[PostOnce]

The other theory being that galaxy-spanning life is incredibly common, it's just that we're too immature/uninteresting to bother coming to visit.

How often do you stop and try to communicate with the queen of a particular anthill?

[jonah]

Well, my dad's (tongue-in-cheek) theory is that all these UFO sightings are them coming over and cruising through the slums. ;)

[patrickaljord]

The article mentions this theory, it says that if life is incredibly common, it would only take one civilization to be curious and come visit us.

[blhack]

I feel like I'm playing into a cliche by even giving this response, but:

Would we recognize it? Would we even know that it had happened? Consider that if there is a civilization capable of traveling across inter-stellar distances, they very likely have got a very different sort of life-span that people on earth. Because of this, their language (if they have something we would recognize as language) could be dramatically different than ours.

Honestly their brains, or "mechanism of creativity" as I guess you could call it, could be something that we would never be able to communicate with.

There are biochemical reasons why extra-terrestrial life would probably be similar to ours, but I can think of no reason why they would be neurologically or psychologically anything like us.

Think about the ants again. Ants have communications, sure, but it's not language, at least not in the human sense. Ants very probably don't have thoughts, and because they don't have thoughts, they don't have a reason to abstract them to words.

This hasn't prevented ants (or bees) from building incredibly interesting and complicated physical and organizational structures.

We've contacted bees. Do you suppose that they realize it?

[jacobn]

What if interstellar travel is just really hard (= no advanced life form has figured it out, and it might just be impossible/not economical), and whatever signals their civilizations generate just aren't strong enough to be picked up by e.g. SETI?

It wouldn't spell "doom" unless you count the sun running out of juice/going supernova. The universe might be packed with life, each such patch effectively isolated to it's own little corner.

[mikeknoop]

But how often are the ants in the presence of another living species?

If the ants were to one day take note of the living creatures around them they would most certainly come to the conclusion that they are not alone.

[PostOnce]

How often do the ants realize they're in the presence of another living species? Do they know humans are alive?

Maybe the aliens have been here all along and we just didn't realize it, heh.

[J3L2404]

It's even beyond that. Learning to write software it seems that some solutions are too involved to even begin to try to explain, so they might not find us uninteresting, they are just lost in thought.