To my nephew James Baxter

Dura woke with a start.

There was something wrong. The photons didn’t smell right.

Her hand floated before her face, dimly visible, and she flexed her fingers. Disturbed electron gas, spiraling dizzily around the Magfield lines, sparkled purple-white around the fingertips. The Air in her eyes was warm, stale, and she could make out only vague shapes.

For a moment she hung there, curled in a tight ball, suspended in the elastic grip of the Magfield.

She heard voices, thin and hot with panic. They were coming from the direction of the Net.

Dura jammed her eyes tight shut and hugged her knees, willing herself to return to the cool oblivion of sleep. Not again. By the blood of the Xeelee, she swore silently, not another Glitch; not another spin storm. She wasn’t sure if the little tribe of Human Beings had the resources to respond to more disruption… nor, indeed, if she herself had the strength to cope with fresh disaster.

The Magfield itself trembled now. Encasing her body, it rippled over her skin, not unpleasantly, and she allowed it to rock her as if she were a child in its arms. Then — not so pleasantly — it prodded her more rudely in the small of the back…

No, that wasn’t the Magfield. She uncurled again, stretching against the confines of the field. She rubbed her eyes — the fleshy rims of the cups were crusted with sleep-deposits and felt sharp against her fingers — and shook her head to clear the clouded Air out of the cups.

The prod in her back was coming from the fist of Farr, her brother. He’d been on latrine duty, she saw; he still carried his plaited waste bag, empty of the neutron-rich shit he’d taken out away from the Net and dumped in the Air. His skinny, growing body trembled in response to the instabilities in the Magfield and his round face was upturned to her, creased with an almost comical concern. In one hand he gripped a fin of his pet Air-pig — a fat infant about the size of Dura’s fist, so young that none of its six fins were yet pierced. The little animal, obviously terrified by the Glitch, struggled to escape, feebly; it pumped out superfluid jetfarts in thin blue streams.

His fondness for the animal made Farr seem even younger than his twelve years — a third of Dura’s age — and he clung to the piglet as if clinging to childhood itself. Well, Dura thought, the Mantle was huge and empty, but there was precious little room in it for childhood. Farr was having to grow up fast.

He was so like their father, Logue.

Dura, still misty with sleep, felt a surge of affection and concern for the boy and reached out to stroke his cheek, to run gentle fingers around the quiet brown rims of his eyes.

She smiled at her brother. “Hello, Farr.”

“Sorry for waking you.”

“You didn’t. The Star was kind enough to wake me, long before you got around to it. Another Glitch?”

“The worst one yet, Adda says.”

“Never mind what Adda says,” Dura said, stroking his floating hair; the hollow tubes were, as always, tangled and grubby. “We’ll get by. We always do, don’t we? You get back to your father. And tell him I’m coming.”

“All right.” Farr smiled at her again, twisted stiffly, and, with his Air-pig’s fin still clutched tight, he began to Wave awkwardly across the Magfield’s invisible flux paths toward the Net. Dura watched him recede, his slim form diminished by the shimmering, world-filling vortex lines beyond him.

Dura straightened to her full length and stretched, pressing against the Magfield. She kept her mouth wide open as she worked stiffness out of her limbs and back. She felt the feathery ripple of the Air as it poured through her throat to her lungs and heart, rushing through superleak capillaries and filling her muscles; her body seemed to tingle with its freshness.

She gazed around, sniffing the photons.

Dura’s world was the Mantle of the Star, an immense cavern of yellow-white Air bounded below by the Quantum Sea and above by the Crust.

The Crust itself was a rich, matted ceiling, purple-streaked with grass and the hairlike lines of tree trunks. By squinting — distorting the parabolic retinas of her eyes — she could make out dark motes scattered among the roots of the trees fixed to the underside of the Crust. Perhaps they were rays, or a herd of wild Air-pigs, or some other grazing creatures. It was too distant to see clearly, but the amphibian animals seemed to be swirling around each other, colliding, confused; she almost imagined she could hear the cool sound of their distress.

Far below her, the Quantum Sea formed a purple-dark floor to the world. The Sea was mist-shrouded, its surface indistinct and deadly. The Sea itself, she saw with relief, was undisturbed by the Glitch. Only once in Dura’s memory had there been a Glitch severe enough to cause a Seaquake. She shuddered like the Magfield as she remembered that ghastly time; she had been no older than Farr, she supposed, when the neutrino founts had come, sweeping half the Human Beings — including Phir, Dura’s mother and Logue’s first wife — away and on, screaming, into the mysteries beyond the Crust.

All around her, filing the Air between Crust and Sea, the vortex lines were an electric-blue cage. The lines filled space in a hexagonal array, spaced about ten mansheights apart; they swept around the Star from far upflux — from the North — arced past her like the trajectories of immense, graceful animals, and converged into the red-soft blur that was the South Pole, millions of mansheights away.

She held her fingers up before her face, trying to judge the spacing and pattern of the lines.

Through her fingers she could see the encampment, a little knot of frantic detail and activity — jostling, terrified Air-pigs, scrambling people, the quivering Net — all embedded in the shuddering bulk of the Air. Farr with his struggling Air-piglet was a pathetic scrap, wriggling through the invisible flux tubes.

Dura tried to ignore the small, messy knot of humanity, to focus on the lines.

Normally the motion of the lines was stately, predictable — regular enough for the Human Beings to measure their lives by it, in fact. Overlaid on the eternal drift of the lines toward the Crust there were pulses of line-bunching: the tight, sharp crowdings that marked the days, and the slower, more complex second-order oscillations which humans used to count their months. In normal times it was easy for the Human Beings to avoid the slow creep of the lines; there was always plenty of time to dismantle the Net, repitch their little encampment in another corner of the empty sky.

Dura even knew what caused the lines’ stately pulsations, much good the knowledge did her: the Star had a companion, far beyond the Crust — a planet, a ball like the Star but smaller, lighter — which revolved, unseen, over their heads, pulling at the vortex lines as if with invisible fingers. And, of course, beyond the planet — the childish ideas returned to her unbidden, like fragments of her lingering sleep — beyond the planet were the stars of the Ur-humans, impossibly distant and forever invisible.

The drifting vortex lines were as stable and secure, in normal times, as the fingers of some friendly god; humans, Air-pigs and others moved freely between the lines, fearlessly and without any danger…

Except during a Glitch.

Now, across the frame of her spread fingers, the vortex array was shifting visibly as the superfluid Air sought to realign with the Star’s adjusted rotation. Instabilities — great parallel sets of ripples — already marched majestically along the length of the lines, bearing the news of the Star’s new awakening from Pole to magnetic Pole.