SETI more expects side-effect radio emissions than purposeful communications. It was started at a time when powerful radars [1] designed to detect ballistic mis

SETI more expects side-effect radio emissions than purposeful communications. It was started at a time when powerful radars [1] designed to detect ballistic missiles were deployed and this radar's emissions are definitely detectable several light-years away. It relies on the same mentality as the Fermi Paradox: it expects that an advanced civilization will master so much energy that its waste should be visible from afar. Only recently have we started considering that efficiency, rather than wastefulness, may be the hallmarks of civilization. But yes, everybody at SETI knows that what they are doing are stabs in the dark. It is like trying to find inhabited lands by looking for tam-tam songs along the coast or to check if there are lighthouses installed where people may have switched to GPS. Still, if there are thousands of civilizations out there, you can bet on off-chances of detecting one. The odds are low but the rewards would be huge. Fewer discoveries would be as consequential as this one. [1] https://en.wikipedia.org/wiki/Duga_radar https://en.wikipedia.org/wiki/Duga_radar