The Fermi Paradox is, essentially: "If alien civilisations exist, why haven't we encountered them or seen signs of their existence?" -Any civilisation of a technological level even on a par with ours would likely blare out radio signals on a constant basis. We have radio telescopes which could detect anything of that order (an entire planetary civilisation's radio chatter) within the galaxy. Why haven't we? -Any one civilisation which decides to colonise on an interstellar level could have colonised (within the speed of light and moving relatively slowly) the galaxy within a few tens of millions of years of exponential growth. Maybe 100 million at the upmost limit. We still haven't seen them, or any sign of them. Why? What do you believe about the Fermi Paradox? EDIT: This includes civilisations a million light years away (who may have died 500'000 years ago from a nasty flu bug for all we know) which we may detect, possibly, in the present day.