nearby stars would prove negative, we would have to conclude that the colonization of the Galaxy has not yet occurred and therefore we must be one of the very few if not the only advanced civilization in the entire Galaxy.