For all we know, our descendants will harness the power of suns or dark energy or higher dimensions or who knows what to create wormholes or space warps. It's obviously speculation
Exactly. Speculation. Fiction.
Please define your terms, because I don't see an absolute equation between speculation and fiction like this statement insinuates.
We've speculated based on circumstantial evidence for years that there was water on Mars.
We've speculated that there were liquid hydrocarbons on the surface of Titan.
Neither of those were fiction.
It's not ridiculous to speculate, but that's all it is. That's my whole point--that all this talk about aliens visiting Earth is speculation until you can produce concrete evidence, and I don't mean the testimony of people who've heard about things second or third hand, or who may be prone to misinterpretation of their surroundings. Extraordinary evidence needs to accompany extraordinary claims.
So, basically, negative until proven positive?
Again, water on Mars, liquid hydrocarbons on Titan. Would you have called those speculation a week ago? This is almost like a Schroedinger's Cat scenario. It doesn't exist until we have proof of existence? If we can't see it, we can't be sure it's there?
That's talking in some pretty serious absolutes, and we've seen pretty conclusive evidence over the years that the universe doesn't exactly deal in such absolutes.
I think it's at least as probable that any technologically advanced civilizations that may have arisen have long since destroyed themselves, been destroyed by natural disaster, or depleted their natural resources to the point that they never left their own solar systems. Maybe only 1 in 1,000,000,000 technological civilizations are able to traverse the stars. The nearest may be three billion LY away and having trouble just investigating their own corner of their own galaxy.
You see, if we're all just speculating about what we can imagine then the sky's the limit. We don't need to worry about reality and just can have ourselves a good old time.
---------------
Why are you imposing human mores on alien species? Yeah, humanity tends to be warlike, but that hardly dictates what any other sentient life form in the universe would do.
We develop in the environment in which we're raised. Humanity came to dominance in an aggressive "kill or be killed" environment. Aliens aren't automatically going to develop in the same kinds of environments, and the aren't going to automatically have the same reactions to stimuli that humans do. We're talking different environments, different circumstances, different everything.
I mean, we can take the nature versus nurture aspect and go crazy with it, but ultimately, with so many variables at play, how can anyone say for certain what another technologically advanced civilization might or might not do? They could implode like humanity probably will, or they could flourish and find technological advances the likes of which our grandchildren will never see.