Where Are the Aliens? Fermi Paradox Redux

Seth Shostak: Where Are the Aliens? Fermi Paradox Redux: "Reconciling an optimistic view of extraterrestrial intelligence with the failure to see any signs of galaxy-wide colonization has become known as the Fermi Paradox, a conundrum that has tempted the imagination of many people. The suggested explanations can -- and have -- filled books."