It is an interesting topic, listening to them talk does get one thinking. The scary part is that Henning's point has a lot of logic from a certain perspective. One question though, why do we always assume aliens are more advanced? What is to say there aren't some that are less so? I suppose the more advanced one's are the most likely to visit.
Read "The Road not Taken", a short story by Harry Turtledove. In the story, space travel/hyperdrive technology is dead-simple, and can be invented and exploited by any ~16th-century-equivalent civilization. All they need to do then is make (mostly) vacuum-proof vehicles and figure out how to navigate.
Most planets *do* discover the technology (except for old, backward, benighted Earth). And most planets *do* what 16th-century Earth did with their high-tech: Explore until you find rich natives, overpower them, and steal their stuff.
There is, of course, no technological imperative to improve any OTHER technology. What they have works fine for over-awing the natives. So it's light signals between ships, and conquistador-type armor, matchlocks, and crossbows when they attack a planet.
So when they attack present-day Earth, matchlocks and crossbows are met by a National Guard unit with machine guns and tanks....
Phil Plait (the Bad Astronomer) has some good points about aliens in his non-fiction book "Death from the Skies." Nothing synchronizes interstellar civilizations; if the aliens show up, they're more probably going to have technology that's MILLIONS of years ahead of ours, not hundreds. None of this, "Their ships are a little faster and the guns are more effective, but we can beat them!"
He also speculates that such a sufficiently-advanced civilization may spend considerable effort ensuring that no OTHER race can ever threaten them.
So maybe we don't WANT to be found.....
Ron Wanttaja
Interesting if true, and put's everything into perspective.
