Vacuum Diagrams

“Who knows? It’s the best we can do. When we have your clearance, we can transmit our data to Earth, and let the experts get at it.”

“Lethe, Frank,” Larionova said. “This looks like a fish. It looks like it could swim. The streamlining, the tail—”

Dixon scratched the short hairs at the back of his neck and said nothing.

“But we’re on Mercury, damn it, not in Hawaii,” Larionova said.

Dixon pointed down, past the dusty floor. “Irina. It’s not all frozen. There are cavities down there, inside the Chao ice cap. According to our sonar probes—”

“Cavities?”

“Water. At the base of the crater, under a couple of miles of ice. Kept liquid by thermal vents, in crust-collapse scarps and ridges. Plenty of room for swimming… we speculate that our friend here swims on his back—” he tapped the desk surface, and the image swiveled “ — and the water passes down, between his body and this carapace, and he uses all those tiny hairs to filter out particles of food. The trunk seems to be lined with little mouths. See?” He flicked the image to another representation; the skin became transparent, and Larionova could see blocky reconstructions of internal organs. Dixon said, “There’s no true stomach, but there is what looks like a continuous digestive tube passing down the axis of the body, to the anus at the tail.”

Larionova noticed a threadlike structure wrapped around some of the organs, as well as around the axial digestive tract.

“Look,” Dixon said, pointing to one area. “Look at the surface structure of these lengths of tubing, here near the digestive tract.”

Larionova looked. The tubes, clustering around the digestive axis, had complex, rippled surfaces. “So?”

“You don’t get it, do you? It’s convoluted — like the surface of a brain. Irina, we think that stuff must be some equivalent of nervous tissue.”

Larionova frowned. Damn it, I wish I knew more biology. “What about this thread material, wrapped around the organs?”

Dixon sighed. “We don’t know, Irina. It doesn’t seem to fit with the rest of the structure, does it?” He pointed. “Follow the threads back. There’s a broader main body, just here. We think maybe this is some kind of parasite, which has infested the main organism. Like a tapeworm. It’s as if the threads are extended, vestigial limbs…”

Leaning closer, Larionova saw that tendrils from the wormthing had even infiltrated the brain-tubes. She shuddered; if this was a parasite, it was a particularly vile infestation. Maybe the parasite even modified the mercuric’s behavior, she wondered.

Dixon restored the solid-aspect Virtual.

Uneasily, Larionova pointed to the markings on the carapace. They were small triangles, clustered into elaborate patterns. “And what’s this stuff?”

Dixon hesitated. “I was afraid you might ask that.”

“Well?”

“…We think the markings are artificial, Irina. A deliberate tattoo, carved into the carapace, probably with the mandibles. Writing, maybe: those look like symbolic markings, with information content.”

“Lethe,” she said.

“I know. This fish was smart,” Dixon said.

The people, victorious, clustered around the warmth of their new Chimney. Recovering from their journey and from their battle-wounds, they cruised easily over the gardens of cilia-plants, and browsed on floating fragments of food.

It had been a great triumph. The Heads were dead, or driven off into the labyrinth of tunnels through the Ice. Strong-Flukes had even found the Heads’ principal nest here, under the silty floor of the cavern. With sharp stabs of her mandibles, Strong-Flukes had destroyed a dozen or more Head young.

Cilia-of-Gold took herself off, away from the Chimney. She prowled the edge of the Ice cavern, feeding fitfully.

She was a hero. But she couldn’t bear the attention of others: their praise, the warmth of their bodies. All she seemed to desire now was the uncomplicated, silent coolness of Ice.

She brooded on the infestation that was spreading through her.

Seekers were a mystery. Nobody knew why Seekers compelled their hosts to isolate themselves, to bury themselves in the Ice. What was the point? When the hosts were destroyed, so were the Seekers.

Perhaps it wasn’t the Ice itself the Seekers desired, she wondered. Perhaps they sought, in their blind way, something beyond the Ice…

But there was nothing above the Ice. The caverns were hollows in an infinite, eternal Universe of Ice. Cilia-of-Gold, with a shudder, imagined herself burrowing, chewing her way into the endless Ice, upwards without limit… Was that, finally, how her life would end?

She hated the Seeker within her. She hated her body, for betraying her in this way; and she hated herself.

“Cilia-of-Gold.”

She turned, startled, and closed her carapace around herself reflexively.

It was Strong-Flukes and Ice-Born, together. Seeing their warm, familiar bodies, here in this desolate corner of the cavern, Cilia-of-Gold’s loneliness welled up inside her, like a Chimney of emotion.

But she swam away from her Three-mates, backwards, her carapace scraping on the cavern’s Ice wall.

Ice-Born came towards her, hesitantly. “We’re concerned about you.”

“Then don’t be,” she snapped. “Go back to the Chimney, and leave me here.”

“No,” Strong-Flukes said quietly.

Cilia-of-Gold felt desperate, angry, confined. “You know what’s wrong with me, Strong-Flukes. I have a Seeker. It’s going to kill me. And there’s nothing any of us can do about it.”

Their bodies pressed close around her now; she longed to open up her carapace to them and bury herself in their warmth.

“We know we’re going to lose you, Cilia-of-Gold,” Ice-Born said. It sounded as if she could barely speak. Ice-Born had always been the softest, the most loving, of the Three, Cilia-of-Gold thought, the warm heart of their relationship. “And—”

“Yes?”

Strong-Flukes opened her carapace wide. “We want to be Three again,” she said.

Already, Cilia-of-Gold saw with a surge of love and excitement, Strong-Flukes’s ovipositor was distended: swollen with one of the three isogametes which would fuse to form a new child, their fourth…

A child Cilia-of-Gold could never see growing to consciousness.

“No!” Her cilia pulsed with the single, agonized word.

Suddenly the warmth of her Three-mates was confining, claustrophobic. She had to get away from this prison of flesh; her mind was filled with visions of the coolness and purity of Ice: of clean, high Ice.

“Cilia-of-Gold. Wait. Please—”

She flung herself away, along the wall. She came to a tunnel mouth, and she plunged into it, relishing the tunnel’s cold, stagnant water.

“Cilia-of-Gold! Cilia-of-Gold!”

She hurled her body through the web of tunnels, carelessly colliding with walls of Ice so hard that she could feel her carapace splinter. On and on she swam, until the voices of her Three-mates were lost forever.

We’ve dug out a large part of the artifact, Irina, Dolores Wu reported. It’s a mass of what looks like hull material.

“Did you get a sample?”

No. We don’t have anything that could cut through material so dense… Irina, we’re looking at something beyond our understanding.

Larionova sighed. “Just tell me, Dolores,” she told Wu’s data-desk image.

Irina, we think we’re dealing with the Pauli Principle.

Pauli’s Exclusion Principle stated that no two fermions — electrons or quarks — could exist in the same quantum state. Only a certain number of electrons, for example, could share a given energy level in an atom. Adding more electrons caused complex shells of charge to build up around the atom’s nucleus. It was the electron shells — this consequence of Pauli — that gave the atom its chemical properties.

But the Pauli Principle didn’t apply to photons; it was possible for many photons to share the same quantum state. That was the essence of the laser: billions of photons, coherent, sharing the same quantum properties.

Irina, Wu said slowly, what would happen if you could turn off the Exclusion Principle, for a piece of fermionic matter?

“You can’t,” Larionova said immediately.

Of course not. Try to imagine anyway.

Larionova frowned. What if one could lase mass? “The atomic electron shells would implode, of course.”

Yes.

“All electrons would fall into their ground state. Chemistry would be impossible.”

Yes. But you may not care…

“Molecules would collapse. Atoms would fall into each other, releasing immense quantities of binding energy.”

You’d end up with a super dense substance, wouldn’t you? Completely non-reactive, chemically. And almost unbreachable, given the huge energies required to detach non-Pauli atoms.

Ideal hull material, Irina…

“But it’s all impossible,” Larionova said weakly. “You can’t violate Pauli.”

Of course you can’t, Dolores Wu replied.

Inside an opaqued bubble-shelter, Larionova, Dixon and Scholes sat on fold-out chairs, cradling coffees.

“If your mercuric was so smart,” Larionova said to Dixon, “how come he got himself stuck in the ice?”

Dixon shrugged. “In fact it goes deeper than that. It looked to us as if the mercuric burrowed his way up into the ice, deliberately. What kind of evolutionary advantage could there be in behavior like that? The mercuric was certain to be killed.”

“Yes,” Larionova said. She massaged her temples, thinking about the mercuric’s infection. “But maybe that thread-parasite had something to do with it. I mean, some parasites change the way their hosts behave.”

Scholes tapped at a data desk; text and images, reflected from the desk, flickered over his face. “That’s true. There are parasites which transfer themselves from one host to another — by