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
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
Roi understood that at least some of this was a logical necessity, not a matter of coincidence. The two points of view, one tied to the rock of the Splinter, the other taking a grand cosmic perspective, were describing exactly the same reality, so of course they had to agree with each other, once you knew how to translate between them. Nonetheless, she couldn’t accept that the fact of the Splinter’s rotation could be both crucial and completely invisible, impalpable, and immeasurable.
She said, “When I throw a stone in the Null Chamber, why can’t I see its path being bent?”
“It’s a subtle effect,” Zak said. “I’ve made some crude measurements of it, but it’s hard to detect just by looking.”
“You’ve measured the Splinter’s rotation!” Roi was astonished. “Why didn’t you tell me that before?”
“I wouldn’t say I’d measured the rotation. My measurements show that the rotation
“But you’ve seen the effect itself?”
“Absolutely,” Zak said.
“Can you show me?”
They went to the Null Chamber, and Zak fished out a device he called a spring-shot from one of the storage clefts. It was a tube fitted with a spring-loaded plunger that could be cocked to varying degrees of compression and then released, propelling a stone from the tube. The projectile emerged in a reasonably predictable direction, with a choice of velocities.
He attached the spring-shot to the wire that marked the Null Line. Then he prepared a “target board”, a flat sheet of cuticle that he coated first with resin, then with a kind of powder. If you pushed a stone against the surface of the target, however gently, the powder sank into the resin, changing the way the two of them scattered the light, leaving a visible record of the point of contact.
He fixed the target board to the Null Line with a bracket, six spans or so rarb of the spring-shot.
“We’re sending this stone straight down the Null Line, so according to the map it should feel no weight at all,” Zak said. “First I’ll make it move as fast as possible, and we’ll see what happens.”
He squeezed the plunger as tightly as it would go, then released it. The stone flew out rapidly, more or less following the wire that marked the Null Line, and struck the target. When they went to examine the board, it was, unsurprisingly, marked at the edge, just beside the wire.
“Now we reduce the speed.”
Roi said, “Now I’m confused. I thought this weight was supposed to increase with speed.”
