It's interesting to think about. For instance, how much space do we need per capita? If we were to pack everyone together giving each a 2ft by 2ft space, the current population would take up the space of a large county or two. That's rather fascinating to think about because it isn't a large amount of space. Obviously it isn't sustainable, but our physical size is small. But then you start factoring in food, shelter, water, mental well-being, etc... It would just be interesting to find out how much space we really need per capita thinking along those lines.