I think that although intelligent life will turn out to be present on many worlds, the odds will be against multiple intelligent societies evolving near each other at the same time. Contact with an alien civilization is more likely to come in the form of messages sent from a very great distance than as weapons sent from nearby. But if acceleration to a good percentage of light speed is possible, then relatively nearby worlds could attack each other, and it's a concern.
If you read that and immediately thought, "That sounds like something I'd read on ESPN.com," I'd love to take you to Vegas next week - my treat. But ESPN it was, as Gregg Easterbrook interrupted his NFL column with a fascinating science lesson involving one of NASA's latest discoveries.
Skip down to the part referencing Dick Cheney if you don't care about the football stuff (despite that header, it is 0% political).
Cincinnati @ Pittsburgh (-10 1/2). I had Cincinnati in line for the upset cover until Chad Johnson was mysteriously deactivated for tonight's game. Steelers roll. PICK: Pittsburgh
Oh ok, I'll pimp ESPN twice in one post - despite their unholy allegiance with the BCS. But ya write about Matt Ryan, you earn a little love.