Greg Egan - Incandescence

It was only after they'd been traveling for nearly a shift and a half, according to Ruz's clock, that they decided to stop and sleep. Before the Jolt, most people had more or less agreed on the length of a shift, growing tired after a similar period of wakefulness. The stretches of darkness had led to an increase in that time, but not always an equal one for each person.

When they woke, Ruz was first in the harness. After a dozen light/dark cycles Roi took his place, and this time she finally felt the burden of pulling the cart uphill. The junub weight grew less than half as rapidly with distance as the garm and sard weights — and they were also traveling rarb, which contributed nothing — but beyond those excuses it was a measure of how slow their progress had been that it had taken so long to reach the point where they really cared which way was up.

The Calm appeared more sparsely populated than ever; apart from occasional couriers that Roi glimpsed in the distance, their role made obvious by carts of their own, the tunnels seemed deserted. The expeditioners passed the time with light-hearted speculation, eschewing any grim predictions about the fate of the Splinter. By the end of the journey's second shift, Roi and Ruz were dragging the cart together, with the lead harnessee also keeping a lookout for obstacles. It was hard work now, and Roi was beginning to feel that their enforced breaks didn't come a moment too soon.

Halfway through the third shift, as they slowed for the onset of darkness, Roi noticed a flicker of light ahead. At first she thought it was merely a lode in the rock that was dimming more slowly than its surroundings, but as the darkness deepened the contrast only grew stronger. A reddish patch of light stood out against the blackness; it was an unsteady glow, but it never failed entirely. It was moving slightly, with a rhythm that reminded her of a person's gait, as if someone was carrying the source of the light toward them.

Ruz said, "Can you hear footsteps?"

Roi listened carefully. "Yes."

"There are five people," Ruz declared. "And some kind of machine."

"I'll take your word for it." A dozen heartbeats later, she could make out two people in the front of a small group. The light was coming from an object strapped to one of their backs.

Zak said quietly, "That I lived to see such wonders."

Roi called out a greeting, unsure if the three of them would be visible by this strange illumination. A reply came back, cautious but friendly.

When the group drew closer, Roi could see that Ruz was correct: there were five people. They made introductions; the light-bearer was called Lud, and the others were Jos, Rud, Cot and Sad.

The light that emerged from the machine on Lud's back was weak, rendering the group sketchily. Their bodies were merely hinted at by a glimmer of surfaces, as if their carapaces had turned to metal. Seeing your companions' beating hearts was not the point, though; this modest light would still be enough to allow you to spot obstacles and walk through the darkness with confidence.

"Where are you headed?" Ruz asked politely. Roi was sure that he was twice as eager as she was to hear how the light machine worked, but it would be discourteous to raise the matter immediately.

"We have no destination yet," Jos replied. "We want to know what's happening to the Splinter, so we've left our teams to search for answers."

Roi could hardly believe what she was hearing. They'd left their teams? How? Had the Jolt shaken them free, like the rubble it had torn from the solid walls?

She said, "We have some ideas about what's happening to the Splinter. We believe something has pushed it, and now it's falling back and forth, in and out of the Incandescence."

Lud said, "Falling back and forth?"

"If you throw something shomal from the Null Line," Ruz explained, "it will reach a certain distance, fall back to the Null Line, go past it some way junub, fall back again, and so on. We think the Incandescence ends if you go far enough shomal or junub, and that's why the light comes and goes."

The group talked this over among themselves, then asked to hear more. Zak remained quiet, which usually meant that he was tired or in pain, so Roi explained his idea of the Splinter orbiting the Hub, and the experiments in the Null Chamber that seemed to support it.

While they were talking the light from the machine faded, and its whirring sound died away. But the walls were already beginning to brighten, and soon Roi had a normal view of everyone. They had a small cart with them, full of metal parts.

Cot climbed on to Lud's back and began turning a handle attached to the machine. Ruz could no longer contain himself. "It's spring driven, isn't it?"

"Of course," Lud said. "Trying to crank it smoothly and walking at the same time would be impossible."

" But what makes the light? " Ruz's tone was drenched with such longing that he might have been a starving child begging for food.

Lud chirped with amusement. "Just two rough surfaces scraped over each other, under pressure. Rough enough to make a disturbance, but not so rough that they'll stick."

Jos added, "I found the effect completely by luck. I was grinding plants into a powder between two stones, and I grew tired of stopping work every time it grew dark. When I ground stone against stone with nothing between them, a faint light seemed to come from the point of contact. At first I thought I was just going mad from the darkness, but the more effort I applied, and the less of the mush there was to smooth the stones, the stronger the light became."

Roi said, "So you've left your old teams now? You've formed a new one, and you're looking for recruits?"

"Not exactly," Cot replied, working briskly to ensure that the spring was fully wound before the darkness returned. "We still don't know what's the best thing to do. We'll form a team if that's necessary, but we're willing to join an existing one if they can make a good case that they know what's going on and that they're doing something useful about it."

Every time Roi thought she could no longer be shocked, these people outdid themselves. It had taken a great struggle for her to tear herself free of her work team to join Zak. On that first journey to the Null Chamber she had never been able to admit her intentions, even to herself. Now here were five people roaming the Splinter, challenging every passing stranger to make a reasoned bid for their labor, as if the whole idea of recruitment had been turned inside out.

Zak spoke softly. "Some people are trying to build a tunnel that will change the way the wind pushes on the Splinter. If they succeed, they hope it will carry us to safety. I'm sure they could use your skills."

Lud said, "I can make no promises, but we'd be happy to talk to them, to hear their case."

Ruz said, "We can draw you a map, give you directions."

"You're not going there yourself?" asked Sad.

"We have another task." Roi explained about the crack in the wall, and the observations that they hoped would clarify both the Splinter's ordinary motion and the nature of the Jolt.

The idea struck a chord with the light-makers, and they seemed torn between joining Zak's expedition and heading for the sardside and the tunnel-makers. Zak, however, explained that he would be making the observations alone and that his two assistants were all that he needed.

Cot said, "Then at least take this with you to help you on your way." He opened the cart and produced a second light machine. "We brought two spares, and plenty of parts. If you take this one, we will still have no trouble reaching the sardside."

Zak said, "Thank you." Roi would have preferred an extra body or two to help pull Zak's cart; this was more weight to carry, and now they'd have no excuse to rest when darkness came. Still, at least this way they could choose their own pace.