That’s true, it does assume interstellar travel is physically possible, but at this point there are forms of interstellar travel that we know are possible.
Solar sails for instance, we know those work, we’ve tried it. Now if you wanted to travel to another star system with a solar sail, it’s just a matter of scaling that proven technology way up. We’re not ready to do that today, and we won’t be ready in the next 20 years, but to think that we wouldn’t be ready in 500 years, I find that idea far fetched.
But a much better technology would be fusion propulsion. With fusion drives you could get your cruising speed up to a meaningful fraction of the speed of light (perhaps 5-10%). At that rate you can make it to the closest stars in less than 100 years. And that technology is not at all far fetched. We truly are approaching working fusion power plants, it’s extremely likely that we can eventually develop fusion propulsion, or at the very least, fusion powered electrical propulsion (ion drive).
As for if it will ever be economically possible, I’m not at all worried about that. The fact is, there are a lot of resources and opportunities right here in our solar system, just waiting for people to utilize them. So people definitely will start mining and manufacturing in space eventually. And as we start to operate more in space, we will naturally continue to iterate and improve our methods of getting around. In short, over time it’s going to get cheaper and cheaper to make space ships and we’re going to get better and better at doing it. The economic factors are likely to fall into place eventually.
And finally, will interstellar travel ever be possible socially? Hey, your guess is as good as mine. I don’t think we have any way to answer that…
Yeah, it totally could be.