Jester, Who's to say we aren't already slaves....maybe we are the tool for terraforming this planet into a hospitable place.....maybe we were engineered with a virus like nature that in time would transform this planet into something the ET's want and they are just overseeing their plan...we say that the reason no life can reach this planet is because of the time it takes to span such distances at sub-light speeds...well a fly has a very short life compared to us...we maybe the fly equivalent to an ET as far as life span is concerned. Australia had to import the european dung beatle into this country the reason is because the dung beatle equivalent here couldn't deal with cattle crap....so I'm saying its possible that we are their dung beattle equivalent. On the other hand why would an ET want to leave their world....some would say to see what else is out there etc...thats a pretty huge effort just to explore....a more plausible reason is out of necessity...now we KNOW our planet can sustain life...and ET would qualify as life, if they left out of necessity and earth seemed a good place to come then we are in the way..... Just some thoughts....BTW this hippie talk about any civilisation advanced enough to reach us would be peacefull...I don't buy it nothing drives life more to do the impossible then the fear of extinction. At present we have't the means to reach a distant planet...or to terraform a near planet or explore past our solar system....If we found out that earth was to die within a certain short time frame i.e. perhaps 2 lifetimes I'm almost certain that technology would be developed in time to save the few fortunate, and we'd be the aliens looking for a new home.