If you combine all our current knowledge of statistics and astronomy, it's nearly comical to believe we're the only intelligent life in the universe. It's easy to get lost in the numbers thrown around - there are billions of stars and planets in our galaxy and billions of galaxies. Humans are rather bad at fully understanding such large numbers.
Despite where this article might lead, it isn't really about science - its about thinking big. Big enough to consider that if there are any aliens with the ability to come visit us, they would almost assuredly not care to.
Stephen Hawking, the famous physicist, said in an interview that aliens visiting us would be similar to Christopher Columbus first landing on North America (not a good event for native Americans). His idea being that they would come for our resources, not with any particular purpose of friendship.
There are a few problems with that thought however. To introduce the idea, consider most any space movie in existence. Movies are of course, just movies, but they have shaped our thinking about meeting aliens. And small thinking it is indeed.
For the rest of the story: http://paultyma.blogspot.mx/2013/04/why-well-never-meet-aliens.html