I just watched the movie "Interstellar," in which the heroes try to begin a colony on another planet in order that the human race survive. Is there any compelling reason to do something like this? To be clear, as far as the heroes know, everyone who is currently alive on earth will die. The point is not to save those people, but only to see that there are future generations of humans that live after them. I can see that we have reasons to save actual, living people--they're capable of suffering, they have various interests, and so on--but those reasons don't apply to the hypothetical inhabitants of a future colony. Why should we care that humanity survive this larger sense?