Samuel Walters wrote:
There's just no material gain that can't be met within your own star system if your technology is advanced enough to synthesize needed substances from raw elements -- and that's a given if you're capable of interstellar flight.
You know all of this for a fact? From which examples of civilizations with interstellar flight are you basing these conclusions?
You don't really have to look at interstellar civilizations to make that extrapolation, you can look at our own. We
"synthesize needed substances from raw elements". But what you seem to be focusing on is not the important part of his statement. There are so many resources available in a typical Sol-type system it's mind-boggling... enough minerals and water to supply hundreds of billions of people. If you have the need to expand beyond your own planet for minerals and water, and you have the technology to send a fleet of ships across light years and to other star systems to get them, you'd have the technology to do the same thing at home. Even if they had to come to our system to access such resources, it certainly wouldn't be worth the hassle to bother us here in the inner solar system when all the good stuff (that would be most energy efficient to remove from the solar system) is from the orbits of the asteroid belt to Jupiter, Saturn and beyond. Unless they were building an enclosed Dyson Sphere 10 miles thick and had to support a population in the trillions, the resources available in their home system should suffice quite nicely for a very long time.