Ringworld

by Larry Niven

  “Another example. Earth produces too little natural fresh water for its eighteen billions. Salt water must be distilled through fusion. This produces heat. But our world, so much more crowded, would die in a day without the distilling plants.

  “A third example. Transportation involving changes in velocity always produces heat. Spacecraft filled with grain from the agricultural worlds produce heat on reentry and distribute it through our atmosphere. They produce more heat on takeoff.”

  “But cooling systems—“

  “Most kinds of cooling systems only pump heat around, and produce more heat for power.”

  “U-u-urr. I begin to understand. The more puppeteers, the more heat is produced.”

  “Do you understand, then, that the heat of our civilization was making our world uninhabitable?”

  Smog, thought Louis Wu. Internal combustion engines. Fission bombs and fusion rockets in the atmosphere. Industrial garbage in the lakes and oceans. It’s often enough that we’ve half-killed ourselves in our own waste products. Without the Fertility Board, would the Earth be dying now in its own waste heat?

  “Incredible,” said Speaker-To-Animals. “Why didn’t you leave?”

  “Who would trust his life to the many deaths of space? Only such a one as me. Should we settle worlds with our insane?”

  “Send cargos of frozen fertilized ova. Run the ships with crews of the insane.”

  “Discussions of sex make me uncomfortable. Our biology is not adapted to such methods, but doubtless we could evolve something analogous ... but to what purpose? Our population would be the same, and our world would still have been dying of its own waste heat.”

  Irrelevantly, Teela said, “I wish we could see out.”

  The puppeteer was astounded. “Are you sure? Are you not subject to the fear of falling?”

  “On a puppeteer ship?”

  “Ye-es. In any case, our watching cannot increase the danger. Very well.” Nessus spoke musically in his own tongue, and the ship vanished.

  They could see themselves and each other; they could see four crash couches resting on emptiness, and the refreshment console in the middle. All else was black space. But five worlds glowed in white splendor behind Teela’s dark hair.

  They were of equal size: perhaps twice the angular diameter of the full Moon as seen from Earth. They formed a pentagram. Four of the worlds were circled by strings of tiny, glaring lights: orbital suns giving off artificial yellow-white sunlight. These four were alike in brightness and appearance: misty blue spheres, their continental outlines invisible at this distance. But the fifth ...

  The fifth world had no orbital lights. It glowed by its own light, in patches the shapes of continents and the colors of sunlight. Between the patches was a black that matched the black of surrounding space; and this black, too, was filled with stars. The black of space seemed to encroach on continents of sunlight.

  “I’ve never seen anything so beautiful,” said Teela, with tears in her voice. And Louis, who had seen many things, was inclined to agree.

  “Incredible,” said Speaker-To-Animals. “I hardly dared believe it. You took your worlds with you.”

  “Puppeteers don’t trust spacecraft,” Louis said absently. There was a touch of cold in the thought that he might have missed this; that the puppeteer might have chosen someone in his place. He might have died without seeing the puppeteer rosette ...

  “But how?”

  “I had explained,” said Nessus, “that our civilization was dying in its own waste heat. Total conversion of energy had rid us of all waste products of civilization, save that one. We had no choice but to move our world outward from its primary.”

  “Was that not dangerous?”

  “Very. Then was much madness that year. For that reason it is famous in our history. But we had purchased a reactionless, inertialess drive from the Outsiders. You may guess their price. We are still paying in installments. We had moved two agricultural worlds; we had experimented with other, useless worlds of our system, using the Outsider drive.

  “In any case, we did it. We moved our world.

  “In later millenia our numbers reached a full trillion. The dearth of natural sunlight had made it necessary to light our streets during the day, producing more heat. Our sun was misbehaving.

  “In short, we found that a sun was a liability rather than an asset. We moved our world to a tenth of a light year’s distance, keeping the primary only as an anchor. We needed the farming worlds and it would have been dangerous to let our world wander randomly through space. Otherwise we would not have needed a sun at all.”

  “So,” said Louis Wu. “That’s why nobody ever found the puppeteer world.”

  “That was part of the reason.”

  “We searched every yellow dwarf sun in known space, and a number outside it. Wait a minute, Nessus. Somebody would have found the farming planets. In a Kemplerer rosette.”

  “Louis, they were searching the wrong suns.”

  “What? You’re obviously from a yellow dwarf.”

  “We evolved under a yellow dwarf star somewhat like Procyon. You may know that in half a million years Procyon will expand into the red giant stage.”

  “Finagles heavy hand! Did your sun blow up into a red giant?”

  “Yes. Shortly after we finished moving our world, our sun began the process of expanding. Your fathers were still using the upper thigh bone of an antelope to crack skulls. When you began to wonder where our world was, you were searching the wrong orbits, about the wrong Suns.

  “We had brought suitable worlds from nearby systems, increasing our agricultural worlds to four and setting them in a Kemplerer rosette. It was necessary to move them all when the sun began to expand, and to supply them with sources of ultraviolet to compensate for the reddened radiation. You will understand that when the time came to abandon galaxy, two hundred years ago, we were well prepared. We had had practice in moving worlds.”

  The rosette of worlds had been expanding for some time. Now the puppeteer world glowed beneath their feet, rising, rising to engulf them. Scattered stars in the black seas had expanded, to become scares of small islands. The continents burned like sunfire.

  Long ago, Louis Wu had stood at the void edge of Mount Lookitthat. The Long Fall River, on that world, ends in the tallest waterfall in known space. Louis’s eyes had followed it down as far as they could penetrate the void mist. The featureless white of the void itself had grasped at his mind, and Louis Wu, half hypnotized, had sworn to live forever. How else could he see all there was to we?

  Now he reaffirmed that decision. And the puppeteer world rose about him.

  “I am daunted,” said Speaker-To-Animals. His naked pink tail lashed in agitation, though his furry face and burry voice carried no emotion. “Your lack of courage had deserved our contempt, Nessus, but our contempt has blinded us. Truly you are dangerous. Had you feared us enough, you would have ended our race. Your power is terrible. We could not have stopped you.”

  “Surely a kzin cannot fear an herbivore.”

  Nessus had not spoken mockingly; but Speaker reacted with rage “What sapient being would not fear such power?”

  “You distress me. Fear is the brother of hate. One would expect a kzin to attack what he fears.”

  The conversation was getting sticky. With the Long Shot millions of miles in their wake, and known space hundreds of light years away, they were all very much within the power of the puppeteers. It the puppeteers found reason to fear them—Change the subject, fast! Louis opened his mouth.

  “Hey,” said Teela. “You people keep talking about Kemplerer rosettes. What’s a Kemplerer rosette?”

  And both aliens started to answer, while Louis wondered why he
had thought Teela shallow.

  Chapter 6 -

  Christmas Ribbon

  “The joke’s on me,” said Louis Wu. “Now I know where to find the puppeteer world. Very nice, Nessus. You kept your promise.”

  “I told you that you would find the information more surprising than useful.”

  “A good joke.” said the kzin. “Your sense of humor surprises me, Nessus.”

  Below, a tiny eel-shaped island surrounded by a black sea. The island rose like a fire salamander, and Louis thought he could pick out tall, slender buildings. Obviously aliens would not be trusted on the mainland.

  “We do not joke,” said Nessus. “My species has no sense of humor.”

  “Strange. I would have thought that humor was an aspect of intelligence.”

  “No. Humor is associated with an interrupted defense mechanism.”

  “All the same—“

  “Speaker, no sapient being ever interrupts a defense mechanism.”

  As the ship dropped the lights resolved: sun-panels, along street levels, windows in buildings, light sources, in parking areas. In a last instant Louis glimpsed buildings slender as rapier blades, miles tall. Then the city flashed up to engulf them, and they were down.

  Down in a parkland of colorful alien plants.

  Nobody moved.

  Puppeteers were the second most harmless-looking sentients in known space. They were too shy, too small, too weird to seem dangerous. They were merely funny.

  But suddenly Nessus was a member of his species; and his species was mightier than men had dreamed. The mad puppeteer sat quite still, his necks bobbing to observe his chosen underlings. There was nothing funny about Nessus. His race moved worlds, five at a time.

  So that Teela’s giggle was a shocking sound.

  “I was just thinking,” she explained. “The only way to keep from having too many little puppeteers is no sex at all. Right, Nessus?”

  “Yes.”

  She giggled again. “No wonder puppeteers don’t have a sense of humor.”

  Through a park that was too regular, too symmetrical, too well tamed, they followed a floating blue light.

  The air was thick with the spicy-chemical smell of puppeteer. That smell was everywhere. It had been strong and artificial in the one-room life support system of the transfer ship. It had not diminished when the airlock opened. A trillion puppeteers had flavored the air of this world, and for all of eternity it would smell of puppeteer.

  Nessus danced; his small clawed hooves seemed barely to touch the resilient surface of the walk. The kzin glided, catlike, his naked pink tail whipping rhythmically back and forth. The sound of the puppeteer’s walk was a tap dance in three-four time. From the kzin came not the slightest whisper of motion.

  Teela’s walk was almost as silent. Her walk always looked clumsy; but it wasn’t. She never stumbled, never bumped anything. Louis, then, was the least graceful of the four.

  But why should Louis Wu be graceful? An altered ape, whom evolution had never entirely adapted to walking on flat ground. For millions of years his fathers had walked on all fours where they had to, had used the trees where they could.

  The Pliocene had ended that, with millions of years of drought. The forests had left Louis Wu’s ancestors behind, high and dry and starving. In desperation they had eaten meat. They had done better after learning the secret of the antelope’s thighbone, whose double-knobbed shoulder joint had left its mark in so many fossil skulls.

  Now, on feet still equipped with vestigial fingers, Louis Wu and Teela Brown walked with aliens.

  Aliens? They were all aliens here, even mad, exiled Nessus, with his brown and unkempt mane and his restless, searching heads. Speaker, too, was uneasy. His eyes, within their black spectacle markings, searched the alien vegetation for things with poison stings or razor teeth. Instinct, probably. Puppeteers would not permit dangerous beasts in their parks.

  They came upon a dome that glowed like a huge, half-buried pearl. Then the floating light split in two.

  “I must leave you,” said Nessus. And Louis saw that the puppeteer was terrified.

  “I go to confront those-who-lead.” He spoke low and urgently. “Speaker, tell me quickly. Should I not return, would you seek me out to slay me for the insult I delivered in Krushenko’s Restaurant?”

  “Is there risk you will not return?”

  “Some risk. Those-who-lead may dislike what I must tell them. I ask again, would you hunt me down?”

  “Here on an alien world, amid beings of such awesome power and such lack of faith in a kzin’s peaceful intent?” The kzin’s tail lashed once, emphatically. “No. But neither would I continue with the expedition.”

  “That will be sufficient.” Nessus trotted off, trembling visibly, following the guidelight.

  “What’s he scared of?” Teela complained. “He’s done everything they told him to. Why would they be angry with him?”

  “I think he’s up to something,” said Louis. “Something devious. But what?”

  The blue light moved on. They followed it into an iridescent hemisphere ...

  Now the dome had vanished. From a triangle of couches, two humans and a kzin looked out into a tame jungle of brilliant alien plants, watching the approach of a strange puppeteer. Either the dome itself was invisible from inside, or the park scene was a projection.

  The air smelled of many puppeteers.

  The strange puppeteer pushed its way through a last fringe of hanging scarlet tendrils. (Louis remembered when he had thought of Nessus as “it”. When had Nessus graduated to “him”? But, Speaker, a familiar alien, had been “him” from the beginning.) The puppeteer stopped there, just short of the presumed boundaries of the pearly dome. Its mane was silver where Nessus’s was brown, and was neatly coiffured in complex ringlets; but its voice was Nessus’s thrilling contralto.

  “I must apologize for not being present to greet you. You may address me as Chiron.”

  A projection, then. Louis and Teela murmured polite demurrers. Speaker-To-Animals bared his teeth.

  “The one you call Nessus knows all that you are about to learn. His presence was required elsewhere. However, he mentioned your reactions on learning of our engineering skills.”

  Louis winced. The Puppeteer continued. “This may be fortunate. You will understand the better when you learn of our own reactions to a more ambitious work of engineering.”

  Half the dome went black.

  Annoyingly, it was the side of the dome opposite to the Projected puppeteer. Louis found a control to turn his couch; but he reflected that he would have needed two’ swiveled heads with independently operating eyes to watch both halves of the dome at once. The darkened side showed starry space forming a backdrop for a small, blazing disc.

  A ringed disc. The scene was a blow-up of the holo in Louis Wu’s pocket.

  The light source was small and brilliant white, very like a view of Sol as seen from the general neighborhood of Jupiter. The ring was huge in diameter, wide enough to stretch halfway across the darkened side of the dome; but it was narrow, not much thicker than the light source at its axis. The near side was black and, where it cut across the light, sharp-edged. Its further side was a pale blue ribbon across space.

  If Louis was growing used to miracles, he was not yet so blasé’ as to make idiotic-sounding guesses. Instead he said, “It looks like a star with a ring around it. What is it?”

  Chiron’s reply came as no surprise.

  “It is a star with a ring around it,” said the puppeteer. “A ring of solid matter. An artifact.”

  Teela Brown clapped her hands and burst into giggles. She strangled the giggles after a few moments and managed to look wonderful
ly solemn; but her eyes glowed. Louis understood perfectly. He felt a touch of the same joy. The ringed sun was his/her private toy: a new thing in a mundane universe.

  (Take Christmas ribbon, pale blue and an inch wide, the kind you use to wrap presents. Set a lighted candle on a bare floor. Take fifty feet of ribbon, and string it in a circle with the candle at the center, balancing the ribbon on edge so that the inner side catches the candlelight.)

  But the kzin’s tail was lashing back and forth, back and forth.

  (After all, that wasn’t a candle in the middle. That was a sun!)

  “By now you know,” said Chiron, “that we have been moving north along the galactic axis for the past two hundred and four of your Earth years. In kzin years—“

  “Two hundred and seventeen.”

  “Yes. During that time we have naturally observed the space ahead of us for signs of danger and the unexpected. We had known that the star EC-1752 was ringed with an uncharacteristically dense and narrow band of dark matter. It was assumed that the ring was dust or rock. Yet it was surprisingly regular.

  “Some ninety days ago our fleet of worlds reached a position such that the ring occluded the star itself. We saw that the ring was sharply bounded. Further investigation revealed that the ring is not gas nor dust, nor even asteroidal rock, but a solid band of considerable tensile strength. Naturally we were terrified.”

  Speaker-To-Animals asked, “How were you able to deduce its tensile strength?”

  “Spectroanalysis and frequency shifts gave us a relative difference in velocities. The ring is clearly rotating about its primary at 770 miles per second, a velocity high enough to compensate for the pull of gravity from the primary, and to provide an additional centripetal acceleration of 9.94 meters per second. Consider the tensile strength needed to prevent the structure from disintegrating under such a pull!”

  “Gravity,” said Louis.

  “Apparently.”

  “Gravity. A touch less than Earth’s. There’s somebody living there, on the inner surface. Hooo,” said Louis Wu, for the full impact was beginning to hit him, and the little hairs were rising along his spinal column. He heard the swish, swish of the kzin’s tail cutting air.