Paolo felt a stirring of unease. Emigration and suicides? Was that why Orlando had been so gloomy? After the disaster of the Forge, and then another three hundred years of waiting, how high had expectations become?
A buzz of excitement crossed the floor, a sudden shift in the tone of the conversation. Hermann whispered, mock-reverentially, "First microprobe has surfaced. And the data is coming in now."
The non-sentient Heart was intelligent enough to guess its patrons' wishes. Although everyone could tap the library for results, privately, the music cut out and a giant public image of the summary data appeared, high in the chamber. Paolo had to crane his neck to view it, a novel experience.
The microprobe had mapped one of the carpets in high resolution. The image showed the expected rough oblong, some hundred meters wide—but the two- or three-meter-thick slab of the neutrino tomographs was revealed now as a delicate, convoluted surface—fine as a single layer of skin, but folded into an elaborate space filling curve. Paolo checked the full data: the topology was strictly planar, despite the pathological appearance.
No holes, no joins—just a surface which meandered wildly enough to look ten thousand times thicker from a distance than it really was.
An inset showed the microstructure, at a point which started at the rim of the carpet and then—slowly—moved toward the center. Paolo stared at the flowing molecular diagram for several seconds before he grasped what it meant.
The carpet was not a colony of single-celled creatures. Nor was it a multicellular organism. It was a single molecule, a two-dimensional polymer weighing twenty-five thousand tons. A giant sheet of folded polysaccharide, a complex mesh of interlinked pentose and hexose sugars hung with alkyl and amide side chains. A bit like a plant cell wall, except that this polymer was far stronger than cellulose, and the surface area was twenty orders of magnitude greater.
Karpal said, "I hope those entry capsules were perfectly sterile. Earth bacteria would gorge themselves on this. One big floating carbohydrate dinner, with no defenses."
Hermann thought it over. "Maybe. If they had enzymes capable of breaking off a piece—which I doubt. No chance we'll find out, though: even if there'd been bacterial spores lingering in the asteroid belt from early flesher expeditions, every ship in the Diaspora was double-checked for contamination en route. We haven't brought smallpox to the Americas."
Paolo was still dazed. "But how does it assemble? How does it… grow?" Hermann consulted the library and replied, before Paolo could do the same.
"The edge of the carpet catalyzes its own growth. The polymer is irregular, aperiodic—there's no single component which simply repeats. But there seem to be about twenty thousand basic structural units, twenty thousand different polysaccharide building blocks." Paolo saw them: long bundles of cross-linked chains running the whole two-hundred-micron thickness of the carpet, each with a roughly square cross-section, bonded at several thousand points to the four neighboring units. "Even at this depth, the ocean's full of UV-generated radicals which filter down from the surface. Any structural unit exposed to the water converts those radicals into more polysaccharide and builds another structural unit."
Paolo glanced at the library again, for a simulation of the process. Catalytic sites strewn along the sides of each unit trapped the radicals in place, long enough for new bonds to form between them. Some simple sugars were incorporated straight into the polymer as they were created; others were set free to drift in solution for a microsecond or two, until they were needed. At that level, there were only a few basic chemical tricks being used… but molecular evolution must have worked its way up from a few small autocatalytic fragments, first formed by chance, to this elaborate system of twenty thousand mutually self-replicating structures. If the "structural units" had floated free in the ocean as independent molecules, the "lifeform" they comprised would have been virtually invisible. By bonding together, though, they became twenty thousand colors in a giant mosaic.
It was astonishing. Paolo hoped Elena was tapping the library, wherever she was. A colony of algae would have been more "advanced"—but this incredible primordial creature revealed infinitely more about the possibilities for the genesis of life. Carbohydrate, here, played every biochemical role: information carrier, enzyme, energy source, structural material. Nothing like it could have survived on Earth, once there were organisms capable of feeding on it—and if there were ever intelligent Orpheans, they'd he unlikely to find any trace of this bizarre ancestor.
Karpal wore a secretive smile.
Paolo said, "What?"
"Wang tiles. The carpets are made out of Wang tiles."
