The Ringworld Engineers

by Larry Niven

  Ringworld, twenty years later:

  The walls bathed him in heat. He started to sweat. It didn’t bother him. He’d used saunas. One hundred and sixty degrees isn’t hot for a sauna.

  The Hindmost’s recorded voice snarled and spat in the Hero’s Tongue, offering sanctuary on the Fleet of Worlds. “Cut that broadcast!” Louis commanded, and it was done.

  Upward-streaming flames screened the windows. The cannon-carrying vehicle had been moved away. A pair of distorted kzinti sprinted across the courtyard, placed a canister under the lander, sprinted back to a doorway.

  These were not quite kzinti: not as civilized as Chmeee. If they got their paws on Louis Wu—but he should be safe enough here.

  Louis squinted down through the flames. There were six of the canisters in place around the lander’s base. Bombs, no doubt. They’d be set off any second now, before the flame could explode them individually.

  Louis grinned. His hands poised above the control board while he fought temptation. Then: he tapped in instructions, fast. The buttons were uncomfortably hot. He braced his legs and gripped the chair back, with his falling jumper to pad his hands.

  The lander rose from the flames. A ring of fireballs billowed below, and then the castle was a dwindling toy. Louis was still grinning. He felt virtuous; he’d resisted temptation. If he’d taken off on the fusion drive instead of the repulsers, the kzinti would have been amazed at the power of their explosives.

  Hail clattered on the hull and windows. Louis looked up, startled, as a dozen winged toys curved down toward him. Then the aircraft were dropping away. Louis pursed his lips; he reset the autopilot to halt his rise at five miles. Maybe he’d want to lose those planes. Maybe not.

  He got up and turned for the stairs.

  Louis snorted when he read the dials. He called the Hindmost. “Chmeee is fully healed and peacefully asleep in the ‘doc. The ‘doc won’t wake him up and let him out because conditions outside are not habitable.”

  “Not habitable?”

  “It’s too hot. The autodoc isn’t set to let the patient step out into a fire. Things ought to cool off now that we’re out of the flames!” Louis ran his hand across his forehead; water streamed to his elbow. “It Chmeee gets out, will you tell him the situation? I need a cold shower.”

  He was in the shower when the floor dropped under him. Louis snatched for a towel and was wrapping it around his waist as he ran up the stairs. He heard hail rapping on the hull.

  Slowly and carefully, as if he still hurt, Chmeee turned from his place at the controls. He squinted oddly. Hair had been shaved away around the eye. Mock skin covered a shaved strip running up his thigh to the groin. He said, “Hello, Louis. I see you survived.”

  “Yeah. What are you doing?”

  “I left pregnant females in the fortress.”

  “Are they about to be killed this instant? Or can we hover for a few minutes?”

  “Have we something to discuss? I trust you know better than to interfere.”

  “The way things stand now, your females win be dead in two years.”

  “They may ride home in stasis aboard Hot Needle of Inquiry. I still hope to persuade the Hindmost—“

  “Persuade me. I have taken command of Needle.”

  Chmeee’s hands moved. The floor surged savagely. Louis grabbed at a chair back and rode it out. A glance at the board told him that Needle’s descent had stopped. The rain of projectiles had stopped too, though a dozen aircraft still circled beyond the windows. The fortress was half a mile below.

  Chmeee asked, “How did you arrange that?”

  “I made slag out of the hyperdrive motor.”

  The kzin moved incredibly fast. Before Louis could do more than flinch, he was wrapped in orange fur. The kzin was pulling Louis against his chest with one arm while the other held four claws against Louis’s eyebrows.

  “Shrewd,” said Louis. “Very shrewd. Where do your plans carry you from here?”

  The kzin didn’t move. Blood trickled past Louis’s eyes. He felt that his back was breaking. Louis said, “It seems I’ve had to rescue you again.”

  The kzin released him and stepped back carefully, as if afraid to move on impulse. He asked, “Have you doomed us all? Or do you have some notion of moving the entire Ringworld back into position?”

  “The latter.”

  “How?”

  “A couple of hours ago I could have told you. Now we’ll have to find another answer.”

  “Why did you do it?”

  “I wanted to save the Ringworld. There was just one way to get the Hindmost’s cooperation. His life’s at stake now. How do I go about getting your cooperation?”

  “You fool. I fully intend to learn how to move the Ringworld, if only to save my children. Your problem is to persuade me that I need you.”

  “The Pak who built the Ringworld were my ancestors. We’re trying to think like them, aren’t we? What did they build in that would do the job? Aside from that, I’ve got two City Builder librarians with a good knowledge of Ringworld history. They wouldn’t cooperate with you. They already see you as monstrous, and you haven’t even killed me yet.”

  Chmeee thought it over. “If they fear me they will obey. Their world is at stake. Their ancestors were Pak too.”

  The lander’s temperature had become uncomfortably cool for a naked man, but Louis was sweating again. “I’ve already located the Repair Center.”

  “Where?”

  Louis considered withholding that information, briefly. “The Map of Mars.”

  Chmeee sat down. “Now, that is most impressive. These displaced kzinti learned a good deal about the Map of Mars during their age of exploration, but they never learned that.”

  “I’ll bet some ships disappeared around the Map of Mars.”

  “The aircraft pilot told me that many ships disappeared, and nothing of value was ever taken from the Map of Mars. The explorers brought home wealth from a Map further to spinward, but they never brought as much wealth as they put into making the ships. Do you need the autodoc?”

  Louis wiped blood from his face with his falling Jumper. “Not just yet. That Map to spinward sounds like Earth. So it wasn’t defended after all.”

  “It seems not. But there is a Map to port, and ships that went there never returned. Could the Repair Center be there?”

  “No, that’s the Map of Down. They met Grogs.” Louis swabbed at his face again. The claws hadn’t cut deep, he thought, but a facial cut bleeds a long time. “Let’s do something about your pregnant females. How many?”

  “I don’t know. Six were in their mating period.”

  “Well, we don’t have room for them. They’ll have to stay in the castle. Unless you think the local lord will kill them?”

  “No, but he may very well kill my male children. Another danger ... Well, I can deal with that.” Chmeee turned to the controls. “The most powerful civilization is built around one of the old exploration ships, the Behemoth. If they track me here, there might be war against the fortress.”

  The aircraft burned like torches as they fell. Chmeee tested the sky with radar, deep-radar, and infrared. Empty. “Louis, were there more? Did any land?”

  “I don’t think so. If they did, they ran out of fuel, and there aren’t any runways ... Roads? Scan the roads. You can’t let them radio the big ship.” Radio would be line of sight, and the Ringworld atmosphere probably had a Heaviside layer.

  There was one road, and tanj few straight patches on it. There were flat fields ... It was some minutes before Chmeee was satisfied. The aircraft were dead, all of them.

  “Next step,” said Louis. “You can’t just wipe out everyone in the fortress. I gather
kzinti females can’t take care of themselves.”

  “No ... Louis, it’s odd. The females of the castle are much more intelligent than those of the Patriarchy.”

  “As intelligent as you?”

  “No! But they even have a small vocabulary.”

  “Is it possible that your own people have been breeding your females for docility? Refusing to mate with the intelligent ones for hundreds of thousands of years? After all, you cull the slave species.”

  Chmeee shifted restlessly. “It may be. The males here are different too. I tried to deal with the rulers of the exploration ship. I showed my power, then waited for them to attempt to negotiate. They attempted no such thing. They behaved as if there was nothing to do but fight until they or I were destroyed. I had to mock Chjarrl, to insult his pride in his ancestry, before he would tell me anything.”

  But puppeteers never bred these kzinti for docility, Louis thought. “Well, if you can’t take the females out of the fortress and you can’t kill off the males, then you’ll tanj well have to deal with them. God Gambit?”

  “Perhaps. Let us do it this way ...”

  Well above arrow range, just above the range of the cannon on the intruder’s vehicle, the lander hovered. Its shadow covered the ashes of the fire in the courtyard. Louis listened to the voices from Chmeee’s translator, and waited for Chmeee’s signal.

  Chmeee inviting archers to fire at him. Chmeee threatening, promising, threatening. Staccato thunder from a laser beam cutting rock, followed by a crash. Hissing, snarling, spitting.

  No mention of Chmeee’s really dangerous master.

  Four hours he was down there. Then Chmeee stepped from one of the narrow windows and floated upward. Louis waited till he was aboard, then lifted.

  Presently Chmeee appeared behind him, minus flying belt and impact armor. Louis said, “You never signaled for the God Gambit.”

  “Are you offended?”

  “No, of course not.”

  “It would have gone badly. And ... I could not have done it. This is my own species. I could not threaten them with a man.”

  “Okay.”

  “Kathakt will raise my children as heroes. He will teach them arms, and arm them well, and when they are old enough he will turn them loose to conquer their own lands. They will be no threat to his own domains, you see, and they will stand a good chance to survive if I do not return. I left Kathakt my flashlight-laser.”

  “Good enough.”

  “I hope so.”

  “Are we through with the Map of Kzin?”

  Chmeee pondered. “I captured an aircraft pilot. They are all nobility, with names and comprehensive educations. Chjarrl told me much about the age of exploration after I mocked the accomplishments of his ancestors. We may assume that there is an extensive historical library within the Behemoth. Shall we capture it?”

  “Tell me what Chjarrl told you. How far did they get on Mars?”

  “They found a wall of falling water. Later generations invented pressure suits and high-altitude aircraft. They explored the edges of the Map, and one team reached the center, where there was ice.”

  “I think we’ll just skip the Behemoth’s library, then. They never got inside. Hindmost, are you there?”

  A microphone said, “Yes, Louis.”

  “We’re heading for the Map of Mars. You do the same, but stay to port of us in case we have to flick across.”

  “Aye, aye. Have you anything to report?”

  “Chmeee picked up some information. Kzinti explored the surface of the Map of Mars, and they didn’t find anything un-Marslike. So we still don’t know where to look for an opening.”

  “Perhaps from beneath.”

  “Yeah, could be. That’d be annoying. How are our guests holding out?”

  “You should rejoin them soon.”

  “Soon as I can, then. You see if there’s data on Mars in Needle’s computer. And on martians. Louis out.” He turned. “Chmeee, do you want to fly this thing? Don’t exceed four miles per second.”

  The lander surged up and forward in obedience to the kzin’s touch. A gray wall of cloud broke to let them through; then there was only blue sky, darkening as they rose. The Map of Kzin streamed below them. Then behind them.

  Chmeee said, “The puppeteer seems docile enough.”

  “Yeah.”

  “You seem very sure of the Map of Mars.”

  “Yeah.” Louis grinned. “It’s a very nice piece of misdirection, but it couldn’t be perfect, could it? They had too much to hide, by volume. We went under the Great Ocean on the way here. Guess what we found when we went under the Map of Mars?”

  “Don’t play games.”

  “Nothing. Nothing but sea bottom. Not even radiator fins. Most of the other Maps have radiator fins to cool the poles. Passive cooling systems. There has to be a system to cool the Map of Mars. Where’s the heat going? I thought it might be going into the sea water, but it wasn’t. We think the heat is pumped directly into the superconductor grid in the Ringworld floor.”

  “Superconductor grid?”

  “Big mesh, but it controls magnetic effects in the Ringworld foundation. It’s used to control effects in the sun. If the Map of Mars plugs into the grid, it has to be the Ringworld control center.”

  Chmeee thought it over. He said, “They could not pump heat into the sea water. The warm, wet air would rise. Cloud patterns would stream inward and outward from great distances. From space the Map of Mars would appear as a great target. Can you imagine Pak protectors making such a mistake?”

  “No.” Though Louis would have.

  “I remember too little about Mars. The planet was never very important to your people, was it? It was no more than a source of legends. I do know that the Map is twenty miles high, to mimic the very rarefied air of the planet.”

  “Twenty miles high, and fifty-six million square miles in area. That’s one billion, one hundred and twenty million cubic miles of hiding place.”

  “Urrr,” said Chmeee. “You must be right. The Map of Mars is the Repair Center, and the Pak did their best to hide it. Chjarrl told me of the monsters and the storms and the distances of the Great Ocean. They would have made good passive guardians. A fleet of invaders might never have guessed the secret.”

  Louis rubbed absently at four itching spots across his eyebrows. “One point twelve times ten to the ninth cubic miles. I have to admit it, that number leaves me numb. What were they keeping in there? Patches big enough to plug Fist-of-God Mountain? Machinery big enough to carry those patches, and plant them, and weld them tight? That winching equipment we saw on the rim wall, for the attitude jets? Spare attitude jets? Tanj, I’d love to find spare attitude jets. But they’d still have room to spare.”

  “War fleets.”

  “Yeah. We already know about their big weapon, but—war fleets, of course, and ships to carry refugees, too. Maybe the whole Map is one big refugee ship. It must have been big enough to evacuate the Ringworld before the population started filling every niche in the ecology.”

  “A spacecraft? Perhaps a spacecraft big enough to tow the Ringworld back into place? I have trouble thinking on this scale, Louis.”

  “Me too. I don’t think it’d be big enough.”

  “Then what did you have in mind when you destroyed our hyperdrive motor?” Suddenly the kzin was snarling.

  Louis chose not to flinch. “I thought the Ringworld might be set up to act on the sun magnetically. I was almost right. The trouble—“

  The Hindmost’s voice blared from a speaker. “Louis! Chmeee! Set the lander on autopilot and flick across to me now!”

  Chapter 29 -

  The Map of Mars

 
Chmeee reached the disc ahead of Louis, in one monstrous bound. The kzin could take orders too, Louis thought. He forbore to remark on the fact.

  The City Builders were looking out through the hull, not at the passing seascape—which was nothing but blue sea and cloud-striped blue sky merging at the infinity-horizon—but at a movie-screen-sized hologram. As Chmeee appeared on the receiver disc they turned and flinched and then tried to hide it.

  Louis said, “Chmeee, meet Harkabeeparolyn and Kawaresksenjajok, librarians from the floating city. They’ve been of great help in gaining us information.”

  The kzin said, “Good. Hindmost, what is the problem?”

  Louis tugged at the kzin’s fur and pointed.

  “Yes,” said the puppeteer. “The sun.”

  The sun showed dimmed and magnified in the hologram rectangle. A brilliant patch near the center was shifting, twisting, changing shape as they watched.

  Chmeee said, “Wasn’t the sun doing that shortly before we boarded the spaceport ledge?”

  “Right. You’re looking at the Ringworld meteor defense. Hindmost, what do we do now? We can slow down, but I don’t see any way to save the lander.”

  “My first thought was to save your valuable selves,” the puppeteer said.

  The sea threw back a highlight from directly below the fleeing Needle. Now it seemed to be growing brighter, with a violet tinge. Suddenly, momentarily, it was unbearably bright. Then it was a black spot on the hull beneath their feet.

  And a thread of jet-black, outlined in violet-white, stood upon the spinward horizon. A vertical pillar, reaching from ground to sky. Above the atmosphere it was invisible.

  The kzin spoke words in the Hero’s Tongue.

  “All very well,” said the Hindmost in Interworld, “but what is it firing on? I assumed we were the target.”

  Louis asked, “Isn’t the Map of Earth in that direction?”

  “Yes. Also a good deal of water and considerable Ringworld landscape.”