Living among the Asteroids in 2125

How might people settle the asteroid belt in 2025? They will need energy, raw materials, agriculture, probably spin gravity, robots, printers, databases, strong magnetic fields (for radiation protection), and so on. They may also need defenses and some form of local government--the response time from elsewhere could be months. We'll look at the state of some relevant technologies now, and where they might be in the early 22nd century, and the kind of lifestyle and culture this would enable.