Destroyer of Worlds

by Larry Niven

  Finally, Baedeker checked the shelter’s external radiation sensor. It barely registered. This moon generated enough of a magnetic field to shield against the radiation belts of the nearby planet. The local field originated in the currents in the salty ocean just beneath his hooves.

  “Ready,” Baedeker declared reluctantly.

  “About time,” Kirsten said. “They’re waiting for us.”

  As though he had not known. What Citizen on an unknown world would not monitor all available surveillance sensors? He tongued a mike control. “We’re coming out.”

  “Excellent,” a Gw’o responded. “We have much to do.”

  Er’o, Baedeker read. So the AI, too, could identify Gw’oth from auditory cues. That made sense. Clearly Jeeves recognized humans and Citizens from their speech.

  The Gw’oth who spoke English—more by the hour—had personalized their voices. Baedeker had noticed emphases on different harmonics and slight variations in pitch. Whether he could rely on the Gw’oth to maintain consistent auditory cues remained to be seen.

  The shelter air lock accommodated only one person at a time. Baedeker let Kirsten precede him, as a favor more than from caution. He activated intrusion alarms. Then his turn came and he stepped onto the icy, vacuumcloaked surface.

  Eight Gw’oth waited in a semicircle beyond the air lock. Despite their transparent protective suits Baedeker could not tell them apart. One stood on all five limbs, the rest on three. The freed limbs coiled around unfamiliar devices or were merely held aloft (for a better view, perhaps).

  The gas giant hung overhead, at nearly full phase, luminous with an eerie blue light. Blue because methane in its upper atmosphere absorbed red. The distant sun could not compete. Baedeker raised his suit heater against a chill he knew was psychological.

  Most directions offered only rippled ice out to the unnaturally close horizon, but a mountain stood a short walk away. Tall structures all but hid its slopes. Solid, aboveground land was exceedingly scarce on this world. Baedeker looked at the peak in vain for a flat, unused expanse where he and Kirsten might relocate their shelter.

  The Gw’o standing on all fives scuttled closer. “Hello again,” it said. “Shall we proceed to the observatory?”

  Er’o, Jeeves commented unnecessarily.

  Baedeker gestured at the shelter. “If used improperly, our equipment can be dangerous.” Such as the self-destruct charge rigged to the intrusion sensors. “For your safety, no one should attempt to enter when we are away.”

  Er’o waggled a limb side to side. (An acknowledgment? A dismissal?) “Thank you for the warning.”

  “Er’o, would you introduce us to your companions?” Kirsten looked unhappy, and Baedeker supposed she was changing the subject.

  “They are not important,” Er’o answered, repeating that side-to-side limb gesture. He started toward the mountain without turning; the two closest of the unnamed Gw’oth accompanied him. The rest took up positions around Kirsten and Baedeker.

  Guards, Baedeker decided: They grasped weapons. Protecting Er’o from Kirsten and Baedeker, or protecting all of them from some external enemy? With a mind of its own one of Baedeker’s forehoofs pawed the ice, spraying ice slivers.

  An escort edged closer, and Baedeker’s radio offered a burst of hums and chirps. Come with me, Jeeves translated on the HUDs.

  They set off together after Er’o.

  An elevated tram went up the mountainside. Its cars were far too small for Baedeker or Kirsten. They proceeded on foot, single file, up a narrow switchback road apparently vacated for their use. Tall buildings to both sides closed off Baedeker’s view. Bare limb tips—thousands of them!—pressed against the windows. Gawkers? Bubbles behind the glass proved what logic had foreseen: water-filled habitats.

  Baedeker peered down cross streets as they passed. Everywhere, Gw’oth in protective suits rushed about on their unknowable business. Some stopped and raised a limb or two, staring, as the entourage passed. He and Kirsten might even have inspired a vehicle crash.

  He was winded as they approached the summit, but also oddly comforted. It was the gapers, he decided. Water dwellers living above the ice were probably the elite, but they gave no evidence of dangerous genius. Er’o was dangerously perceptive, but you would send your best mind to a first contact.

  “This is a fascinating city,” Kirsten was saying. “How many Gw’oth live here?”

  “This is more a research center than a regular city,” Er’o said.

  Not an answer, Baedeker noticed. Was the population a secret?

  “A large research center,” Kirsten persisted. “What types of research?”

  “Many kinds,” Er’o answered vaguely. “But I see we have arrived. For now we will concentrate on astronomy.”

  They rounded a corner and their way forward was in shadow. Baedeker looked upward at the metal dish of a radio observatory. Behind a sturdy (but only knee-high) fence, a squat building served as the antenna’s base.

  “We are here,” Er’o announced, adding something unintelligible in his own language. (A security code, Jeeves guessed.)

  The gates opened, and Er’o passed through. Kirsten and Baedeker stepped over the wall. The guards remained outside.

  Now their work began.

  BAEDEKER WAS HAPPY TO LEAVE their escorts at the barricade. Tiny though Gw’oth were, small weapons could make large holes.

  More Gw’oth met them in the courtyard. These were introduced. In order of ascending pitch, their new acquaintances were Kl’o, Ng’o, and Th’o. They looked as interchangeable as everyone else on this world. (Like three more peas in a pod, Kirsten offered without explanation.) All were mathematical physicists. From the intimacy in which they gathered, with Er’o joining the cluster, Baedeker knew they were close. He guessed they were part of an ensemble mind.

  “We will begin with the radio observatory,” Kl’o said.

  “Excellent,” Kirsten said. She peered up at the enormous dish. It was tipped toward the horizon, providing her an edge-on view.

  Baedeker inspected the antenna, too—more surreptitiously, he hoped—with the ambient-neutrino scanner clipped to a utility loop of his pressure suit. The steel was surprisingly thick and the ghostly image on the instrument screen showed why. All that metal was rife with flaws and microfissures. Here was another example that the Gw’oth had much to learn—in this instance, how to manufacture with atomic-level precision. Baedeker added nanotech to his mental list of the topics to be withheld from the Gw’oth.

  “Putting the antenna here was a compromise,” Er’o volunteered. “Someplace far out on the ice would have reduced the electromagnetic noise, but”—he pointed at the blue orb looming overhead—“the tides pull at the ocean and flex the ice more than they move the rock. The ice surface seldom fractures, but ruptures do occur. So we built on the mountain instead and correct for interference as best we can.”

  “We thought you might look at our filtering algorithms,” Kl’o added. “Perhaps you can suggest improvements.”

  The Gw’oth had set up several electronic slates in the courtyard, and Kirsten crouched over one. Kl’o and Kirsten (and surely Jeeves, in the privacy of her helmet) began a dialogue to learn each other’s mathematical notations. Er’o joined in with them.

  The last two Gw’oth approached Baedeker. Th’o said, “Another matter we hope you might comment upon is combining measurements across observatories. In theory, readouts can be integrated across a collection of instruments. Such a combination should offer the angular resolution of an apparatus as large as the distance between instruments. We have yet to achieve that result.”

  Aperture synthesis, Jeeves offered unnecessarily.

  The AI knew mostly centuries-old Earth technology. If Jeeves knew this technique, why had the Gw’oth not mastered it?

  Ah. The math was not difficult, but the data volumes were significant. Perhaps the Gw’oth ensembles could not process so much data. Baedeker felt more and more relieved. After a poin
t, biological computing surely became more limitation than asset. He plunged a head into an outside pocket to tap out and encrypt a private reminder to Kirsten: Disclose nothing about computers.

  Still, the Gw’oth were wise to ask about aperture synthesis. Baedeker said, “An instrument to span the world. That would give much more detail.”

  Th’o and Ng’o consulted among themselves, an extended dialogue of clicks and whistles. “There are some practical obstacles to an instrument that large,” Ng’o finally offered cryptically.

  Rivalries among political entities, Jeeves wrote, although I do not understand the details. They spoke in an unfamiliar dialect, one Kirsten never tapped on her earlier visits. I am confident of this much: These Gw’oth doubt they could link to distant observatories without revealing more to local authorities than they care to.

  Baedeker felt better and better. political entities sharing this little moon? How absurdly primitive! Citizens had been cohesive within one Concordance for millions of years. And a single world government had been a gift to their human Colonists, whether the New Terrans recognized their unity as such, or not.

  But he and Kirsten were here—even as Sigmund and Eric, aboard Don Quixote, sped from the singularity to report to their government—to get better data. He urgently needed to learn what was rushing at the Fleet. Revealing a little might be the lesser among imprudences.

  Baedeker said, “Kirsten and I can work more productively in our shelter, without our pressure suits. If you provide time-stamped data from several observatories and the exact locations of those observatories, maybe we can do something.” The math was straightforward enough; aperture synthesis merely took computing power. His pocket computer, away from prying eyes, would suffice.

  “I will make arrangements for a copy of the information,” Th’o offered.

  In small groups that formed and scattered and reassembled at dizzying speed, they discussed observations made across the spectrum. They reviewed the theoretical and practical limitations of various instruments. There was much the Gw’oth had yet to learn. Baedeker was resisting complacency when Er’o revealed, almost in passing, that consideration was being given to the subtle repositioning of several orbiting telescopes—

  To use stars between here and the oncoming phenomenon as gravitational lenses.

  Baedeker’s manic complacency vanished. It was all that he could do not to leap the fence and gallop to the shelter.

  In the short while since Don Quixote’s arrival, the Gw’oth had developed a theory of general relativity.

  17

  Hyperwave radio was a wonderful thing.

  Don Quixote was once more 4.5 billion miles from the star the Gw’oth knew as their sun, the separation increasing by fifteen thousand miles every second. It had been a ten-day trek to the edge of the gravitational singularity. Don Quixote could have crossed that distance in three days—if its tanks were fuller. Sigmund was not ready to depend on the Gw’oth for fuel for the trip home.

  Facing Sigmund and Eric in the main bridge display—from ten light-years away—was the New Terran security cabinet. They met in the relative comfort of a secure conference room in the Ministry of Defense. For a small, free-flying planet like New Terra, the singularity began a mere twelve million miles away. Call it a light-minute. The round-trip comm lag between the surface and an orbiting hyperwave relay was tolerable.

  “Thanks for fitting us in, Sabrina,” Sigmund began.

  She smiled humorlessly. “Your message didn’t leave me much choice. Now would you care to elaborate upon ‘Something scary is rushing your way’?”

  That was all Sigmund had known at first. The radioed updates from Baedeker and Kirsten kept adding detail—and with every report the situation grew scarier. “With our help, the Gw’oth have significantly refined their longrange imagery. At first, we knew only that something was heating and disrupting the interstellar medium, something in a cone aimed right at you. Something light-years across.” He paused for them to contemplate the scale of the phenomenon. “We now know what’s causing it. Wave after wave of ramscoops.”

  Two minutes later, everyone was shouting at once. Sigmund waited for Sabrina to impose order.

  She said, “One at a time, people. Governor’s prerogative, I’ll go first. Sigmund, might these be human ships, like Long Pass?”

  Sigmund shook his head. “Unlikely. The human worlds I knew replaced ramscoops with hyperdrive centuries ago.”

  Juan Royce-Hernandez was Sigmund’s deputy at the defense ministry. Juan’s open, honest face belied the insightful mind beneath. He asked, “What exactly are your new friends seeing, Sigmund?”

  Eric leaned toward the bridge camera. “It’s a bit esoteric. Decelerating ramscoops headed this way would show their exhausts. Exhausts pointed this way would be unmistakably hot, and the Gw’oth don’t detect that.

  “What they see is less dramatic but equally compelling. Helium concentrations in the disrupted region are unnaturally high. The obvious explanation is that the excess helium is a fusion byproduct. Think of it as exhaust streaming away from us, cooled and diffused. The Gw’oth astronomers also see turbulence patterns in the interstellar gases that are consistent with magnetic scoops.”

  Another interminable pause. “Thank you,” Juan said. “I have to agree, that sounds like ramscoops. Whoever is on them may be fleeing from the core explosion, just as we are, without benefit of hyperdrive or a planetary drive.

  “The good news, it seems to me, is that these ships are accelerating. Why think they’ll suddenly brake for New Terra, or the Fleet, or the Gw’oth?”

  Sigmund had had the same hope—for maybe a nanosecond. When your only chance of escape from the core explosion was aboard ramscoops, how crowded must those ships be? How intolerable were the conditions aboard? Why wouldn’t you investigate the possibility of using a whole world as your escape craft?

  He would. He could hardly expect those commanding the ramscoops to act differently.

  Neither the Fleet nor New Terra had a spare planetary drive, or the knowledge to make more, or the wealth to acquire more. Only the Outsiders built such drives. Sigmund kept to himself Baedeker’s speculation that he might learn to make one. That hope was an even thinner reed on which to base policy than the wish that the ramscoops might pass by without stopping.

  Centuries of benign servitude had left New Terrans deficient in judging intent. One paranoid’s example could not begin to reeducate them. It was, ironically, for the best that they had bigger causes to worry.

  “There’s more,” Sigmund began cautiously. “True, we believe the ramscoops are accelerating. The turbulence in their wake reveals deceleration episodes. Sometimes elements of their fleet accelerate while others decelerate. I can’t claim to understand the pattern.

  “The leading wave as we see it—which, remember, is from light fifty years on its way—is approaching at about four-tenths light speed. The analysis further suggests that the fleet has often moved faster, up to nine-tenths light speed.

  “With Baedeker’s expert assistance, the Gw’oth have begun surveying solar systems recently passed by the ramscoops.” This was the breaking news, from an urgent message uploaded from the ice moon less than an hour earlier. “I’m sending you a short vid.”

  “Got it,” a technician declared from New Terra. “Projecting it now.”

  Eric brought up a copy for himself in an auxiliary display. “This doesn’t look like much. Bear with me. First, see the dots: the spark of a distant star and the much dimmer glints of sunlight reflecting from its planets. Now”—software improved the contrast—“the enhanced image emphasizes dust rings in the same solar system.”

  Juan frowned. “I thought planets formed from such dust.”

  “That’s right,” Eric answered. “The dust should be long gone, swept up by the planets. So why do selected solar systems in the ramscoops’ wake show planets and dust clouds?”

  “Mining?” Sabrina guessed. “Replenishing their supplies?”


  “That’s one possibility,” Sigmund said. “Here’s a final observation.” He waited for it to be transmitted and opened. This image showed another solar system, but with two brilliant sparks. “Contrary to appearances, that’s not a binary star. One bright spot is a sun, with a perfectly normal spectrum. The second has a completely different, very unique spectrum.

  “That’s the signature of a kinetic planet-killer.”

  MUCH TALK FOLLOWED, all unnecessary, since there could be only one practical decision. Someone must go investigate.

  Who better than Sigmund and his handpicked crew?

  It would not be easy. They had only fifty-year-old data from which to make plans. If the ramscoops had maintained their last observed speed, the fleet was already twenty light-years closer.

  Or, at top speed, the ramscoops might already have advanced to within five light-years of the Fleet of Worlds and New Terra.

  Which led to the topic Sigmund most dreaded: notifying the Concordance.

  “Sabrina, we don’t dare just sit here waiting. Let me see how close the ramscoops have gotten before we involve the Fleet.” Not that Sigmund would limit his intel gathering to that one question. The less specific he got, the less well-intentioned guidance he would need to ignore.

  His recommendation prompted more discussion, much of it unproductive finger-pointing about New Terra’s lack of high-precision observatories. Sabrina, looking grim, finally put a halt to it. “All right, Sigmund,” she said. “You’re our expert. Call in when you know more.” She left up to him if and how to further involve the Gw’oth. “And be careful.”

  On the trip in-system to retrieve Kirsten and Baedeker, Sigmund recorded and relayed personal messages for Penny and the kids. It might be a long time before he saw them again.

  18

  Their sixteen parts integrated, Ol’t’ro considered:

  Humans, Citizens, and whoever rode the onrushing ramscoops. The universe above the ice was vast—and crowded.