Second Genesis gq-2

by Donald Moffitt

  “Now we take those forty-five-degree angles and subdivide them again,” Jao said.

  Eight more lines grew within the spoked figure. These were dotted lines, even paler and more tentative than the lines of the second cross. Not all of them were full-length. Several of them still fell short of the yellow dot’s circular orbit.

  “These are your follow-up extinctions,” Jao said to Jorv, “The ones you say sometimes follow the main events thirteen to fifteen million years later. They subdivide the twenty-six-million-year intervals, and they’re growing outward at different rates, so we can’t fit all of them into the picture. Yet.”

  “Very thin,” Smeh said.

  “So we start with what we do know. Here’s the dinosaurs.”

  One of the arms of the original cross thickened and darkened to burnt orange. The tenuous dotted line following it began to blink for attention.

  “Okay, anything there?” Jao asked.

  Ame and Jorv looked at each other. “The Miocene crisis,” Ame said immediately. “A mass wipeout of shellfish, plankton, some land animals. But it’s only twelve million years later.”

  “Close enough,” Jao said. “Now, let’s skip back one hundred and fifty-five million years to the other really major crisis. The one that wiped out half of all animal families on Earth. Have we got a secondary extinction associated with it?”

  “Yes,” Ame said, catching her breath. “A bigger one this time. A very large extinction of marine organisms that could fall within a ten- to fifteen-million-year period. We couldn’t fit it into our data before without stretching it.”

  “All in knowing how,” Jao said with a grin, while Smeth smoldered.

  Jao thickened the axis and shaded it over to include the following arm. “Very interesting,” he said. “The two big ones are at right angles to each other. Forming two arms of the older cross. And it’s the arms sprouting in their wake that turn out to be the real killers.”

  “As if whatever it is was getting stronger,” Ame suggested.

  “Yah.”

  “Jao—”

  “Not yet. Let’s fill in as many blanks as we can first.”

  Over the next several minutes they assigned eleven extinction episodes to the rotating spokes. Nine of them fit the pattern of the eight major spokes, and two fell within the secondary following position.

  “How do you explain the missing pieces?” Smeth asked.

  “How should I know?” Jao rumbled. “Insufficient data. Fluctuations in the strength of the spokes. Maybe factors that we haven’t figured yet. The sun catches up with a spiral arm every hundred million years or so and stays inside for ten million years. It bobs up and down through the plane in a thirty-three-million-year cycle, if it behaves like the other stars at that radius. Maybe the dust intensifies the killer effect on some passes. Maybe it does the opposite and acts as a shield. Why don’t you try to combine all the cycles and see what you can work out? The important thing is that everything we do have fits the pattern.”

  His belligerence died. Like everybody else in the observatory he was staring at the one big fact that hung before them in the rotating holo image.

  “The ninth extinction and the first extinction are doubled up on the same spoke,” Ame said in a half whisper.

  “It came back again for a second swipe,” Jao said.

  “The second visitation was the last extinction before human beings evolved.”

  “The first swipe was the big double event,” Jorv said. “First the trilobites and all that plankton—ninety percent of sea life. Then half of all animal life on Earth.”

  “And if there was a … a similar follow-up,” Ame said, “it would have come at just about the same time that Original Man disappeared from the universe.”

  Smeth’s harsh voice grated through the ensuing silence.

  “It couldn’t be. Man is an intelligent being, not a—a dinosaur! He would have found some way to protect himself. Or flee. After all, it isn’t as if the entire Milky Way was sterilized the way the Father World’s galaxy was. Some life survived each of these—extinctions and went on to evolve.”

  “When the dinosaurs disappeared,” Jorv said, his young voice getting away from him, “no species of land animal weighing more than twenty pounds survived. Man’s ancestors were very small and primitive. It was the highly evolved species that went. The second time around, that was man.”

  Jao stared thoughtfully at the rotating orange arms of his holo model. “Original Man had only spread a few hundred light-years. At most, a few thousand. You can’t travel faster than the speed of light. You can’t outrun something that extends to the galactic rim and sweeps the galaxy laterally. They could only have caught up with the previous killer arm.”

  He retreated into gloomy contemplation. Nobody else seemed very lively, either. Bram was just about to say something, when Jun Davd did it for him.

  “Let’s not jump to conclusions,” Jun Davd said. “This is all highly speculative. Jao doesn’t have a theory, just a hypothesis. We need more data. We’ll set up a long-term computer model and keep feeding our observations into it.”

  Yah, I’ll get on that today,” Jao said.

  Jan Davd went on, “Original Man’s sector of the galaxy is about thirty thousand light-years from the center, and on our outward spiral, we’ll sweep great areas of the disk over a real-time period of tens of millennia. We’ll be able to make observations that were not possible for Original Man, no matter how much further advanced than us he was.”

  Ame and Jorv looked puzzled, and Jun Davd added gently, “The time wasn’t there for him, you see.”

  As it sank in, the tension began to go out of the room. A few tentative smiles made their appearance. Ame brought her chin up and said to Bram, “You’ve brought us this far, Bramtsu. Nothing can frighten us now. This galaxy is humankind’s heritage, and we’re here to claim it.”

  Smeth edged forward, trying to reestablish contact with Ame. “That’s right,” he said. “The whole thing may be nothing more than a statistical fluke, anyway.”

  “There’s just one thing.” Jao’s voice brought their heads around again. “If the eight-arm model is correct, our sector of the galaxy is due for another brush soon.”

  His hand swept the board, and the rotating orange lines snapped out of existence. The universe came terrifyingly back into sight, a raw torrent of light that slammed them across the eyes and turned the human figures into stark silhouettes. Yggdrasil’s plunge toward periastron had carried it past the black hole’s equator, and the accretion disk had risen out of the floor.

  CHAPTER 5

  “There’s a star in there somewhere,” Jun Davd said through his suit radio. “Its light may be blocked, but it’s shining its heart out in the ten-micron infrared range.”

  Bram clung to a cleat with one gloved hand to keep the trunk’s slow rotation from shedding him into space and turned up the magnification of his helmet visor. “A body-temperature star,” he said. “That fits the picture, all right.”

  He peered past the leafy horizon at a void that was frosty with stars again. After more than two decades of braking, the starbow had separated and strewn its baubles across the sky. The drive was off, and Yggdrasil was towing the probe now, not the other way around.

  But despite the magnificence of the sprinkled stars, it was the sight in the center of his image compensator that occupied Bram’s full attention.

  There was a scratch across the sky—a perfectly straight line, as if a cosmic thumbnail had scraped away the black. Next to the long scratch was a collection of bright squiggles, like cursive writing in an unknown language.

  “The straight line’s about ninety million miles long,” Jun Davd said. Within the crystal bowl of the new space suit, his dark profile was intent on the distant object. “That’s about the same length as the radius of the infrared emission shell the instruments can detect. Does that suggest anything to you?”

  “The only astronomical phenomenon I can think of
that’s that straight and that long is a Type I comet tail,” Bram said. “Except that there’s no coma at one end. In fact, the brightest part, if I read the instruments right, is in the middle.”

  “Yes,” Jun Davd agreed. “And it doesn’t extend outward from where the mass indicators say our shrouded star ought to be. It’s tangent to it.”

  “So that suggests very strongly that it has something to do with the structure that’s enclosing the star. And that those curved scratches—the arcs and hooks—are part of the same manifestation.”

  Jun Davd turned to face him: Somehow Jun Davd managed to be limber, even in the bulky envelope of the human-shaped space suit that had been developed during the last ten years of deceleration by a team under the direction of Lydis. He had the toe of one heavy boot hooked under the horn of a cleat to check his outward drift, and his long-limbed body swiveled halfway around at the hips with a natural grace. He was not one of those people you saw bobbing around at the end of their safety ropes and having to haul themselves in.

  “I agree. I have a computer working on an analysis of the curvatures to see what kind of a three-dimensional shape we can make them fit into. But clearly, we’re looking at an artifact.”

  Artifact. Bram tasted the word with disbelief. From the size of the infrared emission shell, the unseen sun ought to have been a red giant—a swallower of solar systems. An artifact of that radius at the center of the Father World’s system would have engulfed the two inner planets and the Father World itself.

  “A trap around a star,” Bram said slowly. “A trap for energy. When we first began searching for an enclosed star radiating in the ten-micron part of the spectrum, I somehow visualized something like a sphere. I think we all did.” He paused to stare again at the distant wonder. “It’s hard to imagine how any rectilinear material body the size of that could maintain its shape without gravitationally collapsing.”

  “There’s only one answer, then. It’s not straight.”

  Bram looked again, but the line was just as straight as before. “It’s not?” he said.

  “We’re looking at the illuminated limb of another geometric form,” Jun Davd said. “One that can maintain its shape. I can think of at least two: a cylinder and—”

  “Yes,” Bram breathed. “A disk. A spinning disk. Seen edge-on. But it’s still unbelievable.”

  “We don’t know what was possible to Original Man at the height of his glory. Perhaps, given another forty or fifty thousand years, the Nar might have learned how to utilize the total energy of a sun.”

  “Do you really think that’s Man’s sun in there?”

  Jun Davd wrinkled his brow. “One of the suns he used, perhaps. The sun that gave him birth, no. I can’t see him dismantling his own father world to make a beacon. There’s nothing in this system larger than an asteroid. Nothing but a swarm of comets orbiting an invisible mass. And we’re lucky he left us the comets.”

  He broke off to stare across the miles at the cagework trumpet bell of the ramscoop, which was no longer bathed in the spilled energies that had made it bright. A couple of comets had already been stuffed down its throat as start-up fuel for the next intersystem hop—the hop that the absence of worlds here had made unavoidable.

  A space tug floated nearby, waiting to field the next slushball to be sent onward. Two tugs, actually, with a five-mile-wide net strung between them. It was the net that was visible as a fleck of light from a reflected spotlight beam. Bram wondered if his daughter Lydis was one of the pilots.

  Closer at hand, against the fibrous wall of the root system across the way, a work crew was prying another ensnared comet away from Yggdrasil—a small one, less than a mile in diameter. With his magnification up, Bram could just make out the tiny space suited figures. They were melting away the clinging ice with dozens of two-man torches. It would require exquisite nicety of timing on the part of the foreman to make sure that the frozen sphere broke loose at just the right moment to cast it toward the waiting tugs instead of outward into the dark.

  Yggdrasil could spare a few comets. Scores of the captured iceballs beaded the thirsty surface of its root hemisphere. The tree was working bravely to redistribute mass, but the unassimilated treasure trove still caused a wobble in the crown that took some getting used to. There was a lot of dropped glassware in the living quarters these days, but nobody was complaining. Abundance had returned to the tree after the long drought. The pools were filled, there was boating in the lagoon again, and water sports in the spherical pond at the center of the trunk. More important was the increase in metabolic products as Yggdrasil went through a growth spurt—sugars, starches, complex resins, and new cellulose for the factories.

  Bram remembered the excitement when they had entered this queer, gutted system. Four previous ten-micron emission sources had proved to be false alarms—supergiants with circumstellar emission shells that were probably heated dust grains, not worth slowing down for. But the fifth candidate had shown all the symptoms of what the search team had jokingly taken to calling “Jao’s shell.”

  It was Jao who first had proposed the theory of an enwrapped star whose output—by whatever unknown means—had been translated into the cosmos-spanning radio waves of Original Man’s beacon.

  “Where’s all that building material going to come from?” Smeth had scoffed.

  “From the dismantled planets,” Jao had replied. “And maybe they’d have to haul over the planets from a couple of nearby systems, too. They’d be turned into some kind of supermaterial made mostly of hydrogen, carbon, and oxygen—the atmospheres of a couple of gas giants mixed with the goodies at the core, and some cometary ice—you get the picture.”

  “How are you going to keep the shell from drifting off center?” Smeth had expostulated. “And if it rotates, how do you keep its substance from collecting at the equator?”

  “Details,” Jao had replied airily. “We’ll worry about them later. The main thing is to look for infrared sources that fit the basic picture.”

  The search area had been narrowed down to a sphere a thousand light-years in diameter. The Nar, long ago, had pinpointed an approximate location for Original Man’s sun by analyzing wave fronts on a line stretched between the Father World and the new outpost on Juxt, and they had arrived at a value for the galactic year at that radius. Jun Davd, during the thirty-seven-million-year head-on approach to the Milky Way, had refined the figure still further. When the M supergiants and the small hot objects shining through dust had been eliminated, the number of candidates was small. Even so, it was surprising to have found it, apparently, on the first try.

  “I calculate a total energy output for our invisible sun of four times ten to the thirty-third power ergs per second,” Jun Davd had announced shortly after Yggdrasil had settled into a cometary orbit. “That’s based on the number of ergs per square inch falling on our collectors and applying the figure to an imaginary sphere at the radius of our own orbit. All in the deep infrared! It’s consistent with the normal output at all wavelengths of a G-type dwarf similar to both Original Man’s presumed sun and the Father World’s primary. An attractive sun for our type of life, and the Nar’s.”

  Jao had worked out approximate orbital periods for the first few comets Yggdrasil had chased. “Yah,” he’d said. “The comets are moving at the right speed for the postulated mass at the center. Maybe just a little bit high—but, like I said, the beacon builders might’ve dragged in an extra gas giant or two from another system.”

  It was going to be hard to pry Yggdrasil away from the comets after its long thirst. Bram—year-captain again for the fiftieth time—was under a lot of pressure to let the tree graze peaceably for a while in the outer reaches of the cometary halo. The human population of the living spaceship was now up to twenty-five thousand. It was getting a bit crowded along the axis of acceleration. The younger generation in particular had its eye on all the congenial real estate that would open up in the other branches if Yggdrasil went on permanent rotation m
ode.

  But Bram did not dare give in. He had the feeling that if the populace spread out this time, he’d never get them back to the axis.

  At Yggdrasil’s leisurely rate of travel, it would take decades to drift from star to star—centuries or even millennia to search out the G-type dwarfs in this sector of the galaxy for the traces of Original Man. The new people did not have the same sense of urgency—the idea of a goal. For them, Yggdrasil was a way of life. It was more than possible than the citizenry could vote to settle in the first system that had rocky bodies to mine, a cometary shell to seed with a crop of more Yggdrasils.

  Sometimes, on bad nights, Bram had a nightmare that he would never make planetfall again.

  No, he thought. The only solution was to get his little convoy under fusion acceleration as quickly as possible, investigate the mystery at the heart of this system, then boost out again at one g.

  Certain it was that Yggdrasil, left to its own devices, was not going to get much of an outward kick from the starlight to be found here!

  Beside him, Jun Davd said, “I saw something just then.”

  Bram looked, but saw nothing except the faint scratch in the darkness and its attendant squiggles.

  “Within the curve of the larger arc,” Jun Davd said.

  Large, at this distance, meant nothing much more than a fairy’s hangnail, even under full magnification, but Bram stared till his eyes watered.

  Then he could just make it out—the dimmest of patches, like a foggy speck in his faceplate.

  “It’s leaking light,” Jun Davd said. “There are holes in it. That’s diffuse reflection on a surface. Keep watching. And if I’m not mistaken…”

  As if someone had punctured the fabric of space with a pin, a star peeped forth.

  “It’s not the whole star, of course,” Jun Davd mused. “It’s probably the light from no more than ten or twenty percent of its surface to judge by the apparent magnitude. But we wouldn’t have seen a disk, anyway, at this distance, just a point of light.”