I think we now have almost all the necessary technologies which would be required to establish a human colony on a planet of a distant star. This might be attempted by a government at some point in the next two or three centuries, to give us a 'backup' world in case the Sun goes unstable, or a similar catastrophe occurs. 'Simple' events like an asteroid strike on Earth might be mitigated with a moon colony or some very deep bunkers under the Alps, but eventually thoughts will turn to other stars.
I imagine that the first interstellar missions would be by robot probes. A group of scientists formed about 15 years ago, to debate with a brief of getting information back from another star within their lifetimes. Say a scientist will live for a maximum of another sixty years, subtract four years to get a signal at the speed of light from Alpha... you've got fifty-six years left in which to build something and send it across space. Say it takes sixteen years to build this big, fast robot ship (wildly optimistic, but a similar leap of technology as the Apollo Programme)... now you've got 40 years to get your ship to go four light years. It will have to have an initial 'burn', and then coast for almost all of the 40 years, assuming current propulsion. The probe (or parts of it) will have to have another 'burn' once they've arrived, so they don't just shoot past the Alpha system in a matter of days.
If it were possible to 'burn' all the way, the trip might be possible within the time frame. You'd accelerate for the first 20 years, then turn the ship around and decelerate for 20 years. In fact, because the ship would be getting lighter as the fuel was used up, you might be able to accelerate for 24 years, and decelerate for 16. You'd need a HELL of a lot of hydrogen for your NERVA engine, though.
The real manned ship would follow if the probe was successful, revealing a useful environment. (This is unlikely at Alpha.) With current technology, I would probably be forced to take frozen embryos rather than people. Upon arrival at another star, my ship would be able to use solar power again, having been mostly shut down. The human embryos would be grown to term in a synthetic womb (this is the bit we don't yet have), decanted by automatic machinery and raised to young adulthood by a computer system which would teach them the skills necessary to become colonists. I suspect that ensuring these people develop without becoming psychotic would actually be a more difficult task than the engineering of the probe and ship! The lack of human contact during their formative years, and having no human role models could easily have dire consequences.
To develop these million-tonne ships could do one of two things: it would either require such huge advances in technology, cooperation and the like that the human experience is permanently changed for the better, making the world into a utpoia... or. Or it could bankrupt the world government, pollute the biosphere with all the manufacture and space launches required, and put the whole of Earth at risk. Plus all the space hardware would make a fantastic weapon, if it ever fell into the wrong hands before it got sent on its way.
As for faster-than-light (speed of light in a vacuum) travel, I don't see how that could ever be achieved. It'll involve overturning the laws discovered by Einstein. Possible, but consider how long Newtons laws have gone unchallenged.
The future according to Richard Farr / VoinianAmbassador. I look forward to your comments.
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