We are constantly bombarding space with messages from Earth, in hopes that someone will hear it and respond. We've been doing this for years and years, in all directions, and have gotten nothing. In all possibility, it's probably just that we inhabit an insanely minute fraction of the universe, and it hasn't reached anyone yet.
But what if it's quiet for a reason? What if there are no other transmissions being sent our way because there's somebody that people don't want to hear them? If this is the case, we are probably all doomed to intergalactic slavery and/or extermination at the hands of some awful reptilian alien race.