The Ringworld Engineers

“Halrloprillalar is dead. My agents cheated me,” the puppeteer said. “They have known that the Ringworld native was dead for eighteen standard years. I could stay to root them out wherever they have hidden, but it might take another eighteen years. Or eighteen hundred! Human space is too big. Let them keep their stolen money.”

Louis nodded, smiling, knowing that this was going to hurt when he removed the droud. He heard Chmeee ask, “How did she die?”

“She could not tolerate boosterspice. The United Nations now believes that she was not quite human. She aged very rapidly. A year and five months after reaching Earth, she was dead.”

“Already dead,” Louis mused. “When I was on Kzin… ” But there was a puzzle here. “She had her own longevity drug. Better than boosterspice. We brought a cryoflask home with us.”

“It was stolen. I know nothing more.”

Stolen? But Prill had never walked the streets of Earth, to meet common thieves. United Nations scientists might have opened the flask to analyze the stuff, but they wouldn’t need more than a microgram… He might never know. And afterward they had kept her, to take her knowledge before she died.

This was definitely going to hurt. But not yet.

“We need not delay longer.” The puppeteer settled itself in its padded bench. “You will travel in stasis, to conserve resources. I have an auxiliary fuel tank to be dropped before we enter hyperspace. We will arrive fully fueled. Chmeee, would you name our ship?”

Chmeee demanded, “Do you propose to explore blindly, then?”

“Only the spaceport ledge, and no further. Would you name our ship?”

“I name it Hot Needle of Inquiry.”

Louis smiled and wondered if the puppeteer recognized the term. Their ship was now named for a kzinti instrument of torture. The puppeteer mouthed two knobs and brought them together.

Chapter 4 — Off Center

Louis sagged as his weight suddenly doubled. The black Canyonscape was gone. It must be invisible in the starscape now, a changed starscape in which one star, directly underfoot, shone brighter than all the rest. The Hindmost disengaged itself from crash web and pilot’s bench. The puppeteer had changed too. It moved as if tired, and its mane — differently styled now — seemed not to have been set for some time.

Current didn’t deaden the brain. Louis could see the obvious: that he and Chmeee must have spent two years in stasis, while the puppeteer flew Needle alone through hyperspace; that known space, a bubble of explored star systems some forty light-years in radius, must be far behind them; that Hot Needle of Inquiry was built to be flown by a Pierson’s puppeteer, with all other passengers in stasis, and only a puppeteer’s mercy would ever return them. That he had seen a human being for the last time, and Halrloprillalar was dead of Louis Wu’s carelessness, and he was going to feel terribly lonely when the droud came out of his head, which would be soon. None of that mattered while the tiny current still trickled into his brain.

He saw no drive flame. Hot Needle of Inquiry must be moving on reactionless thrusters alone.

Liar’s designers had mounted the ship’s motors on its great delta wing. Something like a tremendous laser blast had fired on them as they passed above the Ringworld, and the motors had been burned off. The Hindmost would not have repeated that mistake, Louis thought. Needle’s thrusters would be mounted inside the impervious hull.

Chmeee asked, “How long until we can land?”

“We can be ready to dock in five days. I was unable to take advanced drive systems from the Fleet of Worlds. With human-built machinery we can decelerate only at twenty gravities. Do you find the cabin gravity comfortable?”

“A bit light. One Earth gravity?”

“One Ringworld gravity, point nine nine two Earth gravity.”

“Leave it as it is. Hindmost, you gave us no instruments. I would like to study the Ringworld.”

The puppeteer pondered the point. “Your lander vehicle includes a telescope, but it would not point straight down. Wait several moments.” The puppeteer turned to its instrument board. One head turned back and spoke in the hissing-spitting-snarling accents of the Hero’s Tongue.

Chmeee said, “Use Interworld. Let Louis listen, at least.”

The puppeteer did. “It is good to speak again in any language. I was lonely. There, I give you a projection from Needle’s telescope.”

An image appeared below Louis Wu’s feet: a rectangle, with no borderlines, in which the Ringworld sun and the stars around it were suddenly far larger. Louis blocked the sun with his hand and searched. The Ringworld was there: a thread of baby blue forming a half-circle.

Picture fifty feet of baby-blue Christmas ribbon one inch wide. String it in a circle, on edge on the floor, and put a candle in the middle. Now expand the scale:

The Ringworld was a ribbon of unreasonably strong material, a million miles wide and six hundred million miles long, strung in a circle ninety-five million miles in radius with a sun at the center. The ring spun at seven hundred and seventy miles per second, fast enough to produce one gravity of centrifugal force outward. The unknown Ringworld engineers had layered the inner surface with soil and oceans and an atmosphere. They had raised walls a thousand miles high at each rim to hold the air inside. Presumably air leaked over the rim walls anyway, but not quickly. An inner ring of twenty rectangular shadow squares, occupying what would have been the orbit of Mercury in Sol system, gave a thirty-hour day and night cycle to the Ringworld.

The Ringworld was six hundred million million square miles of habitable planet. Three million times the area of the Earth.

Louis and Speaker-To-Animals and Nessus and Teela Brown had traveled across the Ringworld for almost a year: two hundred thousand miles across the width, then back to the point where Liar had crashed. A fifth of the width. It hardly made them experts. Could any thinking being ever have claimed to be an expert on the Ringworld?

But they had examined one of the spaceport ledges on the outside of the rim wall. If the Hindmost spoke the truth, they would need no more. Land on the spaceport ledge, pick up whatever the Hindmost expected to find, and go. Fast! Because—

Because within the rectangular telescope image that the Hindmost had set before them, it was painfully obvious. The baby-blue arc of Ringworld — the color of three million Earthlike worlds, too far away for detail to show, but banded with midnight blue from the shadow squares — was well off center from its sun.

“We didn’t know this,” Chmeee said. “We spent a Kzin year on the structure and did not know this. How could we not?”

The puppeteer said, “The Ringworld could not have been off center when you were here. It was twenty- three years ago.”

Louis nodded. To speak would be distracting. Only the joy of the wire now held away horror for the fate of the Ringworld natives, fear and guilt for himself. The Hindmost continued, “The Ringworld structure is unstable in the plane of its orbit. Surely you knew?”

“No!”

Louis said, “I didn’t know myself till after I was back on Earth. I did some research then.”

Both aliens were looking at him. He hadn’t really wanted that much of their attention. Oh, well. “It’s easy enough to show that the Ringworld is unstable. Stable along the axis, but unstable in the plane. There must have been something to keep the sun on the axis.”

“But it’s off center now!”

“Whatever it was stopped working.”

Chmeee clawed at the invisible floor. “But then they must die! Billions of them, tens of billions — trillions?” He turned to Louis. “I tire of your fatuous smile. Would you talk better without the droud?”