All about him were quantum wave functions.

They spread from stars and planets, sheets of probability that linked matter and time. They were like spiderwebs scattered over the aging galaxies; they mingled, reinforced and canceled each other, all bound by the implacable logic of the governing wave equations.

The functions filled space-time and they pierced his soul. Exhilarated, he rode their gaudy brilliance through the hearts of aging stars.

He relaxed his sense of scale, so that there seemed no real difference between the width of an electron and the broad sink of a star’s gravity well. His sense of time telescoped, so that he could watch the insectlike, fluttering decay of free neutrons — or step back and watch the grand, slow decomposition of protons themselves…

Soon there was little of the human left in him. Then, at last, he was ready for the final step.

After all, he reflected, human consciousness itself was an artificial thing. He recalled Green, on the Sugar Lump, gleefully describing tests which proved beyond doubt that the motor impulses initiating human actions could often precede the willing of those actions by significant fractions of a second. Humans had always been adrift in the Universe, creatures of impulse and acausality, explaining their behavior to each other with ever more complex models of awareness. Once they had believed that gods animated their souls, fighting their battles through human form. Later they had evolved the idea of the self-aware, self-directed consciousness. Now Paul saw that it had all been no more than an idea, a model, an illusion behind which to hide. Why should he, perhaps the last human, cling to such outmoded comforts?

There was no cognition, he realized. There was only perception.

With the equivalent of a smile he relaxed. His awareness sparkled and subsided.

He was beyond time and space. The great quantum functions which encompassed the Universe slid past him like a vast, turbulent river, and his eyes were filled with the gray light which lay behind all phenomena.

Space had never been empty.

Within the tight space-time limits of the Uncertainty Principle, “empty” vacuum was filled with Virtual particle sets which blossomed from nothing, flew apart, recombined and vanished as if they had never been — all too rapidly for the laws of mass/energy conservation to notice.

Once, human scientists had called it the seething vacuum. And now it was inhabited.

The Qax was a creature of turbulent space, its “cells” a shifting succession of Virtual particle sets. Physically its structure extended over many yards — a rough sphere gigantic in subatomic terms containing a complex of Virtual particle sets which stored terabits of data: of understanding, of memory stretching back over millions of years.

Like the shadow of a cloud the Qax cruised over turbulent space, seeking humans…

…Is it over? Is humanity destroyed? Lethe, Eve, we’ve covered millions of years. We’ve seen the flight of the Xeelee, the victory of those photino birds. It must be over. What can be left to show me?”

“Watch,” she said patiently. “Watch…”

“I’ve found a bird from the Shell — a bird from space!” Allel ran into the village bursting with her news, her baggy bark shirt flapping.

But nobody was impressed. She couldn’t understand it. Younger children turned back to their games in the dust.

Her mother, Boyd, absently cuffed Allel’s fourteen-year-old head. “Don’t bother me,” she growled, and went about her business.

Boyd’s face was a scarred, complex mask as she moved amongst the groups of men and women, massive and formidable in her coat of quilted cow-tree bark, planning and talking urgently. It was already late afternoon; that evening Boyd would be leading this ragged army south in another assault on the defense of the Bridge.

Allel knew how important this was to her mother; eventually they had to secure a crossing over the river Atad and gain access to the south — otherwise the northern glaciers would surely crush their tiny village before many more winters. Boyd’s fists were clenched white as she argued. Allel knew she was brooding over the prospect of another bloody failure, and decided to keep out of her way.

She found her grandfather, Lantil, ferrying bowls of excrement and other waste from the bark teepees to the clusters of cow-trees at the heart of the village. Lantil dumped out the bowls into the trees’ root systems and tiredly tolerated his granddaughter’s chatter.

She told him how she’d gone out of the village alone and scrambled over the rocky shoulders of Hafen’s Hill, a mile or so away. At the summit she’d thrown herself flat, panting, and stared up in wonder: in the afternoon light the Shell was a glowing quilt, and she’d soon forgotten the wind from the northern ice fields that probed at the crude seams of her shirt…

Allel’s was a world without a sky. Instead the Shell swept from horizon to horizon, covering the land like a glowing lid of blue, green and startling orange. She’d traced the familiar lines of the ocean boundaries and watched clouds wind themselves into an upside-down storm directly above her. She reached up a finger as if to stir the storm on that great plate hanging over her—

— and the bird had tumbled out of the air. She’d scuttled to her knees and cupped the bird in her hands; its heart rattled as ice droplets melted from its wings.

The bird was an ice blue, a spectacular color she’d never seen before. And in its beak was a vivid orange flower.

The precise color of those strange orange splashes on the Shell.

The bird recovered and clattered away, but that didn’t matter. Allel knew it must have lost its way and crossed the Gap between the worlds.

She’d run off down the heathered slopes to her home.

She dogged Lantil’s footsteps as he trudged wearily among the teepees. “But if the world and the Shell are globes, what holds them apart?” Perhaps there were great pillars beyond the horizon…

Lantil pushed a lank of dirty hair back from his brow. “What does it matter?”

“I want to know,” she stamped.

Her grandfather sighed. “All right.” He knelt beside Allel and made a gnarled fist. “There’s the world, Home, round like a ball.” He cupped his other hand around the fist. “And there’s the Shell, a hollow sphere around Home.” Now he broke the fist and twirled a fingertip in a helix inside the cupped hand. “The Sun moves through the Gap, giving us day and night, summer and winter.”

Allel nodded impatiently. “I know all that. But who built it all?”

“People, of course.” He straightened up, massaging his back. “To keep out monsters called the Xeelee.”

Allel, wide-eyed, imagined giants stalking beyond the Shell, beating their fists against ocean bottoms and tree roots.

“Now I’ve got to get on,” Lantil snapped. “Get on with you, child. Get on…” Grumbling, he went back to his chores.

Allel ran off, savoring her newest fragment of knowledge. She imagined flying up to a saucer-shaped land where a world hung in the sky, a ball plastered with rocks and trees.

The next morning she rose at dawn. She pushed her way out of the teepee’s bark flap, letting the gray cold scour out her night fug. She shivered her way to a cow-tree and sucked icy milk from one of its nipples.

The village was hushed in the continued absence of the warriors. A group of old folk and children were at work already, making the most of the precious summer day; they were peeling a fresh sheet of clothlike bark, barely formed, from one of the cow trees. Allel peered furtively up at the Shell. The morning terminator was a gray bar that straddled the horizons, scouring eastward. The night lands beyond were broken by flickering sparks: fires that showed that people lived on the Shell, like flies on that great ceiling.