I recently heard a terrifying prediction: Advances in defense technology will change the way war is waged today as much as industrialization did in World War I. If true — and I don’t know one way or another, my area of expertise is economics — then we could be facing casualties on an unimaginable scale, just as the mechanization of weaponry produced in the early 20th century.As I said, however, I am an economist, and this prediction got me to thinking: What will this transformation mean for the U.S. and global economy? In the past, increases in military spending have…