Isn't that just an assumption though? As short as 1000 years ago traveling to the moon seemed impossible.
Afaik nothing in current physics prevents FTL from being logically possible. Nothing predicts it either but that doesn't mean it's impossible.
General relativity says that maybe you can get something equivalent by taking non-linear paths through space-time but those sorts of things require very radical types of matter to avoid collapsing into a black hole. And realistically, it's IMO very unlikely that these sorts of things would remain in a more complete (e.g. quantum) theory of gravity.
Also, its one thing to go the speed of the light, its another to slow down from it!
That said, I'm not particularly worried about it either. I suspect we will either have scientific value (independently evolve intelligence, which appears rare) or never pose a real threat to them, assuming learning curves remain exponential for civilizations.
What is the reasoning behind this statement?
> and there's no reason to expect the ants:humans ratio to extend to humans:aliens
the same is true of the inverse, being that there's no reason to expect that humans are at the limit of complexity, so for the purpose of speculation as to the likelihood of far more intelligent life, there's no good reason to exclude the possibility.
That said, we're several orders of magnitude away from that, and even we have a theoretical way of FTL travel[1].
[0] https://en.wikipedia.org/wiki/Bekenstein_bound [1] https://en.wikipedia.org/wiki/Alcubierre_drive