Artificial gravity using centrifugal force. We haven't put much effort into learning to live in space- certainly not composted to what we spend on 'defense', aka imperialism.
We're not doing such a hot job of living on one planet, in case you haven't noticed.
Of course we need to learn to get along. We also need to hedge our bet in case we don't.
I don't disagree that the human species has to move into space. Completely agree.
Just looking at how much progress we've made in 50 years on this subject and I think that a hundred years isn't enough.
If we had gone to the moon and established a base for researching this very topic, we would be much farther along. So it's more a matter of commitment than ability.
I've been involved in several scale-ups of new technologies and learned that problems get worse, not easier if they aren't solved before scaling up. Our problems go much farther than technical. If we can't live together on the planet, how can we expect to do so when confined in a metal can in space?
I don't think we are ready. I think we many problems to resolve here before we move out. I support research and small scale bases that are close enough to earth so that we can learn and iterate solutions.