| I assume most of us have read a fair amount of MSF dealing with war vs. alien races/civilizations/etc. But how probable is it in reality, and how soon? Heinlein once commented (in "Expanded Universe") that "The greatest military problem of the next century (i.e., this one) will be that there is no defense against an attack from space", and specifically stated that he wasn't talking about ICBMs. IMPO,(and to get the ball- of whatever- rolling), my "worst case scenario" would be a colonization fleet inbound at sublight velocities (possibly fleeing a doomed star system, as in Duncan Lunan's "Epsilon Bootis' Probe" hypothesis), who determine that (A) Earth is survivable for them, (B) they have nowhere else to go (reached the end of their logistics, etc.), (C) can't share, or just don't want to, and (D) brought enough firepower along to make their claimjump stick JIC. (Yes, I've seen "Independence Day"- but I'm thinking more of Wells' "War of the Worlds".) Likely, unlikely- or is there an even nastier scenario out there? (Please keep the X-Files jokes to a low roar- thank you.) :-).