by Greg Egan
She said, “So Spiral In use the hoops to retreat into virtual reality. But why don’t you use the heating process yourself, just for the energy? If you want to escape from Tallulah, why not take this process and run?”
Rahul gestured at one of the machines in the corner of the chamber, a clunky, unprepossessing structure with a dozen cables snaking out of it. “There’s a sample of deep rock in there. Do you know how much power it’s generating? Less than a microwatt.”
Azar stared at the machine. Her intuition balked at Rahul’s claim, but on reflection it was entirely plausible. In bulk, buried beneath an insulating blanket of rock several kilometers thick, the miraculous fuel would be white hot, but up here in the water a small piece would barely be warmer than its surroundings. Its power to keep the whole planet from freezing came from its sheer quantity, and its spectacular efficiency was tuned for endurance, not a fast burn.
She said, “So in its normal state the process runs slowly. But this isn’t like some radioisotope with a half-life that can’t be changed.”
“No,” Rahul said, “it’s worse than that. If you take a sample of ore containing a radioisotope, you can concentrate the active ingredient. If we purify deep rock – if we remove some of the ordinary minerals it contains in the hope of producing a denser power source – the process down-regulates automatically, maintaining the same output for a given total mass. It knows what you’re doing, and it cheats you out of any gain.”
“Ah.” Azar was torn between empathy for the lizards’ frustration and admiration for the Ground Heaters’ ingenuity. It seemed the femtotech had been designed with very strong measures to protect against accidents and weaponization.
Shelma said, “But in all the time you’ve been studying it, surely you’ve made some progress? You say Spiral In have learned to use the hoops as computing devices; that must give you some insight into the whole process.”
“Using the hoops isn’t the same as controlling their creation,” Juhi said. “It’s like ... building a computer out of fish bones, compared to engineering the biology of a fish. Spiral In learn enough to embed their minds in the rock in the simplest possible way. From that starting point, perhaps they migrate to more refined modes. Who knows? They’ve never come back to tell us.”
“If Spiral In can migrate into the rock,” Azar said, “why are so many of them still here, above ground?”
“After each migration the philosophy dies out,” Juhi replied, “but every few generations it becomes popular again. It starts out as an abstract stance – an idea about what we ought to do, eventually, sometime before we find ourselves confronting the Next Passengers – but then it reaches a critical mass, with enough people taking it seriously for the practicalities to be rediscovered. Then everyone who was serious goes underground ... and everyone who was just spouting empty rhetoric defects to a different philosophy. We’re at a point in the cycle right now where there’s a lot of rhetoric, but not much else.”
Azar was too polite to suggest that Spiral Out seemed to be in much the same state themselves, but in their case there was nothing cyclic about it.
Shelma turned her robot’s gaze from lizard to lizard, as if searching for a crack in their pessimistic consensus. “It must be possible to harness this process,” she said. “To adjust it, to manipulate it. A single nuclear reaction has its rate fixed by physical laws, but this is a system – a flexible, programmable network of nuclear machines. If someone built this system for their own purpose – with details that they chose for themselves, that weren’t forced upon them by the underlying physics – then it can be rebuilt. You should be able to reverse-engineer the whole thing, and put it together again any way you like.”
Jake said, “Someone built the deep rock, that’s true. And if we were willing to choose the same path as the Builders, perhaps we could match their feat. But though the Builders set Tallulah in motion, in the end their philosophy was Spiral In. To make deep rock, the Builders became deep rock.
“I don’t believe it can be done any other way. To understand it well enough to change it, we would have to become it. And then we would have changed ourselves so much that we would no longer want the very thing that we set out to achieve.”
8
As the discussion wound its way back and forth between Tallulah’s uncertain history and the competing visions of its future, Azar seized upon one piece of good news that Rahul let slip almost in passing. The lizards couldn’t re-create the femtotech from scratch, or even ramp it up into a useful form of propulsion, but they did believe that there was a very good chance that they’d be able to graft it. Given an empty world on which to experiment, they hoped that introducing samples of the deep rock into the crust would cause the femtotech to replicate, spreading through the native rock and ultimately creating a second Tallulah.
That was a wonderful prospect, but they’d already missed at least one opportunity. Some two hundred thousand years before, Tallulah had passed through an uninhabited system, but Spiral Out had been at a low ebb and hadn’t even managed to launch exploratory probes. Since then they’d simply been hanging around waiting for their next chance. The Ground Heaters had given them an extraordinary gift, rescuing them from their dying planet, but between the culture of dependency that gift had created, the constant temptations of Spiraling In, and the stress of not knowing whether the next world they encountered would turn out to be the home of the Next Passengers, they had ended up paralyzed.
“You should join the Amalgam,” Azar said, “and use their network to migrate. The kind of world you’re looking for is not in high demand; a frozen planet tidally locked to a faint brown dwarf is of no interest to most space-faring cultures.”
“And it’s no use to us either,” Jake replied, “unless we can enliven it. We can’t send the deep rock through your network, can we?”
“No, but if you spent a century or two manufacturing antimatter from geothermal energy, you could build an engine to carry samples of rock at a significant fraction of lightspeed. And even if for some reason you didn’t have enough spare power to do that, I guarantee that you could find a partner in the Amalgam who’d trade you a few tonnes of antimatter for some deep rock samples of their own. And I mean a few tonnes on arrival at Tallulah, not a few tonnes when it left home!”
Juhi said, “We need to be careful. It’s one thing to hand Tallulah over to the Next Passengers, as the Builders intended, but we don’t want a million strangers flocking here just to mine the planet.”
“Nobody’s going to do that,” Shelma assured her. “If deep rock has any value at all in the Amalgam, it will come from the ability to graft it, or the ability to reverse-engineer it. In either case, a few kilograms would be enough.”
Rahul said, “Whether we choose to join the Amalgam or not, you need antimatter for your own journey, don’t you?”
“A few micrograms would come in handy,” Shelma admitted.
The transceiver sprayed out a chemical ringtone and Rahul replied with a command for it to speak. Azar found the conversation that followed cryptic – and she suspected that parts of it were literally in code – but when it was over Rahul announced, “Someone spotted you in the forest with Jake. The Circlers have destroyed your puppets, but they know more or less what happened now. I think we need to move from here.”
Azar was dismayed. “Can’t you talk to them? Explain the situation? None of our plans should be any threat to them.” The Amalgam would happily leave the Circlers in peace, sending no travelers and no further explorers, but the Spiral Out faction were entitled to emigrate, and to trade a few small pieces of Tallulah’s exotic legacy with the wider galaxy.
Rahul said, “They’re convinced that you’re the New Passengers, and that the fight to retain Tallulah has begun. In the past they’ve viewed Spiral Out as timid fatalists, but now that we’ve come to your aid we’re something worse. We’re traitors.”
On the flight deck Shelma muttered a string of obscenities. “We’re not goi
ng to spark a civil war,” she told the lizards. “We’ll surrender ourselves. It doesn’t matter if they destroy us; we’ll make backups.”
Jake said, “But they understand now that you can do that. You could surrender a thousand machines to them – or one pair of living creatures, and call them your true form – but it won’t be enough to convince them that they’ve put an end to your plans.”
Azar wanted to contest this bleak verdict, but from what she’d seen of the Circlers firsthand it rang true. Whatever the original intention of Tallulah’s creators, it had sounded like a beautiful story: a chariot traveling between faint, forgotten stars, rescuing the inhabitants of dying worlds, offering them a safe, warm home for a few million years so they could build up their strength then fly from the nest – or, if they wished, dive into its depths, into a femtoscale mansion of a quadrillion rooms. In a way, she admired the Circlers for their determination to tear up the script, to scream at their long-vanished benefactors that they would make their own decisions and not just meekly come along for the ride. But the irony was that they were so intent on rebelling against the Builders that they seemed blind to anything that didn’t conform to their own version of the scenario. It was chiseled in stone that one day they would fight the New Passengers for Tallulah, and they had spent so long rehearsing this play that you couldn’t even tap them on the shoulder and suggest a different ending without being dragged into the plot and cast as the villain.
#
Shelma had their mock-lizard body destroy itself, and found a dim but agile P2 fish for the insect to parasitize and modify. A talking fish would attract suspicion, but with some help from the library they managed to engineer speech glands for it that created rapidly decaying words; if they swam up close to a chosen confidante they could emit some short-range chemical whispers with little chance of being overheard. Unfortunately, the lizards’ own medical nanotech wasn’t flexible enough to do the same for them, and Jake and the others recoiled from a friendly offer to let the aliens tweak their speech organs.
Shelma said privately, “This is going to get messy.”
“So how do we fix it?” Azar replied.
“I wish I knew.”
They agreed on a place and time to rendezvous, then Jake, Rahul and Juhi scattered.
Shelma said, “I think we should go back to the surface for a while.”
They took the fish as high as it could go, then left it parked and rode the insect alone for the last few hundred meters. When they broke the water, Azar found herself almost weeping with relief. She was still as far from home as ever, but just a glimpse of the stars after so long without them made her feel that she was back in the right universe again.
Neither the balloon nor the orbiting microprobes had experienced any form of aggression, or noticed anything else unusual. It seemed that the Circlers, for all their paranoia, had been too complacent to create a world bristling with sensors and weapons while Tallulah’s next stop was still so far from sight.
Shelma said, “We should bring the balloon down on the ground somewhere and replicate the library a few times. I think we’re already carrying everything vital, but if our backups have to take over from us we want to be sure that they’re not disadvantaged.” Their backups in the jungle were already receiving incremental memory updates, by radio via the microprobes.
Azar agreed, and they sent the instructions. She paced the flight deck, rubbing her eyes. She had given up the need for sleep, but there was still something irredeemably strange about the feeling of unpunctuated consciousness stretching back into the distance.
“I screwed up,” Shelma said. “I rushed to make contact. We didn’t even know what the factions’ names meant.”
“And I let you do it,” Azar replied. “We’re both at fault. But I don’t believe the situation’s irretrievable. The Circlers have killed some alien zombies, but according to Jake the philosophies have been at peace for millennia; it could still be a step too far for them to start harming each other.”
“How do we defuse their anxiety,” Shelma said, “when there’s no invading army for them to defeat? Do we offer them the microprobes as sitting ducks? I doubt that they could hit targets that small, and even if they could they’d just assume that there were ten thousand more.”
Azar looked up at the stars again, and tried to see them as a hostile, threatening sight. “They need some theater. They need some catharsis.” Clearly Shelma thought the same way too, but then neither of them were exactly experts in the lizards’ psychology. “And we need to talk to Jake again.”
“What do you have in mind?”
“The microprobes are too small, and Mologhat is already gone. So maybe we should think about launching a bigger target.”
#
Only Juhi turned up at the rendezvous point in a remote stretch of ribbon-weed forest. “Jake and Rahul are safe,” she said, “but they’re too far away at the moment.”
“What’s been happening?” Azar asked her.
“We’ve been in contact with most of Spiral Out, and they’ve made a decision. They want to send a delegation with you to the closest world in the Amalgam, to make contact with this culture and report back on the possibilities for trade and migration.”
Azar was encouraged; at least Spiral Out had proved willing to break from its preconceptions.
“We’re prepared to start manufacturing antimatter,” Juhi continued. “But we should compare notes on the process first; if you have a more efficient method we should adopt that.”
Shelma said, “What kind of power sources do you have access to?” The everyday lizard culture they’d seen was based on plant thermoelectrics.
“There are some deep-bore geothermal turbines that are used for specialized research projects,” Juhi replied. “Obviously we can’t tap the whole output, but we should be able to siphon some off discreetly.”
“What if you just built your own turbine?” Azar said. “Would the Circlers do anything to stop you?”
“Right now,” Juhi said, “I don’t think it would be wise to find out.”
Azar turned that statement over in her mind. If people were about to begin clandestine antimatter production, what would happen to them if they were caught?
“We’ve had an idea,” she said, “but I don’t know if it will make sense to you. The Circlers believe we’ve come from a nearby planet, from a star too dim to see. What if we built a spacecraft that might have made a short journey like that ... and then let the Circlers shoot it down?”
Juhi said, “How are you going to power this spacecraft?”
“The azide bulbs you eat when you travel; enough of them could actually get a small craft into low orbit. The Circlers accept that we’re digitized, so they don’t expect the invasion force to be a fleet of thousand-tonne arks.”
“It’s an interesting idea,” Juhi said, “but the hardest part would be contriving their success in destroying the craft. Since your arrival they’ve been dredging up plans for weapons that our ancestors constructed for the last close approach, two hundred thousand years ago. But nobody’s sure now that they still understand those designs.”
Shelma said, “What about surveillance? Are they already monitoring what’s happening in near space?”
“Yes. You can be sure of that.”
“Then the problem,” Shelma said, “is that they’d see us taking off. It would be better to convince them that something new is coming in from deep space.”
Juhi paused, the front of her body twitching from side to side, a motion that Azar now recognized as a sign of anxiety. “I don’t see how we can do that. But let me take this to the others.”
Shelma had the insect’s nanotech construct a sample of a solid-state antimatter factory, and passed it to Juhi for the lizards to copy. It was the Amalgam’s most efficient design, but nothing could get around the fact that it would still need thousands of times more power than any ordinary burrow consumed.
After parting from Juhi they stayed
away from Jute and the other colonies, but the scout mites had placed intercepts on some of the inter-colony trunk fibers long ago. The lizards had no infrastructure in place for quantum encryption, and their standard communication codes were easily cracked; clearly this wasn’t a culture with an entrenched history of bitter enmities and closely held secrets. It was a culture polarized by sudden panic, and Azar clung to the hope that cooler heads would soon prevail.
The tapped conversations were discouraging, though. The idea of Spiral Out as traitors was spreading throughout the Circlers, many of whom were urging each other to keep a close watch on their treacherous neighbors and erstwhile friends. The claim that the alien visitors were benign explorers with no territorial ambitions was largely discounted; two previous examples of Tallulah being colonized were, apparently, sufficient to render other motives unlikely. Azar began to wonder if the best course would be to lie low for a century or two and simply wait for the non-arrival of the trumpeted invasion force to leave the prophets of doom looking like fools.
Rahul met them for the next rendezvous. “Jake’s disappeared,” he said. “I think he’s been imprisoned, but nobody will admit to holding him.”
Azar was speechless. For all the bad news she’d heard from the taps, she’d never believed it would come to this.
“We can send machines to hunt for him,” Shelma said.
“If you can, please,” Rahul replied. “But they will have moved him to another colony, so I don’t know exactly where you should start.”
Azar came to her senses. She instructed the scouts that were already hovering near the fish; they would spread out and replicate, following the fiber trunk lines from colony to colony, spawning search parties as they went.
