I have been thinking about our world without us. When I was a kid, we moved around a lot. Every 18 months or so, our family would pack up and go where the government sent us. There were mid-year moves and summertime moves. We made it as far north as Omaha, Neb., and once and as far west as Alamogordo, N.M., when I was very small. I didn’t know it until I had made my move into adulthood, but I had come to think of those years of practice at making transitions between places and people a gift. As an adult, I could chase promising opportunities that took me to new places because I knew I could make a life wherever I landed. I’d…