SETI vs. SETL
Several decades of listening for signs that somebody out there is try to talk to us have come up empty. There are a lot of theories as to why that might be so, starting from the obvious possibility that civilizations able to communicate with us don't exist. On the other hand, they might have been observing us for a while and concluded that we are too violent or boring to be worth talking to. Or maybe we are some cosmic nature preserve/zoo. Or our name hasn't yet come up for a membership vote in the Galactic club.
In any case the Search for Extraterrestrial Intelligence (SETI) no longer looks that promising. A lot of people think that we should now settle for SETL - the Search for Extraterrestrial Life. For one things, the prospects are looking up - not that we have found any hints, but we have new tools that allow us to look in some plausible places and a raft of plausible places to look, both inside the solar system and beyond.
Within the Solar System Mars is not quite yet confirmed to be a dead planet and several icy worlds appear to have liquid water cores that conceivably support life. Thousands of planets have been discovered beyond the Solar System, and it seems clear that the Galaxy has billions of them. Many of them may well be capable of sustaining life.
Of course we won't be able to get up close and personal with any of them anytime soon, if ever, but our remote sensing tools could well be capable of detecting biosignatures in the near future. Any kind of detailed information about ET life would almost certainly clarify the deepest mystery in biology - how life evolved from non-living matter.