They listened for radio transmissions. I still haven't seen anywhere, where we've deliberately sent a message to a single star system.
supported a "reply" to the Wow! signal
last year, but as far as I can tell, it's just a publicity stunt. Certainly there's no scientific
reason to beam signals deliberately into space. What's your rationale for seeing it done, ConRefit
Given the vast stretches of both time and space over which the universe exists, the odds that another technological civilization exists within meaningful communications range are very low. There may be an advanced technological society that exists right now
, contemporaneous with us, but it may exist in the Andromeda galaxy. Alternatively, there may be a technological civilization within a relatively close distance (say, a few hundred lightyears of us), but it could've gone extinct millions of years ago or not arise for millions of years yet. Either way, communication is not realistic.