Free Astronomy Magazine March-April 2024

sphere of space hav- ing that radius there are approximately 60,000 stars (80% of which are a priori un- suitable to host life as we know it), even the most optimistic re- searchers consider the existence of another technological civiliza- tion in such a small volume (compared to the entire Milky Way) to be highly unlikely. We would therefore be led to believe that no one is watching us from out there. This conclusion, neverthe- less, is not shared by F rontespices and symbolic pages of the two fundamental scientific treatises which between the 16 th and 17 th centuries introduced a new vision of the world, attributing an increas- ingly less central position to the Earth. 3000 light years the dis- tance within which the presence of human be- ings could be detected through “simple” tele- scopic observation. Osmanov writes: “We considered the question of how our artificial constructions are visible to advanced extrater- restrial civilizations. Tak- ing the universality of the laws of physics, we found that the maxi- mum distance where the detection is possible is of the order of 3000 ly and under certain conditions, Type-II advanced alien so- cieties might be able to resolve this problem.” If we want to take Os- manov’s arguments into consideration, we must accept the hypothesis that, in the sphere of space with a radius of 3000 light years surrounding us, there exists at least one Type II civilization. But what is a Type II civilization? Exactly 60 Zaza Osmanov, professor of physics at the Free University of Tbilisi, Geor- gia. In a recent article published in Acta Astronautica , entitled “Are we visible to advanced alien civiliza- tions?”, Osmanov extends to about