The other option, which is what I generally feel, is a sense of purpose that we need to make sure we shepherd the human race in the small way we can to the eventual goal of something like this. That is, it's engendered a bit more thoughtfulness about not just what policies yield the best current outcome, but what if we took a path of advancement slightly less optimized for current ease and happiness and more for future gain?

We are of course very far from being able to correctly plan and carry out anything like that if we really wanted to, given that our current advancement is almost entirely directed by market forces and psychology that we are just beginning to understand, but it's an interesting thought experiment.

Can you ethically deny X people currently for the betterment of n*x people in the future, assuming population growth and expansion? If so, what's to keep us from enslaving all the current people in pursuit of ultimate happiness of some theoretical future? If not, why are we saving anything for future generations rather than consuming it all for our benefit right now? The extremes are of course easy to answer, but the variables that go into it make it interesting to think about.

Interesting responses. If you haven't already, the Foundation trilogy is a must read. Essentially a bunch of really smart folks create a new field of science focused on predicting the geopolitical and technological advances of the future universe to ensure the human race is successful.

Yes, I'm very familiar, although it has been quite a while. :)

I think that some day the humanity will grow too much and will get tired of overpopulation (I'd hope 30 billion would be the number, but if the humanity is arrogant, they would push it up to 100 billion or more), some people will just die because the planet can't provide enough resources, some rich people will buy other peoples live and kill them (give them a ton of money only if they are willing to die soon) and the world population will agree in not growing anymore but enjoying and preserving the planet as it is, maybe staying in a billion population. After that the world will start to restore and men will have to do nothing because machines are already doing everything, and the only jobs the humanity will have are going to be science and entertainment (incluiding arts and sports)... humanity will no longer grow not because they can't, but because they don't want.

That assumes we are constrained to a single planet, and solar system. I'm not sure why once we have the ability to settle other planets and solar systems, why we would ever really be constrained by overpopulation prior to running up against some other constraint, such as another species.

Growth of a space civilization may not be limited by a constant, but by other asymptotes. For example, if FTL travel is really impossible, the accessible space grows with t^3 for three spatial dimensions, which is way less than the exponential growth that or economy is built on.

There obviously will be some constraints on a planet scale, I was addressing more the idea of planet level constraints being a constraint on humanity itself, which implies that humanity is all still on that planet. That is, I think "constraints on the people living on this planet" and "constraints on humanity" won't necessarily always be the same thing, and a in a discussion such as this, a qualification is appropriate.

You are right that the speed of light is very likely a constraint on human population growth based on exactly what you outlined, and while I wasn't thinking of it specifically, falls under what I meant by "some other constraint". :)

Our growing population will be constrained by resources long before we invent a way to colonize other planets.

Well, that's either a (relatively) short-term constraint, or we are no longer advancing. When talking in the context of Dyson spheres, I think that naturally puts the time frame at multiple orders of magnitude longer than any constraint should hold us back, unless we are actually regressing rather than advancing.

Put another way, when talking about tens to hundreds of thousands of years in the future, I'm not sure even a thousand years from now to get even the most rudimentary of interstellar ships registers as more than a blip.

Not with that attitude you won't.

What makes you so certain you will never live to see it? Be proactive and move your efforts to life extension and dependent technology.

Seeing a Dyson sphere being built is some serious life extension. It probably involves lots of major discontinuities and full medium changes.

You can see the manned space program. If you're under 43, there's a decent change you'll never see a human leave Earth because you were born too late. Countless humans died before either of these. You'll always be born too early for some things, and too late for others.

What's exciting to me is what lays in store tomorrow, next year, next decade. Next century is someone else's territory, but mine is so vast I have no reason to be jealous of them.

Plenty of people still leave earth, they just don't go to other planetary bodies.

Hopefully Elon Musk will come through.