http://xkcd.com/638/ http://xkcd.com/638/ "We've searched dozens of these floor tiles for several common types of pheremone trails. If there were intelligent l

http://xkcd.com/638/ http://xkcd.com/638/ "We've searched dozens of these floor tiles for several common types of pheremone trails. If there were intelligent life up there, we would have seen its messages by now."