Dichronauts

by Greg Egan

  Seth slept again, woke and ate. The spoiled fruit they were receiving now was plentiful, and the sheer bulk of it filled his stomach, but it left him feeling weak. Dahlia might have spooked Martha out of using the knife, but this new regime was not the perfect solution that their hosts had been willfully ignoring; it was a gamble that they hadn’t believed was worth trying, until the moral stakes suddenly shifted.

  Theo still didn’t stir. Seth was starting to worry that no nutrients were reaching him, but all he could do was eat as much of the disgusting mush as he could and hope that the quantity he ingested would make up for the fruit’s deterioration. He knew that his body would put itself first: it wasn’t going to cannibalize its own tissues just to feed its Sider. But nor would it treat Theo as dispensable and let him starve to death, if there was any way to avoid it.

  four days after the stabbing, Seth woke to the sound of Dahlia and Iqbal talking. He lay still with his eyes closed and listened to the exchange. They were both being uncharacteristically quiet, and for a moment he wondered if they’d actually made an effort not to disturb him, but that seemed fanciful.

  He could feel the heat in the air, and the glare rendered his eyelids translucent; this was not the usual time for Southites to be up. Just when he thought the conversation was over and that Iqbal must have left, he heard a succession of soft thuds: he was throwing something into the enclosure.

  Dahlia spoke softly. Iqbal replied, more softly still. Then Seth heard him walking away.

  Seth opened his eyes, and saw Ada crawling across the ground. One by one, she picked up the whole, fresh sapote and hid them behind the mound of rotten fruit.

  He fell asleep again, and woke when it was cooler.

  “Are you hungry?” Ada asked him.

  “Yes.”

  “When you taste this, don’t show any surprise.” She fetched a handful of mush from the pile, but there was something more substantial in the middle of it.

  Seth ate what she gave him, gratefully, though he would have preferred Iqbal’s gift without the nauseating camouflage. “Do you really think anyone would notice?”

  “Do you really want to take that chance?”

  Dahlia said, “Iqbal brought food.”

  “Please don’t tell Martha that,” Seth replied anxiously.

  Dahlia laughed, as if the idea was self-evidently preposterous. “No!”

  “Do you think he’s smart enough not to steal too much and give the whole game away?” Seth asked Ada.

  “How would I know? Just because I’m there when they talk, it doesn’t give me any special insight.”

  “Of course not.” Seth hesitated, but he needed to know. “Do you have inspeech with Dahlia?”

  “No.”

  Perhaps that depended too much on both Walker and Sider being at equal stages of development. “All right. But so long as the Southites can’t speak our language, we should still be able to keep a few secrets from them.”

  Seth had been letting Ada cosset him for too long; he crawled over to the trough to get a drink for himself. The wound on his back protested, but it did not tear open, and he managed to lift and lower his shoulder as he moved, instead of scraping it in the dirt.

  As the water trickled into his mouth, he became aware of the ground below his head, and the emptiness above it.

  Theo said languidly, «I dreamed we were back home. When I pinged to the south, there were rocks and mountains, and whole cities full of beautiful buildings.»

  «We’ll get there,» Seth replied. «But it’s going to take a few more steps.»

  17

  Seth turned the crank and the cart shuddered forward, but then something in the mechanism jammed. He tried going backward; the belts moved a little, but then they started to slip. He reversed direction again, and this time managed a full turn of the crank before another component began screeching in protest, loudly enough to discourage him from continuing lest he destroy the whole machine.

  Iqbal approached, hooting with mirth, and reached into the interior of the cart.

  “I did warn you that it’s not perfect yet,” Dahlia said. She and Ada were resting on a blanket, having had the first turn with the cart, until Ada, at least, had wearied of it.

  “That’s fine,” Seth replied. “I’m happy to keep testing for as long as Iqbal wants to keep tinkering.” He waited, stretching his left arm out as far as he could in the cavity around the crank. The couch that supported him on top of the cart was about the most comfortable thing he’d lain on since arriving in the southern hyperboloid, and it even offered Theo a view that included both the ground immediately ahead and a peek into the workings of the machine. For the rider to be able to fix a loose gear or a belt coming off its capstan, though, rather than just observe the problem, remained a prospect for the indefinite future.

  Theo was growing anxious. «They’re not going to let us join the expedition if they think we’re going to hold everyone back.»

  «No. But be patient.» Iqbal’s efforts so far had been heroic, but from what Seth could gather through Dahlia, the twisted belts had been around for generations, and refined over that time for their one intended purpose: allowing the carts to be dragged along with ropes over difficult terrain. The idea that a passenger might ride on top and try to turn the belts by manually intervening in the action of the gear train had never occurred to anyone. What would be the point? And neither Seth, Theo, Ada, nor anyone in the settlement was enough of an engineer to be able to say, from first principles, exactly what ought to be changed to accommodate this new motive force smoothly and efficiently.

  Iqbal withdrew, and gestured at Seth to continue.

  “What did he change this time?” Theo asked. His view had shown three arms weaving between the belts, but the actual target of the intervention had been obscured.

  Dahlia passed the question on to Iqbal. Seth listened carefully, in the vain hope that hearing the two versions one after the other might prove educational. “He tightened the . . . I don’t know the word for it.”

  “In our language, or his?”

  “Yours.”

  “Never mind,” Theo decided.

  Whatever Iqbal had done, the result was impressive. Seth turned the crank cautiously three times without incident, before daring to increase the rate and send the cart trundling forward at something close to his own walking pace. The belt rattled and shuddered as it ran over small stones, and slipped and stuck on patches of mud, but nothing in the mechanism was jamming now merely as a consequence of his efforts to propel it.

  Seth followed the dirt track that led away from the main settlement, with the new orchards on one side, boasting rows of young trees crowded with fruit, and fields full of grain rising high on the other. He was surprised at how quickly his mind adjusted to the peculiar causality of the process: a rotary motion of one arm yielding an effect he was accustomed to achieving with his legs—or here, by flopping around curling his back and dragging his body. But within minutes it felt, if not natural, perfectly intelligible.

  He heard Iqbal hooting triumphantly, and glanced back to see him a few paces behind. He was easily keeping up with the cart, but Seth still felt that his own speed was respectable. The crank was hard work, though, and it used his left arm in ways that he hadn’t been able to exercise by other means. «I’m going to need to practice with this every day until we leave. I just hope our young genius can make a second one that’s just as good.»

  «He should make four: one for each of us,» Theo replied.

  «Really? Even if you could regrow your lizard limbs, I’m not sure they could turn anything.»

  «There might be some further tweaks required.»

  Seth pushed the lever that disengaged and locked the belt closest to his feet, then drove the cart around in a circular arc. It reminded him of doing a forward-flip as a very young child, when his mother and father would squat on either side of him and guide his motion. When he re-engaged the second belt and started back toward the settlement, som
ething wasn’t quite meshing, and the disparity made the cart wobble from side to side. He stopped on a stretch of flat ground and drove back and forward a few times, until the two belts returned to synchrony.

  As he came back to the place where he’d started, Dahlia cheered. “Our turn now!” she enthused.

  “Do I have a choice?” Ada moaned.

  “You’ll love it,” Seth promised her. “Once it’s actually moving, it’s glorious.”

  Dahlia spoke with Iqbal, and he lifted Seth off the cart and carried him onto the blanket. No Southite treated him with more respect, but after his spell of autonomy, simply being held and transported this way felt humiliating.

  When Ada and Dahlia were back on the cart, they set off down the track, retracing his own journey. From his stationary vantage, though his excitement remained fresh in his mind, watching the rattling cart with Iqbal in leisurely pursuit made the modest scale of the achievement painfully apparent.

  «Forget about a new design that Siders can ride,» he told Theo. «We need one that lets the Walker use their southern arm as well, somehow.»

  «And while you’re making wishes, both legs too.»

  None of those refinements were likely, least of all in the short time they had to prepare. The third troop of migrants to the chasm had been due to arrive more than twenty days before, and while some variation in the time it took for each group to make the crossing was only to be expected, Seth understood that the people of the settlement were becoming anxious. The protocol—if he’d understood Dahlia’s version of Iqbal’s explanation—was that the search party would make their way back along at most the final third of the route; by carrying supplies for that limited journey, they’d trade range for speed. If they found nothing, it would be up to the next group coming through from the old chasm to lend assistance.

  It was difficult for Seth to form a clear impression of the kinds of problems that could have befallen the latecomers. Surely it was hard to get lost when your destination was visible from all but the lowest ground, lit up like a flaming beacon? They could have run low on food, or been struck down by sickness, but even then it was puzzling that there hadn’t been one or two among them still able-bodied enough to go for help.

  When Ada and Dahlia came rattling back, Seth called out, “Well done!”

  “That’s me finished for the next ten days,” Ada replied wearily.

  “We should take it all the way back home!” Dahlia suggested. She conversed with Iqbal, then added disappointedly, “He says we’re not supposed to use it where there are too many people. They’re afraid we might hit someone.”

  Ada said, “We’re the only people who couldn’t get out of the way in time. But it’s nice that they don’t want us accidentally crushing each other.”

  As Iqbal lifted her off the cart, she asked Seth, “Are you sure you don’t want to make this trip without me? You’re the surveyor.”

  “You have noticed that I can’t speak the language?”

  Ada made a dismissive sound. “What will you need to say? You tag along, you make the measurements, you come back. Hopefully they find the stragglers safe and sound—and as part of the general rejoicing, they finally make up their minds to give us a boat and point us north.”

  “If it was that easy, I could do it on my own, any time at all.”

  “You need someone with you who can fix the contraption if it breaks,” Ada conceded, “but if that happens, you won’t have to explain anything: the fact that you’re not moving ought to be eloquent enough.”

  “I need Dahlia,” Seth replied, patient but adamant. “Have you really forgotten just how bad things can get when there’s no way to communicate? This is all new territory to me. There’s no point going out there with people who know it if I can’t even talk to them when something goes wrong.”

  Iqbal placed Ada and Dahlia gently on the blanket beside Seth.

  “Well, I gave you the choice,” Ada said. “But if my arm gives out halfway, they’ll either have to throw me on top of your cart beside you, or tie the two carts together with a rope so you can drag me along.”

  “If it comes to that, I’ll do it,” Seth promised rashly. “But only if you’re serious about preparing.” Though she’d joined him in his original exercise regime, her participation had been patchy. He couldn’t blame her for a few lapses in enthusiasm when the prospect of having cause to use their leg muscles again kept receding into the distant future, but this was one journey the Southites weren’t likely to postpone.

  “All right,” she agreed.

  “So if I’m the one who needs towing . . .?”

  “Don’t push your luck.”

  Iqbal returned from having stowed the cart. He picked up Ada and headed for the settlement. Alone with Theo on the blanket, at the deserted junction between three dirt tracks, Seth felt the weight of his helplessness descend with a vengeance. The machine was glorious—when it worked, and when he was actually riding it. But he needed to be sure that he didn’t let any momentary delusions of autonomy go to his head. Everything about their fate remained in the hands of the Southites.

  Theo said, «Iqbal and Dahlia can’t explain everything, but I’ve been watching what he does and building up a picture in my head of how he’s solved different problems. It’s not perfect yet, but I’m getting there. If the worst happens, and the others refuse to stop and help us, I think we’d still have a chance.»

  Seth wasn’t sure if he should feel relief at Theo’s cautious optimism, or fear at the thought of being stranded in the icy wilderness, trying for days on end to slip a belt back onto a capstan.

  Iqbal returned, shrieking cheerfully, and lofted Seth up into his arms. By any measure he was stronger, healthier, and more competent in this world than Seth and Ada—but his elders had ruled that the expedition was far too dangerous for him to take part.

  18

  Seth drove his cart out to the barren plain where the search party was assembling. It was easy to find the spot: the “old home” was lit up directly in front of him, a few degrees above horizontal. He was far from a seasoned navigator here, but this landmark was unmistakable; when the line of lights moved across it, it became brighter than anywhere else.

  With Dahlia’s help, Iqbal had told Seth that the chasm where he’d been born would remain habitable for thousands of days to come. The Southites’ migration seemed to involve a relatively unhurried shift in population from a slowly cooling oasis to a slowly warming one, with a finely calibrated effort to match the numbers to the carrying capacity of the farmland at each end of the route. But if that part sounded manageable enough, the surveyors also needed to be planning a dozen steps ahead, to be sure that they weren’t leading their people into a dead end. The most bountiful chasm would be nothing but a trap if it lacked a successor of its own that would emerge from the cold at just the right time. Seth had been curious as to whether the wild animals here possessed some instinctive grasp of that criterion, or just headed at random for the nearest bright light, but the question had defeated all attempts at translation.

  “Seth!” Dahlia shouted. She’d lingered over her goodbyes with Iqbal, but now she and Ada weren’t far behind. Seth stopped and waited for them to catch up.

  “This is exciting!” Dahlia enthused, as Ada brought her cart alongside Seth’s. “We’re already farther than I’ve ever been from home!”

  “Hmm.” Seth had trained himself to resist the impulse to correct statements like this, but her words still pricked his conscience. He didn’t know exactly what she’d heard from the Southites, but in the absence of any clear account of her origins from her own people, Dahlia had concluded that she’d been born in the river near the settlement, and that Seth and Ada were her parents. Theo, of course, was her brother. Seth had never quizzed her deeply enough to determine what kind of children she thought she might one day bear herself: Siders alone, or Walkers too? But though he’d long ago stopped clinging to the pretext that this lie of omission was no different than the cust
omary delay in revealing the details of reproduction to a child, he had decided that it was up to Ada to choose when and how she explained Dahlia’s history to her. They were the ones who would have to live with the truth.

  The rest of the expedition had already gathered, but the nine Southites were still checking their supplies and redistributing loads from cart to cart. Mostly they were carrying food and fuel, but there was also a large wooden contraption that Seth had never seen before, occupying a cart of its own.

  “Do you know what that is?” he asked Dahlia. He pointed to the device. “That thing on the third cart from your feet?”

  “No. Do you want me to ask?”

  She sounded a little shy about the prospect, and the Southites themselves looked busy. Seth said, “It’s not important.”

  He had decided to stay at the rear of the expedition, so he could watch the routes the Southites took and follow whoever had the least trouble with their cart. There were small rocky outcrops everywhere, but he was hoping that the expedition leaders either had good memories or well-kept records from their own crossing to keep them on a path that had already proved viable.

  “How’s your arm?” he asked Ada.

  “Why, do you want a race?”

  “Maybe on the way back.” Seth was glad that she’d overcome her misgivings about joining the expedition, but they’d been replaced by a ferocious competitive streak. Thanton’s insular culture must have driven her mad, as it would any intelligent child, but it seemed to have left her with only two ways of dealing with obstacles: shrinking into herself in resignation, or setting out to conquer everything in sight. Seth much preferred the latter, in general, but not if she ended up stripping a gear.

  “They’re moving, they’re moving!” Dahlia announced. In fact, only two of the Southites had set off, and they weren’t dragging carts or carrying anything. Seth supposed they were scouts of some kind, who’d go ahead and check the route for problems.