21

While Azelio and Tarquinia debated the merits of different landing sites, Ramiro clung to a rope beside the window and gazed down at the starlit world below. How could he understand Esilio? Of all the sciences he’d studied as a child, geology had been the least developed—and at the time, he’d imagined, the least likely ever to be of use to him. Of the little he remembered, he remained unsure what he should trust. The ancestors had had no idea what a rock was actually made of, while their successors, with all their superior knowledge, had never set eyes on a planet.

“We need to be within walking distance of four or five different kinds of soil, or what will the crop tests be worth?” Azelio said heatedly.

“I appreciate that,” Tarquinia replied. “But if we don’t come down on flat, stable ground, we could damage the Surveyor irreparably.”

Over the eons, Ramiro had been taught, every kind of rock exuded traces of gas, and for a body with sufficient gravity this gas would accumulate into an atmosphere. If the body also happened to orbit a star, winds driven by the temperature difference between day and night eroded the rock, and once there was airborne dust and sand that accelerated the process. The routes of the dust-flows carved out valleys and mountains, shaped as well by the differing durability of the underlying rock. But where had those various minerals come from? As far as he recalled, no one even knew for sure whether they dated all the way back to the entropy minimum, had formed over cosmic time from the sedate decay of some primordial substance, or had been forged in the core of a giant ur-world where liquid fires—contained for a while by its unimaginable gravity—thrashed and churned until the whole thing finally split apart and scattered.

Tarquinia brought an image of the next candidate onto her console, taken in full sunlight with the time-reversed camera. Ramiro struggled to interpret it, but the combination of near-smoothness and suspiciously delicate ridges suggested a plain of wind-ruffled dust into which the Surveyor might sink and vanish.

“Can’t we just settle for the safest-looking ground?” he proposed. “If it turns out that there’s a problem with the soil, we can always ascend and come down somewhere else.”

Azelio turned to stare at him angrily. “I’m not spending years hopping from site to site! That’s not what we agreed to!”

“All right. Forget it.” Ramiro regretted speaking so carelessly; Azelio had his niece and nephew to think of.

Tarquinia summoned another image. “Why do we only have two probes?” she fretted. They could send one down in advance of the Surveyor, and the second if their first choice proved unsuitable, but that was the limit: the probes weren’t sophisticated enough to explore more than one location each.

“Perhaps we could extend the survey for a few more days,” Ramiro suggested. The planet was turning beneath them as they circled from pole to pole; each successive orbit carried them over a different meridian, and though they’d sampled a wide variety of terrain they were still far short of seeing everything. “There has to be a perfect site down there.”

“Exactly!” Azelio replied. He gestured at the console. “None of these are acceptable.”

“We can keep looking,” Tarquinia agreed. “A few more days is nothing.”

Azelio excused himself to check on the plants. Weightlessness wasn’t good for them, but it wasn’t worth setting up the tether again—not unless the selection process was going to stretch out into stints, rather than days.

Tarquinia switched to the live feed from the time-reversed camera: dawn was breaking over a red plain crisscrossed by brown fissures.

“Look at all that land!” Ramiro marveled. If every field of wheat in the Peerless were laid out here side by side, they would pass by in a flicker, lost in the vastness. The sagas were full of journeys on foot that had crossed ancient empires and lasted for years, but nothing he’d read or imagined had prepared him for the scale of the world below. “How could the first travelers ever give up so much freedom?”

“I think the Hurtlers might have helped,” Tarquinia suggested.

“Yes, but I still wouldn’t have been able to do it. We never belonged cooped up in a mountain; it’s a wonder we didn’t all lose our minds generations ago.”

“So you’re set on making this your home?” Tarquinia asked. “Esilio’s won you over already?”

Ramiro buzzed softly. “Esilio’s one thing, but twelve more years of traveling will probably finish me off.” He would have relished defying Greta and staying behind when the Surveyor departed—and it would not have undermined the purpose of the mission if the rest of the crew returned to the Peerless with the news that a colony had already been established. But he couldn’t do it alone.

Tarquinia said, “And wide open spaces are one thing, but you can’t eat dirt. Before you start picturing the flowers on your grave, let’s see if anything can take root here at all.”

The probe parted from the Surveyor, separated by a burst of air before it fired its engines to start the descent from orbit. Ramiro peered over Tarquinia’s shoulder to watch the instrumentation feed. Azelio looked on from Tarquinia’s right, and even Agata had left her calculations for a while to cling to the rope beside him.

As the probe slowed to let gravity bring it down, it didn’t take long to fall back behind the Surveyor’s horizon, cutting the link. “Do you want to sleep for the next few chimes?” Agata teased Ramiro. “I promise to wake you when all the results are in.”

“No thanks.” Ramiro asked Tarquinia to replay the recorded data; something unsettling had caught his eye. “Look at how hot it was, just before we lost contact!”

Azelio said, “We were expecting some frictional heating, weren’t we?”

“Not so soon. Not at that altitude.”

Tarquinia frowned. “We’re not suffering any unexplained drag ourselves, so I don’t see how we could have the density profile that wrong.”

Ramiro didn’t want to argue about the cause; the fact remained that the heating was unexpected. “If this thing burns up out of sight, we’re never going to know what happened—or what we need to change when we try again. If we make the wrong guess we could lose the second probe the same way.”

Tarquinia contemplated this gloomy scenario. “Then we’d better move quickly,” she said.

Ramiro was already strapped to his couch, but Agata and Azelio had to clamber into place as the Surveyor tilted then ascended rapidly. The cabin window faced the stars, but on the navigation console the land could be seen falling away as Tarquinia widened their horizon to re-establish a line of sight to the probe.

When the link was restored she cut the engines, letting them continue the upward arc from momentum alone. Ramiro was dizzy after the unaccustomed weight, but when his head cleared he focused on the data feed. The probe’s temperature was still high, but it was less than before.

“It must have been a false reading,” he decided.

The image feed was growing shaky, as if the probe was being buffeted by high winds. Greta had only provided the expedition with a single time-reversed camera, and the probe’s sunless view of the landscape below was almost impossible to read. The temperature was dropping steadily now. Maybe there was something going on with the cooling air: a valve had jammed when the flow had been needed to dispose of the engine’s heat, but now it had simply snapped open and was overcompensating.

As the juddering machine rushed toward the surface, Ramiro felt equal parts fear and exultation. In the history of the Peerless, no one had ever performed a maneuver that deserved to be described as a landing. But if this small, robust scout couldn’t survive the process, what chance would there be for the Surveyor?

The image turned black. Tarquinia said, “Side camera might be more informative now.” She sent an instruction from her corset, and the feed changed to a slanted view of an expanse of sandy ground. In the middle distance a few small gray rocks broke the flatness.

“It’s down! It’s safe!” Azelio chirped ecstatically, then turned to the instrument feed. “And the temperature’s fine. It’s already close to Tarquinia’s estimate for the surface.”

Agata said, “In Esilio’s terms, it’s been there for days. What other temperature should it be?”

Ramiro struggled to accept this. On one level he understood her reasoning perfectly: according to Esilio’s arrow of time, the probe was about to ascend, with any frictional heating yet to come. And if this was the correct perspective, the high temperature they’d seen when it was still above the atmosphere was due to its earlier heating during its ascent.

“How was it ever cool, up here?” he asked. “Before we launched it? Or in Esilio’s terms: what cooled it after it emerged from the atmosphere?”

“Any answer to that will sound strange from either perspective,” Agata replied. “I suppose it must have happened through interactions with the cooling air—but then, from Esilio’s point of view that air was rushing in from the void and striking the probe in just the right way needed to cool it, while on our terms the probe was releasing cooling air but heating up in the process.”

Ramiro clutched his skull. “Why, though?”

“What’s the alternative?” Agata replied. “Retaining all the heat from this ascent for the next six years, while it was sitting in its bay in contact with the Surveyor?”

“That would have been absurd,” Ramiro conceded. “But the fact that it heated up at all before it hit the atmosphere is absurd, too.”

“Less so,” Agata insisted. “And ‘absurd’ is the wrong description. If I handed you two identical-looking slabs of stone at room temperature—one of which had been heated for a while in a fire the day before—would you expect to be able to tell me which was which?”

“Of course not.”

“Now look at the same situation in reverse. Your failure to guess the stones’ history becomes a failure to predict their future—but the one that would become unexpectedly hot well before it was actually in the fire would not have been doing anything absurd.”

Ramiro couldn’t argue with that. “So I should be grateful on those rare occasions when things make perfect sense from a single perspective, whether it’s ours or Esilio’s. But when that doesn’t work … what are we left with?”

Agata said, “Why should we expect a system as complex as a slab of stone to be predictable, when we don’t know the detailed motion of all its constituent particles? We’re used to making predictions based on nothing but a single number, like temperature or pressure, but the ability to do that depends entirely on our relationship with the entropy minimum.”

“So we’ll be helpless down there,” Ramiro concluded glumly. “Anything could happen.”

“No! Not anything.”

“What can we rely on, then?” Azelio asked.

“Nothing should happen that’s unreasonably improbable,” Agata declared.

Azelio buzzed. “What makes something reasonably improbable?” “Cosmology.”

“I might need a little more guidance than that,” Azelio pleaded.

Agata thought for a while. “If you took a cubic stride of air at a certain temperature and pressure,” she said, “and chose the direction of all its particles at random, then in the vast majority of cases the entropy of that system would increase if you followed it either forward or backward in time.”

She sketched an example.

“But the air we actually deal with every day might well have been released into that large container from a smaller one, which immediately tells us that it’s in an improbable state: one that would shrink of its own accord into a smaller volume if you followed it backward in time.”

“Most cubic strides of gas—in a time-blind, mathematical sense of ‘most’—do not have that property! But the entropy minimum in our past makes it entirely reasonable that we encounter air in that state. The cosmos isn’t full of particles moving purely at random, or there wouldn’t be an entropy minimum at all.

“But the entropy minimum is in our future as well as our past—and Esilio connects us to it in a way we’re not accustomed to. So we’re now in a situation where we might encounter a cubic stride of air that not only occupied a smaller volume in the past, but will occupy a smaller volume in the future.”

“As a fraction of all the ways the particles could be moving, that’s even more improbable than before—but given where we are and the facts of cosmology, it’s not unreasonable.”

Ramiro accepted Agata’s logic, but it was difficult to see what it offered them in practice. “Tell us one thing that you’re sure won’t happen,” he challenged her.

She said, “Two objects in thermal contact will not maintain different temperatures over a long period of time.”

“Because …?”

“Because there are vastly more possibilities in which they share their thermal energy more equally. If you pick a possibility at random, it’s likely to be one of those. Fundamental physics might make the entropy minimum necessary—but we still expect the cosmos to be as random as it can be.”

Ramiro said, “Why am I not comforted by that?”

Agata buzzed. “I don’t mean rocks flying into the air and hitting you in the face for no reason. When individual particles are moving randomly, that makes large assemblies of them more predictable, not less. Most of the time, air will just be air, stone will just be stone, acting the way our instincts expect.”

“And the rest of the time?”

Agata said, “We’ll just have to be prepared for the exceptions.”

Ramiro was on watch, so he stayed in the front cabin monitoring the probe’s data feed long after everyone else had gone to bed. Sitting meekly on the surface of Esilio sending back images of the surrounding landscape, the probe encountered no conspiracies of air, or rock, or heat to impair it. Its temperature remained stable—despite the heat its photonics would be generating in the normal course of things—which seemed to imply that it was exchanging thermal energy with its surroundings in the usual way. Agata appeared to have been right about that much: the earlier, unanticipated heating had taken place for a perfectly good reason, and there was no risk of it happening again while the probe was motionless on the ground.

Tarquinia had put the Surveyor into a new orbit, so high that it matched Esilio’s rotational period, keeping the probe permanently in their line of sight and allowing the link to remain open. Through the window, the planet itself had shrunk to an enigmatic gray disk, but as Ramiro swept the distant cameras back and forth across the starlit plain, the new world appeared as innocent and tranquil as he could have hoped it to be.

“I’m happy with the site,” Azelio announced. “The probe can’t verify every detail, but nothing it’s shown us makes me think we were wrong about the geology of the area.”

Tarquinia turned to Agata. “Any problems?”

“No,” she replied. “If we’re careful, I think we can do this safely.”

“Ramiro?”

Ramiro had no objection to the site, but they could at least try to deal with the one unsettling phenomenon they’d already witnessed. “What if we lower ourselves through the atmosphere more slowly than the probe?” he proposed. “That should keep frictional heating to a minimum, whether you look at it as an ascent or a descent.”

“It would mean more heat from the engines,” Tarquinia pointed out.

“We’ve had no problem with that for a year at a time,” he replied. “I know: venting cooling air into Esilio’s atmosphere might not be the same as doing it in the void. But wouldn’t it be the most cautious approach: moving slowly, trying to keep our temperature constant?”

Tarquinia looked to Agata.

Agata said, “I think Ramiro’s instincts are sound. The closer we can stay to thermal equilibrium, the more predictable things should be.”

“All right then. A slow descent it is.”

Tarquinia turned to her console and began plotting their course down from orbit.

In the sunlit view through the time-reversed camera, Ramiro could see the broken ring of hills directly beneath the Surveyor, their eroded peaks casting long shadows to the east. Azelio had been ecstatic when he’d found this site, with the strange confluence of ancient dust flows that its peculiar topography had allowed. Ramiro didn’t pretend to understand the details, but over time the central valley appeared to have trapped wind-borne detritus from at least four different sources. From on high, the variety in the soils was impossible to miss, with great splotches of competing hues laid over each other like a mess of dyes spilt from a child’s paintbox. But though the colors were layered they remained distinct, which suggested that the whole arrangement was stable. The Surveyor was a great deal heavier than the probe, but if these deposits were prone to subsidence they ought to have shown more mixing under their own weight.

The temperature in the cabin had barely changed since they’d entered the planet’s atmosphere. Ramiro didn’t want to grow complacent; no one would forget the near-fatal surprise the Object had held for its first visitors. But if a mismatch in Nereo’s arrow was a guarantee of mutual annihilation, the arrows of time were more pliable. On this world of lifeless dust with its almost timeless landscape, it did not seem too much to hope for that two opposing directions could coexist.

“There’s the probe!” Agata announced excitedly, pointing to a dark elliptical splotch. It was hard to distinguish the thing itself from its shadow.

The Surveyor was descending at a constant rate, leaving the cabin subject to Esilio’s full gravity—about a third higher than the home world’s. That standard was usually taken as the limit for prolonged acceleration, on the assumption that the ancestors’ physiology had adapted to it over the eons. But the travelers had coped easily enough with far lower gravity than the ancestral norm, and Ramiro did not believe that the settlers would be troubled by this minor increase.

Azelio said, “I can hear the wind.”

Ramiro strained his tympanum. It was hard to distinguish it from the sound of the cooling system, but the gusts were sharper, rising and falling less predictably.

The altitude displayed on the navigation console dropped below one saunter. As Ramiro watched the wind whipping dust across the ground, he began to discern an almost perfect dark circle with a wide penumbral ring, straight below the camera. He would have sworn it was the Surveyor’s shadow, but that made no sense: the sun wasn’t overhead.

A warning appeared below the image: the ultraviolet glare scattered back from the ground was approaching unacceptable levels. Even though the engines’ beams were splayed out to the side—and the camera was counting photons emitted, not received—too much irradiation could damage the sensor. Tarquinia closed the protective shutter and the image turned black.

The altimeter kept working, timing slow infrared pulses that were making it down and back through the dust. Half a dozen strides above the ground, Tarquinia cut the main engines and switched on the air jets to cushion their fall. Ramiro had barely registered the plummeting sensation before the impact drove him hard into his couch. The jolt left him shaken, but when he moved slightly in his harness he felt no pain.

Tarquinia swept her rear gaze across the cabin. “Anyone hurt?”

“I’m fine,” Agata replied, and Ramiro and Azelio echoed her.

The view through the window was so dark that the pane might as well have been a mirror, reflecting back the lights of the cabin. Tarquinia redirected the time-reversed camera to a side-mounted lens; the image showed red dust swirling over the ground, darkening the sky and blotting out the horizon. The sight dragged Ramiro’s attention back to the sound of the wind on the hull; he could hear the difference as the visible signs of each gust rose and fell.

“Is this just … weather?” he wondered. “Like the home world?” He’d read about dust storms in the sagas, but it was hard to know which parts of those stories were real.

Agata said, “I read a memoir by one of the first travelers, a woman named Fatima. She described the dust blowing around at the site of a rocket test, jamming all the clockwork.”

“But it shouldn’t be harmful to people, should it?” Ramiro had no idea how fast the wind would need to be blowing before the dust would start abrading skin.

Tarquinia swiveled her couch around. “I don’t expect so, but no one is going out for at least two bells. I want to be certain that the ground isn’t hot—and I don’t care whether or not Esilio thinks we’re yet to use the engines.”

Ramiro turned beseechingly to Agata, but she said, “Good policy. In Esilio’s terms, the engines’ exhaust came from the environment and entered the rebounders, so that’s violating the local arrow already. We should treat all these non-equilibrium situations as uncertain, and only assume that temperatures will be uniform when everything is settled.”

They passed the time checking the Surveyor for damage, but even the weakest points on the hull—their repairs along the Hurtler gash—seemed to have survived the landing intact. When Tarquinia ran out of things they could inspect—short of taking the engines apart and putting the rebounders under a microscope—they brought out some loaves for a celebratory meal, and Azelio took photographs to show his niece and nephew.

Two bells after they’d touched down, the instruments showed the hull’s external temperature to be no different from the cabin’s. No one challenged Ramiro when he finally moved toward the airlock.

He closed the inner door then hesitated, gathering his courage. There was no need to use the pump—Tarquinia had already raised the cabin pressure to match the external atmosphere. He was wearing his helmet and cooling bag for protection from the dust; he switched on the coherer in his helmet, dazzling himself for a moment until he adjusted the brightness.

There was fine red dust covering the gray hardstone walls of the airlock. He hadn’t noticed it by the dimmer illumination of the safety light. He ran a gloved finger along the seal of the outer door, trying to find the point where it had been breached, but if there was a hole it wasn’t apparent.

It hardly mattered now; however the dust had entered, he was about to let in a great deal more. But as he began to turn the crank, the realization hit him: it hadn’t come from outside. They must have brought it with them all the way from the Peerless, scattered invisibly throughout the craft, with a little more accumulating inside the airlock each time the inner door was opened. Or in Esilio’s terms: the Surveyor’s visit had just ended, and this residue was something they would soon take away with them.

Ramiro shivered, disoriented for a moment, but whether or not this account was correct there was nothing to be done about it. A small, stubborn part of him longed to leave the door closed and … what? Never open it at all, just to see if he could spite this unsurprising message from the future which claimed that, actually, he would? Every time they’d used the time-reversed camera, subtler but even stranger things had happened, as thermal fluctuations in the sensor conspired to create the orderly pattern of photons that the device needed to emit. Every image the camera had shown them had been encoded all along in the not-quite-random vibrations of various objects throughout the Surveyor, waiting to come together at just the right moment.

He leaned against the crank and broke the door’s seal; a gust of wind forced its way through the narrow gap. Dust flew into the airlock, dust flew out, erasing all distinctions between that which they’d brought and the rest. He slid the door fully open, letting the light from his helmet carve a tunnel through the storm. Amidst the chaos sheets of darkness fluttered, where the dust piled together in midair for a moment before scattering again. Cautiously, Ramiro poked his head and shoulders through the portal. He felt the warm wind insinuate itself beneath the fabric of his cooling bag, but it seemed that nothing it carried was small enough, or sharp enough, to reach his skin.

He swept the beam of the coherer across the ground; the wind was raising so much dust that it was impossible to make out the surface below, but given that the Surveyor wasn’t sinking its immediate surroundings were unlikely to prove treacherous. He slid the short boarding ladder out from the airlock; its feet vanished before it touched the ground, but a scant or two further down it encountered firm resistance.

He clambered down the ladder and stood on the surface. Even with the cooling bag encasing his feet there was an unpleasant grittiness against his soles; he took a few steps to see if he’d grow accustomed to the texture, but it remained distracting so he hardened and desensitized the skin. The wind wasn’t strong enough to knock him down, but he couldn’t move confidently without pausing each time it rose up, to recalibrate his efforts to compensate for the force.

“Ramiro?” Tarquinia’s voice came through the link in his helmet.

“I’m fine!” he replied, shouting to be heard above the dust scraping across the surface of his helmet. He closed the outer door of the airlock then walked around to the window and raised a hand; his crewmates raised theirs to shield their eyes from his coherer. “Sorry.” He swiveled the beam upward, out of their lines of sight. “The wind’s annoying, and I can’t see much. But I don’t think I’ve started speaking backward or aging in reverse.”

Agata said, “I’m coming out.”

Ramiro made a quick circuit around the Surveyor; he couldn’t see any damage on the outside of the hull. Agata emerged, stepping gingerly across the swirling sand.

“So this is what a planet’s like,” she said numbly.

“It’s not exactly welcoming,” Ramiro conceded. “But it should be more appealing once the weather improves.” He glanced up at the stars; he could just make out the arc of the rim, its usual dazzle reduced to a pale broken line. Though the wind and the dust were the most intrusive novelties, even the more familiar elements of their surroundings were juxtaposed so bizarrely that they lost their usual meaning: on the slopes of the Peerless strong gravity and an open sky always lay in the same direction. He wondered if he’d ever be able to sleep out here, or if he’d panic and imagine that he was falling into the stars.

“Whenever I pictured the reunion, I always thought of people meeting in a corridor,” Agata confessed. “But it will probably be outdoors—in the countryside, where the vehicles can land safely. It might even look like this.”

“We’ll recreate the center of Zeugma for you later,” Ramiro teased her. “To give you some better imagery for the ceremonies in the town square.”

Azelio joined them. “I’d be happy with some gardens to break the gloom,” he said.

“Be my guest.” Ramiro gestured into the darkness.

“Once the wind dies down.” Azelio turned and swung the light from his helmet across the ground, but the exploratory oval faded into obscurity at a dozen strides.

Tarquinia stepped off the ladder. “Given what we saw from orbit, these conditions shouldn’t last long. It’s coming to evening; we should get some sleep and start work in the morning, so we’ll be able to use the view by sunlight if we need it.”

“Real days and nights!” Agata chirped. “It’s just a shame we couldn’t put a time-reversed camera in every helmet.” She turned to Ramiro. “So will your settlers bring a few gross of the things, or just one for navigation that they’ll destroy on arrival, lest someone put it to an evil purpose?”

Ramiro had never wanted the cameras banned, but nor had he pictured the colony relying on them. “We’ll see by flowers and wheatlight,” he said. “And I’m sure there’ll be something we can use to make lamps.”

“While the sunlight itself goes to waste.”

“Did you ever see sunlight?” he countered. “There’ll be gardens, lamps, a few coherers … much the same as the lighting everyone’s used to, with a lot less moss and a lot more starlight. We won’t be trying to recreate the home world—or the mountain—but no one from the Peerless will find it all that strange.”

Agata was silent for a moment, then she said, “You’re right—and I should wish you luck with it. It’s what we’re here for, after all.”

Ramiro had trouble falling asleep. When he woke, the sound of the storm on the hull was gone, and the Esilian clock he’d set up on his console showed that it was more than a bell after dawn. Esilio’s day was only about two thirds as long as the home world’s; he hoped Tarquinia wouldn’t try to impose the new rhythm on everything they did.

In fact, when he found her at her seat in the front cabin, Tarquinia looked as if she’d been awake all night. “The others are outside,” she said. “The wind’s died down, so we should be able to start work soon, once they stop playing around.”

“Playing?”

“Take a look for yourself,” Tarquinia suggested.

“Will I need my helmet?”

“You won’t need anything,” she promised. “We’ve set up some lights. Just toughen your soles.”

Ramiro felt vulnerable as he approached the airlock without even his cooling bag, but Esilian sand was just sand, and he’d probably had traces of it beneath his feet for the last six years.

When he opened the outer door he saw Agata and Azelio leaping around, buzzing like excited children for no reason he could discern, unless it was sheer joy at the stillness after the storm. A couple of coherers mounted on the hull illuminated the red soil starkly—showing up an extraordinary maze of tracks that testified to his comrades’ exuberance. With the foreground so bright his eyes stood no chance of adapting to the starlight, so even with the dust haze settled everything in the distance was lost in utter blackness.

“What are you idiots doing?” he called out.

“Trying to see which footprints are ours,” Agata replied gleefully. She jumped forward with her rear gaze fixed intently on the place where she’d been standing.

Ramiro was bemused, but then he observed her more closely as she took her next few leaps. Twice, as she jumped out of some indentation in the sand, it vanished. She and Azelio hadn’t actually made all the tracks that he’d attributed to them. Or not yet, they hadn’t.

“Come and join us,” Azelio said. “Some of these must be yours.”

Ramiro stayed on the top rung of the ladder, watching. Each time Azelio lifted his feet, scattered sand un-scattered itself, grains sliding in around the places where he’d stepped to settle more evenly—though not always smoothing the ground completely. After all, Ramiro reasoned, it was possible to walk in someone else’s footprints, or to step several times in your own. It would only be the last footfall on any given spot—prior to the next occasion on which the wind leveled everything—that would unmake the imprint completely.

The crew had talked over possibilities like this, dozens of times. Ramiro knew he had no right to be surprised. But having sought a world where the dissenters could escape the tyranny of foreknowledge, what had he been given? A world where every step he was yet to take would be laid out before his eyes.

“What happens if I try to walk on pristine ground?” he asked.

“Try it and see!” Agata taunted him.

Ramiro descended to the bottom of the ladder, intending to move quickly and get the ordeal over with, but then his resolve deserted him. When he willed his foot to land on unblemished sand, what exactly would intervene to stop him? A cramp in the muscle, diverting his leg to its proper, predestined target? A puppet-like manipulation of his body by some unseen force too strong to resist, or a trance-like suspension of his whole sense of self? He wasn’t sure that he wanted to know the answer. And perhaps that was the simplest resolution: he would lack the courage to walk out across the surface of Esilio for the rest of the mission. He would cower in his room, leaving the work to the others, while he waited to return to the Peerless in disgrace.

Agata was watching him. “Ramiro, there’s nothing to be afraid of.” She was amused, but there was no malice in her voice. “Just step off the ladder without thinking about it. I promise you, the world won’t end.”

Ramiro did as she’d asked. Then he looked down. He’d scrutinized the ground beforehand, and he was sure there’d been no footprints at all where his feet now stood.

He lifted one foot and inspected the sand below. He had created an indentation that had not been there before. That was every bit as strange to Esilio as the erasures he’d witnessed were strange to him.

“How?” he demanded, more confused than relieved.

“You really don’t listen to me, do you?” Agata chided him. “Did I ever tell you that the local arrow was inviolable?”

“No.” What she’d stressed most of all was a loss of predictability—but the sight of her and Azelio unmaking their footprints had crowded everything else out of his mind. Those disappearing marks in the sand might be unsettling, but if he could ignore them and walk wherever he pleased then they were not the shackles he’d taken them to be.

Still …

“What happens if there are footprints that no one gets around to before the next dust storm?” he asked Agata. “Ones that were there straight after the last storm?”

She said, “There can’t be a footprint untouched by any foot. I don’t understand the dynamics of wind and sand well enough to swear to you that there won’t be hollows in the ground that come and go of their own accord—but if you’re talking about a clear imprint, if we could keep our feet away from it, it simply wouldn’t be there.”

Ramiro pondered this, but it seemed much less dismaying than the kind of all-encompassing trail he’d originally feared. Esilio was a world where a certain amount of noisy, partial—and predominantly trivial—information about the future would be strewn across the landscape. There had always been plenty of trivial things that could be predicted with near certainty back on the Peerless, and perhaps as many of them would be lost, here, as these eerie new portents would be gained.

Emboldened, he strode out across the illuminated ground, pausing every few steps to kick at the sand. Sometimes he simply pushed the dust aside; sometimes the dust applied pressure of its own, as it moved in to occupy the space his foot vacated. But that pressure never came out of nowhere: his feet moved as and when he’d willed them to move, followed by the dust but never forced to retreat. Nor were they thrust without warning into the air by a time-reversed version of the dissipation of motion into heat that took place when they landed.

By the time he reached the point where the coherers’ light gave out, he realized that the part of his brain that dealt with his gait and balance had come to terms with the ground’s bizarre behavior as if it were nothing more than an unfamiliar texture: a kind of stickiness that rendered the soil a little unpredictable. He hadn’t slipped over once, or found himself rooted to the ground. On one level, he’d already taken the whole phenomenon in his stride.

Each time there was a dust storm the record of future movements would be erased, but even in a prolonged period of calm the footprints would overlap, conveying very little information. Compared to the crystalline certainties of the messaging system, it would be nothing: a novelty to which the settlers would soon grow accustomed.

Ramiro turned to Azelio. “Entertaining as this is, if you want to start the planting now I’d be happy to help.”

With so little wind about, Ramiro decided that it was worth opening both doors of the airlock so they could pass the plants straight through. Standing on the ground, he was at the perfect height to accept each pot directly from Azelio, instead of climbing up and down the ladder.

“Be careful,” Azelio pleaded.

The advice was redundant, but Ramiro took no offense. Azelio had been nurturing the things for six years—and tending to them while they were spinning in their tethered pods had probably been the most arduous task that any of the crew had faced.

Azelio brought out a dozen of the plants to start with. The wheat was a miniature variety that he’d succeeded in maintaining at a staggered set of stages in its growth cycle, allowing him to compress the time needed to assess its viability in Esilian soil. Instead of waiting a year to be sure that it could survive from sowing to harvest, in one twelfth of that time they’d watch each representative plant advance from its initial level of maturity to that from which another had started.

Ramiro looked over the collection assembled beside the airlock. “And these are all going in the same kind of soil?”

“Yes. Just a few saunters away. I’ve already chosen the spot.”

Ramiro followed Azelio across the bright ground of the Surveyor’s domain and into the starlit valley. The two plants they were carrying put out a healthy red glow, but that didn’t do much to light the way. It was soon clear that, however well their eyes adjusted, they’d need to use the coherers they’d clipped to their tool belts—sacrificing their distance vision for the sake of surer footing. Ramiro tried to balance the confidence he’d gained in dealing with the soil’s peculiar forces with a suitable level of caution. There was no telling what Azelio would do to him if he stumbled and fell, crushing one of his darlings, even if “Esilio pushed me!” was the honest excuse.

“Just here.”

Ramiro squatted and placed the pot on the ground, then swung his beam around the site. “You already dug twelve holes!” he observed. “And I thought you were messing around with Agata all morning.”

Azelio made a noncommittal sound. Ramiro suddenly felt queasy.

“My plan is to dig up all of these plants at the end of the trial and take them back to the Peerless for my colleagues to analyze,” Azelio mused. “So I guess that’s when I’ll see the transition between cultivated and truly pristine ground. But right now, in Esilio’s terms, we’ve just dug the plants up—so on our terms, we’re about to do that. Backward.”

Ramiro said, “You make it sound as if you’ve been practicing time-reversed agronomy all your life.”

“It’s not that hard to see what’s going on, if you think it through,” Azelio replied lightly.

“But you don’t mind following markers like this? Evidence of acts you haven’t performed yet?”

“It’s a little disconcerting,” Azelio conceded. “But I can’t say that it fills me with claustrophobia to know that I’ll carry out the experimental protocols I always planned to carry out.”

Ramiro didn’t argue; the only thing he’d gain by pressing the point was to raise his own level of disquiet again. “Let’s get to work then.”

Azelio squatted beside one of the plants. “The idea is to take it out of the potted soil and brush the roots clean. Pay close attention.” He leaned forward and positioned his hands on either side of the stalk, but then he kept them there, motionless. After a lapse of this, Ramiro said, “What are you doing?”

“I thought it might leap into my hands by itself,” Azelio explained, deadpan. “Dropped in and repotted, Esilio style.”

“One more joke like that and we’ll be burying more than plants here.”

Azelio took a short stone rod from his tool belt and used it to loosen the soil in the pot, then he gently extracted the plant and applied a soft brush to the roots.

“Does it matter if there’s a trace of the old soil clinging on?” Ramiro asked.

Azelio winced. “Yes. If it’s enough to keep the plant growing when it otherwise wouldn’t, that would make the results meaningless. You don’t want the settlers to find out after half a year that it was only contamination that made it look as if they could survive here.”

He carried the freed plant over to the row of holes he hadn’t yet made. “What happens if I try to put it in the wrong one?” he mused. “Is that possible?”

Ramiro aimed his coherer at the nearest of the holes, then watched as Azelio knelt down, a trowel in one hand and the wheat plant in the other. He lowered the plant until its roots were in the hole, then he started adding soil from the surrounding mound. Some of the soil was scooped in with pressure from behind, in the ordinary manner. Some appeared to pursue the trowel, the way the dust sometimes pursued Ramiro’s feet. What decided between the two? Azelio’s own actions had to be consistent with the motion of the soil, but which determined which? Maybe there was no answer to that, short of the impossible act of solving in the finest detail the equations that Agata was yet to discover, revealing exactly which sequences of events were consistent with the laws of physics all the way around the cosmos.

In any case, the laws of physics seemed to allow the plant to end up firmly bedded in Esilian soil. Azelio tried to shake his trowel clean, but each time he flicked it as many specks of dirt rose up from the ground to stick to the blade as parted from it.

“I guess that’s now my Esilian trowel. Do you want to do the next one?”

Ramiro said, “I wouldn’t trust myself to get the roots clean.”

“I’ll deal with that,” Azelio replied. “You can do the planting.”

“All right.”

When Azelio had prepared the second plant, Ramiro accepted it and took it to the next hole. He knelt on the ground; Azelio passed him the trowel then stood back to provide a steady light.

Ramiro gazed down at the neat mound of soil beside the hole. If he’d had a camera here during the dust storm he might have watched the mound rising up, as speck after speck fell into place from the turbulent air. But if an Esilian wind had scattered it, who had given it its shape? If he refused to do it himself, would Azelio be compelled to take his place? But why would one of them be compelled and not the other?

When he’d stomped across the sand beside the Surveyor each disquieting footprint had been blurred into insignificance, but he couldn’t try to complicate this crucial experiment just to obfuscate the issue. He’d always told himself that he’d accepted the true nature of time and choice, and that all he’d objected to in the messaging system was the way it would flatten his deliberations. But even here, with nothing life-changing at stake, the sense of being trapped in the threads of history was more oppressive than it had ever been.

Ramiro’s left arm had grown tired from holding the plant in place over the hole. He shifted it slightly to make himself more comfortable, but as he shifted it back he saw soil rising and adhering to the roots. He stared at this bizarre result for a moment, then decided to stop wasting time delaying an outcome he had no wish to oppose.

He held the trowel to the side of the mound nearest the hole, then drew it closer. The sand followed the blade—not adhering to it and needing to be brought along, but gently pushing it. He lowered the trowel into the hole then withdrew it; the sand parted from the blade and packed itself between the roots of the plant and the side of the hole.

He hesitated, groping for a clearer sense of his role in the task. But what could he actually do wrong? So long as he was committed to making whatever movements with the trowel were necessary until the plant was securely in place, that state of mind and the strictures of the environment ought to work it out between themselves.

He scooped some soil straight into the hole; like the last delivery, it clung to the roots. In Esilio’s terms, this soil had spent at least a few stints packed tightly around the plant; if he could have seen the action in reverse, it would have involved nothing stranger than a clump of sand finally coming loose.

When he was done, Ramiro stood and turned to face Azelio. “So now I have to lure half the travelers here in the name of freedom, then leave them to raise their children in a world where everything they do corrodes their sense of agency?”

Azelio said, “That’s putting it too harshly. When we get back, all you can do is give an honest account of your own experience. They’ll have seen life under the messaging system, so they’ll already have a better idea than we had about this kind of thing—and which way of life they’d prefer.”

“The pro-messagers should come here,” Ramiro declared bitterly. “If they want to know the future, let them know it every step of the way. Leave the mountain to us, and we can go back to living with a single arrow.”

“That’s a nice idea … but good luck organizing the eviction.”

They walked back to the Surveyor to fetch two more plants. “Can you put up some wind breaks?” Ramiro suggested. “If that last dust storm was typical, it might not have uprooted anything, but I’d bet it would have stripped petals.”

“I have a few rolls of tight-weave fabric,” Azelio replied. “I didn’t see any stake holes nearby, but I won’t let that stop me.”

Ramiro fell through the light, willing himself to move faster. He reached down to grab hold of his daughter, but as his fingers brushed her limbless form the wind shifted and tore her away.

Tarquinia grabbed his wrists, dragging his gaze back into focus. “Ssh,” she said. “It’s all right.” She drew away from him slowly, gently separating their remaining adhesions.

“What happened?” he asked her.

“Nothing,” she said. “Nothing’s wrong.”

“No.” He had no children to lose. How many times had he told his idiot body the same beautiful lie? How stupid could it be, that it hadn’t seen through him yet?

He looked past Tarquinia, to the pale gray wall of his cabin. He knew exactly where he was now. The Surveyor was his second prison, and outside it was the third. “How will anyone live here?” he wondered.

“There’ll be a better place than this for a city,” Tarquinia promised. “No dust storms—just gentle winds to sweep the footprints away.”

“That’s not enough.”

“Then you’ll build machines to plant the wheat and harvest it. No one will ever have to touch the soil.”

Ramiro turned to her. “Who’ll build these machines?”

“You will. You and the other settlers.”

“And where will you be?”

Tarquinia said, “I thought you didn’t want to know the future.”