Well, while we're on the topic of aliens, I've had a rather intense debate with a friend of mine about whether or not it's wise for us to send out radio broadcasts and do other things that could make first contact with aliens.
She maintains that aliens are likely predatory and aggressive, much like us. So such signals are tantamount to ringing the dinner bell. Think about what our own explorers did when they made contact. It would be much the same for us.
I agree that aliens would vaguely be like us, denizens of a planet or large moon - likely omnivorous generalists like us. They'd likely have a similar aggressive streak as us, though I'd like to think that total war is an alien (get it?) concept to them. And like us, they might've somewhat tempered their belligerent streak as they became more high-tech and learned to be a little bit more compassionate. Because a superbelligerent alien race would never make it into space at all - they'd simply bomb themselves into oblivion.
Given the vastness of space (space is really BIG), they would have plenty of resources and territory of their own (as would we), so we wouldn't necessarily have to fight over it. This galaxy is big enough for the both of us; neither of us would have any need to fight the other. In fact, we would literally have to go light years out of our way to fight each other. A rather absurd, though not impossible, situation.
Aliens wouldn't truly want our raw resources, the real treasure trove is in our life and its byproducts - culture and technology. Because that's certainly what we're interested in. Why come all that way to destroy when you can study?
And besides, our first contact would likely not be between us personally - but through our machine intermediaries - our probes - who definitely have no harmful intent.
So, instead of fearing aliens and going silent, we should do everything we can to be loud and noticeable to make first contact happen asap. Because any first contact would likely enable a huge technological leap for us, potentially saving countless lives. Imagine a new power source or new medical technology or new spaceflight technology. It's such a massive boost that it's worth betting that the aliens we do meet aren't genocidal.
