“Yes, Colonel Kalinski. Of course. And the importance of finding Earthshine soon, by the way, is only increased.”
Stef could hear the others returning, father and daughter laughing, full of life and energy. And she looked across at the silicon-life explorer from Proxima d, the ice giant. “I wonder if that thing can see us… Just tell me,” she said. “How long have we got?”
“A year,” the ColU said flatly. “No more. The data’s still chancy.”
And Stef immediately thought of Mardina, and the baby.
She pursed her lips and nodded. “A year, then. For now, not a word. Come on, let’s get ready to go on.”
67
The party gradually penetrated deeper into the cold of the Per Ardua farside.
The forty-minute tunnel hops all felt much the same to Beth, but in the short intervals during which they trekked from one tunnel exit to the entrance of the next, always following trails carefully scouted out by Titus with Clodia or Chu, Beth did get glimpses of parts of her world she had never seen before. After all, during the years she’d spent growing to a young adult on Per Ardua, she had never gone farther than the tall forests that screened the terminator zone.
Stef and the ColU had made such a journey as this once before, with Beth’s father and Liu Tao, in a purloined ISF rover. That party had followed a more or less direct course to the antistellar, cutting over the ice surface of a frozen ocean. The gravity tunnels, however, naturally enough, stuck to continental land, detouring around the shores of frozen oceans. As a result the journey was longer than a direct route, and was taking longer than the handful of days that Titus and the ColU had first estimated—but still it would be brief enough.
And while Stef in that earlier party had spent mind-numbing days crossing geometrically perfect ice plains, now Beth saw more interesting features. Eroded mountain ranges from which glaciers spilled like huge, dirty tongues. Places where earthquakes or other geological upheavals had raised and cracked the ice cover, creating frozen cliffs that gleamed a deep blue in the light of their torches.
Yet even these features were probably impressively old, the ColU said. There would always be a lot of weather activity at the terminator, where the warm air and water from the day side spilled into the cold of the night. But here in the dark, weather would always be desperately rare: no clouds, no fresh falls of snow or hail. Even meteor impacts would be infrequent in such an elderly system as this, with much of the primordial debris left over from the planets’ formation long since swept up. So they drove across a sculpted but static landscape—and a landscape bathed in the complex, red-tinged light of an aging Andromeda.
Sometimes they saw more “Titanians,” enigmatic, sharp-edged pyramids standing like mute monuments. But the ColU assured them that the Titanians, in their way, on their own timescale, could be exploring just as vigorously as the humans.
Beth noticed, however, that Stef barely glanced at the sky, or the icebound landscape, or even the Titanians. As they traveled, and in the “evenings” as they rested, Stef sat huddled with the ColU at the back of their sled-cart, or in a corner of their shelter, talking softly, Stef making occasional notes on the glowing face of her slate. Everybody knew what they were discussing: the ColU’s ideas about the fate of the world. Beth tried to read Stef’s expression. There was nothing to be discerned from the ColU’s neutral tone.
At last, one evening, after they had cleared away their meal, with them all bundled in their warmest clothes, their feet swathed in layers of socks, gathered around the warmth of the kernel stove, Stef announced that they needed to talk about the End Time.
“In a way,” Stef began cautiously, “the idea that the world will have an end—that the universe itself will end, and relatively soon—ought to feel natural to us.
“We have no direct experience of infinity, of eternity. Our own lives are short. And the scientists in my Culture proved quite definitively that eternity doesn’t lie behind us, that our universe had a beginning, a birth in a cataclysmic outpouring of energy. Why, then, should we imagine that eternity lies ahead of us, an unending arena for life and mind?”
Beth was sitting beside her pregnant daughter. Now, under a blanket, she took her daughter’s hand, and Mardina squeezed back. Mardina’s eyes were wide in the firelight, her expression blank. This was not a conversation either of them wanted to be part of, Beth was sure.
The ColU was on Chu’s lap, next to Stef. Titus Valerius sat beside the slave boy, listening intently.
And Titus was skeptical. “Well, we Romans had no trouble imagining eternity. Or at least, we failed to anticipate an end. Because we never anticipated the Empire to end—do you see? Unbounded and eternal…”
That sounded magnificent in the legionary’s guttural soldier’s Latin, Stef thought. Imperium sine fine.
The ColU said, “Our own Culture, mine and Stef’s and Beth’s, had its own account of an undying empire—but an empire of scientific logic. We thought we could know the future by looking out at the universe, working out the physical laws that govern it—and then projecting forward the consequences of those laws.
“The universe only has so much hydrogen—the stuff that stars are made out of. The hydrogen will, or would have, run out when the universe is ten thousand times as old as it is now. No more stars. After the stars there would be an age of black holes and degenerate matter—the compressed, cooling remnants of stars—and the galaxies, huge and dim, would begin to break up. There would be a major transition when protons began to decay—that is, the very stuff of which matter is made… In the end everything would dissolve, and there would be nothing left but a kind of sparse mist, of particles called electrons and positrons—a stuff called positronium—filling an expanding, empty universe. Even so, it was possible that minds could survive. Minds more like mine than yours, perhaps. Thoughts carried on the slow wash of electrons—thoughts that might take a million years to complete.”
“That sounds horrible,” Mardina said, and Beth could feel the grip of her hand tighten. “It doesn’t even make any sense. How could a single thought last a million years? I can’t imagine it.”
“But experiences of time can differ,” the ColU said. “In my Culture there was a Christian scholar called Thomas Aquinas—I wasn’t able to trace him in your history, Titus. He distinguished three kinds of time, or perhaps perceptions of time. Tempus was human time, which we measure by changes in the world around us—the swing of a pendulum, the passage of a season. A Titanian ice giant would experience a slower tempus than a human. Aevus was angel time, measured by internal changes—by the development of thoughts, understanding, moods. For the angels, you see, stood outside the human world. And then there was aeternitas, God’s time, for God and only God could apprehend all of eternity at once. The electron-positron minds would not be God, but in the timeless twilight of the universe they might have been like angels…”
“Might have been,” Mardina said, almost bitterly. “Might have been.”
The ColU said, “The positronium angels will never exist. Our universe won’t last long enough for that. And the reason our universe is not eternal is because of the existence of other universes. And we know they exist because we, all of us, have visited several of them.”
“Aye, and fought in them,” Titus said, stirring from his space and pushing back blankets. “But in this universe my bladder’s full. Anybody want more tea? Chu, maybe you could put another pot of ice on the fire…”