Looking at Ricky's screen, the coordinated units moving smoothly as they turned through the air, I said, "You used PREDPREY to program your individual units?"
"Right. We used those rules."
"Well, the behavior looks pretty good to me," I said, watching the screen. "Why is there a problem?"
"We're not sure."
"What does that mean?"
"It means we know there's a problem, but we're not sure what's causing it. Whether the problem is programming-or something else."
"Something else? Like what?" I frowned. "I don't get it, Ricky. This is just a cluster of microbots. You can make it do what you want. If the programming's not right, you adjust it. What don't I understand?"
Ricky looked at me uneasily. He pushed his chair away from the table and stood. "Let me show you how we manufacture these agents," he said. "Then you'll understand the situation better." Having watched Julia's demo tape, I was immensely curious to see what he showed me next. Because many people I respected thought molecular manufacturing was impossible. One of the major theoretical objections was the time it would take to build a working molecule. To work at all, the nanoassembly line would have to be far more efficient than anything previously known in human manufacturing. Basically, all man-made assembly lines ran at roughly the same speed: they could add one part per second. An automobile, for example, had a few thousand parts. You could build a car in a matter of hours. A commercial aircraft had six million parts, and took several months to build.
But a typical manufactured molecule consisted of 1025parts. That was 10,000,000,000,000,000,000,000,000 parts. As a practical matter, this number was unimaginably large. The human brain couldn't comprehend it. But calculations showed that even if you could assemble at the rate of a million parts per second, the time to complete one molecule would still be 3,000 trillion years-longer than the known age of the universe. And that was a problem. It was known as the build-time problem.
I said to Ricky, "If you're doing industrial manufacturing ..."
"We are."
"Then you must have solved the build-time problem."
"We have."
"How?"
"Just wait."
Most scientists assumed this problem would be solved by building from larger subunits, molecular fragments consisting of billions of atoms. That would cut the assembly time down to a couple of years. Then, with partial self-assembly, you might get the time down to several hours, perhaps even one hour. But even with further refinements, it remained a theoretical challenge to produce commercial quantities of product. Because the goal was not to manufacture a single molecule in an hour. The goal was to manufacture several pounds of molecules in an hour. No one had ever figured out how to do that.
We passed a couple of laboratories, including one that looked like a standard microbiology lab, or a genetics lab. I saw Mae standing in that lab, puttering around. I started to ask Ricky why he had a microbiology lab here, but he brushed my question aside. He was impatient now, in a hurry. I saw him glance at his watch. Directly ahead was a final glass airlock. Stenciled on the glass door was MicroFabrication. Ricky waved me in. "One at a time," he said. "That's all the system allows."
I stepped in. The doors hissed shut behind me, the pressure pads again thunking shut. Another blast of air: from below, from the sides, from above. By now I was getting used to it. The second door opened, and I walked forward down another short corridor, opening into a large room beyond. I saw bright, shining white light-so bright it hurt my eyes. Ricky came after me, talking as we walked, but I don't remember what he said. I couldn't focus on his words. I just stared. Because by now I was inside the main fab building-a huge windowless space, like a giant hangar three stories high. And within this hangar stood a structure of immense complexity that seemed to hang in midair, glowing like a jewel.
DAY 6
9:12 A.M.
At first, it was hard to understand what I was seeing-it looked like an enormous glowing octopus rising above me, with glinting, faceted arms extending outward in all directions, throwing complex reflections and bands of color onto the outer walls. Except this octopus had multiple layers of arms. One layer was low, just a foot above the floor. A second was at chest-level; the third and fourth layers were higher, above my head. And they all glowed, sparkled brilliantly.
I blinked, dazzled. I began to make out the details. The octopus was contained within an irregular three-story framework built entirely of modular glass cubes. Floors, walls, ceilings, staircases-everything was cubes. But the arrangement was haphazard, as if someone had dumped a mound of giant transparent sugar cubes in the center of the room. Within this cluster of cubes the arms of the octopus snaked off in all directions. The whole thing was held up by a web of black anodized struts and connectors, but they were obscured by the reflections, which is why the octopus seemed to hang in midair.
Ricky grinned. "Convergent assembly. The architecture is fractal. Neat, huh?" I nodded slowly. I was seeing more details. What I had seen as an octopus was actually a branching tree structure. A central square conduit ran vertically through the center of the room, with smaller pipes branching off on all sides. From these branches, even smaller pipes branched off in turn, and smaller ones still. The smallest of the pipes were pencil-thin. Everything gleamed as if it were mirrored.
"Why is it so bright?"
"The glass has diamondoid coating," he said. "At the molecular level, glass is like Swiss cheese, full of holes. And of course it's a liquid, so atoms just pass right through it."