Vacuum Diagrams

by Stephen Baxter

  By such crude means, Michael Poole and his people had opened up the Solar System.

  "They made Lethe's own mess of Charon," Lvov said.

  She could almost see Cobh's characteristic shrug. So what?

  Pluto's surface was geologically complex, here at this point of maximal tidal stress. She flew over ravines and ridges; in places, it looked as if the land had been smashed up with an immense hammer, cracked and fractured. She imagined there was a greater mix, here, of interior material with the surface ice.

  In many places she saw gatherings of the peculiar snowflakes she had noticed before. Perhaps they were some form of frosting effect, she wondered. She descended, thinking vaguely of collecting samples.

  She killed the scooter's jets some yards above the surface, and let the little craft fall under Pluto's gentle gravity. She hit the ice with a soft collision, but without heat-damaging the surface features much beyond a few feet.

  She stepped off the scooter. The ice crunched, and she felt layers compress under her, but the fractured surface supported her weight. She looked up towards Charon. The crimson moon was immense, round, heavy.

  She caught a glimmer of light, an arc, directly above her.

  It was gone immediately. She closed her eyes and tried to recapture it. A line, slowly curving, like a thread. A web. Suspended between Pluto and Charon.

  She looked again, with her face plate set to optimal enhancement. She couldn't recapture the vision.

  She didn't say anything to Cobh.

  "I was right, by the way," Cobh was saying.

  "What?" Lvov tried to focus.

  "The wormhole instability, when we crashed. It did cause an Alcubierre wave."

  "What's an Alcubierre wave?"

  "The Interface's negative energy region expanded from the tetrahedron, just for a moment. The negative energy distorted a chunk of space time. The chunk containing the flitter, and us."

  On one side of the flitter, Cobh said, space-time had contracted. Like a model black hole. On the other side, it expanded — like a re-run of the Big Bang, the expansion at the beginning of the Universe.

  "An Alcubierre wave is a front in space-time. The Interface — with us embedded inside — was carried along. We were pushed away from the expanding region, and towards the contraction."

  "Like a surfer, on a wave."

  "Right." Cobh sounded excited. "The effect's been known to theory, almost since the formulation of relativity. But I don't think anyone's observed it before."

  "How lucky for us," Lvov said drily. "You said we traveled faster than light. But that's impossible."

  "You can't move faster than light within space-time. Wormholes are one way of getting around this; in a wormhole you are passing through a branch in space-time. The Alcubierre effect is another way. The superluminal velocity comes from the distortion of space itself; we were carried along within distorting space.

  "So we weren't breaking lightspeed within our raft of space-time. But that space-time itself was distorting at more than light-speed."

  "It sounds like cheating."

  "So sue me. Or look up the math."

  "Couldn't we use your Alcubierre effect to drive starships?"

  "No. The instabilities and the energy drain are forbidding."

  One of the snowflake patterns lay mostly undamaged, within Lvov's reach. She crouched and peered at it. The flake was perhaps a foot across. Internal structure was visible within the clear ice as layers of tubes and compartments; it was highly symmetrical, and very complex. She said to Cobh, "This is an impressive crystallization effect. If that's what it is." Gingerly she reached out with thumb and forefinger, and snapped a short tube off the rim of the flake. She laid the sample on her desk. After a few seconds the analysis presented. "It's mostly water-ice, with some contaminants," she told Cobh. "But in a novel molecular form. Denser than normal ice, a kind of glass. Water would freeze like this under high pressures — several thousand atmospheres."

  "Perhaps it's material from the interior, brought out by the chthonic mixing in that region."

  "Perhaps." Lvov felt more confident now; she was intrigued. "Cobh, there's a larger specimen a few feet further away."

  "Take it easy, Lvov."

  She stepped forward. "I'll be fine. I — "

  The surface shattered.

  Lvov's left foot dropped forward, into a shallow hole; something crackled under the sole of her boot. Threads of ice crystals, oddly woven together, spun up and tracked precise parabolae around her leg.

  The fall seemed to take an age; the ice tipped up towards her like an opening door. She put her hands out. She couldn't stop the fall, but she was able to cushion herself, and she kept her face plate away from the ice. She finished up on her backside; she felt the chill of Pluto ice through the suit material over her buttocks and calves.

  "...Lvov? Are you okay?"

  She was panting, she found. "I'm fine."

  "You were screaming."

  "Was I? I'm sorry. I fell."

  "You fell? How?"

  "There was a hole, in the ice." She massaged her left ankle; it didn't seem to be hurt. "It was covered up."

  "Show me."

  She got to her feet, stepped gingerly back to the open hole, and held up her data desk. The hole was only a few inches deep. "It was covered by a sort of lid, I think."

  "Move the desk closer to the hole." Light from the desk, controlled by Cobh, played over the shallow pit.

  Lvov found a piece of the smashed lid. It was mostly ice, but there was a texture to its undersurface, embedded thread which bound the ice together.

  "Lvov," Cobh said. "Take a look at this."

  Lvov lifted the desk aside and peered into the hole. The walls were quite smooth. At the base there was a cluster of spheres, fist-sized. Lvov counted seven; all but one of the spheres had been smashed by her stumble. She picked up the one intact sphere, and turned it over in her hand. It was pearl-gray, almost translucent. There was something embedded inside, disc-shaped, complex.

  Cobh sounded breathless. "Are you thinking what I'm thinking?"

  "It's an egg," Lvov said. She looked around wildly, at the open pit, the egg, the snowflake patterns. Suddenly she saw the meaning of the scene; it was as if a light had shone up from within Pluto, illuminating her. The "snowflakes" represented life, she intuited; they had dug the burrows, laid these eggs, and now their bodies of water glass lay, dormant or dead, on the ancient ice...

  "I'm coming down," Cobh said sternly. "We're going to have to discuss this. Don't say anything to the inner System; wait until I get back. This could mean trouble for us, Lvov."

  Lvov placed the egg back in the shattered nest.

  She met Cobh at the crash scar. Cobh was shoveling nitrogen and water-ice into the life-support modules' raw material hopper. She hooked up her own and Lvov's suits to the modules, recharging the suits' internal systems. Then she began to carve GUTdrive components out of the flitter's hull. The flitter's central Grand Unified Theory chamber was compact, no larger than a basketball, and the rest of the drive was similarly scaled. "I bet I could get this working," Cobh said. "Although it couldn't take us anywhere."

  Lvov sat on a fragment of the shattered hull. Tentatively, she told Cobh about the web.

  Cobh stood with hands on hips, facing Lvov, and Lvov could hear her sucking drink from the nipples in her helmet. "Spiders from Pluto? Give me a break."

  "It's only an analogy," Lvov said defensively. "I'm an atmospheric specialist, not a biologist." She tapped the surface of her desk. "It's not spider-web. Obviously. But if that substance has anything like the characteristics of true spider silk, it's not impossible." She read from her desk. "Spider silk has a breaking strain twice that of steel, but thirty times the elasticity. It's a type of liquid crystal. It's used commercially — did you know that?" She fingered the fabric of her suit. "We could be wearing spider silk right now."

  "What about the hole with the lid?"

  "There are trapdo
or spiders in America. On Earth. I remember, when I was a kid... the spiders make burrows, lined with silk, with hinged lids."

  "Why make burrows on Pluto?"

  "I don't know. Maybe the eggs can last out the winter that way. Maybe the creatures, the flakes, only have active life during the perihelion period, when the atmosphere expands and enriches." She thought that through. "That fits. That's why the Poole people didn't spot anything. It's only fifty-five years since the construction team was here, and even then Pluto was receding from the Sun. Pluto's year is so long that we're still approaching the next aphelion — "

  "So how do they live?" Cobh snapped. "What do they eat?"

  "There must be more to the ecosystem than one species," Lvov conceded. "The flakes — the spiders — need water glass. But there's little of that on the surface. Maybe there is some biocycle — plants or burrowing animals — which brings ice and glass to the surface, from the interior."

  "That doesn't make sense. The layer of nitrogen over water-ice is too deep."

  "Then where do the flakes get their glass?"

  "Don't ask me," Cobh said. "It's your dumb hypothesis. And what about the web? What's the point of that — if it's real?"

  Lvov ground to a halt. "I don't know," she said lamely. Although Pluto/Charon is the only place in the System where you could build a spider-web between worlds.

  Cobh toyed with a fitting from the drive. "Have you told anyone about this yet? In the inner System, I mean."

  "No. You said you wanted to talk about that."

  "Right." Lvov saw Cobh close her eyes; her face was masked by the glimmer of her face plate. "Listen. Here's what we say. We've seen nothing here. Nothing that couldn't be explained by crystallization effects."

  Lvov was baffled. "What are you talking about? What about the eggs? Why would we lie about this? Besides, we have the desks — records."

  "Data desks can be lost, or wiped, or their contents amended."

  Lvov wished she could see Cobh's face. "Why would we do such a thing?"

  "Think it through. Once Earth hears about this, these flake-spiders of yours will be protected. Won't they?"

  "Of course. What's bad about that?"

  "It's bad for us, Lvov. You've seen what a mess the Poole people made of Charon. If this system is inhabited, a fast GUTship won't be allowed to come for us. It wouldn't be allowed to refuel here. Not if it meant further damage to the native life-forms."

  Lvov shrugged. "So we'd have to wait for a slower ship. A liner; one that won't need to take on more reaction mass here."

  Cobh laughed at her. "You don't know much about the economics of GUTship transport, do you? Now that the System is criss-crossed by Poole wormholes, how many liners like that do you think are still running? I've already checked the manifests. There are two liners capable of a round trip to Pluto still in service. One is in dry dock; the other is heading for Saturn — "

  "On the other side of the System."

  "Right. There's no way either of those ships could reach us for, I'd say, a year."

  We only have a month's supplies. A bubble of panic gathered in Lvov's stomach.

  "Do you get it yet?" Cobh said heavily. "We'll be sacrificed, if there's a chance that our rescue would damage the new ecology, here."

  "No. It wouldn't happen like that."

  Cobh shrugged. "There are precedents."

  She was right, Lvov knew. In the case of the "tree stump" life-forms discovered on a remote Kuiper object, the territory had been ring-fenced, the local conditions preserved, once life — even a plausible candidate for life — was recognized.

  Cobh said, "Pan-genetic diversity. Pan-environmental management. That's the key to it; the public policy of preserving all the species and habitats of Sol, into the indefinite future. The lives of two humans won't matter a damn against that."

  "What are you suggesting?"

  "That we don't tell the inner System about the flakes."

  Lvov tried to recapture her mood of a few days before: when Pluto hadn't mattered to her, when the crash had been just an inconvenience. Now, suddenly, we're talking about threats to our lives, the destruction of an ecology.

  What a dilemma. If I don't tell of the flakes, their ecology may be destroyed during our rescue. But if I do tell, the GUTship won't come for me, and I'll lose my life.

  Cobh seemed to be waiting for an answer.

  Lvov thought of how Sol light looked over Pluto's ice fields, at dawn.

  She decided to stall. "We'll say nothing. For now. But I don't accept either of your options."

  Cobh laughed. "What else is there? The wormhole is destroyed; even this flitter is disabled."

  "We have time. Days, before the GUTship is due to be launched. Let's search for another solution. A win-win."

  Cobh shrugged. She looked suspicious.

  She's right to be, Lvov thought, exploring her own decision with surprise. I've every intention of telling the truth later, of diverting the GUTship, if I have to.

  I may give up my life, for this world.

  I think.

  In the days that followed, Cobh tinkered with the GUTdrive, and flew up to the Interface to gather more data on the Alcubierre phenomenon.

  Lvov roamed the surface of Pluto, with her desk set to full record. She came to love the wreaths of cirrus clouds, the huge, misty moon, the slow, oceanic pulse of the centuries-long year.

  Everywhere she found the inert bodies of snowflakes, or evidence of their presence: eggs, lidded burrows. She found no other life-forms — or, more likely, she told herself, she wasn't equipped to recognize any others.

  She was drawn back to Christy, the sub-Charon point, where the topography was at its most complex and interesting, and where the greatest density of flakes was to be found. It was as if, she thought, the flakes had gathered here, yearning for the huge, inaccessible moon above them. But what could the flakes possibly want of Charon? What did it mean for them?

  Lvov encountered Cobh at the crash scar, recharging her suit's systems from the life-support packs. Cobh seemed quiet. She kept her face, hooded by her face plate, turned from Lvov.

  Lvov watched her for a while. "You're being evasive," she said eventually. "Something's changed — something you're not telling me about."

  Cobh made to turn away, but Lvov grabbed her arm. "I think you've found a third option. Haven't you? You've found some other way to resolve this situation, without destroying either us or the flakes."

  Cobh shook off her hand. "Yes. Yes, I think I know a way. But — "

  "But what?"

  "It's dangerous, damn it. Maybe unworkable. Lethal." Cobh's hands pulled at each other.

  She's scared, Lvov saw. She stepped back from Cobh. Without giving herself time to think about it, she said, "Our deal's off. I'm going to tell the inner System about the flakes. Right now. So we're going to have to go with your new idea, dangerous or not."

  Cobh studied her face; Cobh seemed to be weighing up Lvov's determination, perhaps even her physical strength. Lvov felt as if she were a data desk being downloaded. The moment stretched, and Lvov felt her breath tighten in her chest. Would she be able to defend herself, physically, if it came to that? And — was her own will really so strong?

  I have changed, she thought. Pluto has changed me.

  At last Cobh looked away. "Send your damn message," she said.

  Before Cobh — or Lvov herself — had a chance to waver, Lvov picked up her desk and sent a message to the inner worlds. She downloaded all the data she had on the flakes: text, images, analyses, her own observations and hypotheses.

  "It's done," she said at last.

  "And the GUTship?"

  "I'm sure they'll cancel it." Lvov smiled. "I'm also sure they won't tell us they've done so."

  "So we're left with no choice," Cobh said angrily. "Look: I know it's the right thing to do. To preserve the flakes. I just don't want to die, that's all. I hope you're right, Lvov."

  "You haven't told me how we're go
ing to get home."

  Cobh grinned through her face plate. "Surfing."

  "All right. You're doing fine. Now let go of the scooter."

  Lvov took a deep breath, and kicked the scooter away with both legs; the little device tumbled away, catching the deep light of Sol, and Lvov rolled in reaction.

  Cobh reached out and steadied her. "You can't fall," Cobh said. "You're in orbit. You understand that, don't you?"

  "Of course I do," Lvov grumbled.

  The two of them drifted in space, close to the defunct Poole wormhole Interface. The Interface itself was a tetrahedron of electric blue struts, enclosing darkness, its size overwhelming; Lvov felt as if she was floating beside the carcass of some huge, wrecked building.

  Pluto and Charon hovered before her like balloons, their surfaces mottled and complex, their forms visibly distorted from the spherical. Their separation was only fourteen Pluto-diameters. The worlds were strikingly different in hue, with Pluto a blood red, Charon ice blue. That's the difference in surface composition, Lvov thought absently. All that water-ice on Charon's surface.

  The panorama was stunningly beautiful. Lvov had a sudden, gut-level intuition of the rightness of the various System authorities' rigid pan-environment policies.

  Cobh had strapped her data desk to her chest; now she checked the time. "Any moment now. Lvov, you'll be fine. Remember, you'll feel no acceleration, no matter how fast we travel. At the center of an Alcubierre wave, space-time is locally flat; you'll still be in free fall. There will be tidal forces, but they will remain small. Just keep your breathing even, and — "

  "Shut up, Cobh," Lvov said tightly. "I know all this."

  Cobh's desk flared with light. "There," she breathed. The GUT-drive has fired. "Just a few seconds, now."

  A spark of light arced up from Pluto's surface and tracked, in complete silence, under the belly of the parent world. It was the flitter's GUTdrive, salvaged and stabilized by Cobh. The flame was brighter than Sol; Lvov saw its light reflected in Pluto, as if the surface was a great, fractured mirror of ice. Where the flame passed, tongues of nitrogen gas billowed up.

  The GUTdrive passed over Christy. Lvov had left her desk there, to monitor the flakes, and the image the desk transmitted, displayed in the corner of her face plate, showed a spark, crossing the sky.