Hard as it was to believe these stories, let alone know which ones to trust, for anyone who’d so much as crossed the Calm the undeniable fact remained that the weight in the garmside tugged the opposite way to that in the sardside, and the further one went in both directions the stronger this discord became. If the Splinter had suddenly been doubled in size, it was not at all preposterous to imagine that the weight might have been enough to tear rock from rock.
The trouble was, this raised the question of how the old world could have held itself together for more than an instant. The most reasonable answer, it seemed to Zak, was that it must have been born under a different regime of weights, which had only later become so powerful.
During shift after shift in the library, he came across fragments of speculation on these matters, but there was nothing whole, and nothing convincing. The thinkers of the past had left many hints and guesses, but if they had ever fully understood the truth about these mysteries, it had not survived. In the end, Zak decided that he couldn’t spend his life merely sifting through these skins, searching for one more inconclusive sign that his reasoning was not completely misguided. If weight had dictated the history of the Splinter, and however many worlds that had come before it, then weight was what he needed to understand.
Armed with the Map of Weights, some plans for ancient instruments, and copies of the few surviving notes on his predecessors’ methods and philosophies, he’d walked out of the library and headed for the Null Line, ready to begin uncovering the secrets of weight and motion, and to search for something simple that had torn the world apart.
Roi still didn’t understand the wind.
On one level, Zak’s idea of natural motion seemed to explain it perfectly. If things moved in circles around the distant point in the Incandescence that she and Zak had come to call the Hub, and if the smaller the circle the faster they moved, then everything about the wind made sense. On the garmside—closer to the Hub—the wind was moving faster than the Splinter, and so it overtook the rock, blowing in from the sharq ever faster the further garm you went. On the sardside—further from the Hub—the wind was orbiting more slowly so the Splinter overtook it, ploughing through it, making it seem to blow in from the rarb when in truth it was merely failing to flee with sufficient haste in the opposite direction. And between them, in the Calm, wind and rock moved together at exactly the same pace, leaving not so much as a breeze to be felt.
The trouble was, while Zak’s theory gave a simple, persuasive account of the phenomenon, Roi couldn’t reconcile it with the mundane reality of weights. If weight was determined by natural motion, why didn’t the wind follow the weights? If she stood anywhere in the garmside, and a crack opened up in the rock beneath her, surely she would fall away from the Splinter, garmwards. Notwithstanding the wind’s speed in the cross-direction, which might make such motion harder to spot, and the way the rock and the tunnels worked to divert and complicate its flow, Roi’s time among the crops left her thoroughly convinced that the wind wasn’t falling at all.
Shift after shift she struggled with this problem, hoping she might solve it by her own efforts. Finally, she had to admit that the resolution was beyond her. The next time she met Zak, she asked him to defer their scheduled lesson in template mathematics, and she begged him to make sense of the wind before she lost her mind.
Zak was both amused and chastened. “This is my fault, Roi; I should have explained this much sooner. The weights on the map are fine—give or take the question of three versus two and a quarter—but they’re not the whole story.”
“There’s something missing?”
“Yes. There is a kind of weight that the map doesn’t show at all.”
Roi was baffled. “How can that be? Weight is weight. I’ve felt it, I’ve measured it. It’s not something you can hide.”
“No, but the map only shows weights for objects that are fixed firmly to one place in the Splinter.”
“I’ve moved from place to place in the Splinter,” Roi protested, “and the map described correctly how my weight changed.”
“That’s not what I’m talking about,” Zak said patiently. “You moved at a walking pace to a new location, you didn’t race the wind. The wind feels something extra, everywhere, compared to the fixed weights on the map, simply because it’s in motion, not because those fixed weights change from place to place.”
If this was true it had the potential to resolve the paradox, but the idea still struck Roi as very strange. “Why should it feel something extra just because it’s moving?”
“Because the Splinter is spinning,” Zak said. “Now, I know the map already takes account of that, in part. An object fixed to the Splinter is really turning in a circle—a small one, much smaller than its orbit—which frustrates its natural motion and contributes to its weight. There’s one further twist, though. Imagine a stone that’s moving in a straight line, as seen from outside the Splinter. Because the Splinter is constantly turning, as the stone moves, we’re moving too. If we try to trace the path of the stone against our surroundings—against the rocks and tunnels we think of as fixed, but which in truth are turning—the line we see it following won’t be a straight line, because of the way our motion adds to the stone’s. Its path will seem bent, as if there were a weight constantly pushing it sideways. And the faster the stone moves, the greater the apparent weight bending its path.”
“The faster it moves in reality, or the faster we think it’s moving?”
“The faster we think it’s moving.”
Roi struggled to visualize it. If a stone moved in a straight line away from the axis of spin, then the rotation of the Splinter would make it seem to follow a spiral path, forever turning. And if the stone was sitting completely still? Then the motion of the Splinter meant that it would appear to be moving in a circle, again with its path constantly veering sideways.
“I think I understand,” she said. “But the wind doesn’t wrap itself into a spiral. On the garmside, it blows straight from sharq to rarb.”
Zak said nothing.
Roi struck her carapace. “Of course, that’s the whole point! I’ve been wondering why the weights from the map don’t push the wind garmwards, in some kind of curve plunging back out into the Incandescence. But the extra weight from its motion must push it in the other direction, balancing the ordinary weight exactly.”
“That’s right,” Zak said. “The further garm you go, the stronger the garmwards weight, but because the wind is also blowing more strongly, the weight from its motion keeps perfect step, and the two of them always cancel.”
Roi was pleased that she’d finally grasped what she’d been missing, but there was still something frustrating about the whole matter. The Splinter was turning, Zak claimed, and this claim turned out to be absolutely vital in order to make sense of the rest of his vision. Without the strange distortions in weight and motion brought about by the spin, it would have been impossible to reconcile a simple concept such as circular orbits for the wind with the ordinary realities of the Splinter.
However, everything about the Splinter’s rotation seemed to involve a kind of conspiracy of self-effacement. It contributed to the garm-sard weights on the map, but who was to say exactly how much it added? It balanced a hypothetical rarb-sharq weight exactly, but that perfect balance left nothing behind to be felt or measured. And now it conspired with the garm-sard weights again. in order not to bend the wind.