alt Hacker NewsProvided we don't wipe ourselves out, there's no technical reason why we can't go interstellar. It's just way harder and more energy intensive than most people imagine, so I doubt it's happening any time in the next few hundred years.
But we already understand the physics and feasibility of "slow" (single-digit fractions of c) interstellar propulsion systems. Nuclear pulse propulsion and fission fragment rockets require no new physics or exotic engineering leaps and could propel a probe to the stars, if one was so inclined. Fusion rockets would do a bit better, although we'd have to crack the fusion problem first. These sorts of things are well out of today's technology, but it's not unforeseeable in a few centuries. You could likewise imagine a generation ship a few centuries after that powered by similar technology.
The prerequisite for interstellar exploration is a substantial exploitation of our solar system's resources: terraform Mars, strip mine the asteroid belt, build giant space habitats like O'Neill cylinders. But if we ever get to that point - and I think it's reasonable to think we will, given enough time - an interstellar mission becomes the logical next step.
Will we ever get to the point where traveling between the stars is commonplace? No, I doubt it. But we may get to the point where once-in-a-century colonization missions are possible, and if that starts, there's no limit to humanity colonizing the Milky Way given a few million years.
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The other thing we could do to explore the galaxy is to become biologically something we would no longer recognize. We're viewing this from the lens of "humanity must remain biologically static" but I want to point out that that's not physically necessary here and that there is life on Earth that can stop its metabolism for decades and things like that.
We don’t have to completely wipe ourselves out to regress or stagnate. There have been many civilizations that have regressed.
The child within me likes to dream and this is the dream I have!
Yes, it's incredibly easy to do these things once you've done all these other, incredibly difficult things first.
The furthest a human has been is 250k miles (far side of the moon). The fastest a human has traveled is only 0.0037% the speed of light.
The ISS is about 260 miles from the Earth. At that height, the gravity is actually roughly the same as on the surface, it's only because it is in constant freefall that you experience weightlessness on it.
Mars is 140 million miles away. And not exactly hospitable.
I like how you treat "the fusion problem" with a throwaway, "Yeah, we'd have to solve that" as if we just haven't sufficiently applied ourselves yet.
All of those incredibly difficult things we have not even begun to do are the technical reasons we have not gone interstellar and may be the reason we will never do so.
And even if we solve the issue of accelerating a human being to acceptable speeds to reach another star, the next closest star is 4 light years away. That means light takes 4 years to reach. Even if you could average half the speed of light, that's 8 years, one way. Anything you send is gone.
Nuclear pulse and fission fragment designs require no new physics in the same way that a Saturn 5 didn't require new physics when compared to a Goddard toy rocket.
It's easy until you try to actually build the damn thing. Then you discover it's not easy at all, and there's actually quite a bit of new physics required.
It's not New Physics™ in the warp drive and wormhole sense, but any practical interstellar design is going to need some wild and extreme advances in materials science and manufacturing, never mind politics, psychology, and the design of stable life support ecologies.
The same applies to the rest. Napkin sketches and attractive vintage art from the 70s are a long way from a practical design.
We've all been brainwashed by Hollywood. Unfortunately CGI and balsa models are not reality. Building very large objects that don't deform and break under extremes of radiation, temperature changes, and all kinds of physical stresses is not remotely trivial. And we are nowhere close to approaching it.