Quote Originally Posted by Flixy View Post
I get where you're coming from, but first of all you're relying on the big if that a possibly earthlike planet exists relatively near us. But wouldn't it also be be very likely that such a planet would still not be exactly like earth, and require similar terraforming as, say, Mars would, and have the exact same problems you've described here in addition to the problems of getting there in the first place, and the additional problem of getting the resources there to do this? So yeah, I do think terraforming in our own system is likely to happen first because you would need it as a step to go to another galaxy.
I forgot to write that I think artificial habitats are a more realistic prospect for human space habitation than living on planetary surfaces, in this or any other system.

P.S. if you put engines on a space habitat now it's called a generation ship.

And I thought the majority of the issues you've described are due to weightlessness, and would be significantly reduced (or even absent) at low gravity as opposed to (almost) none, and IIRC most proposals for centrifuge like stations aimed for a lower artificial gravity than earth's. Then again, I don't think we know much about this at all right now so it's mostly speculation, and there's likely problems we don't know about yet. Which, I suppose, would be easier to test on a nearby planet instead of flying to another solar system and hope it will be okay (not to mention the health problems of a decade long space flight). Optimistically people would simply adapt to their home planet, and as long as you don't travel you'll be fine. Babies born there might even be better adapted (though have bigger problems returning to earth), with an emphasis on 'might' because it might also be impossible to give birth to a healthy baby under the circumstances. And again, is it that likely that the coincidental nearby earthlike planes are exactly like earth and won't have these problem toos?
I think the idea of a permanent presence on Mars al la Antarctica (these places have quite a lot in common actually) is a good idea, I just don't think a proper colony with people being born, living out their lives and dying there is viable - unless I'm wrong about the gravity thing, which I'm very happy to be.

Also your gravity claim is untrue, the other terrestrial planets do not have "way less" gravity than Mars. There's only Mercury, which has almost identical surface gravity (0,38g instead of 0,376g, so actually marginally bigger), and Venus, which is closer to Earth at 0,905g. Unless you meant minor planets and moons, which are indeed a lot lower.
I did.

Anyway, talking about why they haven't reached us yet, your post describes it might be possible to colonize a near star, 1,500ly away is quite a lot more and might simply be impractical without FTL technology.
I'm not so sure. If you can go 0.8 or 0.9c with some futuristic proposition drive then I think the time dilation gets to the point where the travellers should live to see their destination. The logistical challenge for going to nearby stars is the same as the one for going to distant stars; you just need to be able to build a ship that'll keep people alive for years or decades.

But you wouldn't be expanding your own civilisation that way, just starting new ones.

Your other option is you colonize nearby habitable exoplanets, wait a couple of centuries until they're supporting developed cultures of their own then *they* send out colony ships to worlds near to them and so on and so on. After a few million years of this, your dudes are probably on a significant %age of the milky way.