by Greg Egan
“You have to see this for yourself!” Isidora replied.
The walls of the optics workshop were kept free of the ubiquitous luminous moss, so the room’s deep shadows and controlled lamplight made it eerily reminiscent of its counterpart in Zeugma University—with the surreal placement of people and equipment only heightening Yalda’s sense of wandering into a nostalgic hallucination. Isidora was waiting in a corner where Sabino, a young researcher, was operating one of the microscopes, while clinging to two wooden bars that ran between the erstwhile floor and ceiling.
The microscopes had been back in action for days. Yalda approached, intrigued.
“What’s the new development?” she asked. Two closely spaced clearstone slides were positioned at the focus of the instrument; whatever they enclosed was—unsurprisingly—too small to discern with the naked eye, but they were attached to an elaborate mechanism of levers and wheels that Yalda hadn’t seen before, with a slender rod reaching into the space between them. In front of the small sunstone lamp that was illuminating the specimen was a thin slab of material that she recognized as a polarizing filter.
Sabino said, “Please, take a look for yourself.” He was shy with Yalda, but she could see that he was at least as excited as Isidora.
He moved aside and let Yalda take the bars in front of the microscope. Even the solid wood trembled a little from the shifting forces as they changed places; Yalda waited for the vibrations to die down, then peered into the eyepiece.
The field was full of translucent gray specks, most of them roughly spherical, albeit with jagged outlines. Shape aside, they possessed no visible features, no apparent parts or fine structure. Not all of the specks were in focus; the slides hadn’t been pressed together tightly enough to touch the material, to hold it in place. But the focal plane of the microscope had been adjusted to take in one particular speck; this one was fixed, gripped by a tiny pair of callipers that appeared solid black in their opacity. The other specks, though unconstrained, were barely quivering, demonstrating that the air between the slides was almost motionless.
“What am I looking at?” Yalda asked.
“Powdered calmstone,” Sabino replied.
“Under polarized light?”
“Yes.”
A pinch of fine sand—ground from calmstone or anything else—would not normally look like this. The grains would generally appear variegated in polarized light, made up of half a dozen regions of very different shades of gray. These were uniform, homogeneous.
“So you sorted them?” Yalda asked Sabino. “You picked out the purest grains you could find?”
“Yes. Maybe one in ten gross were like this.”
“One in ten gross? You’ve been busy.”
Yalda hadn’t had time to learn about Sabino’s project since coming up from the navigators’ post, but she could guess the rationale for his painstaking efforts. If solids such as calmstone were composed of regular arrays of indivisible particles—such as Nereo’s putative luxagens—then the best way to study their properties would be to obtain pieces of the material in question in which the array was as close to geometrically flawless as possible. An array of particles that maintained a regular pattern should have the same optical properties throughout; the usual mottled appearance of sand under polarized light ruled that out, but by chance there could always be exceptions. Sabino had found those exceptions, and discarded everything else.
“Try moving the wheel,” he suggested. “The top one on your right.”
Without looking away from the eyepiece, Yalda reached up with the right hand of the pair that sprouted from her chest, and found the wheel. She drew her fingertip along the rim, nudging it very slightly. In response, the callipers between the slides shifted, dragging their tiny cargo some fraction of a scant.
“What am I missing?” she asked. She didn’t think anyone expected her to be impressed by the fact that they could move single grains of sand around.
“Don’t just look at the callipers,” Isidora urged her. “Watch what’s happening around them.”
Yalda turned the wheel gently again; something caught her eye, but as soon as she stopped to try to scrutinize it, it ceased attracting her attention.
She moved the wheel a little more, then when the unexpected thing she hadn’t quite seen began to happen again, she started jiggling the wheel back and forth: jiggling the callipers, jiggling the tiny piece of calmstone it held.
As she did so, a second piece beside it moved in lockstep. Light was visible between the two; they were not touching. But whatever she did to the captive grain, its mimic followed as if they were two parts of a single, rigid body.
“Nereo’s force,” she said softly. “This is it? We can actually see it?”
Isidora chirped with glee, treating the question as rhetorical. Sabino was more cautious. “I hope that’s what it is,” he said. “I can’t think of any better explanation.”
According to Nereo’s equation, every luxagen should be surrounded by furrows of lower potential energy, within which any other luxagen nearby would prefer to reside. For a single luxagen, the furrows would simply be a series of concentric spherical shells, but the same effect acting on a multitude of particles could bind them together in a regular array—and in that case, the pattern of indentations in the energy landscape would extend beyond the array itself, offering the chance for another fragment of a similarly composed material to become ensnared in it. In effect, a sufficiently pure speck of rock could “stick” to another such speck, without the two actually touching.
“You tried this before, when the engines were running?” Yalda asked Sabino.
“Stint after stint,” he replied. “But gravity and friction must have overwhelmed the effect, because I never saw anything like this.”
Which meant that nobody back home could have seen it, either; it was only the condition of weightlessness that had made the experiment viable.
Yalda had been watching Sabino with her rear gaze; now she leaned back from the microscope and turned to face him. “This is excellent work!” she declared. “I’ll want you to give a talk on it to all the researchers, sometime in the next few days. Have you done anything on the theoretical side?”
Sabino produced a sheet of paper from a hold beside the microscope. “So far, only this,” he said.
“These are the energy troughs around a hexagonal array of luxagens,” he explained. “I drew it when I was first thinking about this project, back on the ground. It took about four stints to calculate.”
“I can believe that,” Yalda replied. It was a nice example of the kind of pattern that could persist beyond the edge of a solid—and she could easily picture a second array getting caught in those energy pits, like a truck sinking into another’s wheel ruts. She said, “We’re going to need to find ways to estimate the forces arising from much larger arrays, and to take account of the whole three-dimensional geometry. But don’t worry about that for now; you should concentrate on refining this setup.”
“All right.” Sabino was still a bit dazed, and though Yalda was trying to keep him as grounded as possible, he could not have failed to realize the importance of his discovery. If this experiment could be repeated and elaborated upon, it promised to make the nature of matter the subject of systematic inquiry—ending the days when the differences between a stone and a puff of smoke had no better explanation than the empty incantation that “solid objects occupy space”. Nereo had paved the way, but until now all his beautiful mathematics had remained untested guesswork. It was possible that Sabino and Nereo would be spoken of alongside Vittorio, who had made sense of the orbits of the planets—but Yalda thought it best not to overwhelm the young researcher with florid praise and promises of immortality. What he needed to do now was pursue the work itself.
The three of them talked through some possibilities for the next step; simply measuring the force that had to be applied to pull one grain of calmstone free of another was one obvious goal, but the torques r
equired to twist them out of their preferred alignment might also yield information about the underlying geometry.
They took the discussion to the food hall, where it turned to the question of other minerals: were they all made of the same kind of luxagens, differently arranged? Could geometry alone account for all the differences between hardstone and clearstone, calmstone and firestone? The experiments they’d envisaged so far would only be the start; Yalda could see the chase that Sabino had begun lasting a generation.
But as she finally dragged herself off to her apartment to sleep, she thought: That’s the beauty of it—there is no rush. Time back home had come to a standstill, and any Hurtler that struck the Peerless now would barely leave a mark. The mountain’s resources would not last forever—and they certainly didn’t have enough sunstone to get themselves home by burning it the old way—but at last a tiny crack had opened up in their ignorance as to what a slab of sunstone might actually be.
Yalda climbed into her bed, shrugging at the resin-sticky sand until it covered her body beneath the tarpaulin, more hopeful now than ever that they were following the right course.
Fatima appeared outside Yalda’s office, back from her latest errand. Yalda ushered her in, then asked quietly, “How was Nino?”
“He didn’t look too bad,” Fatima replied. “He said to thank you for the books.”
Yalda was embarrassed. “You’re the one who should be thanked.”
“I don’t mind taking things to him,” Fatima said. “Climbing all those stairs would have been hard work, but now it’s not much different than going anywhere else.”
Yalda did not believe that she was endangering her with these trips—Fatima wouldn’t be blamed merely for following instructions—but she was worried about the effect on the girl of being Nino’s only visitor.
“It doesn’t upset you, having to see him like that?”
“I’d rather he was free,” Fatima said candidly. “He’s been punished enough. But I know you can’t let him out yet. He was kind to me, back when we were both still recruits, so I’m happy to go there and try to cheer him up.”
“All right.” This was the arrangement Nino had wanted, and for now Yalda had no better ideas. “Just promise that you’ll tell me if you start finding it difficult.”
“I will.” Fatima swung back on the ropes as if to depart, but then she stopped herself. “Oh, I checked in on the forest too, on my way back.”
Yalda had almost forgotten that she’d asked her to do that. No one had been officially assigned to monitor the Peerless’s tiny patch of wilderness, and she’d been loath to divert any of the farmers to the task while they were still coming to terms with the onset of weightlessness. “How’s it looking?”
“It’s less dusty there than in the fields and the gardens,” Fatima said. “There were a lot of twigs and petals and dead worms in the air, but nothing larger—the trees haven’t become uprooted, and I didn’t see any arborines flailing around on the ceiling.”
“That’s a relief.”
“I don’t think the wheat’s doing too well there, though,” Fatima added.
“Wheat?”
“There’s a plot of wheat in one of the clearings,” Fatima explained. “It looks as if the stalks were moved there whole—dug up from a field and replanted, not grown there in the plot. But none of their flowers were open when I was there.”
“I see.” Yalda was perplexed; whoever was conducting the experiment hadn’t mentioned it to her.
She sent Fatima to rejoin her physics class, and went looking for Lavinio, the chief agronomist. A note at the entrance to his office said he’d be down in the fields for another two stints. Yalda tried counseling herself to be patient; she didn’t expect to be kept informed about every last scientific activity on the Peerless, and it might attract Lavinio’s resentment if she showed up far from her usual haunts for no other reason than to question him about some trivial experiment.
But how trivial was it? The farmers were far too busy addressing the logistics of weightless harvesting to go and plant wheat in the forest just to test an idle conjecture about the effects of companion species on growth rates. No one would have done this unless it was important.
She couldn’t wait two stints.
Weightlessness had transformed the stairwells from sites of interminable drudgery to the mountain’s smoothest thoroughfares. With a pair of ropes all to herself and no one else in sight, Yalda switched to her high-speed gait: propelling herself forward with all four limbs at once, then releasing the ropes and moving ballistically for as long as possible before brushing them again with whichever hands were necessary to correct any sideways drift and replenish her speed. The moss-lit walls flew by, while the threatening edges of the helical groove that wrapped around her, its jagged steps proclaiming a vertiginous descent guaranteed to end with her head split open, only added to her triumphant sense of control. Once you could survive throwing yourself down a staircase as tall as a mountain, anything seemed possible.
Yalda reached the level of the forest in what felt like less than a bell. When she moved from the stairwell to the access tunnels, her mind insisted on treating all the arborine-proof doors along the way as hatches, and she emerged into the chamber with a strong sense of ascending through a floor. The trees stretched out “above” her did their best to persuade her to realign her sense of the vertical, but all the loose detritus suspended around them rather undermined their case.
The refitting of this chamber had been perfunctory, with just a few unpaired guide ropes suspended between hooks on the wall, so Yalda had to push off from the rock and drift freely through the air to enter the forest itself. Once she was among the trees, though, the branches offered plenty of hand-holds. Tiny dark mites darted past her with exuberant energy, coming and going in a flicker. A green-flecked lizard scampered out of her way, its claws still finding easy purchase in the bark. However ancient and unvarying their instincts, these animals had not been defeated by the change.
She found the clearing Fatima had described—and Lavinio with it. He’d crisscrossed the small treeless space with ropes, the better to access the dying wheat plants. Only now did Yalda feel that the netted soil was below her: she was an aerial spy, sneaking through the canopy like the arborine in her grandfather’s story. She descended with as much creaking of branches as possible, to dispel any appearance of furtiveness.
Lavinio watched her in silence as she approached. He looked grimly unsurprised by her presence, as if he’d already faced such a run of bad luck that an unwelcome visitor right in the middle of it was just what he’d expected.
“Can you tell me what this is for?” she asked him, clambering down a trunk then taking hold of one of his ropes.
“I was hoping the wheat might learn from the trees,” he said.
“Learn what?”
“Up.”
Yalda dragged herself nearer. Disconcertingly, the floor of the forest had become vertical to her again, a cave wall from which the trunks around them sprouted like giant, bristling outgrowths. The wheat stalks were aligned with the trees—but presumably they’d been planted that way, so what was there to learn?
“I don’t understand,” she said. “Is something going wrong in the fields?” She gestured at the limp gray wheat-flowers.
“Not like that,” Lavinio replied. “Here, the flowers don’t know when to open; something in the light confuses them. But up in the fields the mature plants are still healthy.”
“That’s good to hear. And the seeds?”
Lavinio reached down into the soil between the stalks and scrabbled around for a while, then pulled out a seed. It must have been put there by hand, in a separate experiment; none of the sickly plants around it could have produced it, let alone possessed the means to embed it in the ground.
Yalda took the seed from Lavinio and examined it carefully. It was covered with dozens of fine white rootlets that had broken through the skin in all directions, favoring no particula
r side. There was no shoot, though, no beginning of a stalk. The seed did not know which way to grow.
“I thought light and air were the cues for stalk formation,” she said.
“That’s what I was taught. That was the dogma; I never questioned it.” Lavinio took the seed back and turned it between his fingers. “But however shallow the placement… they still don’t seem to find up. Even if half of the seed is uncovered—exposed directly to the light and the air—they don’t get the message.”
Yalda said, “So when the test seeds you sowed in the fields wouldn’t grow, you came down here to see if the forest had a stronger message?”
“That was the idea,” Lavinio said. “With all of this plant material oriented the same way, I was hoping some kind of influence could pass from the trees to the wheat. But the mature wheat just dies here, and the seeds do exactly what they do in the fields.”
Yalda forced herself to remain calm. The mature plants in the fields were still healthy, so the coming harvest wouldn’t be affected; they weren’t facing imminent starvation. But they did not have long to solve this, or there would be no harvest after that.
“What’s happening in the medicinal gardens?” she asked.
“All those shrubs grow from runners, not seeds,” Lavinio replied. “Some of them are sprouting at odd angles, but once the gardeners correct them by hand they’re fine.”
“That’s something.”
Lavinio made a sound of begrudging assent; the disaster was not all-encompassing. But they couldn’t live on holin and analgesics.
Yalda said, “I wish you’d brought this to me sooner.” She could understand him wanting to prove his expertise by dealing with the problem himself, but there was too much at stake for that.
“Frido thought it would be best to find the solution first,” Lavinio explained. “Instead of spreading panic when there was no need.”
Yalda pondered this revelation. Frido knew about the wheat, and he’d kept it from her? Lavinio might have felt that the responsibility for the crops was his alone, but what was Frido’s excuse?