I once visited a town in Spain over which an ancient Roman aqueduct runs, elevated above most of the buildings, even today. It carried an essential ingredient foundational to life in the area, but after the fall of the Empire and the deaths of the architects and engineers who could understand it, the aqueduct stood in the midst of people who could not have repaired it. Relying on mission-critical technology divorced from human understanding is exceptionally risky. Obviously, people have done it before and will happen again, but it makes me nervous.