Still wondering about this. There really should be some analysis somewhere (just for Fermi's Paradox, if nothing else) to answer this question: How fast could

Still wondering about this. There really should be some analysis somewhere (just for Fermi's Paradox, if nothing else) to answer this question: How fast could humanity have reached viable colonies in space -- if we had used Orions or "normal" nuclear rockets? (NERVA, or better). NASA would hardly fund research into their total failure to reach a fraction of what could have been. Is that the reason why this isn't well published? Since we're still here, I think physics experiments to explain Fermi's paradox has to be wrong (unless they destroy a whole solar system). I think I'll email the guy which has centauri-dreams.org and ask. Edit: A meme like virtual worlds which everyone got dependent on, disregarding species and culture, sounds just impossible. It seems more likely that older civilizations kill off the new ones, to be like Greta Garbo (alone). Edit 2: My point is that the "Great Filter" (see http://www.centauri-dreams.org/?p=1848 http://www.centauri-dreams.org/?p=1848) should be behind humanity, unless it is that other civilizations kill new ones, since a large fraction of all civilizations that are where we are in development, would have viable space colonies.