Nanotech

by Gardner Dozois

  Bill Canazetti, his lab partner, told him it was all right to cry. That he shouldn't hold it in. But Henry just shook his head. Later he would do that for Her. Just now, he couldn't.

  There was a preacher. Barbara had been a church-goer, High Church, and Henry had sometimes gone with Her. He wished now he had gone more often. It was a portion of Her life that he could no longer share.

  The preacher (Priest, he supposed. There was a difference.) The priest spoke of comforting impossibilities. Eternal life. The immortal soul. Barbara had gone to a better world. She had left behind this vale of tears. Henry listened. He wanted to believe it. He tried to believe it. It was better to believe such things than to believe that there was no Barbara at all, anywhere. Death was the Great Proselytizer.

  "Most of all," the man in the funny collar said to the assembled group, "Barbara lives on in the hearts and minds of those of us who knew and loved her. We carry some piece of her with us always. . . ."

  Now, that was certainly true. At least, since he had donated Her organs. There was no doubt several people already carried a piece of Her with them. And there was the DNA sample at the lab. Under proper conditions it should last nearly forever. Immortality of a sort, though he doubted that that was what the priest had meant.

  Henry decided that, if Barbry did live somehow in his memories, the first thing he should do when he got home was to record those memories on tape. Everything about Her. That way he could never forget.

  He had kept Her clothes and other things. He couldn't bear to part with them just yet. They were memories, too, in a way; and he wasn't quite ready to cast them out. In fact (and it would shame him if it ever got out), he slept at night with one of Her slips tucked beneath his pillow.

  And then there was Sadie the Lady.

  Henry had talked her into staying. He didn't know why. He had put her up in the guest bedroom and let her wear Barbara's old things. Suspicious at first, she had gradually loosened up. She spoke now, at least once or twice a day; and had wandered off to her closet nest only once. She was still hoarding food, Henry discovered, in several caches around the house, which Henry left undisturbed. It seemed . . . right that she should be in the house.

  The worst part had been the heroin withdrawal. Henry hadn't believed that such agony was possible. Sadie had moaned and sweated and begged him to find her connection. But her connection was in Manhattan and Henry had not allowed her out of the house, despite her pleading, her tears, and her threats. At times, he had to restrain her, physically; and found that, for her condition, she was surprisingly strong. Together, they had finally weathered the crisis; and when it was over they were both drained.

  Afterwards she had begun to show more interest in herself. She bathed more regularly, and brushed and combed her hair. She became a kind of housekeeper, doing odd chores around the house. Cleaning. Cooking his meals. Sometimes mumbling to herself. Once or twice saying a few words out loud. Perhaps it was gratitude. Her way of repaying him for what he had done for her that night on the streets. Or perhaps she was trying to help him through his bereavement. Henry didn't know.

  Sometimes when he saw Sadie in the hall or in the kitchen, Henry squinted his eyes and pretended to himself that she was actually Barbara. The mental novocaine was wearing off and Henry was starting to feel the pain of Barbara's loss. His little game with Sadie helped numb the pain, at least for a little while. It was a harmless bit of self-deception.

  And it was only a game, of course. He knew when he did it that he was only pretending.

  It was two weeks before he returned to work.

  No one else was in the lab yet. Henry had come to work early on purpose. His cubicle was at the far end of the common room, farthest from the door, and he hadn't wanted to face the others, to run the gauntlet of their pity. Not right away. He had wanted some time alone, with Barbara, in the cell library.

  She really was there, in a way. The culture dish contained all the information that was Barbara. Everything, that is, except the experiences and memories that had made Her a person rather than an organism. He told Her how much he missed Her, but mostly he was just silent, remembering things. Then he noticed the time and slipped hastily out of the cell library before anyone could see him there. People wouldn't understand and might think him a little odd.

  He returned to his cubicle and looked around vaguely, as if he were in a strange country. He fiddled with the clutter on his desk and wondered how far Bill had gotten on their project. Bill hadn't been idle, he was sure. The guy was a certified workaholic. The two of them worked well together. The tortoise and the hare. Bill was a great one for leaping ahead in flashes of intuition; while Henry was the plodder who filled in the details and proved whether Bill's gut feeling was something more than what he had eaten for breakfast.

  Well, he couldn't sit here all day looking like a zombie. Lord knows what the others would read into that. He activated the terminal screen and began studying the logbook. Minutes went by.

  "Henry!"

  He turned and saw his partner, Bill Canazetti shrugging out of his jacket. Was it 0800 already? Canazetti laid a hand on Henry's shoulders, a heavy hand that was supposed to be reassuring. "I was so sorry to hear about Barbara," he murmured. "We all were. She was the best."

  Henry took a deep breath. He had been dreading this ritual all morning. Everyone would feel obligated to say something to him. Something to remind him of what he only wanted to forget. The fact that most of them had already done so at the funeral wouldn't stop them. Perhaps it satisfied some inner need; a need to participate in another's grief. Certainly, it did nothing for Henry except pick at the psychic scab. But he could face their awful sympathy now. He really could.

  "Never mind that," he told Canazetti, more gruffly than he had intended. Bill looked hurt, so he added, "it's over with. And besides, Barbry's not really gone. She's still with me. Now it's time to get on with life."

  "Yes, I suppose." Canazetti looked uncomfortable. "Is there—well, anything I can get you?" He was like all the others; eager to help where no help was possible.

  "A cup of decaf would be nice," Henry told him. "I do need to catch up on our project. Let me just read the notes here and then you can fill me in on the details."

  Canazetti nodded slowly. "All right." He left and Henry immersed himself in the notes on the Barnsleyformer.

  He and Bill had been working to improve SingerLabs' line of cell repair nanomachines. To achieve the elusive goal of Whole-Body Repair.

  C/R nannies had changed the face of medicine over the last ten years, ever since Singer had created the first one. Repairing damage to tissues was easy now. All the doctor had to do was inject a dose of microscopic machines into the affected tissue. The nannies would visit each cell; compare it to the blueprints stored in the nucleus; disassemble any proteins not to spec; and reassemble them properly.

  The problem was that, if multiple trauma was involved, only one tissue at a time could be treated. Each nanny was designed specifically for a certain tissue; and, if two nannies were introduced into the body at the same time, each would perceive the other as a foreign body and engage in a war of mutual extermination.

  The information load was the limiting factor. The nannies were controlled by microscopic processors, dubbed Big NIM, that compared DNA strands in triplicate and directed the myriads of C/R machines. But even a single tissue complex involved an incredible amount of data. As Carl Sagan might have put it: Billions and Billions of Bits. There were hundreds of different proteins: enzymes and hormones. There were mitochondria, granules, and countless other cellular structures; each with a detailed set of "drawings" that described what it should look like. The limit seemed to be one tissue per nanny. Whole Body Repair seemed out of reach. There was just too much data to store and process. Big NIM always ran out of memory, no matter how much they stretched its capacity.

  Bill and he had been ready to quit at one point. They had gone to see Old Lady Peeler to tell her it was impossible. There
was a natural barrier, they had said, like the speed of light. Information bits must be carried on matter-energy "markers," and that set a lower limit on the scale for information processors. The machine could not be smaller than its information content. So, there was no way nano-scale processors could ever handle the data load for an entire organism, at least for an organism at the human level of complexity.

  Dr. Peeler had listened to them in silence. Then she stared thoughtfully into the distance, working her lips. Finally, she had shaken her head and muttered, as if to herself, "I wonder how genes manage to do it."

  And of course she was right.

  Genes were natural nanomachines; yet they managed to build an entire complex organism from a single, undifferentiated cell. Morphogenesis, the biologists called it. The "unfolding" of structure from simplicity. Somehow, a zygote managed to contain all the information needed to grow a complete adult.

  And that was a paradox.

  Because the genes really weren't big enough to handle the information load. There just wasn't room for a complete set of elaborate blueprints in such a small space. Yet there had to be. Finally, in frustration, Henry had blurted out, "Maybe there aren't any blueprints at all!"

  And that had reminded Bill of something. A dimly recalled oddity of the early 1980s. Michael Barnsley, an early chaotist, had discovered that random inputs to certain recursion formulas always generated the same precise shape. Take a simple random process, like tossing a coin, and define a positioning rule for each outcome. If the coin lands "heads," move a specified distance and direction from the current position. If "tails," a different distance and direction. Then start somewhere—anywhere!—on a grid and flip a coin. After the first fifty moves or so, start marking the positions where your random process takes you. Eventually, the recorded points will accumulate into a definite shape—the "limit shape." Iterate the process thousands of times. The limit shape is always the same, regardless of the actual sequence of coin tosses.

  Somehow, the end result was encoded in the formula itself, irrespective of the input. It was like a magical machine that always produced the same product, no matter what raw material it was fed.

  One set of Barnsley's recursion formulas generated a drawing of a fern leaf. The same leaf appeared every time he ran the simulation, regardless of the particular random inputs. That led him to suggest that the genes contained information, not on how the leaf was shaped, but on how to run the recursion formulas. With that information in hand, random chance took care of all the rest.

  Many biologists, and even some other chaos scientists, had objected. There is no room for randomness in biology, they had argued. In biology, randomness is death.

  Which was true, but they had missed the point. Randomness was built into the universe. The physicists had shown long ago that randomness underlay all phenomena. It impinged constantly upon biological growth and evolution. Yet, individuals within a species always matured into the same basic shape. Sometimes, two people, unrelated to each other, even wore the same face. And species living in similar ecological niches evolved into similar forms. There had been sabre-tooth cats in Pleistocene North America. There had been sabre-tooth marsupial "cats" in Pleistocene South America. Everywhere the same shapes asserted themselves. The stems of a flower species always branched precisely so. Every flower.

  Once again, science had shown that there were always simple answers to complex questions. Barnsley's algorithm was a transformer. Like an electrical transformer, it changed one thing into another. In this case, it transformed random causes into deterministic results. Bill had dubbed the mechanism a Barnsleyformer, but Henry had his own private name.

  He called it the Template of God.

  Thus far, their work on that fatal Thursday, two weeks ago, Bill and he had learned how recursion formulas generated structure; but they had been stuck on the inverse process. Generating the structure from the formulas was one thing.

  Deducing the recursion formulas from the structure was more difficult. Now Henry saw that Canazetti had found a promising solution and he followed the reasoning closely in the log. Bill had decided that the recursion formulas worked the way they did because certain creatures of the generated structures were "fractal." That is, they were invariant under changes of magnitude. He had developed a technique he called "tyling," in which the structure was tyled with smaller and smaller replicates of itself. In this way he was able to create inductively the generating equations.

  "The trick," he said in Henry's ear, "was getting the number of dimensions right."

  Canazetti's unexpected voice made him jerk and he looked around over his shoulder.

  "Sorry," said Canazetti, handing him his coffee.

  Henry frowned and sipped the brew. He grimaced and looked at the cup. It was as bad as he remembered. He set it aside. "Dimensions," he prompted.

  "Right." Canazetti pulled out his desk chair and rolled it under his backside. "A coin toss gives you a Barnsleyformer with up to two dimensions, a plane. But how many do we actually need?"

  "Three," Henry replied. But he suspected he was wrong. Otherwise, why would Bill have asked him?

  "Wrong." Canazetti shook his head emphatically. "And, once again, the physicists have been there ahead of us. Damned mechanics. Every time a bioscientist rolls over a new rock, he finds a physicist underneath it. No, Henry, there are actually eleven dimensions." Henry looked skeptical, and Canazetti shrugged. "Take my word for it." He held up his fingers. "Three gross spatial dimensions," he said, counting them off. "Length, height, and breadth. Seven quantum hypo-dimensions rolled up in what they call subspace. And . . ." He had run out of fingers and he looked blankly at his hands for a moment before shrugging.

  "And time. I've logged the references in there." He pointed at the disc drive.

  Hemy decided he would review the literature later. It sounded bizarre to him, but then, most of modern physics did. "Then Barnsleyformers must generate biological structure in all eleven dimensions," he murmured. "Son of a bitch. The morphogenesis must be incredibly more complex than we thought No wonder our three dimensional models—Hey, wait a minute!" His head shot up.

  "What?"

  "All the dimensions? Including time? That can't be."

  "Oh? Why not?'

  "Because the time dimension of an organism is its lifespan. How can the gene know ahead of time how long the organism will live?"

  Canazetti shrugged again. "I don't know. It's a hunch. Did you ever read Heinlein's story, Lifeline? But I suspect that the time dimension of the structure only specifies endogenous death. You know, from internal causes, like old age or birth defects. Exogenous death comes from outside the organism. Accidents, like being hit with a virus or an automo—" He cut off abruptly and looked embarrassed. "Sorry."

  Henry was more upset by Canazetti's circumspection than by any reference to Barbara's death; but he kept his silence. What did happen to the morphogenetic pattern when death came from the outside? Eleven dimensions. Might not some part of the pattern survive the truncation, at least for a while longer. At least until the original time span was reached? The Egyptians had believed something of the sort. That the spirit lived on—but only for a while—somewhere beyond our normal senses. There were, after all, those seven other dimensions Canazetti had mentioned. Subspace. Might the "soul" live there?

  A thought began to form in the back of his head.

  Something nebulous and disturbing, that made his chest tremble inside. He ignored it. "Have you begun in vivo experimentation?" he asked.

  "Just last week. I reprogrammed a scyphozoan cell-repair machine with recursion formulas tyled from its own DNA."

  "A jellyfish?"

  Canazetti waved his hand the way only an Italian could. "I wanted something simple enough for a first try, but complex enough to be interesting."

  "And?"

  Canazetti reached past Henry and pressed a few buttons on the computer terminal. A damaged molecular chain appeared on the screen. A phosphorus gro
up was missing entirely and several carbon rings were broken. "These are the scans recorded through the digital microscope," he told him. "Watch."

  Something crawled across the molecules. It looked to Henry like a slime mold; or like tarnish growing at high speed across a set of copper Tinker-Toys. The colloidal agar for the cell repair nano-machines. After a few moments, it faded and the molecules underneath reappeared. Henry whistled.

  "Like brand new," he said. "And fast."

  Fast. What if it had been available two weeks ago? Would it have been fast enough? Henry refused to let himself think about that.

  "Yeah." Canazetti's voice was less than ecstatic and Henry looked a question at him. Canazetti waved his hand in frustrated loops. "There're still a couple of stumbling blocks," he admitted. "For one thing, if you program the nanny with the DNA of one jellyfish, it doesn't work so well on other jellyfish."

  "How so?"

  "Well, every jellyfish carries the basic 'I-am-a-jellyfish' information, but it also carries information that individualizes it: 'I-am-Joe-the-jellyfish.' So, if you use it on a different individual, the nanny tries to restructure it as well as repair it."

  Canazetti called up another visual on the terminal. "The jellyfish on the left," he said, "was repaired with nannies grown from the DNA of the one on the right."

  Henry inspected the two cell diagrams. "How close is the match?"

  "Eighty-seven percent."

  "Nearly complete." Henry's own voice sounded far away. He could hear the rush of his blood in his ears. He felt light-headed. Nearly complete.

  "Only if the donor and recipient are the same species," said Canazetti's voice. "Otherwise it doesn't work at all. Rejection sets in. Even within a species, I suppose the greater the initial similarity, the better it would work. That's just a hunch. But it doesn't help the doctors any. We want to repair cells, not rearrange them."