Limits to the Number of Advanced Civilizations in the Universe

A New Empirical Constraint on the Prevalence of Technological Species in the Universe

Authors:

Frank et al

Abstract:

In this article, we address the cosmic frequency of technological species. Recent advances in exoplanet studies provide strong constraints on all astrophysical terms in the Drake equation. Using these and modifying the form and intent of the Drake equation, we set a firm lower bound on the probability that one or more technological species have evolved anywhere and at any time in the history of the observable Universe. We find that as long as the probability that a habitable zone planet develops a technological species is larger than ∼10−24, humanity is not the only time technological intelligence has evolved. This constraint has important scientific and philosophical consequences.