What about frozen planes, which could be safe from heat-seeking missiles? What about subway turnstiles that were also radiation detectors? What about incredibly long ambulances that connected every building to a hospital? What about parachutes in fanny packs? What about guns with sensors in the handles that could detect if you were angry, and if you were, they wouldn't fire, even if you were a police officer? What about Kevlar overalls? What about skyscrapers made with moving parts, so they could rearrange themselves when they had to, and even open holes in their middles for planes to fly through?