Permutation City Read Online Free PDF Page B

transforming it from a virtual poison into a source of food.
     
    Maria displayed a histogram of mutations occurring in the bacteria's three nutrose epimerase genes; the enzymes these genes coded for were the closest things A. lamberti had to a tool to render mutose digestible -- although none, in their original form, would do the job. No mutants had yet persisted for more than a couple of generations; all the changes so far had evidently done more harm than good. Partial sequences of the mutant genes scrolled by in a small window; Maria gazed at the blur of codons, and mentally urged the process on -- if not straight toward the target (since she had no idea what that was), then at least . . . outward, blindly, into the space of all possible mistakes.
     
    It was a nice thought. The only trouble was, certain portions of the genes were especially prone to particular copying errors, so most of the mutants were "exploring" the same dead ends again and again.
     
    Arranging for A. lamberti to mutate was easy; like a real-world bacterium, it made frequent errors every time it duplicated its analogue of DNA. Persuading it to mutate "usefully" was something else. Max Lambert himself -- inventor of the Autoverse, creator of A. lamberti, hero to a generation of cellular-automaton and artificial-life freaks -- had spent much of the last fifteen years of his life trying to discover why the subtle differences between real-world and Autoverse biochemistry made natural selection so common in one system, and so elusive in the other. Exposed to the kind of stressful opportunities which E. coli would have exploited within a few dozen generations, strain after strain of A. lamberti had simply died out.
     
    Only a few die-hard enthusiasts still continued Lambert's work. Maria knew of just seventy-two people who'd have the slightest idea what it meant if she ever succeeded. The artificial life scene, now, was dominated by the study of Copies -- patchwork creatures, mosaics of ten thousand different ad hoc rules . . . the antithesis of everything the Autoverse stood for.
     
    Real-world biochemistry was far too complex to simulate in every last detail for a creature the size of a gnat, let alone a human being. Computers could model all the processes of life -- but not on every scale, from atom to organism, all at the same time. So the field had split three ways. In one camp, traditional molecular biochemists continued to extend their painstaking calculations, solving Schrödinger's equation more or less exactly for ever larger systems, working their way up to entire replicating strands of DNA, whole mitochondrial sub-assemblies, significant patches of the giant carbohydrate chain-link fence of a cell wall . . . but spending ever more on computing power for ever diminishing returns.
     
    At the other end of the scale were Copies: elaborate refinements of whole-body medical simulations, originally designed to help train surgeons with virtual operations, and to take the place of animals in drug tests. A Copy was like a high-resolution CAT scan come to life, linked to a medical encyclopedia to spell out how its every tissue and organ should behave . . . walking around inside a state-of-the-art architectural simulation. A Copy possessed no individual atoms or molecules; every organ in its virtual body came in the guise of specialized sub-programs which knew (in encyclopedic, but not atomic, detail) how a real liver or brain or thyroid gland functioned . . . but which couldn't have solved Schrödinger's equation for so much as a single protein molecule. All physiology, no physics.
     
    Lambert and his followers had staked out the middle ground. They'd invented a new physics, simple enough to allow several thousand bacteria to fit into a modest computer simulation, with a consistent, unbroken hierarchy of details existing right down to the subatomic scale. Everything was driven from the bottom up, by the lowest level of physical laws, just as it was in