The Diamond Age by Neal Stephenson

be gathered up and sold to certain persons who knew how to clean it and weld one piece of Nanobar to another and make it into protective suits and other shapes.
      Harv had quietly stuffed the piece of cloth into his shoe and then limped home, not saying a word to anyone. That night Nell, lying on her red mattress, was troubled by vague dreams about strange lights and finally woke up to see a blue monster in her room: It was Harv underneath his blanket with a torch, doing something. She climbed out very slowly so as not to disturb Dinosaur, Duck, Peter, and Purple, and stuck her head beneath the blanket, and found Harv, holding the little flashlight in his teeth, working at something with a pair of toothpicks.
      "Harv," she said, "are you working on a mite?"
      "No, dummy." Harv's voice was hushed, and he had to mumble around the little button-shaped torch he was holding in his teeth. "Mites are lots smaller. See, look!"
      She crawled forward a little more, drawn as much by warmth and security as by curiosity, and saw a limp mottled brown thing a few centimeters on a side, fuzzy around the edges, resting on Hanv's crossed ankles.
      "What is it?"
      "It's magic. Watch this," Harv said. And worrying at it with his toothpick, he teased something loose.
      "It's got string coming out of it!" Nell said.
      "Sssh!" Harv gripped the end of the thread beneath his thumbnail and pulled. It looked quite short, but it lengthened as he pulled, and the fuzzy edge of the piece of fabric waffled too fast to see, and then the thread had come loose entirely. He held it up for inspection, then let it drift down onto a heap of others just like it.
      "How many does it have?" Nell said.
      "Nell," Harv said, turning to face her so that his light shone into her face, his voice coming out of the light epiphanically, "you got it wrong. It's not that the thing has threads in it- it is threads. Threads going under and over each other. If you pulled out all of the threads, nothing would be left."
      "Did mites make it?" Nell asked.
      "The way it's made- so digital- each thread going over and under other threads, and those ones going over and under all the other threads-" Harv stopped for a moment, his mind overloaded by the inhuman audacity of the thing, the promiscuous reference frames. "It had to be mites, Nell, nothing else could do it."

    Security measures adopted by Atlantis/Shanghai.
      Atlantis/Shanghai occupied the loftiest ninety percent of New Chusan's land area- an inner plateau about a  mile above sea level, where the air was cooler and cleaner. Parts of it were marked off with a lovely wrought iron fence, but the real border was defended by something called the dog pod grid- a swarm of quasi-independent aerostats.
      Aerostat meant anything that hung in the air. This was an easy trick to pull off nowadays. Nanotech materials were stronger. Computers were infinitesimal. Power supplies were much more potent. It was almost difficult not to build things that were lighter than air. Really simple things like packaging materials- the constituents of litter, basically- tended to float around as if they weighed nothing, and aircraft pilots, cruising along ten kilometers above sea level, had become accustomed to the sight of empty, discarded grocery bags zooming past their windshields (and getting sucked into their engines). As seen from low earth orbit, the upper atmosphere now looked dandruffy. Protocol insisted that everything be made heavier than need be, so that it would fall, and capable of being degraded by ultraviolet light. But some people violated Protocol.
      Given that it was so easy to make things that would float in air, it was not much of a stretch to add an air turbine. This was nothing more than a small propeller, or series of them, mounted in a tubular foramen wrought through the body of the aerostat, drawing in air at one end and forcing it out the other to generate thrust. A device built with several thrusters