"We're ready," Davos said. Xie assented. "Initiate connection."
Davos closed his eyes.
Nothing happened.
"My internal sensors indicate that one of your neural transceivers is only partially active, Davos," Gabriele said. "Please ensure that the unit is fully engaged."
"My apologies," Davos said. Good. Now he knew how sensitive the connection was. Which might just save their lives.
He didn't open his eyes to study Xie's reaction. Entering a command into the transceiver, he felt a tingle spread across his forehead as the unit bloomed to full power.
Underneath his bodysuit, despite his earlier comment, he was sweating profusely.
"Initiate connection," he repeated, and held his breath.
He was tickled by electricity for a few instants. Then a jarring charge, burning the seat straps, nearly flung him from his seat. His skin was on fire and his brain shouted at him to free himself from this death trap. But he clenched his fists and remained seated. The charge increased, crackling in the air as it flashed from the transceivers down through his body. His organs seemed to liquefy.
Then, just as quickly as it had kicked in, the charge subsided and the course of the current reversed; electricity leapt up from his body-suit and into the transceivers, down the cables, and into the ship's network.
A series of explosions deafened them. Acrid smoke followed.
With still-shuddering arms, Davos unstrapped himself from the interface chair and attempted to bounce over to Xie's console. Instead he slumped against the nearest wall.
Xie was floating beside him instants later, eyes wide with shock. "You have first degree burns." She fetched an emergency medkit from her EVA suit and began working it.
"Gabriele only needed one of us to trigger the ship's FTL," Davos said. "Efficient use of resources mandated she kill me. But don't feel too special—I'm sure once the ship had jumped, it would have been your turn."
The little speech exhausted him into silence. Xie's ministrations, superficial as they were, felt good. It had been a long time since she had touched him....
He groaned. "Help me get this damned bodysuit off."
She peeled it from him, reached his torso, and then stopped.
"You knew Gabriele was going to try and electrocute you," she said. "That's why you dyed the fabric."
"Don't stop. It stings like hell." She resumed the delicate separation of singed fabric from flesh. "I suspected as much, yes. I dyed the suit with conducting carbon nanotubes, hoping that if Gabriele tried to electroshock my ass it would create a feedback loop and overload her." He grinned through the pain. "Looks like it worked."
Xie applied a micro-regenerative gel to Davos' skin, which began to slough off the burned areas almost immediately. When she was finished she took off part of her garment and wrapped it around him.
"The question now," she said, "is whether we can fly the ship without Gabriele."
Davos' smile faded quickly. "Afraid not. The human-machine dependency goes both ways."
Xie pulled herself back towards the main screens, peering at the damaged control boards and burnt-out terminals.
"Are you positive?"
"Yeah."
"So why on Earth go through this charade?"
"It was the only way to strip away the AI's sentience sheath," Davos said, "so we could access its memory archives directly. I need water, for chrissakes."
He coughed loudly and his body convulsed. When he was still again she pinched her suit's water tube and he sucked on the valve. His breathing steadied. "Thanks."
"Don't mention it. Now, let's access those archives. I'm pretty sure that on these ships—"
A loud alert blared from a nearby navigation terminal. Xie smacked the control panel repeatedly before obtaining a response. "It looks like... something... is happening around the more massive black hole."
"Something?"
"Hold on." After minutes of clicking, touch-screen swiping, and the occasional knuckle-pop, she said, "More dipoles and energy fields. A second sphere has formed around the massive black hole, similar to the one surrounding the hidden one. Now they're both sealed in perfectly ref lecting spheres, and connected to one another via the cylinder."
"Jesus," Davos murmured, for lack of anything better to say. Then he caught himself thinking an absurd thought. Even though he was seriously injured and probably in the bleakest situation of his life, he realized he hadn't felt this alive in a long time.
Xie perceived the shift and responded to it, as though his mood were contagious. Something approaching excitement dimpled her cheeks. "I think it's time we roll up our sleeves and reach inside Gabriele's memory records."
While Xie scanned for possible residual traces of Gabriele's damaged personality files, it took Davos several hours of painstaking algorithmic reconstruction to make modest progress with her actual memories. More than once he suffered from cardiac arrhythmia. He told himself it was nothing more than stress—because they were in no shape to treat serious subcutaneous injuries, and he'd just as soon not know. By the time he had reassembled near-complete records from the fragments that had survived the feedback overload, his eyes were bleary, his concentration depleted.
Davos found himself studying Xie with a weird sense of unreality. He eased into a placid, floating state, remembering with startling clarity what life had been like at the outset of their shared journey—how full of delight and promise. Then his eyelids became heavy and he sank into a dreamless slumber.
Next thing he knew, Xie's hands were shaking him awake.
"I think I understand now," she said.
He squinted. "So bright... How long was I out?"
"Six hours. I've been scraping by on energy pills for the last two or so and I'm starting to crash. Before that happens, we need to get to the cryo-stasis units. And pray they're still functional."
Blood rushed back into Davos' head. "Cryo?"
"So we can sleep," Xie said. "For a long, long time." He noticed her forehead was grimy with sweat and dirt. "Internal sensors say the units are here." She pointed to a dot on a screen, three corridors away from their current position. "Can you make it that far?"
"Y-yes," he said, and pushed himself from the wall with shaky legs.
As they swam toward the units in zero-g, Xie said, "Good work on the files, by the way. I was able to access Gabriele's core records. During her five centuries of paranoid isolation she concocted some pretty wild theories about the sphere. But among all that crackpot stuff, I found an incomplete thermodynamic analysis that caught my eye." Davos must have been feeling better, because those words sounded ridiculously sexy coming out of Xie's mouth.
"Tell me more," he said.
"Gabriele posited that the black holes are in thermodynamic equilibrium with whatever else is inside the spheres, which we'll assume is radiation—say photons."
"Okay," he said, nodding slowly as he caught on. "I'll play. To simplify things, let's assume that both black holes are non-rotating and uncharged." They turned a corner and propelled themselves down a second corridor.
"Sure," Xie said. "Then the question becomes: what would normally happen if two such black holes were merged?"
Davos pondered for a moment and said, "You'd have a new black hole, the mass of which would be the sum of the masses of the input black holes. And since entropy is proportional to the square of a black hole's mass, merging two together would lead to a total entropy increase."
Another turn, another corridor. "Exactly. At least according to conventional wisdom," Xie said, easing up her pace so that Davos could catch his breath. "But doesn't the Deep Cold seem like an environment specially sensitive to energy and entropy? What if there was another way to fuse two black holes while keeping the entropy constant?"
Davos grabbed an access hatch to stop his flight. "If the black holes were at different temperatures, like thermal reservoirs, and you ran a simple heat cycle between them, you could create a new black hole whose mass wo
uld be smaller than the total mass of the black holes that went in. And the difference in mass—"
"—could be extracted as work."
Goose bumps blossomed all over Davos' skin. He whistled. "A black hole heat engine."
"Exactly."
They had arrived at the cryo-stasis units. It took Davos' brain a few moments to decipher Xie's unwavering expression. Appreciation of his intellect, yes. But there was something else there.
A different sort of intensity.
He drifted closer, parallel parking his body alongside hers. Her exhalations were warm against his cheeks, his mouth.
"Think it through with me," Xie said. She described the various stages of a heat cycle, isothermal and adiabatic expansions. It was hard for Davos to focus on what she was saying. "... and so the cycle beings again. But as the cycle repeats over time, the hot reservoir loses mass and becomes hotter, while the cold reservoir gains mass and becomes colder."
"Normally the temperatures of two bodies in thermal contact would converge," Davos said.
Xie's face was half an inch from his now. "But since a black hole has negative heat capacity, its temperature increases while energy is being extracted. So the less massive black hole will ultimately disappear."
"And because the lifetime of a black hole is proportional to the cube of its mass," Davos concluded, "we know how long it will take for it to sufficiently evaporate so that it no longer interferes with the Geroch's FTL drive. I'm assuming it's going to be a long time. Hence the need for cryo."
He leaned forward and kissed Xie. She slipped the tip of her tongue playfully against his, and he reached forward and held her head in his hands while the heat between them melted the world away. She gripped his back, careful to avoid the burn spots. He reached inside her suit, hands cupping her breasts, and then they were undressing as fast as they could. Everything dissolved into frantic breathing, sweaty rhythms, and the words "I've missed you," followed by a final surrender.
An insistent klaxon pierced Davos' bliss of nonbeing. It went on and on and on. The timed repetitions soon felt like a hammer bashing his skull.
"Make it stop," he tried to say, but his lips and tongue didn't work correctly, so it sounded more like "Meyth i shto."
Then the face-section of his unit clicked and swung open. Cool, fresh air rushed into the warm bubble of his universe.
The alarm stopped. He was ecstatic about that, but far too tired to show it.
"Welcome back to the world of the living," a familiar voice called from somewhere nearby. "I set my unit to wake me up a little ahead of yours." He was supposed to know the speaking face, which leaned forward and kissed him. The eyes, the nose, the lips, the smell, all so familiar. A name: Xie. He knew Xie, yes? With tremendous effort his mind began to form associations and pierce through the fog of cryo-sleep. Xie. Yes. His wife. A mission. The Deep Cold. "I thought you might enjoy sleeping in," she said. "Here, open up."
Unsealing his lips hurt his jaw but he did it anyway. Xie dropped a pill into his mouth. It dissolved on touching his tongue, leaving a tangy taste in its wake.
The nanos worked quickly. Clarity returned, as though an invisible lens had been applied to his reality, correcting its focus. His body felt again. And it hurt. Arms and legs sore, heart palpitating, lungs that stung. A nose from which snot trickled. Ears that were burning and freezing at the same time.
All these discomforts faded next to the realization of what he— they —had achieved.
"Xie," he said, grateful that his words were again intelligible. "Holy shit. We survived. How long...?"
"Eight hundred twenty-four years and three days," she said.
But no smile.
He frowned. "Has the small black hole evaporated enough for us to get out of here?"
"Yes."
"But...?"
Xie stared. "I suppose it was too crazy to work."
"For heaven's sakes, what's going on?"
"Now that the small black hole is weak enough for us to get back to the Geroch and engage our FTL drive, we don't have it."
Davos was stunned into silence.
"The Geroch's systems have suffered irreparable damage," she explained. "Something we didn't account for. As the black hole shrank, the sphere contracted. Our ship was pulled into an ever-tighter orbit, and friction with the sphere's outer energy field corrupted the quantum computer."
Davos' insides twisted. Eight centuries of cryo... the comforts of a myriad known worlds and a lifetime of friends...
All gone.
For nothing.
He ransacked his brain. "What about this ship? Any way we can salvage the Lemaitre's FTL drive?"
"We'd need a new AI to be able to activate it."
Davos studied Xie's ashen expression. He summoned the courage needed to sit upright and was promptly rewarded by dry heaving.
"You need electrolytes," Xie said. It took several hours, but Xie helped him feel human again.
Eventually he reviewed the data Xie had collected and found that she hadn't missed anything. No matter what diagnostics and sensor analyses he ran, there was no escaping the fact that they had no workable FTL.
The next two days he and Xie followed a sullen, almost wordless routine, gathering the Lemaitre's supplies, taking inventory of the ship's functional components, and in general avoiding comments about their situation.
At the start of the third day, after a particularly noxious breakfast, Davos found himself staring at the leftover ration pack.
"Life-pods," he mumbled.
It took a moment for Xie to respond. "What about them?"
"The Lemaitre has several. Each of us gets into one and we head in opposite directions. Double our chances of being rescued."
She pursed her lips. "Two times zero is still zero."
"Think about it," he said. "The Lemaitre is bleeding out all sorts of radiation into space, radiation that's probably masking our life-signals. But if we each took out one life-pod and made for a different edge of the Deep Cold, rations and power would last us several months. During that time our life-signals would be easy to detect against the incredible stillness of the Deep Cold. Whoever farmed these black holes and built the cylinder was here once before, when their radiation killed the Lemaitre's original crew. At least once before. They might still be watching."
Xie seemed to be elsewhere. Then Davos saw tears pooling in her eyes.
"You're right," she said at last. "It's the only way."
His own eyes misted up.
They kissed.
It was tender. Final.
"I love you," he said.
She smiled through her tears. "I suppose it's better to hear it now than not at all," she said, and caressed him.
"Well?" Davos said. "Aren't you going to say you love me back?"
She tousled his hair. They hugged, long and hard, taking in each other's heat, smells, listening to each other's heartbeats. "You'll have to wait until we're in the life-pods."
Davos opened his eyes from a short nap and was greeted by claustrophobia, his only companion during the last ten days. Freezing black nothingness, invisible, impalpable, rushed all around the single-passenger pod. Today the chill seemed to have crept inside. He felt it in his bones.
He waited.
At the appointed time, the signal from Xie's life-pod bleeped to life. Relative to the Lemaitre, they were traveling at roughly sixteen kilometers per second in opposite directions, which meant that today, the eleventh day of their separation, they were over thirty million kilometers apart. At this distance the signal between them was delayed by about a hundred seconds.
"Davos," Xie's voice came through, and for a moment it was as though she were here, inside the space-coffin with him. His body responded with a rush of endorphins. But then stark reality returned. Today was the last day they would speak to one another, in order to preserve power for life-support and propulsion.
Then nothing but the silence of the void.
"I'm here," he sa
id, and began to count down the seconds until she responded. He grimaced. Every second that passed brought them farther apart by another thirty-two kilo-meters, adding another ten-thousandth-of-asecond delay.
"Where else would you be?" she teased. "I love you, Davos. Of course I love you. We both have regrets about how we behaved before all this happened... but I want you to know that you brought me incredible joy and companionship." He heard her choke up and muffle a sob. After a while her breathing became regular again. His own heart was beating so loudly he had to turn up the volume on the com. "I've been doing some thinking," she continued. "Too much idle time on my hands, I guess. Why would someone want to set up a black hole heat engine? And why here, in this desolation? Maybe the questions are connected. I think this is all someone's experiment. It has to be. A way of simulating what the universe will be like countless billions of years in the future, when the background radiation falls below our galaxy's plasma frequency and the rest of the observable universe has gone dark. They've designed it to test whether they'll be able to extract work from black holes. Because every fraction of a fraction of a joule will be precious then. That flash in Gabriele's records—they must have come by to check in on their experiment. The Lemaitre was large; it disrupted things. But the Geroch was small and not active for long. So maybe you were right to suggest the life-pods. They might notice us out here. They may even drop by to stop us from messing up their experiment. And if their radiation doesn't kill us, and they take us in, I'll tell you again how much I love you, only this time in person."
It took a few minutes for Davos to realize that those were his wife's last words to him.
Seconds passed, ponderous. He could feel the distance between them elongate like a rubber band of infinite elasticity, never to snap back into place.
At last he settled on his own farewell message. "If they do show up, I hope they find your pod before mine. Because you'd probably figure out their language in a day." He paused. "During my life, I wish I had done more to speak your language, Xie. The parts of it I did learn enriched me beyond measure. You were the ultimate radiance in my night."
Analog Science Fiction and Fact - July-Agust 2014 Page 31