by Greg Egan
Seth had been staring at an ambiguous speck in the distance, but he’d not yet convinced himself that it was anything more than a transient blemish in the bright line where the sky reflected off the ground’s warm air.
«It could be.» He stood and raised a hand. When this elicited no response, he braced himself against the rock, held his arms high, then tilted them to the north and south. A moment later, the speck grew taller and wider as it deformed into a similar forked line against the heat haze.
«It’s them.» Seth resisted a comradely urge to stride across the desert and meet them halfway. Raina had made it clear that no one was to leave the designated spot until three of the team’s pairs had arrived, and he was not prepared to disobey her instructions again without a compelling reason, however innocent the transgression might seem.
As she approached, Sarah slowed to a dawdle, either out of genuine weariness, or perhaps to tease him for the way he was clinging to the rock. Seth glanced past her to the routes that Raina and Amir had taken, but there was no sign yet of anyone else.
“We’re still hoping to be the last to the rendezvous,” Sarah shouted. “Someone’s sure to overtake us any minute now.”
Theo yelled back, bemused. “The advantage being . . .?”
“Less waiting, of course.”
Seth sat patiently in silence until the conversation could proceed without raised voices.
“See anything interesting?” he asked.
“There were traces of the forest,” Judith replied. “We tripped on a few dead roots under the sand.”
Seth was encouraged. “How old, do you think?”
Sarah said, “They weren’t rock-hard, or crumbling to dust. So I’d bet Amir and Aziz are the ones sitting in the shade of a weyla tree right now.”
Raina and Amina had headed south-west, Amir and Aziz west-south-west. Seth had been worried that Amir might not have fully recovered from the cone storm, so if it was his branch of their four-pronged reconnaissance that ended in success, all the better.
“You do know that Raina would have used the same strategy for the last forest if I hadn’t been sick?” Sarah asked pointedly. “It wasn’t her fault that we missed it.”
Seth had his doubts about the first claim; he suspected that it was only their earlier failure that had inspired this new approach. But that wasn’t important.
“I don’t blame her at all,” he said.
“So why did you do it?” Sarah persisted. “Why run off like that?”
Seth had no wish to be dishonest with her, but to say too much would be disloyal to Amir. “Once we started talking about the orchards in Lida, and picturing the fruit, we could almost smell it. It was impossible to resist.”
“Idiots,” Judith declared smugly. “No self-control.”
«Are you sure the sun sets in the west?» Seth inspoke.
«Stranger things have happened,» Theo replied.
Sarah tipped her head and surveyed the western horizon. “Ah, here they are!”
“Where?” Seth still couldn’t see anyone.
“Almost at the cone.”
He walked a few paces away from her, then turned his whole body toward the south; in this flat desert, it wasn’t impractical to triple his axial span. He ignored the comical distortions the maneuver induced nearby, and concentrated on the southern periphery of his view.
“You’re right,” he said. The new speck could only be Raina and Amina. Assuming no misadventure had befallen them, Amir and Aziz would be recuperating in the forest, waiting for the rest of the team to join them.
as the blotch of dark green in the distance began to resolve itself into foliage, Seth quickened his stride a little in the hope that the others would do the same. But Raina kept to her usual measured pace, and Sarah remained a step or two behind her, so he quelled his impatience and fell back. He wasn’t desperately hungry, and it made sense for them to conserve their strength, but it still felt unnatural not to rush to embrace this thing they’d sought so long, and whose absence would almost certainly have been fatal.
“Why has it drifted so far south?” Theo wondered. “You’d think the trees would stick to whatever solar latitude they’re accustomed to.”
“It could be chasing the rain,” Amina suggested. “Every plant has a preferred range of temperatures, but if the topography shifts the rain a degree or two south, the forest has no choice but to go with it.”
“That sounds familiar,” Judith said wryly. “Is there anything you can name that isn’t dragged along by some force beyond its control?”
“The sun,” Theo replied.
Raina said, “Even the sun only moves because there’s some kind of asymmetry in the world, tugging on its orbit.”
“That’s the usual theory,” Theo conceded. “But I’ve heard a better one.”
Sarah laughed. “Of course you have.”
“Hesethus believed that the sun’s orbit isn’t changing at all; it’s the world that’s moving beneath it. Turning to the north, on our side of the nodes, so it looks like the orbit’s tilting southward.”
Sarah was incredulous. “Are you sure it’s not turning to the east as well? Then you could account for night and day too—all with a single theory in which the sun doesn’t move at all.”
Theo ignored her sarcasm. “If the sun wasn’t orbiting us, it would fall to the ground. And Siméon showed that if the world was rotating once a day, we’d notice air and water swerving in the opposite direction when they flowed from north to south. But before you start protesting that this proves that it must be entirely still, if it’s merely turning north at the speed of the migration the effect will be too subtle to detect.”
“So you’re happy for the sun to follow its orbit—but to explain the migration, you want the whole world to move instead?” Sarah made it sound as if treating the two cases differently was some kind of gratuitous conceptual profligacy.
“Show me the bump in the world that’s pulling on the orbit,” Theo insisted. “If that’s the explanation, I want to see it, I want to measure it.”
Raina said, “There’s no reason why it should be visible to us. If there’s a change in the density of rock deep underground, that could sway the sun, but there’d still be nothing we could see.”
“But whatever it is,” Theo replied, “as the sun gets closer to it, shouldn’t the attraction grow stronger?”
“I expect so,” Raina agreed cautiously. “But that could take hundreds of generations to discern. We don’t have measurements going back that far.”
“If the world is turning around the nodes,” Theo persisted, “that would explain everything.”
“But why is it turning at all?” Sarah demanded.
“Why shouldn’t it?” Theo countered. “There’s no friction in the void. Left to itself, the sun will follow the same circle over and over. Left to itself, the world will keep turning around the same axis. Just as day and night follow from the first motion, the migration follows from the second. What could be simpler?”
“Once the world was turning it would never stop,” Sarah agreed. “But how does an infinite mass start moving in the first place? What could deliver the infinite force required to set the world in motion?”
“I have no idea,” Theo confessed.
“Because it’s impossible,” Judith concluded.
Seth inspoke. «What happens to your plan to un-move the sun, if it turns out that it’s already motionless?»
«It should be even easier to end the migration.»
Seth doubted that it could be easier to bring the world itself to a halt, so that only left one possibility. «You mean you want to make the false theory half true, and have the world drag the sun along with it?»
Theo said, «If a bump in the world that no one has seen can tip the orbit by accident . . . think how much better the job could be done if we all worked together to raise mountain ranges in exactly the right positions.»
the wind had erased Amir’s tracks from the sand,
making it impossible to retrace his route precisely, but apparently he could see his friends coming from the barren east more easily than they could spot him against the camouflage of the forest. Seth heard Aziz shouting to attract their attention, then caught sight of Amir striding jubilantly toward them.
When he reached the group, Amir escorted them westward with the air of a seasoned local welcoming visitors into his home. “You won’t believe how beautiful it is!” he enthused. “We should give up the city and come and live here.”
“And what happens to the rest of Baharabad?” Judith asked.
“That’s what I meant: not just us, everyone.”
“You think this forest could feed that many people?” Judith pressed him.
“It’s not impossible,” Amir insisted. “I’m sure it’s bigger than it used to be—bigger than it’s shown on the maps.”
Seth was relieved that Raina’s plan had succeeded, but the search for food wasn’t over: this was not going to be as easy as robbing an orchard. From where he stood he could already see a bewildering variety of trees, only a few of which he recognized. Most of the branches were high, and, worse, overlapping and entangled; no one was going to be able to reach up from the ground to pluck what they needed in a single move.
Amir led them to a shallow stream he’d found; they drank from it and filled their canteens. They set up camp and rested for a while, then Raina sent Seth and Sarah north to gather what they could before nightfall, while she and Amir went south.
As they sidled through the undergrowth Seth’s eyes adjusted to the dappled sunlight breaking through the foliage, while Theo’s view of the clutter of trunks and branches also grew more refined, as he learned better ways to ping the surfaces and interpret the results. Sarah and Judith proved skilled at spotting fallen nuts among the leaf litter, and ripe berries on some of the knee-high shrubs, but fruit was more elusive. Many of the trees were clearly root-migrants, with a fresh young sapling a few strides south of a middle-aged specimen of the same species—or a shriveled, half-resorbed corpse tree just north of its thriving matriphagous offspring. Plants like these had no need to bother making anything edible to lure animals into spreading their seeds.
Seth raised his face to the canopy, leaving Theo’s view to guide his steps, and was finally rewarded by the sight of a whole branch thick with glistening pink hyperboloids. No one recognized the fruit, but it seemed worth sampling.
“They’re awfully high,” Sarah noted.
“Have you seen any low-hanging fruit?”
“We could go back for rope,” Judith suggested.
Seth stared up into the maze of twigs and foliage. “A rope would just get snagged—and if the branches can bear my weight on the end of a rope, they can bear it with my feet pushing down on them.”
Sarah braced Seth so he could tilt far enough to grab hold of the lowest branch, sparing him the arduous task of shinning up the trunk. He raised himself until his waist was level with the branch, then bent over and rested his arms for a while before bringing his legs up and managing to sit.
«That was hard work,» he confessed to Theo. His current perch was relatively smooth, but twigs from an adjacent branch had already scratched his face and torn his sleeves.
«I think Amir fell in love a bit prematurely,» Theo noted dryly.
«You can’t see Baharabad’s merchants getting their breakfast this way?»
«By lunch, they’d have hired a hundred laborers to clear the ground for the first fields.»
Seth found a secure handhold and maneuvered himself up onto his feet. The trees he’d climbed as a child had all belonged to domesticated species—and been regularly pruned by orchard workers with ladders. «Forget about asking the locals for directions to the nearest forest,» he told Theo. «We should have just brought something to trade with them for food.»
As he hoisted himself up onto the next branch, he heard a squeal nearby, then a blur of leaf-colored limbs brushed past his face. The branch swayed; Seth clung on tightly. Theo’s view showed a scamper sitting further down the branch, one pinger aimed their way, with two tails protruding beneath it, undulating gently. Four clawed limbs gripped the branch tightly, and two other tails were curled around it.
«Do you think we could train it to climb up and bring down the fruit?» Theo joked.
«Bribing it with what?»
«Affectionate tickles?»
Seth had only seen the things in books before, but he knew he shared a certain degree of kinship with it. Some ancient taxonomist had dissected a scamper and shown that the four-limbed, four-tailed animals had light-sensing eyes alone, but hosted their own variety of Siders.
His arms were beginning to tire. He raised himself up until his shoulders were directly above the branch he was holding, then managed to widen the distance between his hands, forcing his lower body higher and making it easier to hook his legs into place. The scamper fled, setting the branch bouncing again; it was an alarming sensation, but Seth doubted that the animal would be so reckless as to risk snapping it, even if it was better prepared to deal with the consequences than he was.
When the movement had died away he began the final ascent. He felt more confident in the mechanics now, even if there was little he could do to keep the twigs from scratching him. Standing on the third branch, the fourth, fruit-bearing one was level with his chest, but the prize itself was farther from the trunk. Seth shuffled cautiously outward, glancing down to check that Sarah was still in place to collect anything he dropped. As he did, it struck him that she was several paces due south of him—yet he was seeing her with his own eyes.
«Do you remember what you said?» he asked Theo. «About the view from on high?» Seth couldn’t hide his delight: the feat was perfectly explicable, but it still felt like a kind of magic.
«Of course,» Theo replied. «Now we just need to find a way to go higher, and we can map everything from here to the steamlands.»
Seth raised his eyes and concentrated on reaching the fruit without getting impaled along the way. Each time he took a step he could feel the branch beneath him bend a little, but if he shifted his weight to the one he was holding, the one at his feet sprang back up smoothly, suggesting that it was yielding to the force rather than suffering any damage.
The pink fruit dangled from pale threads attached to the branch. Seth grabbed the nearest one with his left hand, called down to Sarah, then yanked it free and dropped it.
“Did you get that?” he shouted.
“Yes!” Sarah replied.
He plucked half a dozen more that were all within reach, then sidled out a little farther. Eight more fell; the arduous harvest was finally starting to feel worthwhile. He took another step—
There was a tearing noise from below, and Seth felt air beneath his feet. As he clung to the upper branch, a new sound arose behind him, like a powerful gust of wind ripping through a field, followed by a deafening thud. He tipped his head back to see that the branch he’d been standing on had broken free entirely, and tilted over so far that one end speared the ground. The other end protruded through the canopy and vanished from sight.
“Are you all right?” Sarah called up.
“Yes.” Seth hugged the surviving branch to his chest, trembling with relief at the realization that not only was he uninjured himself, the wayward branch that might have skewered her had done its damage elsewhere. “I just need to think.” The next intact branch below him was out of reach with his legs hanging straight down, but if he moved his feet wider apart he could bridge the gap, albeit at the cost of compromising his balance.
He tried it. There were no clear footholds where he needed them, but he stamped at the obstructing twigs and managed to make space. «Don’t worry,» he muttered. «If I fall, it won’t be head-first.»
«We’re going to be fine,» Theo said calmly.
Seth moved his arms apart and bent his knees, then succeeded in squatting on the lower branch while still maintaining handholds on the upper. He fre
ed one hand and brought it down, then thrust his legs back and lowered himself to lie on his stomach, like a rag thrown over a washing line.
When his limbs were rested, he got his feet onto the branch from which he’d begun his ascent. Then he sidled close to the trunk and used it to help him make the last move, hanging by his hands for a moment, then spreading his feet to touch the ground. Sarah ran up and steadied him as he assumed a normal posture.
He said, “I think I’ll let you climb the next one.”
Sarah walked over to the fallen branch that was slanting up from the ground. Though the part Seth had stood on was thicker than his arms, farther from the trunk it forked into two more slender pieces, and the tip of one of them remained unburied. She took hold of this piece and pulled it sideways, trying to snap it at the junction—which had ended up higher than the point where the branch had originally been attached to the trunk. Seth came and helped her, and together they managed to break it off, while leaving the severed end resting on the main branch.
“Let’s see what we can poke loose with this,” Sarah suggested. There was still some fruit remaining where Seth’s efforts had been curtailed, and they tried manipulating the severed branch so that its far end reached that unplucked bounty. But the geometry wasn’t in their favor: wherever they moved, the prod ended up too close to the trunk.
Judith said impatiently, “You don’t want it to be axial!”
Sarah found a sturdy east-west side branch and broke it off, then cleaned away the twigs. Held vertically it was only a little taller than she was, but with Seth’s help she got it resting on the slanted branch at a point well above their heads, then they carried the lower end north so the far end rose up higher still. Fighting the torque, they maneuvered it into position and started jabbing at the threads that held the fruit in place. It was finicky, exhausting work, but in the end they brought down every target.
Seth was famished, and once he’d taken a bite of the exotic pink fruit and failed to drop dead, Sarah joined him. The flavor was unusually woody, but not unpleasant—a bit like a stone-fruit with traces of bark and sap.
