Why Alien Signals May Have Crossed Earth Unnoticed: A Statistical Look at Technosignature Detectability

To the point

Claudio Grimaldi and Fabio Lucas Carvalho say that even if aliens emit signs of technology, we’re unlikely to detect them because the Milky Way is about 100,000 light-years across, we monitor only a tiny fraction of the sky, signals can be very weak or masked by background noise, and different types of signals—like diffuse waste heat or narrow laser beams—pose different detection challenges, so many signals would have to slip past us unseen for detection to be likely.