by Greg Egan
Azar said, “This is a lot to conclude from one weird ion. Are we sure it’s not an instrument error?”
Before the insect touched the ocean floor it picked a second speck of ash out of the water. Azar had the nanotech rebuild the relevant instruments from scratch and repeat the analysis. There had been no error; all the properties were the same.
5
The nanotech built more moles and sent them down into the rock, but even here where the crust was thinner, Azar knew she would have to be patient.
“Sixty days?” she lamented, pacing the flight deck. She didn’t expect to be able to unravel the nucleon-by-nucleon details of the femtotech in a hurry, but if they could obtain a sample of the deep crust and observe the way its composition was changing as energy was released, that would at least confirm that their overall picture of the Ground Heaters’ process was correct.
Until they had some of this white-hot rock to play with, the practicalities of harnessing the femtotech remained obscure, but Azar’s sense of anxiety at their isolation had almost vanished. To be stranded for nothing, with little to be gained if they managed to return, had been a dismal prospect, but now that the stakes were so high the situation was exhilarating. Prometheus, eat your heart out.
While they waited for the moles to hit pay dirt they continued to explore the ribbon forest, building up a catalog of the three kinds of life that Tallulah’s mysterious fire sustained. Perhaps unsurprisingly, the P2 animals – the newest – were by far the most numerous, having been engineered to be able to digest everything that had come before them. To the older N3s, and the even rarer C3s, the P2s were unpalatable – though not indestructible; the scouts witnessed cases of N3 fish killing off their P2 rivals, even though they were useless as food. What’s more, a few of the C3 creatures were able to feed on N3 flesh; evolution had finally granted them a belated revenge on the first wave of invaders. In another hundred million years, who knew who would be eating whom?
When they first came across the colony of P2 “lizards”, Azar thought that they were charming animals. Spread across a dozen square kilometers of the forest floor, their network of burrows was entwined with the giant ribbon-weeds’ roots, which they tapped for food.
The lizards had two eight-clawed limbs that they used for digging and grasping objects; all their motive force came from their powerful tails. They sensed the world around them with a mixture of IR vision and sonar. Glands in their cheeks excreted complex molecular cocktails, which they squirted at each other almost constantly. Olfactory signaling within a colony of social animals was nothing surprising; the shock came when the scout mites caught some of them squirting the chemicals at inanimate objects in certain chambers within their burrows – and the inanimate objects squirted back replies. On closer examination, the devices turned out to be sophisticated chemical transceivers, linked by a fiber optic network.
“So these are our predecessors,” Shelma said. “They came all the way to Tallulah, in the middle of nowhere, to solve the mystery of its warmth. But they must have found the femtotech long ago, so why are they still here? Why not take the treasure home? Why not spread it across the galaxy?”
“Why leave a world that will keep you warm for a million times longer than any star?” Azar replied.
“Why not build a hundred more worlds just like it?” Shelma countered.
“Let’s ask them.”
The scouts set to work sampling the chemical signals that comprised the lizards’ language, and trying to correlate them with elements in the environment and the creatures’ behavior. It was an impertinent level of eavesdropping, but they had to bootstrap communications somehow, and with no culture or biology in common they couldn’t simply march up to the lizards and start playing charades. Ideally the scouts would have included children as their subjects, in order to share in any lessons they received, but in the entire colony of fifty thousand there were currently no young at all – which suggested that the lizards had cut back their fertility to stabilize the population, while living more or less as long as they wished.
Fiber optic trunk lines connected the colony to others around the planet, and all the data traffic passing through appeared to conform to a single language. If there were any intelligent N3 creatures still around, either they weren’t plugged into the same network, or there’d been a radical assimilation of cultures in one direction or the other.
Fed by the forest and served by their own rudimentary nanotech, the lizards seemed to pass the time socializing. The chemical transceivers granted them access to libraries, but most of the content being summoned appeared very similar to their habitual person-to-person exchanges, suggesting that it was closer to narrative history or fiction than anything more specialized and technical. Then again, even the most naturalistic dialogues might have encoded subtle themes that remained elusive at this stage of the analysis.
The lizards had no apparent social hierarchies, and as hermaphrodites they exhibited no sexual dimorphism, but the scouts identified one curious form of division. Many of the lizards identified themselves as belonging to one of three groups, which were named for the actions of spiraling inward, spiraling outward, and, the clear majority, following a circle. Since this was not a description of anyone’s actual swimming style, it had to be a metaphor, but for what? The scouts had failed to observe anything tangible that correlated with this classification.
After thirty days Shelma declared, “It’s time to introduce ourselves.”
“Are you sure?” Azar was impatient for answers, but it seemed as if the scouts could easily spend another month piecing together further subtleties of the lizards’ language.
“We’ve reached the point where we can greet them politely and explain who we are,” Shelma said. “The way to get more reliable language acquisition now is through dialogue.”
Shelma instructed the nanotech to build two facsimile lizard bodies. These robots would be obvious caricatures, functional but not such perfect imitations that the lizards could mistake them for fellow colonists.
The insect communicated with the robot lizards by line-of-sight laser pulses with a range of just a few meters. Azar and Shelma kept their software on the insect’s processor and operated the lizards by telepresence, monitoring the robots’ points of view without becoming fully immersed in their sensoria or giving up the feeling of being located on the insect’s flight deck.
With her lizard body swimming toward the edge of the colony, weaving its way between the ribbon-weeds, Azar was overwhelmed with happiness. She was more than just a traveler now; she was about to become an ambassador to a hitherto unknown culture. And however physically isolated she was at this moment, she did not feel cut off from her roots in Hanuz. In her mind’s eye, she could almost see the faces of the people she hoped to regale with her adventures.
A lizard approached, seemingly unafraid. The puff of chemicals it squirted through the water was barely visible, but Azar heard the translation loud and clear. “Who are you?”
“We come in peace from another world,” Azar announced proudly. The lizards had not been seen discussing astronomy, but they did have a word for the planet as a whole, and a general inflection for “not this thing, but another of its kind”.
The lizard turned and fled.
On the flight deck, Azar turned to Shelma. “What did I do wrong?” She’d half-expected her claim to be greeted with skepticism – their robot bodies were well within reach of the lizards’ own technology, after all – but perhaps the gamma rays that had triggered the ice halo had served as an ominous calling card.
“Nothing,” Shelma assured her. “Summoning other witnesses is a common response.” Shelma had no prior experience of first contact, but the library confirmed her claim.
Azar said, “What if they’ve forgotten that there are other worlds? They’ve been here for a million years. They might not even remember their own history.”
Shelma was not persuaded. “There’s too much technology around; even if
they fell into a dark age at some point, they would have reconstructed everything by now.” The lizards’ nanotech maintained their health; it could easily have sequenced all the plants and animals around them, just as the Amalgam nanotech had done. Still, without the right context – without libraries of replicator sequences from a thousand other worlds – would they know how to interpret the data?
Azar saw bodies darting through the fronds. The first lizard had returned, with ten, twelve, fourteen friends. She could never have distinguished one from the other unaided, so she invoked software to track their features and assign phonetic names to them all.
Shelma said, “Please accept our good wishes. We come in peace from another world.”
Omar, the first lizard they’d met, replied, “How can that be? It’s not time.”
His companion Lisa added, “You’re not taking Tallulah from us. We’ll never accept that.”
Suddenly all fourteen lizards were speaking at once. Azar’s robot’s senses had no problem following their words; the chemical emissions were tagged with individual markers, so there was no chance of confusing one lizard’s words for another’s. Azar had the audio translation untangled into separate streams.
Some of the lizards were expressing surprise and skepticism, not at the notion of visitors from another world, but at the timing of their arrival. Others seemed to think that she and Shelma were the vanguard of an army of colonists who had come to seize Tallulah, and they defiantly expressed their intention to resist.
Shelma said, “We’re not colonists, we’re merely explorers. We saw Tallulah and became curious.”
“Where is your own world?” a lizard dubbed Caleb demanded.
“My companion and I come from different worlds,” Shelma explained. “Both more than a thousand light-years away.” The software would translate this into the local measure of distance, but with no units suitable for astronomical scales the number attached would be awfully large.
The lizards broke into a fresh cacophony. Such a journey was inconceivable.
Omar said, “Please come with us.”
The crowd pressed around them from all sides, urging them forward. Shelma said privately, “Just go where they ask, don’t resist.”
The lizards seemed unaware of the tiny insect hovering between the larger robots; certainly its laser flashes were outside their visible spectrum. “You think they’re taking us prisoner?” Azar said. It was hard to decide which was more bizarre: the fact that someone might wish to do this, or the fact that they believed it could be done.
“More or less,” Shelma replied. “But at this point I’d rather cooperate than escape. If we can clear up a few misunderstandings, everything should be fine.”
Azar let the pack of lizards guide her through the ribbon-weeds, then down into a burrow. Watching events through the flight deck’s dome made her feel much less claustrophobic than the impression she got from her jostled robot’s senses, but when the narrowing tunnels and the ever tighter crush meant the insect risked becoming conspicuous, they had it crawl inside Shelma’s body. The line of sight between the two larger robots came and went, so Azar put her own lizard on autopilot, meekly complying with the flow of the crowd, and changed the insect’s flight deck scape to show her an external view rather than the innards of its host.
They were taken to a small, bare chamber with a single entrance. After six of the lizards piled in with them, there was little room to spare.
Omar resumed the interrogation, his skepticism undiminished. “Your star must be very dim,” he declared. “We believed that we had many more years.”
Azar thought she was beginning to understand. Tallulah would not come close to another star for a very long time; the lizards had somehow fixed on that event as the most likely occasion for visitors.
“Our stars are very bright, but very distant,” she insisted. “Why do you doubt that? Didn’t your own ancestors travel far to reach this world?”
Omar said, “Their journey took half a year.”
Half a year? Perhaps the real story had degenerated into myth, retold with cozy, domesticated numbers to replace the terrifying reality of interstellar distances.
“At the speed of light?” asked Shelma.
The chamber erupted with expressions of mirth and derision. “Only light travels at the speed of light,” Lisa explained.
The scouts had found no evidence of the lizards digitizing themselves. Had they lost that technology, or had they never possessed it? Could their ancestors really have crossed the light years as flesh?
“So how far would they have traveled,” Azar asked, “in that half-year?”
“Perhaps a billion kilometers,” Omar replied.
Azar said nothing, but the claim was absurd; a billion kilometers was the size of a small planetary system. The lizards had spent too long dozing away the centuries at the bottom of this warm ocean; not only had they forgotten their own history, they had forgotten the true scale of the universe around them.
Shelma persisted. “When we follow the path of Tallulah back in time, it doesn’t come that close to the path of any star for a billion years. Have you been here for a billion years?”
Omar said, “How can you know Tallulah’s path? How long have you been watching us?”
“Thirty thousand years,” Shelma replied. “Not me personally, but people I trust.”
Mirth again. Why was this claim so laughable?
“Thirty thousand years?” Omar said. “Why did you imagine that would tell you the whole story?”
Shelma was bewildered now. “We’ve tracked your position and your speed,” she said. “We know the motion of the stars. What else is there to account for?” Tallulah’s galactic orbit was sparsely populated; chaos would eventually make retrodiction impossible, but the confidence levels over a billion years were still quite tight.
“Eight times since we arrived on Tallulah,” Omar explained, “this world has changed course. Eight times, the heat rose from the ground to bring our path closer to our destination.”
6
An argument broke out among the lizards; they withdrew from the discussion and left the chamber, leaving their guests with only two taciturn sentries. The insect probably could have slipped past these guards, or even burrowed its way back to the surface if necessary, but Shelma insisted that it was better to try to keep the dialogue open, and on consideration Azar agreed.
“So our orphan is a tourist,” Shelma mused. “It steered its way right into the lizards’ home system, and now it’s heading for a new destination. But did the Ground Heaters arrange that, or did the N3 colonists bolt on the engines later?”
“Maybe that’s where the water went,” Azar suggested. The eruptions they’d seen earlier would have no long term effect on the planet’s motion, but a hotter jet that reached escape velocity would do the trick.
Shelma said, “Water would be a strange choice of propellant. Photonic jets would be more efficient.”
“If it was the N3ers doing it,” Azar said, “maybe they didn’t have fine enough control over the femtotech.”
“Maybe. But the N3ers left no biological presence on the land, so they must have been ocean dwellers. Would ocean dwellers throw so much water into space that they lost thirty percent of their real estate?”
“Good point,” Azar conceded. “But why does anyone steer a whole planet from system to system? If it was the Ground Heaters, surely they could have made smaller, faster spacecraft using the femtotech.”
Shelma threw up her hands. “Let’s go back to the beginning. The Ground Heaters grew up with tidal heating. When that started running down, they got lucky; they managed to devise a spectacularly good replacement. So what would they do next?”
“Some cultures would have sent out nanotech spores,” Azar said, “followed by a wave of digitized travelers. But we know they didn’t do that, or the femtotech would still be around somewhere else.”
“They didn’t found colonies, but they still ended
up traveling.” Shelma laughed. “I was going to say that it must have been a deliberate choice – that they could have resisted any natural ejection from their system if they’d really wanted to – but maybe they only had fusion power then. That would explain why’s there’s no deuterium around: they used it all up while they were developing the femtotech.”
“But either way,” Azar said, “once they were free of their star and able to steer themselves, they decided to make the best of it. To see a few sights along the way. And where do you go, if you grew up around a dwarf star? You take a tour of other dwarf stars—”
“Until you find one with an inhabited planet,” Shelma said, “where they’re facing the same problems you faced.”
“And then what?” Azar frowned. “I can’t believe the N3ers conquered the Ground Heaters!”
“No,” Shelma agreed. “And why would they need to? Why wouldn’t the Ground Heaters simply share the femtotech, to help out their fellow thermophiles? If they weren’t feeling generous and sociable, why visit an inhabited world at all? If they’d simply been looking for territory there would have been plenty of sterile worlds for them to choose from.”
Azar said, “Maybe the Ground Heaters died out before they reached the N3 world. They’d programmed some billion-year spree for Tallulah into the femtotech, but they lost heart along the way. The ghost ship came into the N3 system, and the locals couldn’t believe their luck: an empty planet, habitable for ten-to-the-eighteenth years, right on their doorstep! But they couldn’t park it, they couldn’t steer it, they had to go along for the ride. And a quarter of a billion years later, the same thing happened to the lizards.”
Shelma thought for a while. “That almost makes sense, but I can’t quite believe that neither of these free-riders had any interest in turning the femtotech into a propulsion system and founding a few colonies elsewhere.”