The simplest answers to questions may not necessarily be the best ones but then again… According the today’s Guardian, Danish researcher Rasmus Bjork believes he may the answer to the Fermi Paradox (the conflict between predictions that life was elsewhere in the universe and the conspicuous lack of aliens who have come to visit): Extra-terrestrials have yet to find us because they haven't had enough time to look.
A civilisation using sub-light speed probes would take billions of years to map out only a fraction of the galaxy. It might get lucky and pick up broadcasts that have leaked out into space but "… unless they can develop an exotic form of transport that gets them across the galaxy in two weeks it's still going to take millions of years to find us," said Mr Bjork.
What Mr Bjork has to say comes as no huge surprise. Unless ET really has Warp drive or can conquer hyperspace (I really must watch less sci-fi!) then we will probably wait a long time.