L. A. L. da Silva
Alexander von Humboldt Scientific Research Nucleus, Omega Centauri Network for the Advancement of Scientific Education,
Caixa Postal 109, CEP 95590-970, Tramandaí, RS, Brazil. E-mail: luizastronomo@gmail.com
Received: 24 September 2021; Accepted: 15 November 2021
Keywords: Astrosociology, extraterrestrial civilizations, Fermi’s Paradox
Abstract
We present an alternative equation to estimate the probable number N of self-conscious intelligent technological societies (SCITSs) within the radius of the observable universe. This equation has only one poorly-known factor, Pc, the SCITS’s formation probability, which can be estimated within an uncertainty by a factor of 102 (10−11 ≤ Pc ≤ 10−9) by applying the restriction imposed by Fermi’s Paradox. The SCITS’s formation rate for a typical spiral
galaxy is then estimated as ≈1 civ Gyr−1. For a very optimistic maximum life expectancy ≈108 yr, the conclusion is that two civilizations never coexist in the same galaxy. Our estimated values for Pc are compatible with current biological and astrophysical evidences. We also propose an alternative astrosociological classification scheme which enables us to speculate about possible evolutionary paths for SCITSs in the universe. The so-called
‘Closed Bottle Neck’ (CBN) scenario suggests that civilizations are no exit evolutionary ways. We argue that simply there would not be interstellar travels nor Galaxy colonization or a Galactic Club. Thus Fermi’s Paradox results eliminated, and the perspectives about the future of our own civilization may not be positive.