Fermi's Paradox
It occured to me that we tend to give a moment of silence to those who have died tragically, and also to those who are terminally ill. Perhaps we seem to be alone in the universe because whatever civilized life is out there has sadly withdrawn, giving the People of Earth a hundred year moment of silence as we hurdle towards our demise....
http://www.progressive.org/0801issue/mill0801.html