She drew the pod to a stop, and allowed it to descend, slowly, toward the wing surface.

Spinner, gazing down, couldn’t tell how far away the nightblack, featureless floor was. Was Louise intending to land there?

The pod’s descent slowed.

Louise, working her control console, caused the pod’s small vernier rockets to squirt, once, twice, sending them down toward the wing surface once more. But again the pod slowed; it gradually drifted to a halt, then, slowly, began to rise, as if rebounding.

Louise’s face was alive with excitement. “Spinner, could you feel that? Do you see what’s happening? This close, the wing surface is actually gravitationally repulsive. It’s pushing us away!”

Spinner eyed her. “I know you, Louise. You’ve already figured out how a discontinuity drive would work. You were expecting this antigravity stunt, weren’t you?”

Louise smiled and waved a hand at the Xeelee craft. “Well, okay. Maybe I made a few educated guesses. This ship isn’t magic. Not even this antigravity effect. It’s all just an exercise in high physics. Of course we couldn’t build one of these.” Her eyes looked remote. “Not yet, anyway…”

“Tell me how it works, Louise.”

At extremes of temperature and pressure, spacetime became highly symmetrical (Louise told Spinner). The fundamental forces of physics became unified into a single superforce.

When conditions became less intense the symmetries were broken. The forces of physics — gravity, nuclear, electromagnetic — froze out of the superforce.

“Now,” Louise said, “think of ice freezing out of water. Think back to what we saw on Callisto — all those flaws inside the ice, remember? The freezing of water doesn’t happen in an even symmetrical way. There are usually defects — discontinuities in the ice.

“And in just the same way, when physical forces freeze out of the unified state, there can be defects — but now, these are defects in spacetime itself.”

Space was three-dimensional. Three types of stable defects were possible: in zero, one or two dimensions. The defects were points — monopoles — or lines — cosmic strings — or planes — domain walls.

The defects were genuine flaws in spacetime. Within the defects were sheets — or points, or lines — of false vacuum: places where the conditions of the high-density, symmetrical, unified state still held — like sheets of liquid water trapped within ice.

“These things can form naturally,” Louise said. “In fact, possibly many of them did, as the Universe expanded out of the Big Bang. And maybe,” she went on slowly, “the defects can be manufactured artificially, too.”

Spinner stared out of the pod at the nightfighter. “Are you saying — ”

“I’m saying that the Xeelee can create, and control, space-time defects. We think that the ‘wings’ of this nightfighter are defects — domain walls, bounded about by loops of cosmic string.

“Spinner-of-Rope, the Xeelee use sheets of antigravity to drive their spacecraft…”

The domain walls were inherently unstable; left to themselves they would decay away in bursts of gravitational radiation, and would attempt to propagate away at speeds close to that of light. The Xeelee nightfighter must actually be stabilizing the flaws, actively, to prevent this happening, and then destabilizing the flaws to gain propulsion.

Louise believed the Xeelee’s control of the domain-wall antigravity effect must be behind the ship’s ability to shield the pilot cage from acceleration effects.

“All this sounds impossible,” Spinner said.

“There’s no such word,” Louise said aggressively. “Your trip was a real achievement.” Louise, clearly excited by the Xeelee’s engineering prowess, sounded as alive and full of enthusiasm as Spinner had ever heard her. “You gave us the first big break we’ve made in understanding how this nightfighter operates — and, more significantly, how we can use it without destroying ourselves.”

Spinner frowned. “And is that so important?”

Louise looked at her seriously. “Spinner, I need to talk this out properly with you. But I suspect how well we use this nightfighter is going to determine whether we — the human species — survive, or perish here with our Sun.”

Spinner gazed out at the Xeelee craft, at the scores of drone ’bots which clambered busily across the face of its wings.

Perhaps Louise was right; perhaps understanding how something worked did make it genuinely less threatening. The Xeelee nightfighter wasn’t a monster. It was a tool — a resource, for humans to exploit.

“All right,” she said. “What next?”

Louise grinned. “Next, I think it’s time to figure out how to take this nightfighter on a little test jaunt around the Solar System. I’d like to see what in Lethe happened here. And,” she said, her face hardening, “I want to know what’s happening to our Sun…”

18

Milpitas put down his pen.

Annoyingly, it drifted away from the surface of his desk and up into the air, cart-wheeling slowly; Milpitas swiftly scooped up the offending item and swept it into a drawer, where it could drift about to its little insensate heart’s content.

He climbed stiffly from his chair and made his slow way from the office.

Fine white ropes had been strung out along the Temple’s warren of corridors. By judiciously sliding one’s closed fists along the rope, one could quite easily maintain the illusion — for oneself and others — of walking, as normal. He passed another Planner, a junior woman with her tall, shaven dome of a scalp quite gracefully formed. Her legs were hidden by a long robe, so that — at first glance anyway — it could have been that she was walking. Milpitas smiled at the girl, and she nodded gravely to him as they passed.

Excellent, he thought. That was the way to deal with this ghastly, offensive situation of zero-gee, of course: by not accepting its reality, by allowing no intrusion into the normal course of things — into the usual, smooth running of their minds. By such means they could survive until gravity was restored. He moved through the corridors of his Temple, past Planner offices which had been hastily adapted to serve as dormitories and food stores. Beyond the closed doors he heard the slow, subdued murmur of the voices of his people, and beyond the Temple walls there continued the steady, sad wailing of the klaxon.

He worked his way out from the bowels of the building, out toward the glistening skin of the Temple. He had conducted an inspection tour like this every shift since the start of the emergency. His assistants formed a complex web of intelligence throughout the Temple, of course, and reports were ready for him whenever he requested them. Some contact had even been maintained with the other Temples, thanks to carefully selected runners. But, despite all that data, Milpitas still found there was no substitute for getting out of his office and seeing for himself what was going on.

And, he flattered himself to think, perhaps it comforted the people — the lost children he’d gathered here into his protection, in the midst of this, their greatest crisis — to be aware that he, Milpitas, their Planner, was among them.

But, he thought, what if gravity were never returned?

He pulled at his chin, his fingernails lingering on the network of AS scars they found there.

They would have to adjust. It was as simple as that. He evolved vague schemes for stringing networks of ropes across the Decks; there was really no reason why normal life — at least, a close semblance of it — should not resume.

The discipline of the Planners had already persisted for almost a thousand years. Surely a little local difficulty with the gravity wasn’t going to make any difference to that.