Observational Constraints on Technosignatures and the Fermi Paradox

To the point

Although scientists search the cosmos for signs of advanced civilizations beyond deliberate signals, there are no unambiguous technosignatures yet because interstellar radio leakage is too faint, our surveys are far from exhaustive, and infrared searches for megastructures largely find natural explanations, even as Wright, Carrigan, and Tarter have formalized the observational limits and future instruments may still reveal what we cannot yet detect.