Larry Niven - The Ringworld Engineers

“That was no solar flare that hit us.”

“The flare stretched out several million miles over a period of twenty minutes. Then it lased in violet.”

“Oh my God .”

“A gas laser on a very large scale. The earth still glows where the beam fell. I estimate that it covered a region ten kilometers across: not an especially tight beam, but it would not normally need to be. With even moderate efficiency, a flare that large would power a gas laser beam at three times ten to the twenty-seventh power ergs per second, for on the order of an hour.”

Silence.

“Louis?”

“Give me a minute. Hindmost, that is one impressive weapon.” It hit him, then: the secret of the Ringworld engineers. “ That’s why they felt safe. That’s why they could build a Ringworld. They could hold off any kind of invasion. They had a laser weapon bigger than worlds, bigger than the Earth-Moon system, bigger than… Hindmost? I think I’m going to faint.”

“Louis, we don’t have time for that.”

“What caused it? Something caused the sun to jet plasma. Magnetic, it has to be magnetic. Could it be one function of the shadow squares?”

“I wouldn’t think so. Cameras record that the shadow square ring moved aside to allow the beam to pass, and constricted elsewhere, presumably to protect the land from increased insolation. We cannot assume that this same shadow-square ring was manipulating the photosphere magnetically. An intelligent engineer would design two separate systems.”

“You’re right. Absolutely right. Check it anyway, will you? We’ve recorded all possible magnetic effects from three different angles. Find out what made the sun flare.” Allah, Kdapt, Brahma, Finagle, let it be the shadow squares! “Hindmost? Whatever you find, don’t curl up on me.”

There was a peculiar pause. Then “Under the circumstances, that would doom us all. I would not do that unless there was no hope left. What are you thinking?”

“There is never no hope left. Remember.”

The Map of Mars was in view at last. It was farther away than the Map of Earth — a hundred thousand miles straight to starboard — but unlike the Map of Earth, it was one compact mass. From this angle it showed as a black line: twenty miles above the sea, as the Hindmost had predicted.

A red light blinked on the lander’s instrument board. Temperature: a hundred and ten Fahrenheit, just right for a spa. No lights blinked on the big coffin that held Chmeee. The autodoc had its own temperature controls.

The kzinti defenders seemed to have run out of explosives. Their supply of firewood seemed infinite.

Twenty thousand miles to go, at four miles per second.

“Louis?”

Louis eased himself out of the sleeping field. The Hindmost, he thought, looked awful. Mane rumpled, the garnets rubbed off along one side. He staggered as if his knees were made of wood.

“We’ll think of something else,” Louis told him. He was wishing he could reach through the wall, stroke the puppeteer’s mane, give reassurance of some kind. “Maybe there’s some kind of library in that castle. Maybe Chmeee already knows something we don’t. Tanj, maybe the repair crew already knows the answer.”

“We know the same answer. A chance to study sunspots from underneath.” The puppeteer’s voice was wintry-cool, the voice of a computer. “You guessed, didn’t you? Hexagonal patterns of superconductor embedded in the Ringworld floor. The scrith can be magnetized to manipulate plasma jets in the solar photosphere.”

“Yah.”

“It may have been just such an event that pushed the Ringworld off center. A plasma jet formed to fire on a meteoroid, a stray comet, even a fleet from Earth or Kzin. The plasma impacted the Ringworld. There were no attitude jets to push it back into place. Without the plasma jet, the meteor itself might have been sufficient. The repair crew came later: too late.”

“Let’s hope not.”

“The grid is not a backup for the attitude jets.”

“No. Are you all right?”

“No.”

“What are you going to do?”

“I will follow orders.”

“Good.”

“If I were still Hindmost to this expedition, I would give up now.”

“I believe you.”

“Have you guessed the worst of it? I compute that the sun can probably be moved. The sun can be made to jet plasma, and the plasma can be made to act as a gas laser, forming a photon drive for the sun itself. The Ringworld would be pulled along by the sun’s gravity. But even the maximum thrust would be minuscule, too little to help us. At anything over two times ten to the minus fourth power gravities of acceleration, the Ringworld would be left behind. In any case, radiation from the plasma jet would ruin the ecology. Louis, are you laughing ?”

Louis was. “I never thought of moving the sun. I never would have. You actually went ahead and worked out the math ?”

Wintry-cool and mechanical, that voice. “I did. It can’t help us. What is left?”

“Follow orders. Hold us at four miles per second antispinward. Let me know when I can flick across to the lander.”

“Aye, aye.” The puppeteer turned away.

“Hindmost?”

A head turned back.

“Sometimes there’s no point in giving up.”

All the lights glowed green. Whatever the medical situation, the autodoc was handling it somehow. Chmeee was alive in there — alive, if not healthy.

But the flight-deck thermometer indicated a temperature of a hundred and sixty degrees Fahrenheit.

The Hindmost said, “Louis, are you ready to cross?”

The Map of Mars was a black dash below the line of hologram “windows,” straight to starboard. The Map of Kzin was a good deal harder to see. Ahead of Mars by several degrees of arc, and fifty thousand miles farther away, Louis made out blue-gray dashed lines against a blue-gray sea.

He said, “We’re not exactly opposite yet.”

“No. The Ringworld’s spin will still impose a velocity difference between Needle and the lander. But the vector is vertical. We can compensate for long enough.”

It took Louis a moment to translate those words into a diagram. Then “You’re going to dive at the ocean from a thousand miles altitude?”

“Yes. No risk is insane now, given the position your insanity has put us in.”

Louis burst out laughing (a puppeteer teaching courage to Louis Wu?) and sobered as suddenly. How else could an ex-Hindmost regain any of his authority? He said, “Good enough. Start your dive.”

He dialed and donned a pair of wooden clogs. He stripped off his falling jumper and rolled it around the impact suit and utility vest, but kept the flashlight-laser in his hand. The empty seascape had begun to expand.

“Ready.”

“Go.”

Louis crossed a hundred and twenty thousand miles in one giant step.

Kzin, twenty years ago:

Louis Wu sprawled on a worn stone fooch and thought well of himself.

These oddly shaped stone couches called foochesth were as ubiquitous as park benches throughout the hunting parks of Kzin. They were almost kidney-shaped, built for a male kzin to lie half curled up. The kzinti hunting parks were half wild and stocked with both predators and meat animals: orange-and-yellow jungle, with the foochesth as the only touch of civilization. With a population in the hundreds of millions, the planet was crowded by kzinti standards. The parks were crowded too.

Louis had been touring the jungle since morning. He was tired. Legs dangling, he watched the populace pass before him.

Within the jungle the orange kzinti were almost invisible. One moment, nothing. The next, a quarter-ton of sentient carnivore hot on the trail of something fast and frightened. The male kzin would jerk to a stop and stare — at Louis’s closed-lip smile (because a kzin shows his teeth in challenge) and at the sign of the Patriarch’s protection on his shoulder (Louis had made sure it showed prominently). The kzin would decide it was none of his business, and leave.