“The design for the Space Shuttle called for the creation of reusable solid rocket boosters, massive cone-tipped cylinders that would lift the Shuttle to 150,000 feet before falling away and floating to the ground on parachutes for recovery and reuse. This worked surprisingly well. The boosters were built in Brigham County, Utah, and shipped to Florida for takeoff. After each use, they’d be recovered from the open ocean, freighted to port, refurbished and, once again, shipped to Florida. The boosters were about 150 feet long, but they were precisely 12.17 feet in diameter—because they had to fit on a special railway flatcar for those overland shipments. The aerospace engineers who sat down to design those solid rocket boosters had a lot of parameters to juggle—the pull of gravity, the efficiency of rocket fuel, the weight of the payload. But mixed in with those parameters, immutable and inarguable was the width of a railcar, which was foreordained by the width of the Roman chariot wheelbase, which was, in turn, determined by the metalbeating know-how of Roman blacksmiths. Infrastructure casts a long shadow.”