I agree, I also can't see a paradox in terms of nature. And I would like to add an aspect of sociology (sociology is rarely discussed at this topic): Given mankind's industrialization period and decline of the ecosystem is normal it takes longer to get to an exoplanet than to ruin it. - So, what interstellar space travel really would be is this: The living mankind on Earth gives up itself and its home planet to spread the genes of those who plan its demise. http://www.hashsign.eu/html/blog/dominance/hadfield-hawking-... My answer to the Fermi Paradox is this: These bastards shouldn't get away with it.