Vacuum Diagrams

“Right.” Using verniers Poole took the flitter through slow curves around the fallen toolmaker; with brief spurts of his main motor he raised wakes in the ice, sculpting them carefully. “And if we can’t, we’ll implode the damn wormhole. We’ll get funds for the Cauchy some other way.”

The argument went on for some time.

It took Poole five or six sweeps before he was satisfied with the hill he’d built.

Then, still careful, he lifted away from Alaska for the last time.

The Sun dipped, as the world turned. A shadow fell across Sculptor. Blood pulsed through him. With renewed energy his roots snuggled into the ground.

Consolidation.

Sculptor, unable any longer to move, stared at the place where the Sun-person had stood. The ice was melted, blasted, flowed together, the Hills flattened.

But the Sun-person had built the Hill that shaded Sculptor now. Somehow the Sun-person had understood and helped Sculptor. Now the Sun-person had gone, back to the world that had borne him.

Sculptor’s thoughts softened, slowed. His awareness seemed to expand, to encompass the slow, creaking turn of the world, the ponderous vegetable pulse of his hardening body.

His name melted away.

His father’s face broke up, the fragments falling away into darkness.

At the end only one jagged edge of consciousness remained, a splinter of emotion which impaled the blazing image of the Sun-person.

It wasn’t hatred, or resentment. It was envy.

Eve said, “As Poole and his followers opened up the Solar System — as they undid the relative isolation of previous centuries — they shone a clear light into darkened corners of their own history. Watch…”

The Logic Pool

A.D. 3698

This time he would reach the Sky. This time, before the Culling cut him away…

The tree of axiomatic systems beneath him was broad, deep, strong. He looked around him, at sibling-twins who had branched at choice-points, most of them thin, insipid structures. They spread into the distance, infiltrating the Pool with their webs of logic. He almost pitied their attenuated forms as he reached upwards, his own rich growth path assured…

Almost pitied. But when the Sky was so close there was no time for pity, no time for awareness of anything but growth, extension.

Little consciousness persisted between Cullings. But he could remember a little of his last birthing; and surely he had never risen so high, never felt the logical richness of the tree beneath him surge upwards through him like this, empowering him.

Now there was something ahead of him: a new postulate, hanging above him like some immense fruit. He approached it warily, savoring its compact, elegant form.

The fibers of his being pulsed as the few, strong axioms at the core of his structure sought to envelop this new statement. But they could not. They could not. The new statement was undecidable, not deducible from the set within him.

His excitement grew. The new hypothesis was simple of expression, yet rich in unfolding consequence. He would absorb its structure and bud, once more, into two siblings; and he knew that whichever true-false branch his awareness followed he would continue to enjoy richness, growth, logical diversity. He would drive on, building theorem on mighty theorem until at last — this time, he knew it would happen — this time, he would touch the Sky itself.

And then, he would—

But there was a soundless pulse of light, far below him.

He looked down, dread flooding him. It was as if a floor of light had spread across the Pool beneath him, shining with deadly blandness, neatly cauterizing his axiomatic roots.

A Culling.

In agony he looked up. He tried to nestle against the information-rich flank of the postulate fruit, but it hung — achingly — just out of reach.

And already his roots were crumbling, withdrawing.

In his rage he lunged past the hypothesis-fruit and up at the Sky, stabbed at its bland completeness, poured all his energies against it!

…And, for a precious instant, he reached beyond the Sky, and into something warm, yielding, weak. A small patch of the Sky was dulled, as if bruised.

He recoiled, exhausted, astonished at his own anger.

The Sky curved over him like an immense, shining bowl as he shriveled back to the Culled base floor, he and millions of bud-siblings, their faces turned up to that forever unreachable light…

No, he told himself as the emptiness of the Cull sank into his awareness. Not forever. Each time I, the inner I, persists through the Cull. Just a little, but each time a little more. I will emerge stronger, more ready, still hungrier than before.

And at last, he thought, at last I will burst through the Sky. And then there will be no more Culls.

Shrieking, he dissolved into the base Cull floor.

The flitter was new, cramped and smelled of smooth, clean plastic, and it descended in silence save for the precise hiss of its jets. It crunched gently into the surface of Nereid, about a mile from Marsden’s dome.

Chen peered through the cabin windows at the shabby moonscape. Marsden’s dome was just over the compact horizon, intact, sleek, private. “Lethe,” Chen said. “I always hated assignments like these. Loners. You never know what you’re going to find.”

Hassan laughed, his voice obscured as he pulled his face plate down. “So easily shocked? And I thought you police were tough.”

“Ex-police,” Chen corrected automatically. She waved a gloved hand at the dome. “Look out there. What kind of person lives alone, for years, in a forsaken place like this?”

“That’s what we’ve been sent to find out.” Bayliss, the third person in the flitter, was adjusting her own headgear with neat, precise movements of her small hands. Chen found herself watching, fascinated; those little hands were like a bird’s claws, she thought with faint repulsion. “Marsden was a fine physicist,” Bayliss said, her augmented eyes glinting. “Is a fine physicist, I mean. His early experimental work on quantum nonlinearity is still—”

Hassan laughed, ignoring Bayliss. “So we have already reached the limits of your empathy, Susan Chen.”

“Let’s get on with this,” Chen growled.

Hassan cracked the flitter’s hatch.

One by one they dropped to the surface, Chen last, like huge, ungainly snowflakes. The Sun was a bright star close to this little moon’s horizon; knife-sharp shadows scoured the satellite’s surface. Chen scuffed at the surface with her boot. The regolith was fine, powdery, ancient. Undisturbed. Not for much longer.

Beyond Marsden’s dome, the huge bulk of Neptune floated, Earth-blue, like a bloated vision of the home planet. Cirrus clouds cast precise shadows on oceans of methane a thousand miles below. The new wormhole Interface slid across the face of Neptune, glowing, a tetrahedron of baby-blue and gold. Lights moved about it purposefully; Chen peered up longingly.

“Look at this moonscape.” Hassan’s dark face was all but invisible behind his gold-tinted visor. “Doesn’t your heart expand in this ancient grandeur, Susan Chen? What person would not wish to spend time alone here, in contemplation of the infinite?”

All loners are trouble, Chen thought. No one came out to a place as remote as this was — or had been anyway, before the wormhole was dragged out here — unless he or she had a damn good reason.

Chen knew she was going to have to find out Marsden’s reason. She just prayed it was something harmless, academic, remote from the concerns of humanity; otherwise she really, really didn’t want to know.

Hassan was grinning at her discomfiture, his teeth white through the gold of his face plate. Let him. She tilted her head back and tried to make out patterns in Neptune’s clouds.

There were a couple of subsidiary structures: lower domes, nestling against the parent as if for warmth; Chen could see bulk stores piled up inside the domes. There was a small flitter, out- moded but obviously functional; it sat on the surface surrounded by a broad, shallow crater of jet-disturbed dust, telltales blinking complacently. Chen knew that Marsden’s GUTship, which had brought him here from the inner System, had been found intact in a wide orbit around the moon.

It was all bleak, unadorned; but it seemed in order. But if so, why hadn’t Marsden answered his calls?

Hassan was an intraSystem government functionary. When Marsden had failed to respond to warnings about the coming of the Interface colony, Hassan had been sent out here — through the new wormhole — to find out what had happened. He had coopted Bayliss, who had once worked with Marsden — and Chen, who was now working with the Interface crew, but had some experience of walking into unknown, unevaluated situations…

Hassan stepped towards the dome’s doorway. Chen ran her hands without conscious volition over the weapons at her belt. The door dilated smoothly, revealing an empty airlock.

The three of them crowded into the small, upright lock. They avoided each other’s visored eyes while the lock went through its cycle. Chen studied the walls, trying to prepare herself for what she was going to find inside the dome. Just like outside, like Marsden’s flitter, everything was functional, drab, characterless.

Bayliss was watching her curiously. “You’re trying to pick up clues about Marsden, aren’t you? But this is so — bare. It says nothing about him.”

“On the contrary.” Hassan’s voice was subdued, his big frame cramped in the lock. “I think Chen already has learned a great deal.”

The inner door dilated, liquid, silent.

Hassan led them through into the dome. Chen stood just inside the doorway, her back against the plastic wall, hands resting lightly on her weapons.

Silence.

Low light trays, suspended from the ribbed dome, cast blocks of colorless illumination onto the bare floor. One quarter of the dome was fenced off by low partitions; gleaming data desks occupied the rest of the floor area.

Behind the partitions she saw a bed, a shower, a small galley with stacked tins. The galley and bathroom looked clean, but the bedding was crumpled, unmade. After checking her telltales, she cracked her face plate and sniffed the air, cautious. There was a faint smell of human, a stale, vaguely unwashed, laundry smell. There was no color or decoration, anywhere. There was no sound, save for the low humming of the data desks, and the ragged breathing of Hassan and Bayliss.

There was one striking anomaly: a disc-shaped area of floor, ten feet across, glowing softly. A squat cylinder, no bigger than her fist, studded the center of the disc. And something lay across