But when the blue ice of the plateau came into sight ahead of them, she realized that she had no hope of remaining silent all day, and it would be better to speak and be ridiculed now than to interrupt her friends when they were trying to work.
“If we placed mounds of black sand over the ice in the right pattern,” she asked, “do you think we could grow a plateau like this somewhere else?”
“I don’t see why not,” Bridget replied, managing to sound both intrigued and annoyed—as if she resented being forced to think about anything when the sun had barely cleared the horizon, but found the idea too enticing to ignore. “If you covered a big enough area, there’d probably be some roots positioned in the right place to get things started. It might take a while, but maybe it would be worth it, just to be ready for the next solar flares.”
“I’m thinking about more than the flares,” Freya confessed. “With the natural version, in the end most of the dirt will get stuck in the ice or blown away… but if people were actively tending the surface, who knows how high we could make the plateau?”
Gro said, “I think I know where you’re heading with this.”
“You do?” Freya waited, hoping to be spared the humiliation of having to spell it out herself if Gro had already decided that the idea was preposterous.
“Raise a tall enough mountain,” Gro guessed, “and the sheer weight of it will start to create new fractures. What better way to encourage more geysers?”
Freya wasn’t sure how to reply. If it was true that the ice would crack all the way to the ocean under the kind of load she was imagining, that would be the perfect outcome. But it would be dishonest of her to take credit for it. It wasn’t what she’d had in mind at all.
“That might happen,” she said. “But can we be sure that it would?”
Hanna said, “That depends on how long you can keep adding more ice.”
“Suppose we can coax the roots into doing the job for as long as we like,” Freya replied. “Keep the tips warm, so they can’t tell that they’re already high above the surface, and keep capturing all the water vapor they put out.”
Hanna grunted irritably. “If there’s no limit to how high you go, then of course the mountain’s going to break the ice eventually. You might as well pick a number, tell me to start counting, then ask if I’ll ever reach a number greater than yours.”
Erna said, “That’s not true.”
“It’s basic arithmetic!” Hanna retorted.
“It’s basic arithmetic that counting takes you past any given number,” Erna agreed, “but the comparison is false. Just because the height of a mountain increases without bounds, that doesn’t mean its weight will do the same.”
Hanna was silent for a while, then she conceded, “You’re right.”
Bridget said, “What?”
“Gravity is stronger close-up,” Hanna replied. “The farther you go above the world, the weaker its pull will be.”
“Yes,” Bridget agreed, “but it never goes away completely.”
Hanna said, “It does, when Tvíburi’s gravity cancels it out and starts pulling in the other direction.”
“Who said anything about putting the mountain right below Tvíburi?” Bridget protested.
“Nobody.” Erna was amused. “That’s not the argument I had in mind! Though if you want to put the mountain there, that will only help make it lighter.”
Freya kept quiet; her friends were doing all the work for her, and any contribution she could make would be superfluous.
But now Hanna was confused. “How does the mountain not grow heavier, if you don’t use Tvíburi?”
Erna said, “What’s one, plus a quarter, plus a ninth, plus a sixteenth… and so on, forever?”
“I have no idea,” Hanna replied.
“Nor do I,” Erna admitted, “but if I had to guess, I’d say it’s less than two, and I’m sure it doesn’t grow without bounds. The weight of a mountain would be like that—at least until it grew so tall that its own gravity started to affect the result as much as the gravity of the world itself.”
“I think we can rule that out,” Bridget said dryly. “However eager the roots are to oblige us, they’re not going to drain the whole ocean.”
“No.” Erna turned to Freya. “But it’s your mountain, after all. Where do you want to put it?”
“Right under Tvíburi,” Freya confessed.
Gro said, “That makes no sense! Why reduce the weight?”
The group had almost reached the plateau. Freya was having second thoughts; perhaps she should accept the alibi Gro was offering her, and be done with her own madness.
But she couldn’t stop herself.
“If we can break the ice and make new geysers, the job would be done,” she said. “But if that doesn’t work, if the ice bears the weight… then maybe we can build a mountain that takes us halfway to Tvíburi.”
Her companions became quiet. Freya listened to their footsteps crunching through the powdered ice, grateful that at least no one had fallen to the ground laughing.
“Why only halfway?” Hanna asked.
Freya wasn’t sure if the question was meant sarcastically, but she took it in good faith. “Tvíburi isn’t perfectly still in the sky,” she replied. “It moves slightly nearer and farther away, and even turns its face a little. If we tried to make a solid bridge of ice all the way between the worlds, it would just snap.”
“All right. But why stop at the halfway point? Why not get closer? Three quarters? Nine tenths?”
Freya said, “I suspect that ice is like most things: better at holding together when you squeeze it than when you pull on it. We know it can take a lot of weight pushing down on it—but imagine a column of ice, as tall as the two worlds are distant, just hanging from the sky above Tvíburi. I think it would break long before it reached that size. And even if I’m mistaken, I doubt that the root tips would keep growing in the same direction once gravity was telling them they were headed down, not up.”
“I can’t argue with any of that,” Hanna declared. “But it makes the next question more painful.”
Freya said, “Do your worst.”
“What possible use would it be, to go only halfway? If we could travel to Tvíburi itself, it might have the best soil and the thickest air we could hope for. But halfway through the void, there won’t even be air. We’d struggle to survive for a day! What would be the point of getting there?”
Freya had lain awake contemplating exactly that problem. “I can’t be sure,” she said. “But we’d be closer to Tvíburi, and we wouldn’t just be staring up at it, hoping for some impossible magic to raise us into the sky. Instead, we’d be staring down at it, hoping for something less magicaclass="underline" a way to descend. There are lizards that glide down from the tallest cliffs—and a few crazy people have mimicked them, riding contraptions that use the same principles.”
Bridget said, “But even from a cliff, it’s dangerous, and you can’t take much more with you than your own body. If you want to relocate whole villages to Tvíburi…”
“I know,” Freya replied. “But if we could send a dozen people across, with enough supplies to get started, that would be something. They could found a new village on their own. Then at least life would go on, however bad things became on Tvíbura.”
From the silence that followed, it was clear that no one took much comfort from that prospect.
Freya said, “Or, Tvíburi might have Yggdrasils too, and then the people who crossed over could start raising their own mountain. If we could grow two separate mountains, both reaching into the void, we might be able to join them with a bridge of ropes, long and flexible enough to survive the changing positions of its endpoints. Then we’d have a path all the way from the surface of Tvíbura to the surface of her twin. And if the fortunes of one world fell while the other’s rose, we could take our pick between them.”