"We're a long way from the Calm," Roi pointed out, "and the hatchlings can't move as quickly as adults. It would take us two shifts, at least. If we're breaking up, we might be heading into danger." If the Splinter divided symmetrically, the Calm was the last place you'd want to be when the halves violently parted company.
"That's true," Gul said. "And if we're going to get thrown around again, travel is probably unwise unless we're sure our lives depend on it. Let's wait and see if we can make sense of the situation." The hatchlings were milling around them making plaintive sounds, but their small bodies were resilient and none of them appeared to have been harmed by the fall. Gul chirped soothing words to them at his most reassuring pitch.
The walls around them were growing darker now. At first, Roi had thought it was just the afterglow from the flash continuing to fade, but as she increased the sensitivity of her vision to compensate, she realized that she was straining at the edge of her ability.
"Am I going blind?" she asked Gul. "Or is the Incandescence fading?" Maybe the flash had damaged her sight.
He said, "Either we're both going blind, or it's fading."
The hatchlings fell silent, as if the darkness itself was a source of tranquility for them. Perhaps it was lulling them to sleep, just as the voluntary cessation of vision induced drowsiness. Roi could think of no other experience with which to compare it; the Incandescence might penetrate the rock more weakly in the depths of the Splinter than it did at the edge, but for the all-pervading glow to change before her eyes was unprecedented.
As the darkness grew deeper, Roi tried to stay calm. Whatever was happening to the Splinter was not a fate that anyone had predicted, but it was better to be perplexed and alive than to face those long-anticipated cataclysms.
"Can there be a hole in the Incandescence?" Gul wondered. "A gap, a void?"
"If there is, why did we never pass through it before?"
"Perhaps it moves, perhaps it wanders around," he suggested. "And that flash of brightness was. a concentration of the Incandescence at the edge of the void, heaped up like the rubble dug from a hole."
Roi had no idea if that made sense; she had never thought of the Incandescence as something you could make a hole in by any method. "Can you feel the wind?" It was a measure of how disoriented she was that she had to ask, that she couldn't trust her own senses.
"No. There's nothing. The rock is making a sound I've never heard before, but it's not from the wind."
Roi was relieved by this small sign of consistency. "I suppose that means we're not simply going blind. Wind and brightness, gone together."
With the Incandescence gone, how would they eat? How would they survive?
If the hole they had entered was not too large they should emerge from it soon, as the Splinter continued its orbit around the Hub. If it enclosed their whole orbit, though, they would remain in darkness until it moved away of its own accord.
Roi said, "How long do you think it's been, since the darkness started?"
Gul rasped amusement. "My mind's not that clear. I wouldn't like to guess."
"Less than half a shomal-junub cycle, I'd say." Roi had watched the cycling stones so many times, the rhythm of it was stamped into her mind. "We don't know for sure that the Splinter's orbit has the same period, but that's what the simplest geometry implied. So if there's a gap in the Incandescence that's smaller than our orbit, we ought to emerge from it in less than one shomal-junub cycle."
"That sounds reasonable," Gul said cautiously. "The gap itself might be moving around, complicating things, but if it's moving slowly then everything should repeat about once every orbit."
Just a few heartbeats later, the walls began to brighten. Roi tensed, preparing herself for a recurrence of the violence that had preceded the onset of darkness, but the light from the rock climbed calmly and steadily back to its normal strength, and the wind resumed its usual susurration, unaccompanied by any sudden shifts of weight or blinding flashes.
The strange creaking and rasping from the rock did not abate, though.
"Half a shomal-junub cycle," Roi said. "Almost exactly half."
Some of the hatchlings began to stir. Gul made soothing noises and drew them close to his body. "Why would a void in the Incandescence be half the size of our orbit?" he said. "That seems like too much of a coincidence."
Roi took advantage of the normal light to survey the chamber. All the hatchlings were accounted for, and the basic structures around her were intact — the entrances to the chamber were clear, the ceiling hadn't fallen — but there were some cracks in the walls that she was sure she'd never seen before. The rock continued its maddening groan. If she could feel no change in weight, what was tormenting it?
She could hear people in the distance, calling to each other, fearful and confused. "Where should we go for safety?" she asked.
Gul said, "We're as safe here as anywhere. There's nowhere to go."
The light and the wind began to fade again. Why were some things repeating themselves, while the flash and the jolt had happened only once?
Roi said, "
We were pushed.
" The pattern was unmistakable; she'd tossed enough stones in the Null Chamber to know how to set things cycling back and forth. "That's what threw us off the ground. It wasn't the fact that we entered the void that did it: the push came first, the disturbance came first. Whatever struck us changed our orbit slightly, enough to knock us into the void."
"Why is the void half as big as our orbit, though?" Gul protested.
The darkness thickened, the wind fell away. Roi pictured the orbit of the Splinter, and the motion of the stones in the Null Chamber. What happened twice in every shomal-junub cycle? The "falling" stone passed by the "fixed" one. First it passed it on its way shomal, then it did so again on its way junub. Twice in each cycle, the stones were close together. And twice, they were far apart.
"The void's not half as big as our orbit," she said. "It's far bigger than that. And it hasn't wandered up to us by chance; it hasn't moved at all. It's been right beside us all along."
Gul was silent for a while, contemplating her cryptic remarks. Then he said, "If the Incandescence isn't
everywhere
, but we never left it before, then maybe it's confined to a thin layer around the plane of our old orbit. Now something's disturbed the Splinter, and we're moving shomal and junub — above and below that plane — for the first time."
"Exactly!" Roi said. "Out of the Incandescence, then back. Twice every shomal-junub cycle. The whole Splinter has become the falling stone."
She waited, picturing the stones in her mind's eye. As one imaginary stone ascended from its low point and approached the other, the walls began to brighten.
Gul said soberly, "We're lucky we survived this. And lucky we can understand it." Then he let out an ecstatic chirp that woke half the hatchlings. "We're not going to die!" He scooped up two bewildered children and tossed them on to his back, then started running around in a circle. "Darkness, light, it doesn't matter! We're safe, we're fine. Everything is perfect!"
Roi watched him, dizzy with relief herself, if not so exuberant. This was not the end of the Splinter, not the plunge into the Hub that Neth had foretold. The crops would suffer, though. There would be food shortages, and everyone would struggle to complete their work as the darkness came and went.
The strange event had shown them something new about the Incandescence, even as it had confirmed Zak's picture of the Splinter orbiting the Hub. It might even persuade some people to accept his ideas and agree to the tunnel. The loss of crops was a hard price to pay, but in the end it might change things for the better.
The one thing that worried Roi most was that she still had no idea what dazzling thing had flown past and knocked them out of their orbit. Where had it gone? To the Hub? Into the void? Could it cross their path again?
And if it did return, which way would it push them next?
Zak stretched his legs out across the wall of his chamber, trying to ease the pain in the joints. "I have a plan," he said. "But I'm going to need your help."
"Whatever you want from me, just ask." Roi had left the hatchlings in Gul's care to travel to the Null Line and check on Zak's condition. He had survived the Splinter's Jolt and the aftermath, with members of the theorists' team still bringing him food regularly, in spite of their own problems and distractions. His health had been fading for a long time before the event, though, and Roi suspected that his death was close now.
Zak said, "When I was working in the library, I heard about a crack in the wall at the junub edge. Some people had climbed right through it and reached the Incandescence."
Roi was skeptical. "Are you sure that's not just a story?"
"I have a map."
"You always have a map. Did anyone come back?"
"Of course not. The Incandescence killed them; nobody has ever walked into it and survived. It's not just the strength of the unfiltered wind: even at the Calm, there's something fatal, something that the rock protects us from."
Roi could see where this was heading. "You think it might be possible to survive there, now? In the times when our orbit takes us right out of the Incandescence?"
"It's worth trying," Zak said. "We don't know how long the new orbit will last. This might be our only chance to look into the void."
There had already been measurable changes in the orbit. Although the period of the complete light/dark cycle remained the same, with Ruz's clock it had been possible to detect a small reduction in the time the Splinter spent in darkness. This suggested that the total distance they were traveling away from the old orbital plane had diminished slightly.
Other experiments in the Null Chamber had shown that the Null Line had, strictly speaking, vanished; although the weight throughout the chamber remained very small, there was no longer a line of perfect weightlessness running through the Splinter. The small weights that were present now were difficult to measure, but they seemed to undergo cyclic changes. Tan had suggested two possible explanations for this: either the Splinter's rate and axis of spin had been disturbed in such a way that the spin weight no longer canceled the rarb-sharq weight, or the rarb-sharq weight itself was no longer constant throughout each orbit, and hence could no longer be canceled by
any
constant spin.
In either case, the ceaseless groaning of the rock was probably due to the fact that the weights throughout the Splinter were no longer fixed; the precise forces were always shifting, repeatedly tightening and relaxing their grip on the rock. Tan believed that the price to be paid for this restlessness would be a gradual return to a state of alignment, whether that meant a change in the Splinter's spin, its orbit, or both.
Roi said, "This journey will be hard for you. Someone younger and healthier should go instead."
"Someone younger and healthier might climb out through the crack in the wall and never come back. It makes far more sense for me to risk the last few shifts of my own life than to allow someone else to throw away the best part of theirs."
"You can barely walk," Roi protested. "How are you going to reach the junub edge?"
"I've arranged for some couriers to bring me a cart."
"Are they going to deliver you to your destination as well?"
Zak said, "I want you to pull the cart. You and Ruz. Ruz has already made some instruments for me, to allow me to take measurements of whatever's there to see."
"So you want Ruz along to fix them if they break?"
"Yes."
Roi didn't ask what her own purpose would be, apart from sharing the load. She said, "You should have peace and ease at the end of your life, not a dangerous journey like this."
Zak rasped irritably. "If I knew that the Splinter was safe, I'd have peace. But I'm sure that it's not, so the best I can do is keep struggling to make that happen."
Roi made a sound of acquiescence. "What do you think it will tell us? Looking into the void?" The thing that had lit up the rock when it touched them seemed to have vanished, but then, from inside the Splinter the whole Incandescence seemed to vanish when they were no longer immersed in it.
Zak said, "We've been half right about a lot of things, but there's something missing from our theories, something whose nature we haven't even guessed yet. If we don't learn to understand it, it will kill us."
When Roi returned to the hatchlings' chamber to explain her plans, she found Gul in pain, full of ripe seed packets. She had helped him dispose of them many times before, but she was surprised that he hadn't found someone else while she was gone.
"I've been busy with the hatchlings," he said. "What was I supposed to do? Walk the tunnels begging for a mate, with the children lined up behind me copying every move?"
The hatchlings were asleep, so there was no danger of that now, but Roi had no contraceptive leaves. She was too tired to go hunting for the stupid weed, but she couldn't bear to see Gul in so much pain.
"Open your carapace," she said. "I'll take them."
"Are you sure?"
"Quickly, before it gets dark. If I can't see what I'm doing you'll be sorry."
As she snipped the seed packets free and loaded them into her egg cavities, the pleasure that spread through her body felt muted. Without the contraceptive to compete with them, the packets were producing far weaker secretions than she was accustomed to. She had never been entirely sure why it had always seemed right to keep her eggs from being fertilized; she had understood that the Splinter could only feed so many mouths, but other people made hatchlings all the time. Now, with the crops diminished, that should have been a stronger reason than ever, but even as the rush of contentment faded she felt no regret for what she'd done.