Raft xs-1

by Stephen Baxter

  They stood on a low ledge; Rees took a step down and was soon floating in the air, his feet a few inches from the window-floor. Nead lingered nervously. “Come on, it’s easy,” Rees said. “Just swim in the air, or bounce up and down until your feet hit the deck.”

  Nead stepped off the ledge and tumbled forward, slowly bobbing upright. He reminded Rees of a child entering a pool for the first time. After a few seconds a slow smile spread across the young man’s face; and soon he was skimming about the room, his feet brushing at the window below.

  Rees took him on a tour around the machines.

  Nead shook his head. “This is amazing.”

  Rees smiled. “This equipment is among the best preserved of the Ship’s materiel. It’s as if it were unloaded only last shift… We call this place the Observatory. All the heavy-duty sensors are mounted here, and this is where — as a member of my Nebular physics team — you’ll be spending most of your time.” They stopped beside a tube ten feet long and encrusted with lenses. Rees ran a palm along the instrument’s jewelled flank. “This baby’s my favorite,” he said. “Beautiful, isn’t she? It’s a Telescope which will work at all wavelengths — including the visual. Using this we can see right down into the heart of the Nebula.”

  Nead thought that over, then glanced at the ceiling. “Don’t we ever need to look outwards?”

  Rees nodded approvingly. Good question. “Yes, we do. There are ways of making the roof transparent — in fact, we can opaque the floor, if we want to.” He glanced at the instrument’s fist-sized status panel, “We’re in luck; there are no observations currently running. I’ll give you a quick guided tour of the Nebula. You should know most of what I’ll tell you from your studies so far, and don’t worry about the details for now…” Slowly he punched a sequence of commands into the keypad mounted below the sensor. He became aware that the lad was watching him curiously. Maybe he’s never seen anyone with such rusty keyboard skills, Rees reflected, here on this Raft of a hundred supply machines—

  The stab of old resentment shocked him. Never mind…

  A disc of ceiling faded to transparency, revealing a red sky. Rees indicated a monitor plate mounted on a slim post close to the Telescope. The plate abruptly filled with darkness punctuated by fuzzy lens shapes; the lenses were all colors, from red through yellow to the purest blue. Once more Nead gasped.

  “Let’s review a few facts,” Rees began. “You know we live in a Nebula, which is an ellipse-shaped cloud of gas about five thousand miles across. Every particle of the Nebula is orbiting the Core. The Raft is in orbit too, embedded in the Nebula like a fly on a spinnng plate; we circle the Core every twelve shifts or so. The Belt mine is further in and only takes about nine shifts to complete its orbit. When the pilots fly between mine and Raft their trees are actually changing orbits! Fortunately the gradients in orbital speeds are so shallow out here that the velocities the trees can reach are enough for them easily to fly from one orbit to another. Of course the pilots must plan their courses carefully, to make sure the Belt mine isn’t on the other side of the Core when they arrive at the right orbit…

  “Here we’re looking through the Observatory roof and out of the Nebula. Normally the atmosphere shields this view from us, but the Telescope can unscramble the atmospheric scattering and show us what we’d see if the air were stripped away.”

  Nead peered closer at the picture. “What are those blobs? Are they stars?”

  Rees shook his head. “They’re other nebulae: some larger than ours, some smaller, some younger — the blue ones — and some older. As far as we can see with this Telescope — and that’s hundreds of millons of miles — space is filled with them.

  “All right; let’s move inwards.” With a single keystroke the picture changed to reveal a blue-purple sky; stars glittered, white as diamonds.

  “That’s beautiful,” Nead breathed. “But it can’t be in our Nebula—”

  “But it is.” Rees smiled sadly. “You’re looking at the topmost layer, where the lightest gases — hydrogen and helium — separate out. That is where stars form. Turbulence causes clumps of higher density; the clumps implode and new stars burst to life.” The stars, balls of fusion fire, formed dense bow waves in the thin atmosphere as they began their long, slow fall into the Nebula. Rees went on, “The stars shine for about a thousand shifts before burning out and dropping, as a cool ball of iron, into the Core… Most of them anyway; one or two of the kernels end up in stable orbits around the Core. That’s where the star mines come from.”

  Nead frowned. “And if the path of a falling star intersects the orbit of the Raft—”

  “Then we’re in trouble, and we must use the trees to change the Raft’s orbit. Fortunately star and Raft converge slowly enough for us to track the star on its way toward us…”

  “If new stars are being formed, why do people say the Nebula is dying?”

  “Because there are far fewer than before. When the Nebula was formed it was almost pure hydrogen. The stars have turned a lot of the hydrogen into helium, carbon and other heavy elements. That’s how the complex substances which support life here were formed.

  “Or rather, it’s life for us. But it’s a slow, choking death for the Nebula. From its point of view oxygen, carbon and the rest are waste products. Heavier than hydrogen, they settle slowly around the Core; the residual hydrogen gets less and less until — as today — it’s reduced to a thin crust around the Nebula.”

  Nead stared at the sparse young stars. “What will happen in the end?”

  Rees shrugged. “Well, we’ve observed other nebulae. The last stars will fail and die. Deprived of energy the airborne life of the Nebula — the whales, the sky wolves, the trees, and the lesser creatures they feed on — will cease to exist.”

  “Are there truly such things as whales? I thought they were just stories—”

  Rees shrugged. “We never see them out here, but we have plenty of evidence from travellers who’ve entered the depths of the Nebula.”

  “What, as far as the Belt mine, you mean?”

  Rees suppressed a smile. “No, even further than that. The Nebula is a big place, lad; there is room to hide a lot of mystery. Perhaps there are even lost human colonies; perhaps the Boneys really exist, and all those legends are true… of the subhuman whale-singers lost in the sky.”

  The boy shuddered.

  “Of course,” Rees mused, “there are puzzles about the native life of the Nebula. For example, how can it exist at all? Our records show that life in the home universe took thousands of billions of shifts to evolve. The Nebula isn’t anything like that old — and will be far younger when it dies. So how did life arise?”

  “You were telling me what will happen after the stars go out…”

  “Yes. The atmosphere, darkened, will steadily lose heat, and — less able to resist the gravity of the Core — will collapse. Finally the Nebula will be reduced to a layer a few inches thick around the Core, slowly falling inwards…”

  The young man, his face pale, nodded slowly.

  “All right,” Rees said briskly. “Let’s look inwards now — past the Raft’s level, which is a thousand miles from the edge of the Nebula — and in to the center.”

  Now the monitor filled up with a familiar ruddy sky. Stars were scattered sparsely through the air. Rees punched a key—

  — and stars exploded out of the picture. The focus plummeted into the Nebula and it was as if they were falling.

  Finally the star cloud began to thin and a darker knot of matter emerged at its center.

  “What you’re seeing here is a layer of detritus in close orbit around the Core,” Rees said quietly. “At the heart of this Nebula is a black hole. If you’re not sure what that is right now, don’t worry… The black hole is about a hundredth of an inch wide; the large object we call the Core is a dense mass of material surrounding the hole. We can’t see through this cloud of rubble to the Core itself, but we believe it’s an ellipsoid about fifty mile
s across. And somewhere inside the Core will be the black hole itself and an accretion disc around it, a region perhaps a hundred feet wide in which matter is crushed out of existence as it is dragged into the hole…

  “At the surface of the Core the hole’s gravity is down to a mere several hundred gee. At the outer edge of the Nebula — where we are — it’s down to about one per cent of a gee; but even though it’s so small here the hole’s gravity is what binds this Nebula together.

  “And if we could travel into the Core itself we would find gravity climbing to thousands, millons of gee. Hollerbach has some theories about what happens near and within the Core, a realm of what he calls ‘gravitic chemistry’—”

  Nead frowned. “I don’t understand.”

  “I bet you don’t,” Rees laughed. “But I’ll tell you anyway, so you’ll know the questions to ask…

  “You see, in the day-to-day turmoil of things we — even we Scientists — tend to forget the central, astonishing fact of this cosmos — that the gravitational constant is a billon times larger than in the universe from which man arose. Oh, we see the macroscopic effects — for instance, a human body exerts a respectable gravitational field! — but what about the small, the subtle, the microscopic effects?”

  In man’s original universe, Rees went on, gravity was the only significant force over the interstellar scale. But over short ranges — on the scale of an individual atom — gravity was so tiny as to be negligible. “It is utterly dominated by even the electromagnetic force,” Rees said. “And that is why our bodies are shambling cages of electromagnetism; and attractive electrical forces between molecules drive the chemistry that sustains our being.

  “But here…” He rubbed his nose thoughtfully. “Here, things are different. Here, in certain circumstances, gravity can be as significant on the atomic scale as other forces — even dominant.

  “Hollerbach talks of a new kind of ‘atom.’ Its fundamental particles would be massive — perhaps they would be tiny black holes — and the atom would be bonded by gravity in novel, complex structures. A new type of chemistry — a gravitic chemistry — would be possible; a new realm of nature about whose form even Hollerbach can scarcely begin to speculate.”

  Nead frowned. “But why haven’t we observed this ‘gravitic chemistry’?”

  Rees nodded approvingly. “Good question. Hollerbach calculates that the right conditions must prevail: the right temperature and pressure, powerful gravitational gradients—”

  “In the Core,” Nead breathed. “I see. So perhaps—”

  There was a soft boom.

  The Bridge shifted slightly, as if a wave were passing through its structure. The image in the monitor broke up.

  Rees twisted. A sharp smell of burning, of smoke, touched his nostrils. The Scientists were milling in confusion, but the instruments seemed to be intact. Somewhere someone screamed.

  Fear creased Nead’s brow. “Is that normal?”

  “That came from the Library,” Rees murmured. “And, no, it’s not bloody normal.” He took a deep, calming breath; and when he spoke again his voice was steady. “It’s all right, Nead. I want you to get out of here as quickly as you can. Wait until…” His voice tailed away.

  Nead looked at him, half-understanding. “Until what?”

  “Until I send for you. Now move.”

  The boy half-swam to the exit and pushed his way through the crowd of Scientists.

  Trying to ignore the spreading panic around him Rees ran his fingers over the keyboard of the Telescope, locking the precious instrument into its rest position. Briefly he marveled at his own callous coolness. But in the end, he reflected, he was responding to a harsh, terrible truth. Humans could be replaced. The Telescope couldn’t.

  When he turned from the keyboard the Observatory was deserted. Paper and small tools lay scattered over the incorruptible floor, or floated in the equilibrium layer. And still that smell of burning hung in the air.

  With a sense of lightness he crossed the chamber floor and climbed out into the corridor. Smoke thickened the air, stinging his eyes, and as he approached the Library images of the imploded foundry and of the Theatre of Light confused his thoughts, as if his mind were a Telescope focusing on the buried depths of the past.

  Entering the Library was like climbing into an ancient, decayed mouth. Books and papers had been turned to blackened leaves and blasted against the walls; the ruined paper had been soaked through by the efforts of Scientists to save their treasure. There were three men still here, beating at smoldering pages with damp blankets. At Rees’s entry one of them turned. Rees was moved to recognize Grye, tears streaking his blackened cheeks.

  Rees ran a cautious finger over the shell of ruined books. How much had been lost this shift? — what wisdom that might have saved them all from the Nebula’s smoky death?

  Something crackled under his feet. There were shards of glass scattered over the floor, and Rees made out the truncated, smoke-stained neck of a wine-sim bottle. Briefly he found himself marveling that such a simple invention as a bottle filled with burning oil could wreak so much damage.

  There was nothing he could do here. He touched Grye’s shoulder briefly; then he turned and left the Bridge.

  There was no sign of security guards at the door. The scene outside was chaotic. Rees had a blurred impression of running men, of flames on the horizon; the Raft was a panorama of fists and angry voices. The harsh starlight from above flattened the scene, making it colorless and gritty.

  So it had come. His last hope that this incident might be restricted to just another attack on the Labs evaporated. The fragile web of trust and acceptance that had held the Raft together had finally collapsed…

  A few hundred yards away he made out a group of youths surrounding a bulky man; Rees thought he recognized Captain Mith. The big man went down under a hail of blows. At first, Rees saw, he tried to defend his head, his crotch; but blood spread rapidly over his face and clothing, and soon fists and feet were pounding into a shapeless, unresisting bulk.

  Rees turned his head away.

  In the foreground a small group of Scientists sat numbly on the deck, staring into the distance. They surrounded a bundle which looked like a charred row of books — perhaps something recovered from the fire?

  But there was the white of bone amid the charring.

  He felt his throat constrict; he breathed deeply, drawing on all his experience. This was not a good time to succumb to panic.

  He recognized Hollerbach. The old Chief Scientist sat a little apart from the rest, staring at the crumpled remains of his spectacles. He looked up as Rees approached, an almost comical mask of soot surrounding his eyes. “Eh? Oh, it’s you, boy. Well, this is a fine thing, isn’t it?”

  “What’s happening, Hollerbach?”

  Hollerbach toyed with his glasses. “Look at this. Half a million shifts old, these were, and absolutely irreplaceable. Of course, they never worked—” He looked up vaguely. “Isn’t it obvious what’s happening?” he snapped with something of his former vigor. “Revolution. The frustration, the hunger, the privations — they’re lashing out at what they can reach. And that’s us. It’s so damn stupid—”

  Unexpected anger flared in Rees. “I’ll tell you what’s stupid. You people keeping the rest of the Raft — and my own people on the Belt — in ignorance and hunger. That’s what’s stupid…”

  Hollerbach’s eyes in their pools of wrinkles looked enormously tired. “Well, you may be right, lad; but there’s nothing I can do about it now, and there never was. My job was to keep the Raft intact. And who’s going to do that in the future, eh?”

  “Mine rat.” The voice behind him was breathless, almost cracked with exhilaration. Rees whirled. Gover’s face was flushed, his eyes alive. He had torn the braids from his shoulders and his arms were blood-stained to the elbows. Behind him a dozen or more young men approached; as they studied the Officers’ homes their faces were narrow with hunger.

  Rees fou
nd his fists bunching — and deliberately uncurled them. Keeping his voice level he said, “I should have turned you in while I had the opportunity. What do you want, Gover?”

  “Last chance, rat,” Gover said softly. “Come with us now, or take what we dish out to these vicious old farts. One chance.”

  The stares of Gover and Hollerbach were almost palpable pressures: the stink of smoke, the noise, the bloodied corpse on the deck, all seemed to converge in his awareness, and he felt as if he were bearing on his back the weight of the Raft and all its occupants.

  Gover waited.

  7

  The rotation of the tethered tree was peaceful, soothing. Pallis sat by the warm trunk of the tree, chewing slowly on his flight rations.

  A head and shoulders thrust their way through the mat of foliage. It was a young man; his hair was filthy and tangled and sweat plastered a straggling beard to his throat. He looked about uncertainly.

  Pallis said softly: “I take it you’ve a good reason for disturbing my tree, lad. What are you doing here?”

  The visitor pulled himself through the leaves. Pallis noticed how the boy’s coverall bore the scars of recently removed braids. Shame, Pallis reflected, that the coverall itself hadn’t been removed — and washed — with equal vigor.

  “Regards to you, tree-pilot. My name’s Boon, of the Brotherhood of the Infrastructure. The Committee instructed me to find you—”

  “I don’t care if Boney Joe himself shoved a fibula up your arse to help you on your way,” Pallis said evenly. “I’ll ask you again. What are you doing in my tree?”

  Boon’s grin faded. “The Committee want to see you,” he said, his voice faint. “Come to the Platform. Now.”

  Pallis cut a slice of meat-sim. “I don’t want anything to do with your damn Committee, boy.”