Ringworld

"They were hidebound prisoners of routine, ill-equipped to make such a decision. They panicked," said Nessus. "They mutinied. The Pioneer's pilot managed to lock himself in the control room long enough to land the Pioneer on the spaceport ledge. They murdered him for it, for risking the ship and their lives, says Halrloprillalar. I wonder if they did not in truth murder him for breaking tradition, for landing by rocket and without formal permission."

Louis felt eyes on him. He looked up.

The spacer-girl was still watching them. And Nessus was looking back at her with one head, the left.

So that one held the tasp. And that was why Nessus had been looking steadily upward. She wouldn't let Nessus out of her sight, and he dared not let her off the tasp's lovely hook.

"After the killing of the pilot, they left the ship," said Nessus. "Then it was that they learned how badly the pilot had hurt them. The cziltang brone was inert, broken.

They were stranded on the wrong side of a wall a thousand miles high.

"I do not know the equivalent of cziltang brone in Interworld or the Hero's Tongue. I can only tell you what it does. What it does is crucial to us all."

"Go ahead," said Louis Wu.

The Ringworld engineers had designed fail-safe. In many ways it seemed that they had anticipated the fall of civilization, had pla

The meteor defenses, for instance, were so utterly failsafe that Halrloprillalar -

"Call her Prill," Louis suggested.

— that Prill and her crew never considered that they might not be working.

But what of the spaceport? How fail-safe would it be, if some idiot left both doors of the airlock open?

There weren't any airlocks! Instead, there was the cziltang brone. This machine projected a field which caused the structure of the Ringworld floor, and hence of the rim wall, to become permeable to matter. There was some resistance. While the cziltang brone was going -

"Osmosis generator," Louis suggested.

"Perhaps. I suspect that brone is a modifier, possibly obscene."

— air would leak through, but slowly, while the osmosis generator was going. Men could push through in pressure suits, moving as against a steady wind. Machines and large masses could be drawn through by tractors.

"What of pressurized breathing-air?" Speaker asked.

But they made that outside, with the transmutors!

Yes, there was cheap transmutation on the Ringworld. It was cheap only in great quantity, and there were other limits. The machine itself was gigantic. It would make just one element into just one other element. The spaceport's two transmutors would turn lead into nitrogen and oxygen; lead was easy to store and easy to move through the rim wall.

The osmosis generators were a fail-safe device. When and airlock fails, a veritable hurricane of breathing-air can be lost. But if the cziltang brone broke down, the worst that could happen would be that the airlock would be closed to space — and incidentally to returning spacemen.

"Also to us," said Speaker.

Louis said, "Not so fast. It sounds like the osmosis generator is just what we need to get home. We wouldn't have to move the Luir at all. Just point the cziltang brone -" He pronounced it as if it started with a sneeze — "at the Ring floor under the Liar. The Liar would sink through the Ring floor like quicksand. Down, and out the other side."

"To be trapped in the foamed plastic meteor buffer," the kzin retorted. Then, "Correction. The Slaver weapon might serve us there."

"Quite so. Unfortunately," said Nessus, "there is no cziltang brone available to us."

"She's here. She got through somehow!"

"Yes …"

The magnetohydrodynamicists virtually had to learn a new profession before they could begin to rebuild the cziltang brone. It took them several years. The machine had failed in action: it was partly twisted and partly melted. They had to make new parts; recalibrate; use elements they knew would fail, but maybe they'd hold long enough …

There was an accident during that time. An osmosis beam, modified by bad calibration, went through the Pioneer. Two crewmen died waist-deep in a metal floor, and seventeen others suffered permanent brain damage in addition to other injuries when certain permeable membranes became too permeable.

But they got through, the remaining sixteen. They took the idiots with them. They also took the cziltang brone, in case the new Ringworld turned out to be inhospitable.

They found savagery, nothing but savagery.

Years later, some of them tried to go back.

The cziltang brone failed in action, trapping four of them in the rim wall. And that was that. By then they knew that there would be no new parts available anywhere on the Ringworld.

"I don't understand how barbarism could come so fast," said Louis. "You said the Pioneer ran a twenty-four year cycle?"

"Twenty-four years in ship's time, Louis."

"Oh. That does make a difference."

"Yes. To a ship traveling at one Ringworld gravity of thrust, stars tend to be three to six years apart. The actual distances were large. Prill speaks of an abandoned region two hundred light years closer to the mean galactic plane, where three suns clustered within ten light years of each other."

"Two hundred light years … near human space, do you think?"

"Perhaps in human space. Oxygen-atmosphere planets do not in general tend to cluster as closely as they do in the vicinity of Sol. Halrloprillalar speaks of long-term terraforming techniques applied to these worlds, many centuries before the building of the Ringworld. These techniques took too long. They were abandoned halfway by the impatient humans."

"That would explain a lot. Except … no, never mind."

"Primates, Louis? There is evidence enough that your species evolved on Earth. But Earth might have been a convenient base for a terraforming project aimed at worlds in nearby systems. The engineers might have brought pets and servants."

"Like apes and monkeys and Neanderthals …" Louis made a chopping gesture. "It's just speculation. It's not something we need to know."

"Granted." The puppeteer munched a vegetable brick while he talked. "The loop followed by the Pioneer was more than three hundred light years long. There was time for extensive change during a voyage, though such change was rare. Prill's society was a stable one."

"Why was she so sure that the whole Ringworld had gone barbarian? How much exploring did they do?"

"Very little, but enough. Prill was right. There will be no repairs for the cziltang brone. The entire Ringworld must be barbarous by now."

"How?"

"Prill tried to explain to me what happened here, as one of her crew explained it to her. He had oversimplified, of course. It may be that the process started years before the Pioneer departed on its last circuit …"

There had been ten inhabited worlds. When the Ringworld was finished, all of these had been abandoned, left to go their way without the benefit of man.

Consider such a world:

The land is covered with cities in all stages of development. Perhaps slums were made obsolete, but somewhere there are still slums, if only preserved for history. Across the land one can find all the by-products of living: used containers, broken machines, damaged books or film tapes or scrolls, anything that ca