We keep wondering why aliens have not made contact with us. And we keep wondering why we have not been able to find intelligent life in the universe. But do we even know what we are looking for?
Imagine an anthill somewhere near the building you live in. In it, are ants who wonder if there is life outside the anthill. Their explorers venture out into the grass that extends in all directions and come back with nothing. Their astronomers (antronomers?) train their telescopes outwards and report that they can see no anthills. Largely, the ant community comes to the conclusion that they are alone in the universe.
Occasionally they see immense objects wandering about in the vicinity of their world. These are too large for them to make sense of and mostly stay clear of the anthill. The ants sometimes daringly climb up these objects to look for other ants but they find nothing and find themselves mysteriously brushed off by unseen forces. The view that they are all alone in the universe takes root among the ants.
Now return to being yourself. If human beings knew that cosmic loneliness of the aforementioned sort was haunting ants, how much would we care? Would we care enough to communicate the fact of our existence to them? What, if anything, could we tell them about ourselves? What, if anything, would an ant understand of the scale on which humanity operates? What would economics mean to ants? Or religion, or literature, or even things as basic as reading glasses?
An ant’s capacity for understanding is not limited by absence of information. It is limited by the ant’s inability to process information even when it is abundantly available to it. The ant is not looking for life so much as it is looking for ants.
The human quest for extraterrestrial intelligence is marred by this same limitation. We are looking for something, but we do not really know what we are looking for. We have some ideas regarding what it will look like when we do find it, but for the most part, these ideas are pictures of us. We are staring out into the cosmos with unblinking eyes, looking for our own reflection.