Vacuum Diagrams

by Stephen Baxter

  But not this lot. Not the new generation.

  This was his third flight with the boy Gover. And the lad was still as sullen and obstructive as when he'd first been assigned to the trees; when they got back to the Raft Pallis would be more than glad to hand him back to Science.

  His gaze roamed around the red sky, restless.

  The air of the Nebula was, as always, stained blood-red. A corner of his mind tried to measure that redness — was it deeper than last shift? — while his eyes flicked around the objects scattered through the Nebula above and below him. The clouds were like handfuls of grayish cloth sprinkled through miles of air. Stars fell among and through the clouds in a slow, endless rain that tumbled down to the Core. It was as if he were suspended in a great cloud of light; the star-spheres receded with distance into points of light, so that the sky itself was a curtain glowing red-yellow. The falling stars were an array of pinpoints dwindling into the far distance; the depths of the Nebula, far below him, were a sink of murky crimson.

  The light of the mile-wide stars cast shifting shadows over the clouds, the scattered trees, the huge blurs that might be whales. Here and there he saw a tiny flash that marked the end of a star's brief existence...

  In his time, the world had changed around Pallis. The Nebula seemed to be choking up. The crisp blue skies, the rich breezes of his youth were memories now; the very air was turning into a smoky crimson sludge.

  The world was dying, and no one knew why, or how to stop it.

  And one thing was for sure. Pallis's trees didn't like this gloom.

  He sighed, trying to snap out of his introspection. The stars kept falling no matter what the color of the sky. Life went on, and he had work to do.

  A heavy cloud, fat with rain, drifted over the Belt, reducing visibility to a few yards; the air it brought with it seemed exceptionally sour and thin.

  Rees prowled around the cables that girdled his world, muscles working restlessly. He completed two full circuits, passing huts and cabins familiar since his childhood, hurrying past well-known faces. The damp cloud, the thin air, the confinement of the Belt seemed to come together somewhere inside his chest.

  Questions chased around his skull. Why were human materials and building methods so inadequate to resist the forces of the world? Why were human bodies so feeble in the face of those forces?

  His father used to say the mine was killing them all. Humans weren't meant to work down there, crawling around in wheelchairs at five gee.

  Now his parents were dead.

  Rees was still a boy. But he faced a prospect of nothing more than to labor in the kernel mines, to have his health broken by the monstrous gravity, to die young.

  Shards of speculation glittered in the mud of his overtired thinking. His parents had had no better understanding of their circumstances than he had; there had been nothing but legends they could tell him before their sour deaths of overwork: children's tales, of a Ship, a Crew, of something called Bolder's Ring...

  But his parents had had — acceptance. They, and the rest of the Belt dwellers, accepted their lot.

  Only Rees seemed plagued by questions, unanswered doubts. Why couldn't he be like everyone else? Why couldn't he just accept and be accepted?

  His arms, punctured by hot metal, ached. A vague anger suffused him. Well, why should he accept this? Why should he die, broken-down by the five gee of the Star's kernel, without learning more, the truth of the world?

  He had to find out more. And in all his universe there was only one place he could go to find it.

  The Raft. Somehow he had to get to the Raft.

  The shadow of the great tree slid over the Belt. A rope had uncoiled from the tree trunk and lay across the fifty yards to the Belt, brushing against the orbiting cabins. A man came shimmering confidently down the rope; he was scarred, old and muscular, almost a piece of the tree himself. The man dropped without hesitation across empty air to a cabin and began to make his way around the Belt.

  A sudden determination crystallized in Rees. He hurried around the Belt to his cabin.

  It took minutes to gather up some food, wrapping dried meat in bundles of cloth, filling cloth globes with water.

  Then he climbed to the outer wall of his cabin.

  Rees clung to his cabin by one hand. The rotation of the Belt carried the cabin steadily towards the tree's dangling rope.

  As the rope approached, a thin sweat covered his brow. Was he somehow throwing his life away in this impulsive gesture? Would he, in the end, have the courage to take the decisive step?

  Staring at the magnificent tree he probed at his emotions. There was no fear. There was only elation; the future was an empty sky, within which his hopes would surely find room.

  When the rope was a yard from him he grabbed at it and swarmed without hesitation off the Belt.

  A file of miners clambered up to the tree, iron plates strapped to their backs. Under the tree-pilot's supervision the plates were lashed securely to the tree rim, widely spaced. The miners descended to the Belt laden with casks of food and fresh water, delivered from the Raft in payment for the kernel metal.

  Rees, watching from the foliage, stayed curled closely around a two-feet-wide branch — taking care not to cut open his palms on its knife-sharp leading edge — and he kept a layer of foliage around his body. He had no way of telling the time, but the loading of the tree must have taken several shifts.

  He was wide-eyed and sleepless. He knew that his absence from work would go unremarked for at least a couple of shifts — and, he thought with a distant sadness, it might be longer before anyone cared enough to come looking for him.

  Well, the world of the Belt was behind him now. Whatever dangers the future held for him, at least they would be new dangers.

  In fact he only had two problems. Hunger and thirst...

  Disaster had struck soon after he had found himself this hiding place among the leaves. One of the Belt workmen had stumbled across his tiny cache of supplies; thinking it belonged to the despised Raft crewmen the miner had shared the morsels among his companions. Rees had been lucky to avoid detection himself, he realized... but now he had no supplies, and the clamor of his throat and belly had come to fill his head.

  When the final miner had slithered down to the Belt Pallis curled up the rope and hung it around a hook fixed to the trunk. He hated these visits to the Belt, the way he was forced to negotiate so hard with these ragged, half-starved miners. He shook his head and turned his thoughts with some relief to the flight home.

  "Right, Gover, let's see you move! I want the bowls switched to the underside of the tree, filled and lit before I've finished coiling this rope. Or would you rather wait for the next tree?"

  Gover got to work, comparatively briskly; and soon a blanket of smoke was spreading beneath the tree, shielding the Belt and its star from view.

  Pallis stood close to the trunk, his feet and hands sensitive to the excited surge of sap. It was almost as if he could sense the huge vegetable thoughts of the tree as it reacted to the darkness spreading below it. The trunk audibly hummed; the branches bit into the air; the foliage shook and swished and skitters tumbled, confused at the abrupt change of airspeed; and then, with an exhilarating surge, the great spinning platform lifted from the star. The Belt and its human misery dwindled to a toylike mote, falling slowly into the Nebula, and Pallis, hands and feet pressed against the flying wood, was where he was most happy.

  His contentment lasted for about a shift and a half.

  He prowled the wooden platform, moodily watching the stars slide through the silent air. The flight just wasn't smooth. Oh, it wasn't enough to disturb Gover's extensive slumbers, but to Pallis's practiced senses it was like riding a skitter in a gale. He pressed his ear to the ten-feet-high wall of the trunk; he could feel the bole whirring in its vacuum chamber as it tried to even out the tree's rotation.

  This felt like a loading imbalance... but that was impossible. He'd supervised the stowage of the
cargo himself to ensure an even distribution of mass around the rim. For him not to have spotted such a gross imbalance would have been like — well, like forgetting to breathe.

  Then what?

  With a growl of impatience he pushed away from the trunk and stalked to the rim. He began to work around the lashed loads, methodically rechecking each plate and cask and allowing a picture of the tree's loading to build up in his mind—

  He slowed to a halt. One of the food casks had been broken into; its plastic casing was cracked in two places and half the contents were gone. Hurriedly he checked a nearby water cask. It too was broken open and empty.

  He felt hot breath course through his nostrils. "Apprentice! Come here!"

  The boy came slowly, his thin face twisted with apprehension.

  Pallis stood immobile until Gover got within arm's reach; then he lashed out with his right hand and grabbed the apprentice's shoulder. Pallis pointed at the violated casks. "What do you call this?"

  Gover stared at the casks with what looked like real shock. "Well, I didn't do it, pilot. I wouldn't be so stupid — ah!"

  Pallis worked his thumb deeper into the boy's joint, searching for the nerve. "Did I keep this food from the miners in order to allow you to feast your useless face? Why, you little bone sucker, I've a mind to throw you over now..."

  Then he fell silent, his anger dissipating.

  There was still something wrong.

  The mass of the provisions taken from the casks wasn't nearly enough to account for the disruption to the tree's balance. And as for Gover — well, he'd been proven a thief, a liar and worse in the past; but he was right: he wasn't nearly stupid enough for this.

  Reluctantly he released the boy's shoulder. Gover rubbed the joint, staring at him resentfully. Pallis scratched his chin. "If you didn't take the stuff, Gover, then who did? Eh?" By the Bones, they had a stowaway.

  He dropped to all fours and pressed his hands and feet against the wood of a branch. He closed his eyes and let the tiny shuddering speak to him. If the unevenness wasn't at the rim, then where...?

  Abruptly he straightened and half-ran about a quarter of the way around the rim, his long toes clutching at the foliage. He paused for a few more seconds, hands once more folded around a branch; then he made his way more slowly towards the center of the tree, stopping halfway to the trunk.

  There was a little nest in the foliage. Through the bunched leaves he could see a few scraps of discolored cloth, a twist of unruly black hair, a hand dangling weightless; the hand was that of a boy or young man, he judged, but it was heavily callused and it bore a spatter of tiny wounds.

  Pallis straightened to his full height. "Well, here's our unexpected mass, apprentice. Good shift to you, sir! And would you care for your breakfast now?"

  The nest exploded. Skitters whirled away from the tangle of limbs and flew away, as if indignant; and at last a boy half-stood before Pallis, eyes bleary with sleep, mouth a circle of shock.

  Gover sidled up beside Pallis. "By the Bones, it's a mine rat."

  Pallis looked from one boy to the other. The two seemed about the same age, but where Gover was well-fed and ill-muscled, the stowaway had ribs like the anatomical model of a Scientist, and his muscles were like an adult's; and his hands were the battered product of hours of labor. The lad's eyes were dark-ringed. Pallis remembered the imploded foundry and wondered what horrors this young miner had already seen. Now the boy filled his chest defiantly, his hands bunching into fists.

  Gover sneered, arms folded. "What do we do, pilot? Throw him to the Boneys?"

  Pallis turned on him with a snarl. "Have you cleaned out the fire bowls yet? No? Then do it. Now!"

  With a last, baleful glare at the stowaway, Gover moved clumsily away across the tree.

  The stowaway watched him go with some relief; then turned back to Pallis.

  The pilot raised his hands, palms upwards. "Take it easy. I'm not going to hurt you... Tell me your name."

  The boy's mouth worked but no sound emerged; he licked cracked lips, and managed to say: "Rees."

  "All right. I'm Pallis. I'm the tree-pilot. Do you know what that means?"

  "I... yes."

  "By the Bones, you're dry, aren't you? No wonder you stole that water. You did, didn't you? And the food?"

  The boy nodded hesitantly. "I'm sorry. I'll pay you back—"

  "When? After you return to the Belt?"

  The boy shook his head, a glint in his eye. "No. I'm not going back."

  Pallis frowned. "What about your parents?"

  "They're dead. Both of them."

  Pallis bunched his fists and rested them on his hips. "Listen to me. You'll have to go back. You'll be allowed to stay on the Raft until the next supply tree; but then you'll be shipped back. You'll have to work your passage, I expect..."

  Rees shook his head again, his face a mask of determination.

  Pallis studied the young miner, an unwelcome sympathy growing inside him. "Well, I'm stuck with you for now. Come on."

  He led the boy across the tree surface, towards his little stock of rations.

  After a dozen yards they disturbed a spray of skitters; the little creatures whirled up into Rees's face and he stepped back, startled. Pallis laughed. "Don't worry. Skitters are harmless. They are the seeds from which the trees grow..."

  Rees nodded. "I guessed that."

  Pallis arched an eyebrow. "You did?"

  "Yes. You can see the shape's the same; it's just a difference of scale..."

  Pallis arched an eyebrow. Smart lad.

  The boy ate, as if he'd never been fed.

  After letting the boy sleep for a quarter shift Pallis put him to work. Soon Rees was bent over a fire bowl, scraping ash and soot from the iron with shaped blades of wood. Pallis found that his work was fast and complete, supervised or un-supervised. Gover suffered by comparison... and by the looks he shot at Rees, Pallis suspected Gover knew it.

  Rees joined Pallis and collected his shift-end rations. The young miner peered absently around at the empty sky. As the tree climbed up towards the Raft, away from the Core and towards the edge of the Nebula, the air was perceptibly brightening.

  "Come on," Pallis said. "Let me show you something."

  He led the boy towards the trunk of the tree.

  Surreptitiously he watched as the boy half-walked across the foliated platform, his feet seeking out the points of good purchase and then lodging in the foliage, so allowing him to "stand" on the tree. The contrast with Gover's clumsy stumbling was marked. Pallis found himself wondering what kind of woodsman the lad would make.

  They reached the trunk. Rees stood before the tall cylinder and ran his fingers over the gnarled wood. Pallis hid a smile. "Put your ear against the wood. Go on."

  Rees did so with a look of puzzlement — which evolved into an almost comic delight.

  "That's the bole turning, inside the trunk. You see, the tree is alive, right to its core."

  Rees's eyes were wide.

  Rees woke from a comfortable sleep in his nest of foliage. Pallis hung over him, silhouetted by a bright sky. "Shift change," the pilot said briskly. "Hard work ahead for all of us; docking and unloading and—"

  "Docking?" Rees shook his head clear of sleep. "Then we've arrived?"

  Pallis grinned. "Isn't that obvious?"

  He moved aside. Behind him the Raft hung huge in the sky. A single star was poised some tens of miles above the Raft, a turbulent ball of yellow fire a mile wide, and the huge metal structure cast a broadening shadow down through miles of dusty air.

  Under Pallis's direction Rees and Gover stoked the fire bowls and worked their way across the surface of the tree, waving large, light blankets over the billowing smoke. Pallis studied the canopy of smoke with a critical eye; never satisfied, he snapped and growled at the boys. But, steadily and surely, the tree's rise through the Nebula was molded into a slow curve towards the rim of the Raft.

  The Raft grew in the sky until it blocked
out half the Nebula. From below it showed as a ragged disc a half-mile wide; metal plates scattered highlights from the stars and light leaked through dozens of apertures in the deck. As the tree sailed up to the rim the Raft foreshortened into a patchwork ellipse; Rees could see the sooty scars of welding around the edges of the nearer plates, and as his eye tracked across the ceilinglike surface the plates crowded into a blur, with the far side of the disc a level horizon.

  At last, with a rush of air, the tree rose above the rim and the upper surface of the Raft began to open out before Rees. He found himself drawn to the edge of the tree; he buried his hands in the foliage and stared, open-mouthed, as a torrent of color, noise and movement broke over him.

  The Raft was an enormous dish that brimmed with life. Points of light were sprinkled over its surface. The deck was studded with buildings of all shapes and sizes, constructed of wood panels or corrugated metal and jumbled together like toys.

  A confusion of smells assaulted Rees's senses — sharp ozone from giant machines around the rim, wood smoke from a thousand chimneys, the hint of exotic cooking scents from the cabins. And people — more than Rees could count, so many that the Belt population would be easily lost among them — people walked about the Raft in great streams; and knots of running children exploded here and there into bursts of laughter.

  He made out sturdy pyramids fixed to the deck, waist-high. And out of each pyramid a cable soared straight upwards; Rees tilted his face back, following the line of the cables, and he gasped. To each cable was tethered the trunk of a tree. To Rees one flying tree had been wonder enough. Now, over the Raft, he was faced with a mighty forest. Every tethering cable was vertical and quite taut, and Rees could almost feel the exertion of the harnessed trees as they strained against the pull of the Core.

  A hundred questions tumbled through Rees's mind. What would it be like to walk on that metal surface? What must it have been like for the Crew who had built the Raft, hanging in the void above the Core?