11

"N O, THERE'S NO chance this thing could be two billion years old," said Dr. Katz to one of the marines. "It would have eroded in this environment long ago."

They were all crammed into an inflatable airlock at the axis of the spinning habitats. The lock was transparent. Michael had trouble focusing on his suit checklist, because his gaze kept drifting to the infinite expanse of stars surrounding them. It was nothing he hadn't seen before— but to say that was to completely miss the point. There were few sights more awesome than space itself, devoid of worlds.

He tried to concentrate on the nasal twang of Katz's voice. "Any dust and debris we encounter comes at us as high-energy cosmic radiation. A few thousand years of that and even the best structure will deteriorate. No, this ship can't be more than a century or two old, if that."

"Yeah, what about this radiation thing," said another marine. "We're going so fast now, if we hit anything bigger'n a pin, we're vapor, right?"

"Maybe so," said Katz, "but you and I can't begin to comprehend just how empty it is out here. Every second each one of us is passing through about a million and a half times our own body's volume worth of space. In all that volume, we're only hitting a few stray particles— the rest have been cleared out of the way by the plow sail and there weren't that many to begin with."

The marine didn't look reassured. Michael couldn't say he blamed him.

"The stars don't look any different," said the first marine, who now had his suit check completed and his helmet dogged. Michael was still struggling with his gloves. "Isn't there supposed to be some kind of 'starbow' thing happening?"

"Popular misconception," said Katz. "Nope; you'd need a spectrograph to figure out our velocity. We might as well be standing still as far as I can tell."

Michael glanced behind him. Rue Cassels was already in her suit and was chatting with one of her crew. There were three of the halo-worlders on this jaunt, plus two marines and four scientists, Michael included. His scientific qualifications were pretty thin compared to some of the others, but he did have the benefit of five years spent with Dr. Herat.

The professor was suited up too. "Snap to it, Bequith. Here, let me help you." Dr. Herat settled the helmet on his head. "Nervous?"

"Of course. What kind of a fool do you take me for?"

Herat laughed. "There! You're all set. Not a second too soon, too— they're evacuating the airlock."

Michael looked around, expecting to see the transparent balloon crumpling in around them. It took him a few moments to figure out that since there was no air pressure outside it, it wouldn't collapse even when all the air inside was removed.

"Load up! Four to a cart!" shouted the lead marine. Space suited figures began jumping up to the waiting EVA carts; these were little more than I-beams with clips, spare oxygen, and supply nacelles and a motor at the back. Michael clipped his safety line to one and found himself face-to-face— or more properly, faceplate-to-faceplate— with Rue Cassels.

"Mr. Bequith," she said brightly. "I'm sorry for my behavior in the cantina this morning. It was rude."

"No offense taken," he said, a little stiffly to his own hearing.

"It just threw me when you said you were from Kimpurusha," she said. The cart lurched into motion and Michael grabbed for a handhold. Without missing a beat, Rue continued, "I didn't realize I felt so strongly about it."

Michael tried not to look beyond her to where the translucent habitats were rapidly receding. They seemed the only objects in all of space.

"I feel pretty strongly about it, too," he said. He quickly checked to ensure that she had opened a private channel between them; then he said, "I was involved in a rebellion against the R.E. when I was seventeen."

He couldn't see her face now; she was a silhouette against the diamond-hard stars. She didn't say anything for a moment and he thought he must have revealed too much. Then she said, "I feel like an idiot."

"What do you mean?"

"Here I go knowing just how different all us halo-worlders are from each other and it never occurred to me that people from High Space might be diverse, too. I just assumed you were all one big happy family."

"I remember before the Reconquista," he said. "It was only twenty years ago."

"I guess so," she said. "We only heard about Kimpurusha four years ago. I grew up thinking that of all the worlds, it, at least, would never give over to the R.E."

Now that he thought about it, it was plain that news about Kimpurusha's fall would not even now have reached the farthest outposts of the Cycler Compact. Dispatches from his brothers at the monastery, sermons, and theological abstracts were still winging their way at light-speed to the struggling colonies around isolated Jovian planets and methane dwarfs hanging in the silent darkness between the lit worlds. For them, the events of his childhood had not yet occurred.

"Turnover in five seconds," said the marine flying the cart.

"Hang on," said Rue. "No, like this." She drew his hand to a ring he hadn't known was there. "And watch the stars— it'll keep you from throwing up."

There was a stomach-lurching moment as the cart flipped over; watching the stars turn seemed to work, though, since that way Michael knew the feeling was real and not the phantom-falling sensation that he always had when weightless. "Deceleration in five," said the marine.

"There it is," said Rue. Her silhouetted arm pointed almost straight down. "Lake Flaccid."

Somebody had a floodlight and was roving it over the structure; there was no way to tell where the light was coming from, of course, since there was no air here to show a beam. Michael could see a disembodied oval of illuminated metal, which zipped to and fro dizzyingly, sometimes sliding off the giant sphere and disappearing completely. The first time that happened, he thought the light had been switched off, the effect was so total. It didn't help that the habitat rotated, so the vision of metal sliding through the spotlight made it seem as though the beam itself was moving, even when it wasn't.

"First time we came here," said Rue, "I was so scared. The place looks like my home, you know— like Allemagne. But it wasn't. It could hold anything— monsters, maybe, ghosts. I swear I have never been so frightened in my entire life as I was when we went to open the airlocks of the lake."

He laughed shakily. "I can believe that."

Whoever held the spotlight switched it to broader illumination and the whole habitat appeared, a ghostly white metal sphere covered with zigzag seams. A little vapor hazed off it; the marine, his voice flat, said, "See a bit of hydrogen evaporating from the heat of the lamps." They were probably still half a kilometer away and the light was not very strong. Michael decided he would not ask what the local temperature was.

The other cart blinked into existence below them; simultaneously its shadow appeared, hugely distorted, near the limb of the sphere.

"Knock knock," said someone; it sounded like Katz. "Anybody home?"

"There's two hotspots," said Corinna Chandra. She was on the other cart. "Opposite one another. Last time we found a hatch by one. Maybe there's one by the other."

"Did you mark the hatch you used?" asked Dr. Herat.

"We clipped a line to a ring there. You can see it at four o'clock."

It took a while for Michael to see it, because Corinna's four o'clock was his ten o'clock. A thin thread of white hovered just over the habitat's horizon; that must be it.

"We'll explore the second entrance later," said Dr. Herat. "Today we're going to follow your original route in. This time out we're interested in the lake, not the external structure."

Michael stared at the sphere, which was fast becoming a giant wall below them. "Decel burn," said the marine. Michael held on as weight reappeared for a second. Then they were drifting ever so gently in the direction of that dangling cable.

People from the other cart were grabbing for the line; Michael hardly noticed. He couldn't take his eyes off the sphere. He did not need the NeoShinto AI to help him feel awe of this place.

He imagined diminutive Rue Cassels floating here with her companions. Just them— alone, unknown to the rest of humanity and about to open an inhuman door. His admiration for her kept growing.

"Go, Corinna," said Rue. One of the anonymous space suits began to pull itself hand over hand up the line. Corinna stopped at a broad disk of ribbed and spikey, slightly purple material and began digging at an indentation near its edge.

"The airlock's a magnetic liquid; right now it's frozen so the magnets aren't on," said Corinna. "This switch turns on the heat and magnets at the same time. Watch." She withdrew her hand and the purple surface suddenly roiled and shimmered like an oil slick. Corinna reached over and her arm disappeared up to the shoulder in the material. "See?"

"Wait for us," said the lead marine. Both carts were at the cable now and Michael watched as they reeled themselves in.

"What's fun," said Rue, "is that the air pressure inside wants to pop you out like a grape seed. It's easier to get out than in, which doesn't strike me as too safe."

"On the other hand," said Dr. Herat, "there's no moving parts."

They were clustered around the disk now. "There's a bar just inside the edge here," said Corinna. "Just grab and do a flip— like so." She reached into the disk, somersaulted, and disappeared into it. The marines followed.

The material of the disk was denser than Michael expected— almost a meter thick and lens-shaped. It resisted his passage like a strong wind. When he completed his roll, though, he found himself floating inside a cylinder about four meters long and three across. It was brightly lit by the marines' floodlights and lined with ordinary-looking rectangular locker doors.

"You inspected these?" Herat pointed at them.

"Yeah," said Rue. "Nothing in them. Spotlessly clean, too. Like they'd never been used." She was undogging her helmet. "It's just nitrogen in here, so monitor your mesobots to make sure you don't come down with nitrogen narcosis. And keep your nosepiece in." She demonstrated the oxy clips, which promptly made her sound congested. Michael pulled up an inscape readout to watch the nitrogen scrubbers in his own bloodstream. He situated it down and to the right in his peripheral vision, so it wouldn't get in the way.

"Next is the strap palace," said Rue. She was obviously enjoying playing tour guide. "Come along, don't dawdle."

The far end of the cylinder had a two meter-wide opening in it. This turned out to be the entrance to a long round corridor. As Rue's name for it implied, the corridor was strung with hundreds of rubbery straps, each as wide as Michael's waist. They crisscrossed the space at various angles, making it impossible to see down the length of the cylinder.

"This is bizarre," said Katz unnecessarily. "What the hell are these things?"

Herat said, "I'd say the logical equivalent of handholds or steps, for something that uses its whole body for locomotion. Bequith?"

His scalp crawled looking at the things. "Maybe." Rue was hauling herself from strap to strap, closely followed by the two marines. The lights cast weird tongues of shadow across everything.

"This is like nothing I've ever seen," said Katz.

"But we can infer a lot from it," said Herat. "They were less than two meters in diameter, probably not more than three long; look, if you were a fish or an eel, you'd be able to bounce your way along this corridor pretty quickly. If it were completely open, you'd be whacking the walls or adrift— there'd be nothing for your body to undulate against."

"You think they're fish?"

"Why not? After all, everything below here seems to be full of some kind of liquid."

The corridor ended in a large long space Michael recognized from photographs as the shore of Lake Flaccid. It was spookier in real life: a long cylinder, like a cave or tunnel, lit only by darting flashlight beams, with darkness at its far end. Rue had overshot her landing and now hung in the very center of the space. She was fiddling with her wrist rockets, trying to jet back. In freefall, up and down were arbitrary choices; Michael could choose to think he was looking down a wide deep well, but it was more comforting to choose one side of that well and decide that it was «down» and that the side opposite it was "up." Indeed, in unspoken agreement everyone drifted over to one wall and oriented their feet down to it. Michael did the same and now he could imagine the cylinder was lying on its side and he and the others were standing inside it.

"Strange. What are these?" Katz's voice made no echoes here. He was shining his lamp at some translucent circles set in the floor. "Lights?"

"That's what we thought," said Corinna. She took a tiptoe step and sailed over to one. "But they're gelatinous and have things embedded in them. Like a jelly salad."

Katz joined her. "It's dark stuff, different shapes and sizes. Looks like… peas… and something cylindrical… and a square block. Can't be a light."

Herat dismissed the circles with a wave of his hand. "Signs. Actually," he said, looking around, "this place is festooned with writing. It's just that it's for beings who see with sonar."

Everybody turned to stare at Herat. Michael hid a smile; the professor was showing off, but he had to admit it was impressive. Herat's ability to look at an alien artifact and determine its purpose was legendary. These scientists were seeing that ability in action for the first time.

"Let's see what this lake is made of, shall we?" Dr. Herat folded himself cross-legged and gradually drifted down to rest on the lip above the gray substance Rue had called a lake. Michael wouldn't have known that the gray stuff wasn't solid if he hadn't been briefed. It simply looked like the ends of the cylinder were metal and the slightly wider middle part was this gray material. It was hard for the planet-born to imagine a cylindrical pool, after all; the lake was below him, but it also curved up to each side and was overhead. Reason told him that because the habitat rotated, the liquid would move outward because of centrifugal force. It was much easier just to ignore the liquid above him and see only what was below.

One of the scientists, Dr. Salas, was a materials specialist. He hunkered down with Dr. Herat and they dipped things in the lake for a while, talking in low murmurs, sometimes laughing. One of the marines had unpacked some fish-shaped mesobots and now held one over the lake; its sonar was able to penetrate the strange surface with ease. Michael opened an inscape view of the sonar signal and got his first view of the bottom of the lake.

Evan Laurel saw the inscape window and drifted over. "Stuff conducts sound really well." He pointed out a feature in their shared window. "Hey, that looks like an armchair…. Except it's a good four meters across."

"There are openings in the walls," said the marine.

"Yeah. We figured we'd make some of those our first target. Gravity gets pretty steep as you go down. At the bottom it's twice Earth-standard."

The other marine had drifted out across the lake and was inspecting the far end.

Dr. Herat began to laugh. "Of course! It's a perfect solution!"

They all clustered around him. He grinned, holding up a jar full of grayish stuff. "It's not a liquid at all! It's actually made of fine little beads, a bit bigger than sand grains. It's a granulated aerogel!"

The marines exchanged an uncomprehending glance. "Aerogels are ninety-nine percent air," said Herat. "We use them as insulation. They weigh almost nothing, but they're pretty strong. Our hosts, here," he waved around at the tunnel, "found they could make a kind of substitute for water, at a thousandth the weight. The grains don't crush easily, but they'll deform and move past each other. They behave mechanically almost exactly like a liquid."

Katz nodded vigorously. "Cheaper to accelerate," he said.

"I kind of thought that was what it was," said Evan. "But I didn't want to say so in case I was wrong."

"So now what?" asked Rue. "Can we go in it?"

"Oh, sure! It's not going to have any effect on our suits. And the sonar penetrates it. Perfect."

"In that case, we'd better set up camp. Corinna?"

She and Evan began unpacking and pasting down a pressure tent. "Just like old times, huh?" said Evan with a grin.

Herat shot a significant glance at Michael; that was his cue to butt in and make sure the halo-worlders followed proper quarantine procedure. He went over and politely asked to help. Meanwhile Herat, Rue, and the others crouched at the edge of the lake and ran their hands through it, discussing how best to proceed.

They erected two pressure tents and stuck them to the floor using a degradable glue. After several more hours spent surveying the axis, they retreated to the tents. Michael was in the larger tent, with Herat, Salas, Katz— and Rue Cassels. They stripped out of their suits, but left the black skintight underlayer on, as per regulations. In the event of a depressurization, the underlayer would protect them for several minutes.

There was almost no gravity here, so they pitched their sleeping bags standing up. That left plenty of floor space, where Salas and Herat hunkered down to play with samples of the aerogel. Katz fussed with the air mix for a while, then put on blinkers and earplugs and climbed into his sleeping bag. "See you in the morning, if that concept still has value around here," he said.

Michael sat down next to Herat. His employer had an uncharacteristically dreamy expression on his face. "Look at this place," said Herat, peering out of the tent's small window.

Michael called over his shoulder. "We've seen alien technology before."

"Yes… but this is different."

Michael nodded.

"How?"

They both turned their heads. Rue Cassels stood behind them. "How is this different?" she asked.

Herat scratched his ear. "Hmm… pretty fundamental question." Herat and Michael turned, offering a place in their circle. Rue drifted down to sit with them.

"Well," said Herat, "you know the R.E.'s been expanding through what used to be the cycler civilization for sixty years now. We actually had the FTL drive twenty years before that, but Earth hushed it up and started slowly, with exploratory vehicles that deliberately avoided the suns colonized by the cyclers. Even then the plan was to arrive at the cycler worlds with overwhelming force and complete knowledge about the stellar neighborhood.

"We sent exploration ships out to search for Earthlike worlds. The program concentrated almost exclusively on single, G-class stars like the sun. We did find life, everywhere, in fact. The universe is overflowing with it, it appears in unthinkable environments. It thrives brainless and without senses on nearly every world that could sustain liquid water. But intelligent life? That's another story. We didn't find any during that period— not currently existing intelligence, that is. But everywhere we went, we found the ruins of great ancient civilizations… cities and shattered fleets; burnt-off continents still radioactive after a million years… and everywhere, we found Earthlike planets that had been bombarded by meteors all at the same time, sixty-five million years ago.

"I spent a summer on the Yucatan peninsula, in Mexico, studying the Chicxulub crater. It's sixty-five million years old; the meteor that made it caused the extinction of the dinosaurs. I'm partly responsible for naming the particular aliens who made that crater and thousands like it throughout the galaxy. The Chicxulub, you see, were the last pangalactic civilization. They wiped out every other sentient species in the galaxy by sending out self-reproducing planet killers— von Neumann machines— that bombarded every world that had animal life bigger than a fly. Then they died out in turn.

"The Chicxulub left the galaxy empty of technological species. Our studies showed that it took at least thirty million years for new toolmaking species to develop from the Chicxulub extinction event.

"The Chicxulub partly explain why the galaxy is so empty of intelligent life— but not completely. In the early years of the exploration the Panspermia Institute was formed and I was one of the first graduates. They filled our heads with idiotic notions; I was starry-eyed and intent on uncovering a galactic pyramid of consciousness, with microbes at the bottom, ancient wise species at the top, and us somewhere in the middle— A vision inherited from the mystical writings of Teilhard de Chardin, though I had never even heard his name at that point. But the stupid ideas we got from him resulted in the fiasco the Institute's in now.

"Our goal was to find our counterparts— conscious, toolmaking aliens whose civilizations might help us understand our own. We would find or help establish a galactic government, integrate our culture with those alien ones and follow the path to species-maturity. It was a fine vision and heavily funded by the R.E. We even built a giant orbital station, called Olympus, which was to be the home for our ambassadorial counterparts."

Rue nodded. "And you sponged our wealth off relentlessly to pay for it, until places like Chandaka can no longer survive on their own."

"Yes, but we thought it was for a good cause! We genuinely believed that the outcome would be a galactic civilization with a future history of millions, maybe billions of years, with humanity as the founders and chief patrons. Think of it! What greater dream could there be?"

Rue shook her head. "But the halo worlds could never be a part of it. We can't travel at faster than light. We could never visit Olympus."

"Well." Herat looked uncomfortable. "Nobody on Earth ever really believed anyone would live in the halo by choice. How could people live their whole lives without seeing the light of a sun? No— anybody born on a lit world would wither and die in the halos and we thought— they thought— that over time, the halo worlds would be abandoned. That's still the prevailing opinion in the R.E.

"So the Rights Economy went from being a completely local, Earthbound incestuous loop into a kind of panhuman taxation empire. It expanded like a swarm of locusts, devouring the inhabited lit worlds of the cycler civilization, bypassing the halo worlds and leaving them stranded and alone." Herat sighed. "I know it's a tragedy. I saw it happen. But at the time… it made so much sense. The R.E. was the only way to maintain control over the far-flung colonies, to prevent them from developing into political rivals, or from going transhuman on us.

"Anyway, thousands of ships were fanning out across the galaxy, searching for intelligent species. There was life everywhere, after all— why not life like ourselves?"

"Hang on," said Rue. "It sounds like you're saying you never found aliens. But I've heard about them— they do exist."

"Ah, well." Herat smiled sadly. "For political reasons, we have found it necessary to label certain species and… things… as aliens. Don't get me wrong— there are starfaring species out there, like the hinge foxes, or the autotrophs. We have found intelligent entities. Just… not what we expected. Not what we were looking for.

"Take the autotrophs. Because their planet had a more active carbon cycle than Earth, oxygen from photosynthesis took a billion years longer to concentrate in their atmosphere. Animals never developed, because autotrophic life— life that produces its own nutrients from ambient energy and minerals— had a billion extra years to evolve.

"The autotrophs developed in a kind of Eden, where predation didn't exist. They developed technology more as an outgrowth of their own bodies than as a cultural phenomenon. Imagine their shock when they began to visit other worlds and discovered that creatures who actually ate one another were dominant nearly everywhere.

"We've met the autotrophs. But they won't speak to us. To them, we are the worst possible moral abomination, right down to the cellular level.

"Then there's the solitaires. They're individual creatures, we know that. Each one has built a starship around itself and they travel all over the galaxy. But they don't have the concept of language at all; they're solopsists. Since we haven't even met one, we can only theorize about how they developed technology; I think they reproduce by budding and the new bud takes away the knowledge of its elder. But who knows?

"And there's the sylphs, who are incredibly dangerous. We set up colonies on six sylph worlds before we even knew they existed. A biologist on one of the colonies made the discovery that every form of life on her planet had identical DNA— from the giant fern forests to sea slugs at the bottom of the ocean, it was one species, just expressing different genes to become different life-forms. And even the plants had nervous systems. What's more, the colonists had all reported various levels of radio and electronic interference on these worlds. It turns out the sylphs communicate constantly— it's a global network that passes experiential information back and forth. By the time we realized this, a good ten percent of the colonists themselves were sylphs— changelings, replaced in the womb by mimics.

"After an initial panic we realized the sylphs weren't attacking, they were just doing what they do— adapting to a new feature of the environment, in this case us. The changelings didn't even know they were sylphs— their human consciousness was completely separate from the underlying sylph mind.

"Discovering this, we made the fatal mistake: We tried to communicate with them.

"The result," said Herat sadly, "was the extermination of a colony of twenty-five thousand people and the subsequent cauterization of the continent they'd lived on by our navy. It turns out that to the sylphs, the highest ideal is adaptation. To them, the notion of adapting your environment to suit you is horrifying.

"They happily cohabited with us as long as they saw us as just another feature of the local environment. When they realized we were conscious beings like themselves, they were so outraged that they moved to destroy us. We had to wipe out one entire sylph culture in order to prevent the information spreading to the others. The sylphs have FTL and they're incredibly powerful. We're now in the midst of pulling our colonies off their worlds— slowly and carefully."

Rue took off her sunglasses and rubbed her eyes. "That's awful."

"Well, the R.E. became a lot more cautious after that. About eight years ago, I was assigned to explore the various ruins we'd found and try to come up with a general pattern for the rise and fall of galactic civilizations."

"Really?" She seemed fascinated by that idea. "Is that when you hired Mike?" She turned her dark eyes in his direction.

"Shortly after," said Herat. "We visited hundreds of worlds and we did find a pattern. But we resisted accepting it, until we visited a place called Dis and were hit over the head with it." He smiled ironically.

"Go on," said Salas. "I've heard of Dis— what's it like?"

"Dis is a rectangular piece of woven fullerene, ten meters thick, four hundred kilometers wide, and five hundred long. Three billion years ago, it was part of a ring-shaped orbital structure almost two thousand kilometers in diameter. It had two-hundred kilometer high walls on the edges of the ring to keep atmosphere in and it rotated to provide gravity. At some time after its abandonment it must have been hit by an asteroid, which tore it apart. The part we found is in a highly elliptical orbit around a white dwarf star that was once a G-class sun. This sun long ago swelled up, swallowed its planets, and shrank again. Dis is the only legacy of a magnificent species three billion years old.

"Most of the soil and structures that were on the inside surface of the Dis ring were knocked off it in the catastrophe, but we found one nearly intact city and thousands of kilometers of subsurface tunnels. They left records and we were able to piece together a little of their history.

"They wanted their civilization to last forever— that's the one thing we do know about them. They built for the ages in everything they did. The evidence is that they did last a very long time— maybe eighty million years. But early on, they discovered a disquieting truth we are only just learning ourselves. It is this: Sentience and toolmaking abilities are powerful ways for a species to move into a new ecological niche. But in the long run, sentient, toolmaking beings are never the fittest species for a given niche. What I mean is, if you need tools to survive, you're not well fitted to your environment. And if you no longer need to use tools, you'll eventually lose the capacity to create them. It doesn't matter how smart you are, or how well you plan: Over the longest of the long term, millions of years, species that have evolved to be comfortable in a particular environment will always win out. And by definition, a species that's well fitted to a given environment is one that doesn't need tools to survive in it.

"Look at crocodiles. Humans might move into their environment— underwater in swamps. We might devise all kinds of sophisticated devices to help us live there, or artificially keep the swamp drained. But do you really think that, over thousands or millions of years, there won't be political uprisings? System failures? Religious wars? Mad bombers? The instant something perturbs the social system that's needed to support the technology, the crocodiles will take over again, because all they have to do to survive is swim and eat.

"It's the same with consciousness. We know now that it evolves to enable a species to deal with unforeseen situations. By definition, anything we've mastered becomes instinctive. Walking is not something we have to consciously think about, right? Well, what about physics, chemistry, social engineering? If we have to think about them, we haven't mastered them— they are still troublesome to us. A species that succeeds in really mastering something like physics has no more need to be conscious of it. Quantum mechanics becomes an instinct, the way ballistics already is for us. Originally, we must have had to put a lot of thought into throwing things like rocks or spears. We eventually evolved to be able to throw without thinking— and that is a sign of things to come. Some day, we'll become like the people of Dis, able to maintain a technological infrastructure without needing to think about it. Without needing to think, at all…

"The builders of Dis faced a dilemma: The best way to survive in the long run on any world they colonized was to adapt yourself to the environment. The best survivors would be those who no longer needed technology to get by. They tried to outlaw such alterations, but how do you do such a thing for the long term without suppressing the scientific knowledge that makes it possible? Over tens or thousands of millennia, you can only do this by suppressing all technological development, because technologies intertwine. This tactic results in the same spiral into nontechnological life. So inevitably, subspecies appeared that were better survivors in a given locale, because they didn't need technology in that locale. This happened every time, on all their worlds.

"The inhabitants of Dis had studied previous starfaring species. The records are hard to decipher, but I found evidence that all previous galactic civilizations had succumbed to the same internal contradictions. The Dis-builders tried to avoid their fate, but over the ages they were replaced on all their worlds by fitter offspring. These descendents had no need for tools, for culture, for historical records. They and their environment were one. The conscious, spacefaring species could always come back and take over easily from them. But given enough time… and time always passes… the same end result would occur. They would be replaced again. And so they saw that their very strength, the highest attainments they as a species had achieved, contained the seeds of their downfall.

"This discovery finally explained to us why toolmaking species are rare to begin with. It takes an unusual combination of factors to create a species that is fit enough to survive, but at the same time is so unfit in its native environment that it must turn to its weakest organ, its brain, for help. Reliance on tools is a tremendous handicap for any species; only a few manage to turn it into an asset.

"The builders of Dis knew they were doomed. We all are: technological civilization represents a species' desperate attempt to build a bubble to keep hostile environments at bay. Sentient species also never cooperate with one another over the long term, because the environments they need in order to live are incompatible. Some, like the Chicxulub, accept this easily and try to exterminate everyone else. Even they can't stop their own evolution and so eventually they cease to be starfaring species. Destruction or devolution are the only choices.

"It's hard to see how we can cohabit with the autotrophs and the sylphs, if humanity is bent on expansion and so are they. Something catastrophic is bound to happen; and if not, well, we'll just evolve away from what we are, sooner or later."

"That's about as bleak a story as you can get," said Rue. She scowled off into space for a while. "But you still haven't answered my question: how is Jentry's Envy different?"

Herat nodded. "Two things. One is something we found on Dis, something that scares me even to think about. But I'll start with the other, obvious one: Jentry's Envy appears to have been built for more than one kind of species to use— not just more than one species, more than one kind. It implies the one thing we've never seen: multispecies cooperation. If it's not a fluke, a one-time happening in the history of the galaxy, then it suggests there may be a way to break the cycle of competition and destruction that's ruled since the first stars were born.

"But the other thing, the thing that scares me right now, is that while we were on Dis we found evidence that a number of other races had visited Dis in the past— searchers, like ourselves. In two places, we even found Lasa graffiti."

"Graffiti?"

"Well… artifacts and writings, like the ones on the habitat here. We haven't fully translated it, but the point is that one of those pieces of writing dates to the Lasa period, two billion years ago. We know it's Lasa because it illuminates the meaning of other samples we have— it's either Lasa or somebody who could think in the language. But the other…

"The other thing was a piece of Lasa technology that also appears genuine, because its integrated data storage has the unforgeable mathematical signature of the Lasa," said Herat. "But when we dated it, we found it to be only twenty thousand years old."

Salas whistled and sat back. "Two billion years…"

Herat shook his head. "It's impossible. But every time I see the pictures of that habitat out there, with the Lasa writing on it, I wonder… Were the poor inhabitants of Dis right— is a permanent civilization possible? If so, how? What's frightening is the thought of how you might have to live— how you'd have to understand the world— in order to maintain a civilization for two billion years."