Vacuum Diagrams

by Stephen Baxter

  What is this place? How did I get here? And...

  What's my name?

  His face grew slick with sweat; his breath sawed through his mouth. He perceived the shape of answers, like figures seen through a fog. He writhed against the shining ground.

  The answers floated away.

  A meaningless jingle ran around his mind: "We're here because we're here because we're here because we're here..."

  The grass vanished. He waited, hollow.

  Three men walked slowly through Sugar Lump City. Paul trailed Taft and Green, their urgent talk washing past his awareness. The sights, sounds and smells of the new City poured into his empty memory.

  The embryonic street was lined with blocky buildings of foamed meteorite ore. Most of the buildings were still dark, silent. Paul passed a construction site. Huge machines with ore spouts like mouths clawed aside meteorite debris and sprayed out floors and walls. The cold air was filled with dust, the stink of machine oil — and an incongruous tang of fresh-cut wood. Four workmen stalked around the site, shouting at the huge devices which did their bidding.

  Taft and Green had paused at the knee-high lip of a light well. Paul joined them and peered into the well. The exposed surface of the Sugar Lump, twenty feet down, was a shining disc. A beam of light thrust straight up from the well and splashed against curved mirrors above their heads, illuminating the surrounding streets.

  Shadows passed beneath the exposed plane like fish in a light-filled pond.

  The sky was blue-black. Above the City's thin layer of air Spline warships prowled, visibly spherical.

  Paul felt he was floating, suspended between mysteries above and below.

  "Coexistence with the Xeelee," Taft was saying. "That's what the colony is about. The meteorite impact which smeared rock over this Face of the Lump was a miraculous break. By terraforming this region and colonizing it we can prove to the Xeelee we don't have to go to war with them." He was a tall, heavily-built man of about physical-forty; the well's under-lighting gave his bearded face a demonic power, and when his metallic Eyes fixed on him, Paul felt a psychic shock.

  "And isn't your mysterious waif here going to endanger that?" Taft demanded.

  ...And one day, Paul realized, this man would try to kill him. He edged closer to Commander Green.

  Green interposed his short, blocky frame between Taft and Paul. Well light glittered from his ornate Navy epaulets. "Your colonization project isn't under question at present, Dr. Taft," he said briskly.

  "Isn't it?" Taft raised bushy eyebrows. "Then call off your Spline war dogs. Spend your resources on my terraforming efforts down here."

  Green spread callused hands. "Let's stick to the point, shall we? You know I don't have the authority to call off the exclusion fleet. And those who do are unlikely to withdraw as long as there's so much mystery, so much threat associated with the Sugar Lump."

  Taft snorted. "Threat? The government acts like a bunch of superstitious fools every time the Xeelee are mentioned. Look, Green, we've made a lot of progress. We've established that the Lump is an artifact, fabricated from Xeelee construction material—"

  "And that's about all you have established," Green said with a touch of steel. "Despite the money you've spent so far."

  "Commander, Xeelee construction plate isn't tissue paper. You can't just cut a hole in it."

  "I know that. So it seems to me that Paul here — with his proven non-local perception abilities — is our best hope of getting some hard data." He winked at Paul. "What I fail to see is what threat Paul represents to you."

  Taft stared at Paul. Well light glittered over his metal Eyes, and again Paul was flooded with a nameless fear. "I won't discuss this in front of the boy," Taft said.

  Paul worked to keep his voice level. "I'd like to hear what you have to say. And I'm not a boy, Doctor. Physically I'm twenty years old."

  Green grinned, showing even teeth. "Good for you."

  "Damn it, Green, we don't know anything about this — boy — of yours. He's found in a fouled, ill-fitting pressure suit on the exposed Face at the edge of the City. Nobody knows who he is, or how he got there — including Paul himself, so he says—"

  "His amnesia is genuine," Green broke in. "And as to how he got to the Lump — Taft, have you ever traveled on a Spline ship?"

  Taft glared at him. "Do I look like a Navy goon?"

  "A Spline warship," Green said patiently, "is a living creature. A sphere miles across. Its human crew occupy chambers hollowed out of the stomach lining. A Spline ship is a big, complex, disorderly place. If Paul was a stowaway he won't have been the first—"

  "He's an unknown," Taft insisted. "And by introducing him into this situation we incur an unknown risk."

  "But what's beyond question is his bizarre, quantum-mechanical perceptive faculty. He represents an enormous opportunity."

  Taft folded his arms and stared into the light well. "Suppose I refuse to cooperate?"

  "I have sufficient authority to force you, frankly," Green said quietly. "Officially this is a war zone."

  "I'll go over your head."

  "I could have you arrested. Requisition your staff. Doctor, you haven't much choice."

  Slowly, Taft nodded. "You're right, Commander. I don't have any choice. For the present." And he shot another savage metallic glance at Paul.

  "I'm glad we agree," Green said dryly. "Now, I believe you've a plan to have Paul taken to an Edge. That seems a good idea."

  Taft nodded reluctantly. "And if necessary we could go on to a Corner Mountain."

  "We?" Green asked suspiciously.

  Taft indicated the construction site a few yards away. The four workmen had gathered around a machine which had shattered a nozzle against a stubborn lump of rock. "You can see how busy we are," Taft said. "I'm not going to sacrifice my schedules for this — venture. I'll accompany the boy myself."

  The four workers sang softly as they hauled at the broken nozzle. Paul strained to hear their words, struck by an unaccountable feeling of significance.

  Green said carefully: "Of course I'll escort you both."

  "As you wish."

  "Well, shall we start?"

  The words of the work song drifted through the cold air: "We're here because we're here because we're here because we're here..."

  Paul stood transfixed. The words echoed around his head.

  Green touched his arm. "Paul? Are you okay?"

  Paul turned with difficulty. Green's lined face was reassuring. "That song," Paul said. "What does it mean?"

  Green listened for a few seconds, then chuckled. "Paul, soldiers and sailors have been singing that for centuries. Whenever they're forced to do something they don't particularly like. The tune's called 'Auld Lang Syne'. It's thought to predate the Qax Occupation..." He searched Paul's face. "Have you heard it before?"

  "I... don't know. Maybe."

  Green smiled sadly. "Come on. Let's catch up with Taft before he has us thrown off the Lump."

  Taft escorted them to a car at the edge of the City.

  The air here seemed colder and thinner. Raw meteorite material, scorched and fragmented, crunched under Paul's feet. On the horizon the Face of the Sugar Lump lay naked, as still and flat as a sea of light — a sea which stretched thousands of miles until it plummeted over an Edge, as if over some huge waterfall of photons.

  Twin cables ran over the debris and out over the Face. "We've laid cables across all the Lump's Faces, and along the Edges," Taft said with an ironic smile. "We've wrapped up this huge mystery like a birthday parcel, eh, Paul?" He opened up the car. It was a cylinder about forty feet long which clung like a glassy insect to its cables. Most of the hull was transparent, and it contained two rows of five large seats which were suspended from complex sets of gimbals. Taft helped Paul settle; straps were passed over his shoulders and around his waist, giving him a vicarious sense of security.

  Taft took a seat near the front end of the car, before an instrument panel whic
h centered on a small joystick. Taft pushed the stick forward and, with a jolt, the car began to pull itself along the cables.

  They crawled out of the City's dome of atmosphere. The sky's deep blue faded, exposing hard stars. Spline ships drifted past the stars, diamond sharp.

  The dark meteorite material grew sparse, and soon they were sailing smoothly over a glowing ocean. Occasional shadows, faint and miles across, washed from horizon to horizon.

  Taft opaqued the hull, turning the car into a comfortable bubble of normality. Paul clung to his straps and settled into an uneasy sleep.

  Light returned in a flood. Paul snapped awake... and screamed.

  His chair had swiveled back on its gimbals. The nose of the car had tipped up through at least ten degrees. Outside, the Sugar Lump had tilted, too. He was falling backwards—

  Green stood before him. "Paul. Stop it. You're perfectly safe."

  His throat was tight; he gulped for breath. "What's happening?"

  He heard Taft laugh. "I've told the damn kid what to expect on this trip."

  "Then tell him again," Green snapped. He turned and, clinging to handholds, made his way to the car's small galley area.

  Taft reclined comfortably in the drive chair. He was eating a small peach; gobbets of orange flesh clung to his beard. "I didn't realize your memory continues to fail, mystery boy—"

  "Skip it, Taft," Green said casually.

  Taft took another bite at his fruit. "Very well. Look, Paul, the surface on which the colony sits is utterly flat. The center of gravity of the Sugar Lump is somewhere beneath the center of the plane. The air we've been burning out of the meteorite material is attracted towards the center of gravity, so it clings to the middle of the plane as a kind of low dome. But now we've climbed away from the air and we're being pulled back to the center of gravity. So your chair swivels until it points straight down to the center — but that means it's at an angle to the plane's local vertical. We seem to be climbing up an incline. By the time we get to the Edge we'll appear to be climbing at almost forty-five degrees. See?"

  Paul twisted in his chair until he could look back the way the car had climbed. The twin cables were geometrically perfect lines laid over a shallow, glowing slope. Thousands of miles distant, covered by a blue dome of air, the brownish meteorite debris lay splashed over the unblemished plane.

  It looked as if the whole arrangement should slide off into space.

  Paul shuddered and turned away. Green stood awkwardly on the tilting floor, sipping a coffee. "How do you feel? Better?"

  Paul shrugged. "How should I feel? Commander, the Sugar Lump has been strong enough to withstand a major meteorite impact. Without so much as a scratch. How am I going to get through it?"

  Green ran a hand over his closely-cropped, graying hair. "Paul, the Xeelee always build big. And tough. I'll tell you about Bolder's Ring sometime... what I'm saying is that the awe you feel won't go away. But you'll get used to it.

  "And remember, you're not a meteorite. You're not trying to blast your way through." He lowered his voice. "And that's been Taft's mistake. He's fired off lasers, projectiles, particle beams — like a stream of little meteorites, yeah? And the success he's had is precisely zero.

  "You're different, Paul." Green leaned forwards, his expression a crumpled mixture of compassion and fascination. "You've this extraordinary talent. You're not unique; I don't want you to think that." He smiled. "None of us has any doubts about your humanity... and all of us share your faculty, your quantum-mechanical way of seeing things, to some extent. Did you know that the dark-adapted eye, even without augmentation, can pick up a single photon? So straightforward human senses can perceive events at the quantum level. And there's speculation that consciousness itself is a quantum process... What's different about you is the strength of this — talent. The rest of us live here in the macro world, this smoothed-over mock-up of the truth. But sometimes you can see beyond the approximations and shams; you seem to be able to see right down to the fundamental level of quantum wave functions." Green's voice grew intense. "You see, Paul, in Taft's Universe the surface of the Lump is certain to keep out a meteorite. But in your Universe nothing is certain."

  Paul twisted away. "I don't want to be uncertain, Commander. I'm frightened. I don't even know my real name."

  Green grasped his shoulders. "Look, Paul, you are a puzzle to us. There's no point pretending otherwise. But the parts of the puzzle have to be connected. Where you came from must be connected with the way you are. And by doing this thing, by extending your talent to its limits, I believe you're going to discover more than what the Xeelee are up to inside the Sugar Lump. I believe you'll discover yourself."

  Paul found himself shuddering. He tried to concentrate on the straps around his waist, the reassuring hands on his shoulders.

  "Yeah," Taft said slyly. "Or maybe you'll discover you're nothing more than a vacuum diagram. What about that, eh, Paul?"

  "A what?"

  "Shut up, Taft."

  "Come on, Commander. If this is a revision class, then let's revise it all." Taft stepped up to stand before Paul, grinning, brittle with bitterness. "You told me how you took Paul up to the Spline fleet, put him through a crash course on how to be a human. Well, what about your quantum physics, Paul? Remember Feynman diagrams? Those cute pictures which show particles interacting, living, dying?"

  "Taft..." Green growled.

  "Well, now, here's a remarkable little interaction. From out of nowhere pop three particles — a pion, a proton, and an antineutron. Of course conservation is violated all over the place — but thanks to the Uncertainty Principle nothing is absolute in this Universe. I presume that's the concept our naval friend was groping for just now. And then the diagram closes up. The three particles recombine — they disappear back into the vacuum again, and conservation is reasserted. What a relief!

  "But what really happens is that the antineutron is created at that final impact and moves back through time to initiate the creation of the other particles! Bizarre enough for you? And so this particular Feynman picture is a closed loop. A vacuum diagram. The particles come from nothing and return to nothing." He grinned. "We're here because we're here because—"

  Green raised one massive uniformed arm, pushed Taft away easily, muttered something Paul couldn't hear.

  Paul closed his eyes, hoping to make the incomprehensible Universe disappear into the vacuum from which it had sprung.

  The approaching Edge was a knife-blade across the stars. The car climbed the one-in-one slope ever more slowly, finally stopping a hundred yards from the rim. "Come on, Paul," Green said. "We walk from here." Briskly he helped Paul seal himself into a light, one-piece pressure suit. "And go easy. Remember we're that much further from the Lump's center of mass; gravity is only about half what it is in the City."

  Paul climbed through the car's membranelike airlock. A handrail had been bonded to the surface a few yards from the car. Paul stumbled towards it. The apparent forty-five-degree slope was without purchase, and his motions felt slow and dreamlike, as if he were underwater.

  Clinging closely to the rail he turned and surveyed the Sugar Lump.

  Beneath his feet was a hillside of glowing glass. Shadows bigger than cities moved through it. Paul knew the Face was a square six thousand miles to a side, and he had half-expected to see details of far Edges and Corners from this vantage point; but beyond a few hundred miles the surface collapsed in his vision into a single, shining line of light. Sugar Lump City was a low dome of blue, improbably clinging to the center of the line.

  "Paul," Green said softly. "Look up."

  Paul craned his neck. A Spline warship swooped overhead, no more than ten miles from the Edge. Paul could make out valley-sized wrinkles in the fleshy sphere, weapon emplacements twinkling in deep pocks. Finally the warship sailed over the Edge of the world, rolling grandly.

  "They know we're here," Green said. "That was a salute roll."

  His voice seemed to c
ome to Paul from far away. A sense of distance swept over him; it was as if he were shrinking, or as if the Universe were receding in all directions.

  "Paul?... Are you okay?"

  "What's wrong with him? Damn it, the kid's a liability."

  "Take it easy, Taft. Sometimes this state of semifaint is a prelude to his heightened awareness phases. Come on, help me get him to the Edge."

  The words swam by like fish. Green and Taft stood to either side of him, grasping his arms. They were figures of wood and paper, moving with dry rustles. The light of the Lump burned through them.

  At last they stood in a line on the rim of the world. The Edge was an arrow-straight ridge, with the two identical Faces falling away on either side. It was like standing on the roof of some huge house. Cables had been laid along the Edge; a second car clung to them. Bundles of maintenance equipment had been fixed to the surface close to the car site.

  "I hope this trip was worth it," Green said, panting.

  Taft barked laughter. The sound was like a dry leaf crumpling. "Well, you asked for my guidance and you got it. Obviously the stresses on the material are higher here than close to the center of a Face. So if your wonder boy is going to gain access he has as good a chance here as anywhere. Watch out for the Edge itself, though. It's sharp as a knife, down to the finest limits we can perceive."

  "No," Paul said.

  Green and Taft stared at him, releasing his arms. With the loss of physical contact they became still more insubstantial, receding from his vision like ghosts.

  He knelt awkwardly and ran a gloved finger along the Edge. The stuff was soft; it rippled. It was like running a hand through a fine, multicolored grass.

  Words like "sharp" were meaningless, of course; wooden words used by macro-men.

  Green had given him the language to understand what he was perceiving: that this was the fundamental level of reality, the grain of quantum-mechanical probability wave functions.

  An event was like a stone thrown into a pond; probability functions — ripples of what-might-be — spread out through space and time. Macro-men might see the pale shadows where the waves were thickest.