Any suggestions on how to get the human population down to 500 million? Should we use mass sterilizations or an engineered virus? What about populations that refuse to comply and somehow combat our best efforts at exterminating them with the chemical or biological methods?
And while we're at it, shouldn't we take this as an opportunity to further improve mankind's genetics by picking the survivors from the brightest and healthiest 5 percent of the current population, ones with no criminal record, no trace of resistance to authority, and no heritable genetic problems?
I do think humans ought to try to get a handle on running THIS planet before trying to go run some other ones. Exploration is fine, and beneficial, but colonization is not the best use of resources when people are still starving to death.