Dichronauts

by Greg Egan

  With the sun low in the western sky, it was hard to believe that it could ever threaten anyone, let alone blast abandoned cities into dust. Seth stood for a moment, savoring the smell of the hay that still clung to his sleeves, then he bade the children goodbye and set out for home.

  3

  «Something’s wrong,» theo said as they approached the house. «Can you hurry?»

  Seth broke into a run—though they were coming from the west, so if he couldn’t see anything amiss himself, nor could Theo. «What’s the problem?»

  «My sister’s in trouble.»

  «How do you know?»

  «I can hear her.»

  Seth had reached the porch. He unlocked the door and stepped inside. “Elena?” he called out. She didn’t reply. «What’s Irina saying?» he asked Theo.

  «It’s muffled. But I think they’re in their room.»

  Seth climbed the stairs, bracing himself, unsure what to expect. He knocked gently on his sister’s door. “Elena? Are you all right?”

  “Go away! I’m busy!”

  “Can I talk to Irina?”

  “We’re both busy.”

  “Can’t she tell me that herself?”

  “Just leave us alone.”

  Seth stayed by the door. Theo said, «You need to do something. She’s crying out for help.»

  Seth didn’t doubt him, but the claim was confusing. «Why doesn’t she pitch it so everyone can hear?»

  «Something’s constraining her.»

  Constraining? “Elena?” Seth called again.

  “Go away!” she shouted. “I’m trying to study!”

  «Just open the door,» Theo urged him.

  «She’ll have locked it.»

  «There’s a key in our parents’ room.»

  «For emergencies.»

  «This is an emergency.»

  Seth said, “I need to talk to Irina! It’s important!”

  “She’s asleep.”

  “I thought you said she was busy.”

  “She’s busy sleeping, I’m busy studying. You might want to listen to Theo yammering away all day, but normal people work out a better way.”

  “I know she’s not sleeping,” Seth replied. “Theo can hear her.”

  Elena fell silent. Seth could hear movement in the room. He waited for his sister to come to the door.

  «Get the key! Now!» Theo’s tone had turned frantic.

  «Why?»

  «She’s hurting her!»

  Seth ran to his parents’ room. «Where is it?»

  «By the window.»

  Seth grabbed the key and sprinted back to Elena’s door. He pushed the slotted card into the lock, then tugged on the handle until the door unlatched and the counterweights flipped it up against the ceiling.

  Elena had a band of cloth fitted tightly around her head from chin to cranium, covering every visible part of her Sider. But she’d slid the longest left finger of her right hand under the binding, deep into the place where —

  Theo screamed at her, “Stop!”

  The word left Seth’s skull ringing. Beyond all the rage and anguish it carried, the sheer force of it made him feel like he’d been punched.

  Elena pulled her hand away and sank to her knees. Seth steadied himself and approached her. He took hold of the cloth and started easing it forward; there was blood on the material, spots and streaks in yellow and red. When the whole thing was free he dropped it on the floor and gazed down at Irina.

  The membrane of her right pinger was torn, and there was a dark unnatural space between her damaged flesh and the tunnel through Elena’s skull. Two rivulets were seeping from the cavity, entwined but immiscible.

  Theo said, «They need a doctor.»

  Seth stood in silence, swaying.

  «Seth? They need help.»

  «I know.» He put a hand on Elena’s shoulder. “Do you think you can walk to the clinic with me?”

  Elena started sobbing. “I didn’t have a choice! She didn’t give me any choice!”

  “We can fix this,” Seth promised. “But you need to come with me.” He couldn’t leave her alone while he fetched the doctor; he had no idea now what she might do. Their neighbors wouldn’t be home yet, and there was no one else nearby on whom he could call for help.

  He took her hands and pulled her to her feet, then tipped his head and started backing out of the room. Elena resisted for a moment, but then she let him lead her into the corridor and down the stairs. On the porch, Seth scrawled a note on the message board, then they set out into the twilit streets.

  Lamps showed in a few scattered windows, but as Seth headed west the paving stones beneath his feet were all but lost in the gloom. Elena kept her face to the east and followed him by touch alone. When they finally reached the corner and began sidling south, it was like stepping halfway into daylight again, with Theo’s crisp vision revealing every crack and bump on the path well enough for Seth to plan his movements. But this was the side of Irina’s injury; to Elena, they were walking into darkness. Seth did his best to steer her past the hazards, and offer a cue when she needed to take a larger step than usual, but he couldn’t bring himself to offer verbal advice. Avoiding the humiliation of advertising her condition to passing strangers was only part of it. So long as no one spoke, everything he’d seen in her room felt contained by the silence.

  When they entered the clinic the lamplight was dazzling. Seth counted at least twenty patients waiting on the benches, huddled miserably, alone or with companions who glowered at him as if he’d come to usurp them from their places in the queue. He got Elena seated, then took a numbered card from the dispenser by the door.

  The doctor’s assistant approached and bent down to examine Elena and Irina. “This is urgent,” he said sternly. “Come with me.”

  The assistant took Elena by the arm. Seth started to follow them, but when he reached out for his sister’s hand she pulled free. “Just wait for me,” she said.

  Seth sat on the bench. Theo hadn’t spoken to him since they’d left the house, and he didn’t know what to say himself. The silence made him feel hollow; Theo was still sharing his view, but everything Seth saw, by light or by echo, seemed dead and empty.

  When their parents arrived, Elena and Irina were still with the doctor.

  “What happened?” Seth’s father asked.

  “They were bleeding,” was all Seth could say. “Both of them.” He wondered if Theo was talking with his own father at a higher pitch, beyond any Walker’s hearing.

  Irina’s mother spoke quietly with the doctor’s assistant, then the assistant led the four parents in the direction of the consulting rooms. Seth leaned back on the bench and closed his eyes, then shut out Theo’s view.

  In the darkness of his skull, Theo finally spoke.

  «Elena’s pregnant.»

  Seth had no wish to follow this partial revelation to its logical conclusion, but Theo always chose his words with care. «Just Elena?»

  «Irina refused. Elena went alone.»

  The claim was surreal; if not for the night’s horrors, Seth would have laughed and called Theo’s bluff. No playground know-it-all, let alone biology teacher, had ever raised such a possibility.

  «So what will happen with the baby? She’ll have a side-blind child?»

  «They’ll try to adopt an unpaired Sider,» Theo guessed. «I don’t know how easy that is, but it happens.»

  Seth felt as if he was sinking into the darkness. He didn’t want to open his eyes and face the crowd of strangers, who had by now all surely guessed his family’s bizarre affliction.

  But the strange, curdled shame he felt had nothing to do with Elena and Irina. What disturbed him the most was the sense of his own naïveté. How could it never have occurred to him that a Walker and a Sider could disagree on their choice of partners? That the idea hadn’t been put to him long ago by some giggling schoolmate or sober adult was no excuse: what kind of idiot could fail to imagine the dilemma, unprompted?

  Th
eo’s father was always prattling on about give and take, always talking down the notion that both Walker and Sider could ever get their own way and be entirely happy. And though his son had proved him wrong about that once, it wasn’t the last choice the pair would face. There was a lifetime more to come.

  Theo said, «They’re back.»

  Seth opened his eyes. Their parents were walking slowly between the benches, holding Elena’s hands. There was a bandage on her head, covering the wound but not entirely blinding Irina’s right side. Seth stood and waited for them, then led the way to the exit.

  No one spoke aloud in Seth’s range of hearing on the way home, but Theo said, «They’re going to be all right. The doctor told them there’s no permanent damage.»

  «Good.» They reached the corner and headed east. Seth looked up into the warm yellow light from the windows of the houses. No permanent damage.

  4

  Seth had barely finished breakfast when Samira strode to the center of the encampment so Maria could announce the first task of the day. “Each group is to make their own estimate of longitude. There’ll be points for tighter error bounds—but be sure you can justify them, or your grade will be zero.”

  “I’d say our longitude is ninety degrees east,” Sarah whispered, reaching across the dining blanket and grabbing the last of the bechelnuts. “Plus or minus ninety.”

  The three Walkers in Seth’s group rose to their feet, then he and Amir picked up the blanket and shook it clean. Sarah fetched pegs and string from their toolbox, then they sidled away from the tents. They’d camped in the middle of a grassy plain, which offered a clear view of the horizon but was not the ideal site from which to obtain a geological bearing.

  “Find some exposed rock,” Judith suggested.

  “There’s none around here,” Aziz replied. “We passed an outcrop earlier, but it would take half a day to get back to it.”

  Sarah said, “Then we’ll make the best of what we’ve got.” She and Amir each took one end of the string and pulled it taut in a roughly east-west direction. Seth moved closer, then the three of them crouched down so he and Theo could judge the string’s alignment with the ground. The blades of grass would be arranged to catch the most sunlight, revealing very little about the land itself. The hidden roots would be intimately connected to the soil, but though the stems were visible, they gently twisted from root to leaf, making it difficult to use them as a guide.

  Between the grass, though, it was possible to discern a series of faint, broken striae crossing some of the patches of exposed ground. However loose the individual grains of sand were, however free to be rattled by the wind and the rain, they couldn’t turn far from their neighbors’ average direction without bumping into each other. If they could all have conspired to move at once, they might have ended up offering a skewed bearing; after all, that was what the grass had done, with the sun coordinating the conspiracy. But lifeless soil subject to random disturbances was blocked at every turn. Short of digging down to bedrock—and hoping that it was either nicely marked, or easy to cleave—exploiting these imperfect signs of order was the best chance they’d have of determining geological east.

  Sarah pegged her end of the string, then Seth gestured to Amir, sending him sidling back and forth until the alignment was as good as they could hope for.

  Amir pegged the bearing, then went and fetched the theodolite. He set it up with two legs of the tripod touching the string to orient the platform, spent a few minutes leveling it, then took a sighting of the rising sun through the alidade.

  “Seven and a half degrees north,” he announced. The angle was small enough that there was no point using a conversion curve: it implied that they were that much less than a right angle, or eighty-two and a half degrees, east of the western node.

  “So in ten days, we’ve come two degrees east?” Theo sounded shocked. “I thought we were heading due south!”

  “See what happens when there are no street signs?” Sarah replied, mock-aghast at such wild meandering.

  Seth could understand Theo’s response, but he felt more exhilarated than anxious himself. This land was too close to Baharabad to have remained unmapped, but they’d come to it empty-handed in order to practice the surveyor’s art: to get a little lost, and then to find their bearings.

  Aziz said softly, “Look to the north.”

  Seth had been caught up in his own view; he switched his attention to Theo’s.

  To his left, in the distance, the grass was trembling: the blades displaced by some unseen force, then rebounding, only to be unsettled again. Seth could feel no movement in the air where he stood, and the disturbances looked less like the rippling of a breeze than the work of a thousand separate tiny whirlwinds.

  “Axis lizards,” Judith proclaimed.

  “Are you sure?” Amir asked.

  Theo said, “We can hear them. They’re pinging like crazy.”

  The seething in the grass was moving closer. Seth glanced at the other members of the group, trying to decide if he’d seem timid or merely prudent if he suggested evasive action. He had always thought of axis lizards as harmless, but in the city he’d only encountered occasional lost stragglers, and he had no idea how a whole swarm would behave.

  «Doesn’t it confuse you?» he asked Theo. Whatever kind of din Theo was hearing from the lizards, the view he was sharing seemed unaffected.

  «Not really. It’s like being in a crowd of people who are speaking a language you don’t understand. It’s distracting, but it doesn’t make your own conversation with the landscape disappear.»

  Seth braced himself: the swarm was almost upon them. As the first wrinkled forms showed between the tufts of grass on his left, then began crossing into his own view to the east, he realized with relief that the animals were opting for prudence and would split up and flow around these oddly shaped strangers.

  He watched them stream by a few paces in front of him: long green bodies between front and rear pingers, scurrying south on six clawed feet. With their legs more or less horizontal, they could lift their feet and reposition them without any of the hip-swiveling nonsense that a Walker had to perform when sidling. And with their mouths on their bellies, they could snatch up hapless insects even as they bolted across the plain.

  “There goes your grandma, Judith,” Amir joked.

  “Fuck off.”

  Theo said, “Thousandth cousin, maybe.”

  “Why would they ever want to crawl into our heads?” Seth wondered. The swarm was navigating perfectly well without the benefits of his own form of vision.

  “Free meals,” Sarah replied.

  “Anyone want to rejoin them?” Amir asked.

  “Just give me a wheeled cart and that’s the last you’ll see of me,” Aziz replied whimsically.

  “You’d never keep up with them,” Sarah replied.

  “This cart has magic wheels that let it roll straight north and south,” Aziz joked.

  The last of the lizards darted away to the south, with the swarm veering west to avoid the tents. Seth was mindful of Theo’s silence. Free meals or not . . . did he envy his cousins?

  Amir said, “Seven and a half degrees, but now someone needs to help me get the error bounds right or it will all have been a waste of time.”

  later in the morning, each of the four groups set up a shadow tracker and began plotting the curve cast by the tip of the gnomon across the platform. Seth, Amir, and Sarah took turns marking points, dotting the paper with dark indentations.

  Seth sidled a few steps away from the tracker and glanced at the paper through Theo’s view.

  «The pits are deep enough,» Theo informed him. «But would it really matter if they weren’t?»

  «Probably not.» Seth wasn’t expecting his eyes to droop shut halfway through the exercise, as they might well have done if he’d been sentenced to a life of helping Theo read badly printed law books. But it still seemed like a minimal courtesy to make all their records bimodally legible. He gl
anced across the camp toward Samira. «Do you think she likes being a teacher? She hardly ever speaks to us.»

  «She never dozes off,» Theo noted. «And she’s never slow to write on the board in lectures—it never looks as if Maria needs to prompt her.»

  «That’s true.» Seth supposed the pair had found an agreeable way to divide up their tasks, and if Samira chose not to complicate the lectures with her own interjections, that didn’t mean she was unhappy, or disengaged.

  They plotted the shadow across noon and beyond, then Sarah and Judith performed the analysis and handed it on to the others to check. Seth could find no flaws in the result, and Theo confirmed it: the expedition had reached fifteen degrees north of the midwinter circle. Compared to Baharabad’s average solar latitude of twenty-three, this was beginning to sound positively adventurous. Seth doubted that he’d feel like a true surveyor until he’d seen the shadow of the gnomon vanish at noon, but the distance they’d covered no longer seemed trivial.

  With latitude and longitude in hand, the students spent the afternoon revising their maps, making use of the new information to adjust their earlier estimates of the locations of various features they’d encountered along the way. Theo had been shocked that they’d skewed so far east, but as the group worked through their logs of theodolite measurements it was easy to see how small uncertainties had mounted up across the dozens of sightings, loosening the rigid struts of the imaginary grid they’d drawn across the landscape.

  Sarah stippled the Annoying Hills into place in their new position, brushing paper dust and pigment onto the ground as she worked. “I don’t know why we’re bothering,” she joked. “Before long this will all be in summer, and no one will care where these hills were or what they looked like.”

  “Before that, I think the road-builders would quite like to avoid them,” Aziz replied.

  Judith said, “The city won’t come this way at all. It’ll just follow the river.”

  “The Zirona won’t last forever,” Seth replied, though he was more assured of the truth of this claim by the fact that he’d heard it stated in lessons than by any gut feeling about the nature of the thing. The Zirona River flowed the full width of the habitable zone from north to south, supporting five cities along the way—giving it a far more impressive air of permanence than if it had split up into a hundred insignificant streams that trickled away into mud flats on the midwinter plains. But apart from the possibility of changes in topography reshaping its course, the summer rainstorms that fed it could always grow less intense, or drift to the east or west, as the new terrain entering the northern steamlands altered the weather patterns there.