Ultima

59

After leaving Earthshine, Beth took her time to get back to the substellar.

She made a number of detours, exploring the scenery along the route. It wasn’t as if there was anybody waiting for her. Or so she thought. And it wasn’t as if she could get lost; the substellar was the easiest place to find in the entire hemisphere.

She searched water courses and lakes, looking for traces of builders. She found plenty of stem beds, of the kind that had sustained builder communities before. The little creatures had been modular, and assembled themselves, literally, from the reed-like stems, which were themselves complicated pieces of biological machinery. But here she found no trace of the builders, or their works: the shelters they built for their young, the middens they constructed from the remains of their dead, the elaborate dams and dikes they built to control the water flowing through their landscapes. She thought she would have all the time in the world to pursue such interests. She was, after all, home—even if home had changed while she’d been away.

She was almost disappointed when she got back to the substellar and found the Hatch wide-open.

She unpacked her stuff, and boiled water for tea, and waited for the new arrivals.

Practical matters came first, as ever.

It was immediately obvious, when Stef and the rest of the group came through the Hatch, that Beth’s two-person bubble tent was much too small for the eight of them—or nine, if you counted the ColU. So, just an hour after Titus Valerius had led the way through the Hatch, and as the rain began to fall, Beth organized Clodia and Chu Yuen to take down her tent and fix it up as a kind of improvised roof, stretched across a stand of close-growing stem-trees. This arrangement wouldn’t be much use in a storm, Stef could see, of the kind she remembered lashing the substellar of Per Ardua even on a good day. And still less would it offer any shelter if Per Ardua fell into another of its starspot winters. But today, as if in welcome of the new arrivals, the rain fell in gentle verticals from a cloudy sky, and the improvised canopy was enough to keep them dry.

Beth even lit a small fire and began brewing tea: tea she had gathered herself, she said, from a plant she’d found growing wild here, brewing in a clay pot she’d cast herself.

“Always takes a while to boil in an open bowl,” she said apologetically.

Nobody objected. The group was very quiet, in fact, gathered around the unnecessary warmth of the fire, as they waited for the tea.

Stef glanced around at her unlikely companions, relics of multiple collapsed histories, participating in what she supposed was a kind of welcoming ceremony. Titus Valerius sat with his daughter, who leaned against his muscular bare legs. Titus himself looked restless, baffled, oddly resentful, like a bull in a cage, Stef thought. Maybe he was still sulking from missing out on the battle at the habitat hub.

And Clodia was staring with obvious hostility at Mardina, who was rubbing some kind of ointment into the bare shoulders of Chu Yuen. The former slave had taken his shirt off, and Stef could see how his shoulders and chest had been chafed by friction from the heavy pack that bore the ColU. Stef, already thinking ahead to how they would survive here in the days and weeks to come, made a mental note that the ointment, whatever it was, wouldn’t last forever. But they had the ColU, she reminded herself, which for now sat on a rock of its own, liberated from its customary backpack, interior lights gleaming. The ColU was a machine specifically designed to survive in the conditions of Per Ardua, and would no doubt be full of recipes for such things as skin ointments…

But Stef’s old-lady maundering at this moment was missing the point, she realized, the central theme of the little scene. After their adventure at Hanan Cuzco, both the girls had been glad to be reunited with Chu Yuen—but of course there was more to it than that. Chu was the only young man here—perhaps in all this world—and Mardina and Clodia were the only young women, though Clodia was a few years younger. Mardina seemed close to Chu, but Stef had no idea if there was a genuine relationship there. Anyhow, what you had here was a Chinese Adam—and two Eves.

Oddly, Stef recalled, it was not unlike the scheme the ISF and its controlling UN agencies had drawn up for the original colonization of Per Ardua, in a different reality: to seed the planet with apparently impossibly small groups, a dozen people each or so, screened for genetic diversity, and let them work it out. Beth herself was a survivor of all that. In the end the colonists had found their own way, basically by abandoning the ISF plan and congregating at the substellar. But they had left behind a trail of blood and lust and jealousy. Trouble ahead, Stef thought, just from the difficult triangle of these youngsters alone.

And then there were Inguill and Ari Guthfrithson, sitting side by side on the far side of the fire, not speaking, looking around at the group, at Beth’s improvised homestead—at the forest, the tall shafts of Per Arduan stem-trees, presumably the most alien life-form either of them had seen before. Beth, who had never visited the Inca Culture, was astonished by the sight of this woman in her cloak of hummingbird feathers. Inguill, looking around greedily at this new world, would say only through the ColU’s translation interface that she was here to extend the glory of the Sapa Inca.

What did the future hold for those two, Inguill and Ari? They were both scholars, both highly intelligent and manipulative people. They had both, in their separate histories, more or less deduced the existence of alternate realities from the accounts of jonbar-hinge survivors, if not from scraps of evidence they’d turned up themselves. Stef wondered how they felt now that their questing had brought them to this strange, sparse, distant, unexpected place. Watching them, she realized she really had no clear idea what they were thinking—what they were scheming. Penny seemed to have been suspicious too; she had restrained Ari from following Earthshine through the Hatch on that other Mars. It was a strange thought that Stef probably had less in common with them, two fellow humans, than with the ColU: a mind calm, analytical—and loyal.

Loyal, yes. And that reflection made her realize that once again she was missing a central point. Ari, Beth, and Mardina were father, mother, and daughter. And yet they had barely acknowledged one another after the initial moments of shock as the group had emerged from the Hatch and the family was reunited. Even now, sitting in this little circle around the fire, they could scarcely be farther apart. Not to mention Earthshine, who was Beth’s grandfather in some sense, off to the other side of the planet.

“Families,” she muttered. She caught Beth looking at her with a grin. “Sorry. Did I say that out loud?”

“At least you broke the silence,” Beth said.

“Perhaps we’re all in some kind of state of shock. This has been a peculiar… journey. It’s difficult to know what to say.”

Beth nodded. “Well, then, just say what you feel. You, at least, have been here before, Stef. As I have. And indeed the ColU.”

The colonization unit sat silently, inner lights winking.

Beth pressed, “You know I’m right, don’t you? Earthshine wouldn’t accept it. But you know this is Per Ardua. You knew it from the minute you walked through that Hatch—as I did, months back. I could see it in your face.”

Stef sighed, and looked out at the world, the mix of muddy Arduan green-brown with the more brilliant splashes of Earth life—the vertical shadows that were appearing now that the rain was stopping, and the clouds above were clearing from the face of the overhead star. “Yes,” she admitted. “I spent enough of my own life here. I think I could even sense it in the gravity, that slight, peculiar lightness you feel, like nowhere else I ever walked. Of course it’s Per Ardua. But it’s different, right? No traces of the human structures that used to be here—this was the UN’s administrative center, after all, and a pretty well-developed city grew up here. But then we don’t know what timeline we’re in now, what became of Earth and Per Ardua—”

“People got here,” Beth pointed out, “from whatever version of Earth. They must have. Otherwise no tea.”

“Or, strictly speaking,” the ColU said now, “no heavily evolved wild descendant of a tea plant.”

Stef said carefully, “So the evidence of my senses tells me—yes, this is Per Ardua. But the differences are significant.” She glanced up, at the pale image of Proxima that, as the clouds cleared, was beginning to shine through the fabric of the shelter-canopy. “Even the star seems different, somehow, subtly. My senses, my perception of the world, say one thing. But my head tells me that this isn’t the Per Ardua I know. Not quite.”

Titus Valerius grunted, and took an angry, impatient swig of water from a flask dangling from his heavy belt. “You talk of abstractions. This world is one thing or another, it is what you remember from before, it is not. What does it matter? We are here, now, in this place.” He glanced around at the group, at their pitifully small pile of equipment, Beth’s and the Romans.’ “Our hands and hearts and muscles, and the resources we find around us—that is all we have. That is all that matters. And,” he said pointedly, looking at Beth, “those we share this world with.”

Beth sighed. “And we are all there is. Look, I can’t prove that we’re alone here. I haven’t explored every square kilometer of the planet. But while Earthshine was here we did do some exploring, and I walked a good way off to the southeast when he began his trek to the antistellar. I didn’t see anybody else, or any traces of their works. Nothing but the bedrock structures we found buried under the dirt here.” She’d shown them the sonar images on her slate. “I’m ready to be proved wrong. But I don’t believe there’s another human soul on this world—nobody save Earthshine, wherever he is now.”

“And he,” Stef said drily, “is neither human nor has a soul.”

“I didn’t even find any evidence of the complex life we saw here before. When I was a kid. The builders, the structures they made, the other life-forms like the kites in the air, the fish-analogues in the water courses.”

“No animals?” Titus snorted. “It doesn’t sound like much fun. You can’t hunt a tree.”

Clodia patted his knee. “Come, Father. Look on the bright side. We’re Romans, the only Romans in all this world. You could be the Caesar of Per Ardua.” She wrinkled her nose. “The world already has a Latin name. I never thought of that before. How strange.”

“That’s a long story,” Beth said. “I think my own mother was responsible for that.”

Titus growled and shook a leonine head. “There’s no value in conquering a wilderness. No farmers to tax!”

Beth said, “But there’s plenty of work to do here. I’ve made a start, with shelter, tools.” She grinned. “I’ve dug a latrine ditch. With eight of us using it, we’d better get that extended, fast.”

“We must save the compost,” the ColU said gravely. “For the farm we will someday build.”

Beth went on, “The good news is there’s air to breathe, water to drink—I don’t know if we had a right to expect that on the far side of a Hatch on Mars. There’s even food to eat. Not just tea. I’ve found root vegetables, things like peas, beans, squashes, even something like maize, I think, but gone wild.”

All this was slowly sinking in for Stef. “Wild variants of crop plants presumably brought from Earth. From an Earth.”

The ColU said, “They could be domesticated once more, given time and patience.”

“Time, yes. ColU, how much time must it have taken for the various strains to drift so much?”

“Not long,” the ColU said. “Not nearly as long as, for example, it must have taken for the installation here at the substellar, whatever it was, to erode away to its foundations and then be covered over by meters of earth. That is a better indication of duration. There has evidently been plenty of time here for all this to happen—time behind us—even if, as I fear, there may be little time ahead of us.”

They all stared at the complex little unit, its glistening lights.

“Textbook enigmatic,” Stef said, annoyed.

Titus growled, “You know, that twisted piece of junk always seems so much less human when it isn’t in the bag on the boy’s back. When you can see what it really is. Do you have something you want to tell us, you glass demon?”

But the ColU was silent.

Beth broke in, “I’ll talk to it… I grew up with it, remember. We’ll figure out what’s on its mind, and what to do about it.”

“All of which,” Titus said, “is less of a priority than digging that latrine you talked about. We’ve got spades and other tools in the bundles of gear from the Malleus. At least in the army I was used to that.” He rubbed his daughter’s shoulder. “As is my Clodia, who grew up in army camps.”

“I can dig a ditch,” Clodia said defensively. “I wanted to be in the army, before all this made a mess of everything.”

Stef studied Titus. “This won’t be the life you’re used to, Titus Valerius—or you, Clodia.”

“We came here in pursuit of Earthshine,” the ColU said simply.

“Well, that’s true, but—”

“The glass demon is right,” Titus growled. “That was the mission we set ourselves. That was what I expected, and all I expected. That remains so.” He glanced around, at the stem-trees, the face of Proxima dimly visible through the canopy. “And this is where we have been brought—where Earthshine was brought. We must remember we are not the only agents in this matter. The beings who control the Hatches—”

“The Dreamers,” Beth said. “As Earthshine calls them. Among other, more insulting names.”

“We build these Hatches—we Romans, and you Incas,” and he nodded at Inguill. “But we have no control over how they work, do we? Over what points they connect, how they take a traveler from this place to that, one world to the next. Any more than a trained ape shoveling coal into the maw of a steam engine has control over the layout of the track. Even Earthshine does not control this.”

And Stef knew he was right. In her own root reality, the Hatch at the substellar of Per Ardua had been linked to a Hatch on Mercury, not Mars. Maybe it still was, in some higher-order dimensionality. But for this trip, it was as if the points had been changed, the travelers rerouted…

Titus Valerius said, “The Dreamers sent Earthshine to this world, this place—if it is your Per Ardua or not—they could, presumably, have sent him anywhere. And they allowed us to follow. Yes—allowed! The Dreamers are like our old gods, before the light of Jesu filled the Empire—jealous gods who meddle endlessly in the affairs of humans. We have been brought here for a reason, even if we don’t yet see it ourselves, fully.” Titus shook his huge head. “What we Romans do have is a sense of mission. Of purpose. As far as I’m concerned that mission remains to be fulfillled—and if the first step in doing that is to dig a latrine ditch, well, that was the first step in the winning of most of our provinces, I daresay, so let’s get on with it. Just as soon as that tea brews. Well, I remember once on campaign—”

Everybody stopped listening. Beth passed around cups and began to ladle out her tea, which was boiling at last.

And Stef looked over at Inguill and Ari, who had barely said a word since arriving in this new reality.

In the heart of this world, as in a hundred billion others—

In the chthonic silence of an aged planet—

There was satisfaction.

The Dreamers understood little of the beings whose destinies they manipulated, little enough of the primary constructs of organic chemistry, let alone the second-order creature of silicon and metals that had been born in their industries, the creature that had done so much damage to the Dreaming. United in wider coherences themselves, they comprehended little of individuality, of identity.

It wasn’t clear to the Dreamers if any of these creatures were truly intelligent at all.

So, to minimize the risk of a mistake, they had allowed the organic-chemistry creatures who had clustered around their silicon-metal leader to follow it to this place, this ultimate destination. Perhaps they were necessary to supplement its existence. Perhaps they even formed part of its intelligence, in some collective form. Perhaps this composite group could yet achieve an understanding beyond any individual, just as it was for the Dreamers.

In a sense, Titus Valerius was right. The group had been given a mission, of sorts, by the Dreamers. But it had not been compassion that had led the Dreamers to reunite this group on this world at this time: to bring Beth Eden Jones back into contact with her daughter, and the father of the child. It had not been manipulation on a human level. It had been more a question of imposing order. Of tidying up loose ends.

But time was short, and ever shorter.

And the Dream of the End Time was blossoming into actuality.

60

The new arrivals agreed to live to a clock and calendar based on what Beth had already set up—her twenty-four-hour cycle was some hours adrift of theirs, which they had brought from Yupanquisuyu. But that meant that they had to stay awake a few extra hours that first night, and then they slept uncomfortably on improvised beds, mostly under the canopy.

Beth, more used to the conditions of Per Ardua, was happy to lie out in the open. And, Stef wondered, maybe that helped her to adjust to this company, to get over the resentment she must feel at this sudden intrusion into the little world she had been constructing for herself—even if her own daughter had been among the intruders.

In the morning Beth served a breakfast of more tea and food from her stock: mostly potato, boiled and dried. The new arrivals ate hungrily but without relish, and Stef could see Beth was faintly embarrassed at not being able to offer them anything better, a totally illogical feeling but understandable.

Titus organized a party—himself, Clodia, Ari and Inguill—to extend that latrine ditch. “It has to be done!”

And Beth led Stef, Mardina and Chu bearing his pack with the ColU, on a short tour of her little homestead.

It was a well-chosen spot, Stef could see immediately. Beth had made her camp on top of a low rise, away from any obvious water courses; she’d have lived through all but the most monumental flooding events. But there was a stream for drinking water on the lower ground only a short distance away, and a forest clump on top of the rise that could provide fuel for burning and other materials. And Beth had put in a lot of work. In addition to her bubble shelter she had already started to construct lean-tos and tepees, supported by the sapling-like stems of young native trees, and with dead stems woven to create a kind of thatch. Under the lean-tos, and in holes in the ground, she’d built up a food store: the remains of the rations she’d brought through the Hatch, as well as wild food she’d gathered from the countryside. She was even building a kind of cart.

As they looked around the little compound, Stef was reminded that Beth Eden Jones was, after all, a pioneer, a daughter of pioneers, who had survived in this unearthly wilderness for decades. And Beth, apparently instinctively, had gone to work applying all the wisdom she’d acquired in those days—wisdom, Stef supposed, that had been entirely useless back on Earth, after she and her parents had returned through the Hatch to Mercury. It must have felt good to use those skills, to find purpose again.

Beth showed them her clocks.

She’d set up a whole array of them, using sand and water dribbling through funnels woven from dead stems: improvised hourglasses, all running independently. And on a tree trunk nearby she was notching off the days. “I have two chronometers,” she said. “My wristwatch, and a timekeeper in the pack Earthshine gave me from his support unit. This homemade stuff is for backups for when the power eventually fails—”

“Timing will no longer be a problem,” the ColU said blandly. “I have internal chronometers, which—”

“Which will work until you run out of power,” Beth said firmly. “I did learn some basic disciplines from my ISF-lieutenant mother, ColU. You should know that. You always have backups.”

The ColU seemed to chuckle, to Stef’s hearing. Since when had a farm robot learned to chuckle? It said now, “Just like old times, Beth Eden Jones.”

“Sure it is. I’m aiming for bigger barrels, smaller nozzles, that won’t require refilling—oh, for several days, enough time for me to make decent excursions from this site without losing track of time.”

“Of course,” Mardina said, “you won’t need all that now, Mother. Not now that we’re all here. As long as there’s one person to stay behind and tend the fire and change over the clocks and whatever—”

She was casually holding the hand of the silent Chu Yuen, Stef noticed. She risked a glance at Beth, who raised her eyebrows in response. She’s not letting that boy out of her sight, and to hell with doe-eyed Clodia.

Beth said breezily, “If I’d known a whole gang of you was going to turn up, I’d not have gone to all this trouble, would I? In the meantime, come see what else I’ve built.”

She seemed proud of the plots she’d cleared, and started to seed with crops of her own. “I may never get to see these potatoes and peas and whatnot become fully domesticated. But it’s a start.”

“Of course,” the ColU said, “now that I am here to advise, we can make much faster progress.”

Beth fumed. “More advice? I was doing pretty well before you ever showed up, you clanking heap of—”

“The work’s doing you good, Mother,” Mardina said quickly. “I haven’t seen you look so fit in years. Or as slim.”

“Thanks,” Beth said drily.

“The crops are also going to be a useful winter larder,” Stef said, “in case Prox ever decides to let us down again.”

“A future winter is very unlikely,” the ColU murmured, peering from the slate on Chu’s chest, its voice muffled by the fabric of the pack. “The Proxima Centauri in the sky above is rather different from the beast we knew, Colonel Kalinski. Much less irregular. And the incidence of flares must be a lot lower too.”

“I figured that,” Beth said. “But I took precautions even so.” She pointed to a stromatolite garden, a huddle of table-like forms glistening brown in the watery Prox light, only a hundred paces away. “I picked out a storm shelter to hide in—hacked away the carapace in advance. Of course we need to extend that so there’s shelter for all of us. But…” She raised her face to the sky, the heavy bulk of Proxima directly overhead. “I don’t know what’s going on here. This is Per Ardua. But why is it so different from what I remember? Even the jonbar hinges didn’t change Earth itself that much, aside from what humanity was able to do to it.”

“We are here to seek answers to such questions,” the ColU said. “That is true even of Earthshine. Especially true of him, even if his method of inquiry is somewhat destructive. Chu Yuen, would you please turn around? Pan the slate—let me see the sky, the landscape from this vantage… And, Beth Eden Jones, would you show me a handful of the soil you are so assiduously cultivating?”

“Why do you want to see that? Oh, very well.”

Stef watched the former slave swivel on the spot, slowly, even gracefully. And Mardina was watching him too. He was nineteen, twenty years old now. Having spent a few days with him, Stef knew that Chu Yuen was working to get his body in better physical condition, and he studied, too, reading from slates, generally alone. All this was in order better to serve the ColU, he said. Stef felt a kind of faint echo of lust of her own. If she could shave off a few decades, the Mardina-Clodia-Chu triangle could well become a quadrilateral…

Beth, her cupped hands holding a mass of soil, was grinning at Stef knowingly.

“Beth Eden Jones, please hold the soil up before the slate. That’s it—ah! See that?”

Stef and Mardina closed in to see. Something was wriggling in the dark brown soil, pale and pink. It was an earthworm, Stef saw with a jolt of wonder. There could be nothing more mundane than such a thing, and yet here it was burrowing through the ground on a world of another star.

“This is no surprise,” the ColU said. “A potato from Earth needs soil from Earth, which is more than just dirt; soil is a complex and nutrient-rich structure in its own right. Do you remember, Beth Eden Jones, how my primary duty in the days of pioneering with your parents was to manufacture soil, using Per Arduan dirt as the basis?”

Beth laughed. “I remember we had to haul tons of it with us when we moved.”

“I even had a miniature womb in my lost body, within which earthworms and other necessary creatures could be grown from stem cells. Of course I used these facilities to buy us acceptance with the Romans, on the planet of Romulus.

“But I was designed for Per Ardua. That was then. Now look at what we find. A soil that is evidently neither Arduan nor terrestrial, a soil that is evidently capable, still, of supporting Arduan life, like the stems, and yet an earthworm that might have been airlifted from a Kansas farm wriggles through it without hindrance.”

Beth was wide-eyed, looking down at the worm with new understanding. “You know, when I was digging my fields I forked over these things without even thinking about it. Yet here they are.”

“Colonel Kalinski, how long do you think it would take for earthworms to permeate the continents of Per Ardua? How long for the two ecologies to mesh in this way?”

“I’m a physicist,” Stef said, faintly baffled. “Not a biologist. A hell of a long time, I’m guessing.”

Beth said, “A lot more than the few decades since humans first got here—the few decades I remember anyhow.”

Stef said slowly, “In previous jumps through the Hatches—previous jonbar hinges—we jumped from location to location, maybe reality to reality, but without a jump in time. Correct? That’s aside from lightspeed delays. If you took the Hatch from Mercury to Per Ardua, it was like a teleport from world to world, with a signal taking four light-years to get to its destination—so you’d emerge four years later.”

“And when we passed through the jonbar hinges,” the ColU said, “save for lightspeed delays, as you say, as near as I could determine the calendars always synchronized. Given some common starting event like the founding of Rome, we could always synchronize our chronologies—”

“Have we crossed through time, then?” Mardina asked, a little wildly. “Is that what you’re saying? Are we off in some future? How far? What would happen if we tried to go back through the Hatch? And—why should it be this way?”

“I have only tentative answers to those questions,” the ColU said gently. “We must wait to learn more.”

“OK,” Beth said. “Then come and learn about this…”

She led them farther away from her camp, down a slope toward the narrow, fast-flowing stream that provided her fresh water. Here, by the stream bank and in the water, stems grew more thickly.

Beth paddled out into water that lapped over her boots, and knelt to touch a broken stem, almost tenderly. “One reason I came back to the substellar to live is because Earth life seems to prosper best here. Well, the stuff I could see—I wasn’t searching for earthworms. And I needed that, of course, to survive, the food crops. But if you go farther out there are stretches that could be the Ardua we used to know, Stef, ColU. Stem banks and Arduan forests and stromatolites. But there are no builders. Not a trace of them. No middens and dams… No kites. None of the complex forms we saw when I was growing up—hell, that helped us survive.”

“No more Mister Sticks,” said the ColU gently.

“What happened to it all, ColU?”

Stef asked, “Could it have been another jonbar hinge? I was there when you were debriefed, remember, Beth. When you first came through the Hatch to Mercury. You’d seen evidence of a much higher civilization constructed by the builders.”

“Yes. We found a map, a parchment in a Hatch. A global canal network—”

“None of which you saw evidence of on the ground, or which subsequent human exploration turned up. Wiped out by a hinge, maybe. Is it possible that’s happened again, ColU?”

“Unlikely. We’ve seen that the jonbar hinges tend to redirect the destiny of an intelligent species, rather than eliminate it altogether.”

“You mean,” Beth said sourly, “they’re made into better Hatch builders. Just as happened with humans, whatever the cultural cost.”

“Precisely. Of course it’s not a neat process. The builders we saw seemed to have fallen away from that capability, somewhere in their own past. But I think what we’re seeing here is not the product of a jonbar hinge but—”

“The result of time,” Stef said, looking around, beginning to understand. “And worlds too, the framework for life, change with time. I’m being slow here, slow to pick up your hints, ColU. I am, or was, a physicist—not an astrophysicist, but I ought to be able to think about huge spans in time, as they did.

“With time—a lot of time—as dwarf stars like Proxima age, they settle down. Become more quiescent. Planets too lose their inner heat. Volcanism, tectonic shifts tend to seize up. Per Ardua was a pretty active place when we knew it, Beth, and Prox helped too by serving up star winters, flares. But now, it’s evidently much more quiescent. A quieter world under a quieter sky. And on a quiet world—”

“You can live a quiet life,” the ColU said. “Beth Eden Jones, a big brain is expensive, energetically. On a more static Per Ardua, such luxuries have long since been evolved out. They just weren’t needed any more, you see? Instead all you need to do is find a sunny rock, spread out your photosynthesizing leaves, and bask forevermore.”

Beth stared around. “So that’s what became of the builders? If they devolved—broke back down to the stems they were made of—how long would that take?”

“So,” Stef said, “we come back to time again, ColU. And a hell of a lot of it, it seems.”

“A clock is ticking,” the ColU said now. “I saw this when I was able to study the universe, aboard the Malleus Jesu, in the gulf between the stars. Echoes in the sky, of past events and future.”

“What clock?” asked Stef, growing exasperated. “What events?”

“Beth Eden Jones, you have done a fine job of survival here. But our mission is to do more than survive. We must find Earthshine—while we still have time to do so. And I can’t see the sky from here. Not in this permanent day. I must see the sky, I must…”

“Why?” Stef snapped.

“Because that is my ticking clock.”

“We’ll have to leave here, then,” Beth said.

“Yes. We need to follow Earthshine, we must make for the antistellar… We must cross the darkened face of the world. We’ll need to prepare—warm clothes, food. It will take some time—but we must do this as soon as we can. I will tell you more when I know for sure myself,” the ColU said patiently. “But for now, let’s begin to plan. We have a long journey ahead… Come, Chu Yuen, if you please.”

As Chu turned to begin the walk back to Beth’s camp, Stef saw Mardina’s hand slip into his, and squeeze tightly.

61

When Stef and the others returned to the camp, and began the discussion about leaving for the antistellar, Ari drew Inguill aside.

They walked away from the others, on the pretense of inspecting the latrine ditch they had been working on. When they were out of earshot, Ari plucked out his earpiece. “I can speak Latin,” he said in that tongue. “Can you?”

“A little.” Inguill removed her own earpiece. “I studied it in the course of my historical surveys. And my grasp has been refreshed by my contact with your group.”

Ari took the earpieces and set them down some distance away. “Then let us communicate in that way. I would prefer not to have our conversation passed through Collius.”

She smiled. “I think I know why.”

He eyed her. “You and I are not like these others—”

“‘These others,’” she said drily, “include your daughter and her mother.”

He smiled back. “That’s a long story. Nevertheless, you and I see further than the rest. We would not have come on this astonishing journey across the reality sheaves otherwise. Indeed I was blocked, once, from progressing even faster, from following this Earthshine into mystery, through a Hatch on a different Mars. And now we are here, in this place, wherever it is—”

“Wherever and whenever.”

“We are not here to dig ditches.”

“I agree with that,” she said.

“Or to grow potatoes, or build lean-tos. Or to wait around until my daughter and Clodia Valeria rip each other to pieces over the Xin boy.”

She laughed. “You noticed that too. Then why are we here, Ari Guthfrithson?”

“Isn’t it obvious? We are fascinated by the jonbar hinges. Whole histories are being wiped away, as if by the wave of a hand. To have such power—”

“You think that is what this Earthshine has gone to seek.”

“Isn’t that obvious too?” His eyes glittered. “Now my wife and the rest, goaded by the ColU, are considering an expedition. We will all march off into the dark and the cold. But first we will grow more root vegetables, so that we won’t be hungry. Even then we will move at the pace of the slowest of the group. And all the time we will be in the control of the ColU—”

“What are you suggesting, Ari?”

He stepped closer to her, close enough to whisper. His face was hard, determined. She could smell boiled potatoes on his breath.

“I’m suggesting that you and I should leave, now.”

She’d known this proposal was coming, yet her heart beat faster in response. “You’re talking about walking around the world. How—”

“There may be ways to move more quickly. We can follow the trail Earthshine left.” He pointed to the southeast. “It’s clearly visible. As for food, the store my wife has built up should be enough to sustain two.”

She grinned. “If stolen from her.”

“If stolen, yes. The pressure suit she has preserved since she came through the Hatch from Mars would provide enough warmth for us, I believe—it is a thing of multiple layers, a thing designed for the harshness of Mars, which, even if separated out, could protect the two of us from the chill of this place, Per Ardua. There are tools, even weapons we could take.”

“You would betray your wife?”

He shrugged. “I don’t think of it that way. Perhaps I am saving her from her own foolishness.”

“Why should we do this?”

“Because of the power this Earthshine pursues. Huge power, for those brave enough to grasp it. And worthy of it.”

She took a breath. “I feel—intoxicated. As I have ever since I started to uncover the strange mystery of this weaving of history. As if I were a child, plummeting down a hub-mountain glacier, out of control… We have both already walked away from our worlds, the very reality we knew, the history, the culture. Now here we are speaking of walking off into the dark. To our deaths—or unknowable glory.” She looked at him. “Do you believe that when your history died, your gods died?”

He shrugged. “In the Christian tradition, Jesu died and lived again. And in the tradition of my ancestors, all the gods die, in a final war at the end of time, but another cycle begins.”

She nodded. “Our priests also talk of cycles of calamities that punctuate time. Perhaps on some deep level we, our ancestors, already knew this is true, this meddling by the Dreamers—whoever and whatever they are.”

“So,” he said, “will you come with me? Will you dare outlive your gods?”

Again, a breath. “When do we leave?”

62

Titus Valerius, like Ari and Mardina and some of the others, had trouble adapting to the unending day of Proxima, Stef saw. The legionary found it difficult to structure his day, to sleep at night.

But he was in his element when it came to planning the trek to the antistellar. Even the betrayal of Ari and Inguill, who had taken so much of their stock and supplies with them, seemed to make no difference. He had a way of defeating problems just by waving them away.

“So we must walk around this empty world. Pah! In my time I have participated in marches the length and breadth of Europa, Africa, Valhallas Inferior and Superior, and deep into Asia. Marches across hostile territories, into the frozen tundra where wild horsemen still lurk at the fringes of continent-spanning forests—and through Valhallan jungles where every leaf conceals a scorpion, where every shadow is likely to turn out to be a skinny little warrior with a blowpipe. What dangers do we face here? That we will trip over an earthworm? We will do this. I will lead you. We will march—and that is what the Roman army is for, above all else: marching. And if we have the spare energy, I might have you all build a road while we’re at it, to ease the journey back. Why, I remember once on campaign—”

“I’m enjoying this performance, Titus Valerius,” Stef said with a grin, “but I don’t believe a word of it. For one thing, you’re not a surveyor, or a mapmaker. There’s going to be nothing to wage war against on this trip. This will be an exercise in planning, Titus Valerius. In logistics. In survival.”

“Survival? In a country where potatoes and beets grow wild? Why, it will be like a stroll through the estates of the Emperor Hadrian.”

She eyed him. “ColU, do you think he really understands what he’s taking on?”

The ColU sat on the ground beside the two of them, on a blanket spread out over the rusty dirt outside the shelter. Nearby, a low fire flickered, slowly boiling up another pot of water. “Titus Valerius is a brave man and we are lucky to have him at our side.”

Stef grinned. “Tactfully put.”

Titus Valerius scowled. “You tell me, then, star lady. Describe what it is about this journey that I don’t understand.”

“I have done this before, Titus. To begin with, we are going to have to travel all the way around half a circumference of the world.” With a broken stem she sketched a circle in the dirt, alongside a bold asterisk to which she pointed. “Here’s Proxima, the star. The circle is Per Ardua, the planet. Per Ardua keeps one face to the star at all times. So—” She cut Per Ardua in half with a bold stroke, and scribbled over the hemisphere turned away from the star. “One half is always in daylight, one side is always in shadow—in endless night. The substellar, the point right under the star in the sky, is here.” A thumb mark, on the world’s surface right beneath the star. “Which is where we are. And that’s why the star is always directly over our heads. The antistellar is on the other side of the world.” Another thumb mark. “It couldn’t be farther away from this spot. And to travel there…” She sketched a broken line stretching around half a circumference of her planet, from substellar to antistellar. “You see? The shortest possible distance we have to travel is half of a great circle—I mean, if we just head straight for the antistellar. That’s without detours, for such details as mountain ranges and oceans and impenetrable forests and ice caps. And the distance—ColU?”

“Per Ardua is a little smaller than Earth. Around twelve thousand Roman miles.”

“And, can you see, Titus? Half of that will be in daylight, and half in the dark. Six thousand miles across icebound lands and frozen oceans.”

“In the dark?” Titus was frowning now. “Where nothing will grow?”

“Nothing but icicles on your beard. Exactly. Now do you see the challenge? We had a vehicle, motorized. It was still gruelling. Beth has been building a cart.”

Titus nodded. “Even if we completed it, we would have to pull it. We have no engines, no draft animals. On the march, without vehicular transport, we expect to cover around twenty miles a day. So the journey would take us…”

Stef smiled. “Leave the mental arithmetic to me. Six hundred days. The best part of two years!”

“And one of those years in the dark and cold, where nothing grows.”

She nodded. “It’s easy for us to express an ambition to reach the antistellar, Titus. But it may not be physically possible.”

He grinned. “You should be a centurion, Colonel Kalinski.”

“Really?”

“You never tell a Roman something isn’t possible. Romans know no limits.”

“We have one advantage,” the ColU said. “Ari and Inguill went ahead of us, as you say—and Earthshine went ahead of them. There ought to be a trail we can follow, easily visible on the surface of this static world. For, even if Ari and Inguill can have had little idea what they were walking into, Earthshine will have known what he was doing. I have no doubt he would have carried a full information store on Per Ardua, as explored by our people, Stef, in our home reality.”

Titus frowned. “You mean, he had maps of this world?”

“More like a memory of maps.”

Titus pointed at the ColU. “And you, demon. Do you have a memory of such maps too?”

“In my humble way, I was one of the pioneers of Per Ardua myself. And after humanity’s large-scale emigration to Per Ardua I made sure I kept track of the latest survey data, the exploration results. Yes, I ‘remember’ the maps—at least of Per Ardua as it was.”

“Very well.” Titus lifted the ColU bodily, and set it at the edge of the blanket, facing an unmarked stretch of dirt. “Together, you and I will draw a map of this world—the parts I need to know about—so that I understand. Then I will take my daughter, Clodia, with light packs, and we will follow the tracks of Earthshine, and Ari and Inguill, to scout out a route. Meanwhile, you, Stef, will organize the preparations here. Get that cart ready to travel. Gather potatoes and beets. Grow more potatoes! It may be some weeks before we are ready to leave. And as for the dark side—let us get there first, and then we will plan anew.”

She saluted him Roman style, fist to chest and then arm raised. “Yes, Centurion! You’re right, you know.”

“I am?”

“If anybody can get us to that damn antistellar, you can. I have faith in you, Titus. Maybe not as much as you have in yourself… Tell me one thing, though. Why are you taking Clodia on this scouting trip?”

He grunted. “Isn’t it obvious? To keep her away from Mardina and the Xin slave boy. We’ve enough troubles already. Now then, ColU, tell me where to begin with this well-remembered map of yours…”

63

In the end it was more like two months before Titus Valerius, having returned from his scouting expedition with Clodia, declared that they were ready to depart.

They broke camp. Everything useful and lightweight was loaded onto Beth’s cart, or was stored on improvised packs on the walkers’ backs. They loaded as much as they could of the food store Beth had begun, cooked and dried and packaged up. Titus had decreed that they would forage as they moved, saving as much of their store as possible. The ColU itself was on the cart to relieve Chu of his burden, bundled up in a blanket and lashed in place.

The camp had been Beth’s home since she had first come here through the substellar Hatch with Earthshine. Stef watched her regretfully closing down her array of homemade clocks.

At last Stef found herself helped up onto the cart, with Beth at her side. Titus handed Stef the lightweight ropes that constituted the cart’s rudimentary steering system.

“Thanks,” Stef said sourly. “So the old lady is baggage on the trip.”

Titus scowled at that. “Yes. You’re the oldest. You’ll walk the least. Your job is to control the cart. But you will get off that cart and walk when I tell you, because I need you to stay fit and healthy.” He had a sheaf of bits of parchment and paper on which he’d worked out his schedule for the trip, tucked under his damaged arm. “It’s all in the plan.”

Stef sighed. “I hate to be a burden.”

“Just do as you’re told.”

“Yes, Centurion!”

Beth held Stef’s hand. “I wouldn’t worry about it. He thinks of you as a soldier, if maybe a wounded one, or he wouldn’t be so tough on you.”

Stef grunted. “Well, I was military myself. I guess you’re right. With men like Titus, it’s when they’re nice to you that you have to worry.”

“And as for walking…” Beth patted the frame of the cart. “Be careful what you wish for. This is my design, remember, and we’re not exactly overstocked with tools and raw materials, especially since Ari and Inguill took so much of the good stuff. If this gets us halfway to the terminator, I’ll be impressed.”

“Oh, I think we’ll do better than that,” Stef said, though she spoke more in hope than expectation as she looked back at the cart.

The basis of it was the frame of “wood”—actually split-open trunks of stem-trees from the substellar forest—lashed together with rope and vines that Beth had begun to build. It rode on wheels of wood rimmed with rope. Rims of steel or iron would have been better, but they didn’t want to take the time to build a forge to achieve that, and they’d brought spare wheels.

In addition, the ColU had ordered that sled-like rails should be fixed to the cart’s underside, an obvious preparation for the icy dark-side journey to come. And, under the direction of the ColU and Titus, the cart had even been made ready to serve as a shallow-draft boat. The sides had been built up and the whole had been made waterproof, with a coating of the marrow that you could extract from any stem or the trunks of the forest trees. The “marrow” wasn’t marrow but a complex organic product in itself, capable of a kind of internal photosynthesis based on the abundant heat energy available from Proxima. The travelers disregarded this biological miracle, and were only interested in using it as a kind of sticky gunk to seal cracks in their cart.

Stef thought it was all a marvel of improvisation and ingenuity, but they could only hope their preparations were adequate to meet the challenges ahead.

At last they were ready to go. Under Titus’s rough direction, they formed up into a kind of column. The cart, of course, needed pushing and pulling, and Titus himself, Clodia, Mardina and Chu were assigned to that duty, two ahead, two behind. They’d have some help from Beth, but she was spared the worst of the work. In her late fifties, she was being treated as another honorary old lady, to Beth’s irritation and Stef’s amusement.

“This is it, then,” Titus cried. “A journey around this strange world—a journey that begins with a single step.” He drew his pugio, his dagger, and held it aloft. “Are you ready for war?”

“Yes!”

“I said—are you ready?”

“Yes!”

“Then we advance!” He settled into his own padded harness, positioned his damaged arm, and leaned into the traces.

The cart jolted into motion, nearly throwing Stef off in the very first moment.

So it began.

Titus and Clodia had scouted out their route well. It roughly tracked the trail created by Earthshine and then followed by Ari and Inguill, but from the beginning it was almost all downhill—or at least on a gentle declining slope—and led through reasonably open country, following the water courses that threaded away from the high ground of the substellar plateau. The “draft animals” seemed pleasantly surprised to find that the exercise wasn’t as hard as they might have feared, although Stef kept her mouth shut about that, given that she didn’t have to share in the labor.

Titus called a halt after about a quarter of an hour, so that people could make minor adjustments to boots and harnesses and other bits of clothing. Then they pressed on for another half hour, until Titus called another stop for water, and then another half hour when he rotated the crew, with Beth slipping into the traces vacated by Mardina.

After just three hours—Stef guessed they’d gone only five or six miles—Titus decreed that they were done for the first day.

The rest were anxious to keep moving now they’d started, with the thousands of miles that lay ahead of them weighing heavily on their minds. But Titus was nothing if not an experienced marcher, and he knew what he was doing. He had them all strip off their boots, bathe their feet in a stream, and then slip into the loose, open camp sandals he’d had them make. This first day, unpracticed, it would take them longer than usual to make camp, to get into the routine of digging a latrine ditch and gathering food and collecting water, and Titus wanted to be sure they did all this properly. Also Titus wanted to check over the cart, to see if it was passing this ultimate test of roadworthiness. They had spare parts and pots of marrow to fix up obvious flaws.

“Come on, come on!” Titus chivvied them as they got to work. “When Roman legionaries are on the march they set up camp every night—”

“Sure they do.”

“And you don’t hear a word of complaint—”

“Sure you don’t!”

“Why, I remember once on campaign—”

“Save it, Titus Valerius!”

Once the labor of the camp building was done, and they were gathered around the fire they’d built for the night, Stef could see the wisdom of Titus’s management. They’d all encountered unexpected difficulties, even if Stef’s had been only the lack of a cushion under her bony behind. And they were all more tired than they’d expected to be. But they’d got through the day, they’d done everything Titus had demanded of them, and they knew now they only had to repeat this routine in the days to come.

Before they bundled up under their blankets and clothing heaps to sleep, huddling together under Beth’s stretched-out tent, Titus came around one more time, accompanied by Clodia with a simple medical pack. The legionary insisted on checking everybody’s feet, for bruises, chafing, incipient blisters. “Now that you’re all soldiers on the march, you’ll learn that your most important items of equipment are your feet. Look after them and the rest follows. And the sooner you’re all capable of doing this for yourselves, the better.”

“Good night, Titus Valerius.”

“Good night, auxiliaries…”

And, after Titus had done his round, Stef heard rustling, saw shadows slip through the dim light under the canopy. They were unmistakable: Chu Yuen and Mardina Eden Jones Guthfrithson, clutching blankets, hand in hand, making their way out from under the canopy and into the shade of the forest.

The next day they made better progress. And the day after that, better still.

Stef made a deliberate effort not to count the days, not even to try to estimate the distance traveled. She knew she could leave that kind of management to Titus and the ColU. And besides, she slept better if she tried not to think about the monumental journey ahead. She thought of this as a new way of life, a long tunnel of routine that was going to fill her days for the foreseeable future. Sleep, break camp, march, make camp, sleep… Without beginning, and without end.

But, gradually, the country began to change.

They descended from the substellar high ground, and the haulers began to lose the benefit of the downward slopes Titus had cunningly scouted for them. On the other hand, the weather on the lower ground, away from the permanent low-pressure system over the substellar point, became milder, less turbulent. Day by day there was less wind and rain. And the vegetation around them responded. Now the broken forest that characterized the relatively unsettled substellar gave way to more open country, with forest clumps separated by broad swaths of ground-hugging, light-trapping vegetation.

During the long hours between the days’ marches, the ColU had Chu carry it out into the country away from the camp to inspect the changing terrain. Out of curiosity, and when she had the strength, Stef followed them—often with Beth, who was curious to see more of what had become of this world that she still thought of as home.

At the end of one unremarkable day, they walked side by side over a plain almost covered in sprawling green leaves, like tremendous lilies, Stef thought. Systems of three leaves united at a central stem, covering the ground, and basking in Proxima light. When she knelt down to look closer she saw that the leaves were firmly anchored to the ground by fine tendrils, covering every square centimeter. No competitor was going to swipe this plant’s growing space, this share of the starlight. It was a very Arduan scene. But when she dug her hand into the ground beneath the leaf, she came up with what looked like an authentic sample of terrestrial soil, complete with an earthworm, a thing like a woodlouse, and other creeping terrestrial creatures.

As they walked back to camp, Stef gradually got a broader sense of the wider landscape. With the star static overhead, and every square centimeter of ground colonized thickly by the green of life, this part of the world was like a huge, collective, cooperative system, optimized over time to extract every scrap of energy from the light falling from the sky. Stef felt as if she were in some huge greenhouse, old and decayed, the glass choked by lichen, moss and weeds—with here and there a vivid splash of Earth life embedded in the rest.

In the middle of the next day they came to the bank of a river, wide, placid.

Stef clambered off her bench and hobbled over to Titus. He was standing with his one good hand on his hip, staring out at the water, grinning. “This is as far as I came with Clodia, during our scouting trip. Well, I judged we need come no farther. This river clearly flows out of the substellar point,” and he waved his hand back in the direction of Proxima, “and, no doubt fed by many tributaries, continues to flow in a roughly southeasterly direction. Well, you can see that. Now, Stef, tell me I’m no surveyor. Madam, I present a highway as straight and true as any Roman road. And now, for a time at least, we can all ride in comfort, as you have been all the way from our first camp.”

“Aye aye, cap’n.”

“I beg your pardon?”

“I imagine that didn’t translate…”

They made camp in the usual manner. Then they got to work reassembling their cart into a small boat—detaching the wheels and axles, going over the seals with their marrow caulking, and digging out paddles they’d crudely made from dead stems lashed up with rope.

In the breaks, they took advantage of the river, washing their feet and clothes, dunking their whole bodies luxuriously in water that ran refreshingly cool. But Titus banned any swimming. Though the river ran with a strong current, it was obvious that the bed was choked with life, and he didn’t want anybody getting caught up in that.

It took them forty-eight hours before they were ready to embark. After so long on the road, many days already, they had all learned not to rush.

As with their first day’s walk, Titus decreed that their first jaunt in the boat would be a short one, to ensure they ironed out any flaws. He made sure that those to whom he entrusted the paddles had fabric wrapped around their palms for protection, and ponchos improvised from lightweight survival blankets to keep off the spray. They even had to wear their light camp sandals, so that their boots, precious items of equipment, could be bundled in waterproofs. It was all detail with Titus, Stef observed.

It visibly infuriated Titus that, lacking an arm, he couldn’t manage a paddle himself. But he insisted on riding at the stern, where a crude rudder had been attached.

Once they were all loaded aboard, their stuff lashed down, Chu shoved them off from the bank with a mighty jab of his paddle against a rock, and they drifted out toward the center of the river. Titus was at the stern with his rudder, Stef at the prow with her back to the river. Of the four rowers, Chu and Clodia sat together to Stef’s right, and Beth and Mardina, mother and daughter, to her left. For the first couple of miles they were all silent, save for Titus’s curt commands: “That’s it, we’ll keep to the center where it’s deepest… Paddle a bit less vigorously, Chu and Clodia—you’re too strong and you’re shoving us to the bank. We’ll balance you up better when we stop… That’s it… If we can let the current take the boat away without us having to do any work at all, I’ll be happy…”

Stef found herself anxiously watching the deck under her feet, looking for leaks. She had crossed interstellar space in kernel-drive starships, and had even walked between realities through a technology that was entirely alien. And yet a ride in this ramshackle craft, with just a few meters of water beneath her, was somehow more terrifying than all of that.

But they hadn’t gone far before she was distracted by the atmosphere in the boat itself. Mardina glared at Chu and Clodia, and Clodia glared back.

“Ouch,” Stef said at length. “I never heard a silence so loud. What the hell’s the matter?” But of course she anticipated the reply.

“Her,” Mardina burst out, pointing a finger at Clodia.

Clodia looked ready to leap across the boat and take her rival on.

“Sit still,” Titus commanded his daughter. “Wield your oar. You too, Mardina. Snarl at each other if you must, but you will not imperil this vessel… What’s this about?”

Clodia glared. “Do you really not understand, Father?”

Titus sighed. “Being not entirely without senses—yes, Mardina, Chu, I’ve seen you two sneaking off in the night.”

Chu hung his head, Stef observed, as if he were still a slave who had been caught doing wrong.

“But,” Titus said heavily, “that doesn’t mean you’re lovers. Just because you sleep together. I mean, I remember once on campaign—”

Clodia growled, “Oh, Father.”

“Well—whether or not, Mardina, I don’t see what your problem is with Clodia.”

Mardina flared. “You see us sleep together but you don’t see what she’s doing? The way she’s sitting beside him now. The way she looks at him. Leans against him. Holds onto his arm when the boat rocks—”

“Don’t be absurd.”

“Actually, Titus,” Beth said with a rueful smile, “I noticed the same thing. I don’t think there’s any malice, though, Mardina. I don’t think she can help it. Look, girls, the problem isn’t with the two of you, or with Chu. It’s just that there’s only the three of you, three youngsters—in this boat, on this whole wretched planet. This problem was always going to come up.”

Mardina glared at her. “Oh, how helpful that is, Mother. So what do you suggest we do? Kill each other over Chu, the way those colonists did on Per Ardua like you’re always telling me?”

“Ideally we will avoid that,” Titus said with a dangerous calm. “But while you three work it out, here are the military rules. We’re on a mission here. And we also face a challenge to survive, as simple as that. You three can bed-hop as much as you like,” and he kept his eyes averted from his daughter as he said it. “But if you come to blows, if I get a hint of a sniff of suspicion that you’re putting us all in danger—why, then, I’ll put a stop to the whole business. I’ll cut your pecker off, slave boy, and skin it and use it as a wind sock. Let’s see these young women fight over you then.”

Chu seemed to think that over. “It would be a big wind sock, sir—”

“Shut up.”

For a time they progressed down the river in silence.

Then, from inside its waterproof wrapping, the ColU spoke up. “Well, this is awkward. Shall we sing a song? There’s one you may remember, Beth, from your childhood, with Yuri Eden and Mardina Jones—not that we had a boat in those days. Row, row, row your boat… Come, please join in…”

As they drifted on down the river its voice echoed from the life-choked water.

64

With time the great waterway broadened and deepened, with many tributaries flowing into it from the surrounding land, just as Titus had predicted.

Then there came a day when “their” river passed through a confluence and became a tributary of a much wider river still. Soon the flow was so wide that it was difficult to make out the far bank. “We lucked out,” Stef said. “We found the local Mississippi.” But of her companions, only the ColU and Beth knew which river she meant, and even Beth, Arduan-born, wasn’t sure.

Titus insisted that they should stay close to the bank, fearing stronger currents in the middle of the channel—and, just possibly, more aggressive life-forms than they’d yet encountered. Even so, they swept on with what felt like ever-increasing speed.

Without the physical effort of the march—the hardest work was the daily labor of hauling the craft up the bank for the night—and with Proxima sinking almost imperceptibly slowly in the sky behind them, the days passed in ever more of a blur to Stef. Even so it was a surprise when the ColU announced that they had already been traveling for sixty days.

The character of the landscape around the riverbanks was changing once more. Much of the vegetation was waist high, and Stef was reminded of the prairies of middle America—or rather, of museum reconstructions she’d seen of such ecologies as they’d been before the climate Jolts. With the air cooler and Proxima lower still, the ground-blanketing “lilies” were no longer so successful, and plants that bore leaves tilted toward the star did better. There were even trees here, or tree-like structures, with big leaves competing for the life-giving light, some stubby and fern-like, some quite tall and rising above the “prairie flowers.” But in this more open country some terrestrial plants fared better too, and the travelers gratefully scooped up handfuls of wild potatoes, yams—even grapes from vines that grew laced over Arduan trees, a cooperation across the two spheres of life that the ColU said it found pleasing.

The ColU never asked for stops. It seemed too aware of the pressure on them all to make good progress, and to push on with the journey. But sometimes, during their “night” stops, it would ask Chu, or perhaps Beth or Stef, to take it to sites of particular interest. Such as exposed rock formations—which were rare; this Arduan continent was worn as flat as the interior of Australia. And the ColU would ask for samples to be taken, for fossils to be sought.

“You’ll remember, Beth Eden Jones, how frustrated I used to get! This planet was once so active, chunks of its surface forever churning up, that any fossils were destroyed, the very layers they had formed in disrupted—the whole fossil record was a mess. Now that the world is so much more quiescent, there’s at least a chance of finding some kind of decent record, at least of comparatively recent life-forms…”

But all it ever found were what looked to Stef like matted banks of reeds, compressed into the sandstone and petrified. If there was no significant change, no extinction or evolution, she supposed, you were going to get a featureless fossil record, no matter how well preserved. Nothing but stems for—how long? Millions of years?

What Stef did notice herself, and she discussed it with the ColU, was an utter lack of evidence of the works of humanity.

“We know people were here, once, on this Per Ardua. Right? The potatoes and the grapevines wouldn’t be here otherwise. But where are their towns? Oh, the buildings would burn down and crumble away, but where are their foundations, and the waste dumps, and the outlines of farmers’ fields? Where are the remains of their roads and rail tracks? We were on the way to setting up farms and mines all the way to the terminator. But it’s all just as it was at the substellar—gone. How long would it take to erode all that to dust, ColU?”

But, as always, the ColU refused to speculate about time. “We will know soon enough,” it said. “As soon as I see the dark-side sky. We will know how long then.”

Once the ColU asked to be taken into a stromatolite garden, where those complicated mounds of bacterial layers, each about chest high, were growing together in a close crowd.

“Of all the Arduan life-forms I have observed—save only the builders themselves—this is perhaps the most characteristic,” the ColU said happily from its pack on Chu’s back. “And the most enduring. Here, before all the rest, probably, and still growing strong, even now in the end days.”

And Stef wondered, End days?

“Yet,” the ColU said now, “there seems to be something subtly different about these specimens. Beth, Chu, do you have knives?”

It had Beth slice open one of the stromatolites, through its carapace and thick trunk. Within was a greenish mush, vaguely stratified. Beth dug in with her hands, but yelped, “Ow!” and pulled back quickly. “Something bit me…”

She called Chu and Stef over, and, more cautiously, they dismantled the slimy interior of the stromatolite, chunk by chunk.

Then they found the ants’ nest. Black bodies, big, each maybe a thumb-joint long, came swarming out in protest at the intrusion of daylight.

The ColU seemed thrilled. “How wonderful! More ecological integration, more cooperation. Perhaps the terrestrial insects feed off detritus trapped in the layers of the growing stromatolite. And the structure as a whole must benefit from the internal mixing-up of the insects. Two life-forms originating on worlds light-years apart, evolving ways to live and work together, for the benefit of all.”

“I expect there’s a moral lesson in all this,” Beth said drily.

Again Stef was left with more questions than answers. Yes, she could understand the evolution of a cooperative community like this. But how long had that evolution taken? Time—the great mystery of this new Per Ardua.

They cleaned off their knives, packed the mushy organic material back into the wounds they’d created, and—with one last silent apology from Stef to the mutilated stromatolite—they returned to their riverside camp.

Ninety days out from the substellar, their faithful river at last flowed into a broader body of water, a lake perhaps, maybe even a sea. It was wide, stretching beyond their horizon, and choked with green life.

They decided not to try to cross it in the boat. So they camped on shore for a couple of days while reassembling their boat into a cart, and began the process of hauling their way around the lake, hoping to find a way to continue southeast, following their great circle. The haulers grumbled, and Titus chided them for their lack of fitness after so many days on the river.

After a couple of days they came to what appeared to be a broad isthmus, a neck of land separating their own lake and a neighbor that looked even more extensive. The isthmus led to what appeared to be higher ground to the southeast, densely carpeted with forest.

With relief that they were able to resume their southwestern course, they continued across this natural bridge. Titus strode boldly at their head, hauling on his harness with the vigor of a man half his age, Stef thought. He was magnificent in this setting, with the light of the slowly descending Proxima glimmering on the water around him, and casting an ever-lengthening shadow ahead of him: he was the last of the Romans, pursuing one last impossible mission. Not that she was about to tell him so.

They reached the bank of forest at the far side of the isthmus. Compared to the substellar forest, this was sparse, patchy—but, in the long shadows, quite gloomy. Titus and Clodia spent a day scouting out a likely route, and settled on another water course, heading south from the isthmus and cutting a track through the forest.

On they marched. As Proxima lost ever more height in the sky, so the nature of the vegetation around them changed again. The trees grew taller now, with big flaring leaves that strained to the northwest toward the lowering star, and at their feet the gathering shadows were broken by a greenish glow, reflections from the huge sprawling triple leaves. In some of these pools of illumination they found termite mounds, familiar from Earth, feeding off the reflected light of another star: another cute example of the cooperation of interstellar life in this strange environment.

They reached yet another milestone: a hundred and twenty days since leaving the substellar camp. When Stef looked back she saw that the disc of Proxima, dimmed and bloated by refraction in the thickening air, now touched the horizon. And when she looked ahead she could see splashes of light, islands in the sky. She remembered this from her last jaunt across the terminator, with Yuri Eden and Liu Tao, long ago. She was seeing the light of Proxima catching the peaks of mountains, while their bases were in permanent night, the shadow of the planet.

That was when Mardina announced she was pregnant.

65

They built a camp in a valley of twilight.

They had walked into the shadow of the world, Stef realized. The sky, laden with thick cloud, was pitch-black. The only light they had, save for their own torches, came from the mountain that loomed over this valley, worn by time but still so tall that its summit and higher flanks were splashed by sunlight, and some of that daylight reflected into the valley below. Stef suspected they had stalled in this last scrap of light, before penetrating the interminable dark ahead, for reasons of instinct as much as logic; they couldn’t bear to leave the unending Proxima day behind.

Titus Valerius, as always, took charge. First he had them build a camp on a rocky outcrop rising from the generally muddy ground—and it would always be muddy here at the terminator, the ColU had warned, when it wasn’t snowing or icebound. It always rained at the terminator. As warm air from the day side spilled over into the chill of endless night, it dumped its moisture, and the ground everywhere would be waterlogged. But at least on this rock they could build a fire, and sleep out of the damp, and keep any rain off with their tent canopy supported by a frame of stem-tree trunks.

Then, once they were established, Titus gathered them in the glow of the fire. In the deepening cold they were already wearing extra layers of clothing, stuffed with padding; they all looked fat and clumsy.

“We’ve done well so far,” Titus said. As he spoke, he ladled out a stew of potatoes and cabbage. “Mostly thanks to the rivers. A hundred and twenty days to these shadow lands, faster than I anticipated. But we’ve still got the same distance to cross again, and in the dark and the cold all the way, as I understand it. Yes?” He looked around at them somberly. “Some of you know this world; I was never here before. Sitting here I find myself uncertain about whether this mission will even be possible, the six of us dragging a cart through the dark for thousands of miles. Well, we must do the best we can. Just as we planned, we will now consider our situation, and prepare for the adventure ahead.”

Stef smiled at his choice of words. Adventure, not ordeal. The man was a natural leader. Looking around the group, she saw that he held everyone’s attention—everyone save Mardina, perhaps, who seemed unable to eat the cabbage, and was folded over on herself, her knees drawn up to her chest.

“There are six of us, plus the ColU,” Titus said now. “Four of you, all save myself and Clodia, will make one last effort to gather supplies. Clearly nothing will grow on the ice of the dark side, I understand that, so you must gather what you can from the nearside vegetation that grows in the sunlit areas a little way back, or even on the illuminated peak above us. By the time we leave, our cart must be full, our packs bulging. Perhaps we can find a way to reduce more of the food, to boil it, compress it. If the challenge is too much, we can do this more gradually, setting up a series of caches, pushing deeper into the cold.”

Stef put in, “At least we’ll have no trouble with warmth, thanks to the Romans’ kernel oven. There will be no trees growing on the farside ice, no fuel for fires.”

“True,” Titus said.

Beth said, “So while we’re foraging and boiling potatoes, you and Clodia—”

“We will be scouting,” Titus said with a grin. “We’ll go exploring into the dark, a little way at least. Looking for a route forward. And looking for a way to shorten this trip.”

Beth frowned. “How would that be possible?”

“I’ve no idea. But then, I’ve never been here before.” He glanced at the ColU, which sat on a folded-up blanket. “And, in a sense, neither have any of you, since—if I understand your hints correctly—somehow a great span of time separates this world from the one you knew before. Who knows what might have happened in all that time? Perhaps Per Ardua had its own Romans who left behind a road, straight and true as an arrow, leading us straight to the antistellar.”

Stef smiled. “I suppose it’s worth a look.”

Now Titus turned to Clodia. “And I will have you at my side, child, because you will be a valuable companion on such a mission. I’ve seen enough on this journey already to know that.”

“Thanks,” Clodia said flatly.

Titus looked at Mardina. “The alternative is for you to stay here and assist Mardina. You may imagine how much I know about pregnancies. Perhaps it would help Mardina to have another young woman at her side.”

Mardina looked back at him bleakly. “Forget it. My mother’s here. And Stef.”

“And me,” the ColU said. “Remember my programming. I was designed to fulfill the medical needs of a growing colony. Indeed I administered the birth of Beth Eden Jones herself, many years ago. While I am no longer capable of practical intervention, I can—”

“You can shut up,” Mardina snapped at it. “That’s what you can do. I don’t need anything. Not yet.”

Titus glared at her and at Clodia. “At any rate, your rivalry over the boy, Chu Yuen, is over, at least for now. Yes? When the baby comes, you can work out for yourselves how you want to organize your lives, and your loves.”

Stef smiled at him. “Titus Valerius! I’m shocked. I thought you upright Romans were monogamous.”

“Different moralities apply on the battlefield.”

“I wasn’t aware we were on a battlefield.”

“Tell that to the ice. Why, I remember once on campaign—”

“Not now, Father,” Clodia said, and she turned her back.

After a night’s sleep Titus and Clodia bundled themselves up in layers of clothing, packed bags, and slipped away, off to the southeast, deeper into the dark.

The rest got on with collecting foodstuffs and fuel for the fire. Chu, Mardina and Beth explored the diffusely lit valley, and made longer treks back into the lands of daylight. Chu and Mardina also made some climbs up the flank of their mountain, into the island of life and light up there. Beth found the steeper climb all but impossible herself, and she was unhappy about leaving it to her pregnant daughter. But the ColU pointed out the pregnancy was barely begun, its own tests showed that Mardina was as healthy as could be expected, and there was really no reason to hold her back.

Stef assuaged her own guilt by doing what she could at the camp: refurbishing the cart, preparing the food they gathered, fixing meals.

And she worked with the ColU at its studies, biological, geological, astronomical.

The species of vegetation the youngsters brought down from the illuminated summit turned out to be complex. Some of it was familiar, descendants of either Arduan life or terrestrial. But some was stranger, what appeared to be essentially terrestrial root crops but with leaves with a peculiarly Arduan tinge to the green. The ColU grew excited at this, and insisted that Stef dice up samples to be fed into its own small internal laboratory for analysis.

“Do you remember our own trek to the far side with Yuri Eden and Liu Tao, long ago? We passed these terminator islands of light that I longed to explore. I could see even then that such islands really were isolated from each other, especially as we pressed deeper into the dark, just like islands in an ocean. And just as on Earth, islands are natural laboratories for evolution…”

It took it a full day of analysis before it was prepared to announce its conclusions.

The remnant ColU unit had only a tiny display screen, meant for showing internal diagnostics of the AI store itself. Stef squinted to see with tired, rheumy eyes. “That’s a genetic analysis,” she said at last. “But there’s a mixture there. Of terrestrial DNA, and the Arduan equivalent…”

“All from the one plant,” the ColU said. “An unprepossessing tuber that you might trip over in the dark. I’m not even sure if it would be edible, for humans—”

“Just tell me what you found, damn it!”

“Integration. A product of a deep integration of the two biospheres. Colonel, this plant is like a terrestrial vegetable, but with Earth-like photosynthesis replaced by the Per Arduan kind—the version tuned to Proxima light, which exploits the dense infrared energy that Proxima gives off. Do you see? In the very long run, it is as if there have been two origins of life on this world, Stef Kalinski. The first origin was when Arduan life emerged—and we know even that was related to the emergence of life on Earth; there was a deep biochemical linkage enabled by panspermia. And the second origin was when humans arrived at this world—Yuri Eden and Mardina Jones and all the rest—and brought with them a suite of life-forms from Earth.”

“Ah,” Stef said. “The ISF thought they were exploring the stars. In fact they were seeding life.”

“Ever since Lex McGregor walked here and made his speeches, the dual biosphere has been evolving. At first there must have been extinctions on both sides, as forms unable to adapt to the new conditions went to the wall. After that, over a hundred thousand years, a million years, there must have been speciation as new forms emerged and adapted to the new conditions. New kinds of potato, adapted to the thinner Proxima light. And in ten or a hundred million years, there would be time for integrated ecologies to emerge, as the surviving life-forms evolved together.”

“Like the ants in the stromatolite. Like bees and flowers, back on Earth. But this is more, deeper, this mutated metamorphosis. A symbiogenesis,” Stef breathed.

“Exactly. The deepest symbiosis possible, the most intimate life cooperation of all. It is just as the mitochondria in your own body’s cells, Stef, were once independent organisms. They became integrated into your cells to serve as sources of energy, yet they retained their own genetic heredity, a kind of memory of their free-swimming days. Terrestrial life, from amoebas and complex cells upward, is a product of a deep integration of many forms of life. Genesis through symbiosis, indeed.”

“And now, here on Per Ardua, we’re seeing the same thing over again. How long would it take? How much time has elapsed here since humans arrived? How far into the future have we been projected, ColU? More than millions of years, more than hundreds of millions…”

The ColU simulated a sigh. “I apologize for my reticence. You have asked these questions many times before. I can make only rough guesses based on the data I have so far, the evidence from the geology here, the biology—even from the evolution of the star itself. I will be able to make much more accurate estimates of the date when I see the dark-side sky, and I can gather astronomical data. But of course there is an upper bound.”

Stef frowned. “An upper bound? How can there be an upper bound on the future—what upper bound?”

“The End Time,” the ColU said simply.

That was when Mardina and Chu burst into the camp, scuffed and dusty and breathing hard.

Mardina said, “You keep saying you want to see the sky, ColU.”

“Yes—”

“Well, your luck is in. You can see it from the slope, not much of a climb from here. Chu, get him into his pack.”

“See what?” Stef demanded. “The stars?”

Mardina gave her only a quizzical look. “Sort of. See for yourself. Come on! And where’s my mother?”

The four of them, Stef, Chu, Mardina and Beth, stood on a hillside, looking out over the night lands of Per Ardua, over an ocean of dark. Only the faintest reflected glow from the summit above reached them here.

And above them, in a terminator sky marred for once only by scattered cloud…

Not stars, no, Stef saw. Not just stars. It was a band of light, an oval, an ellipse—no, surely it was a disc tipped away from her, all but edge on. The overall impression was of a reddish color, but bright white sparks were scattered over the pink, like shards of glass on a velvet cushion. There was a brighter blob at the center, and lanes of light sweeping around that core. As eyes adapted to the low light she saw finer detail, what looked like turbulent clouds in those outer lanes, and here and there a brighter spark, almost dazzling. And when she looked away from this tremendous celestial sculpture, she could see stars—ordinary stars, isolated sparks scattered thin, though many of them seemed reddish too. But the sky was dominated by the great ellipse.

And, oddly, the thing she noticed next was Mardina’s hand slipping into Chu’s, and squeezing tight.

Stef said sharply. “You know, ColU, you should have warned us about all this.”

“But I was never sure. I can never lead; I can only advise.”

“It’s a galaxy,” Beth said, a little wildly. “Even I know that much. Like our Galaxy, the Milky Way… But what the hell’s it doing up there? Is it our Galaxy?” She shook her head. “I grew up on Per Ardua, remember, on the day side. I never even saw the stars until I got to Mercury. Has Proxima been—I don’t know—flung out of the Galaxy somehow, so we see it from the outside?”

“Nothing like that,” the ColU said gently.

“That’s not our Galaxy at all,” Stef snapped. “That’s Andromeda, isn’t it? Bigger than ours, I think. The two galaxies were the biggest of the local group. Now, when I was a kid playing at astronomy with my father, on the rare nights we had clear skies in Seattle—”

And, in some realities, with her impossible sister Penny by her side.

“—we used to look for Andromeda. Fabulous in a telescope, but you could just see it even with the naked eye. A smudge of light. Now that, I would say,” and she started taking rough sightings of the width of the object with her thumb, “is, what, thirty times the apparent diameter of Earth’s sun?”

“More like forty,” the ColU said.

Mardina was staring at her. “So how did that thing get so big?”

“It didn’t. It got closer.” Stef closed her eyes, remembering her own basic astronomy classes from long ago. “In my time Andromeda was two and a half million light-years away. Right, ColU? But even then we could see it was approaching our Galaxy. The two star systems were heading for a collision, which—well, which would be spectacular. Now, as I recall, the best predictions for the timing of that collision were way off in the future. Four billion years or more?”

“More like four and a half,” the ColU said.

Stef squinted. “So if that beast, which is around two hundred thousand light-years across, is that apparent size in the sky, I could estimate its current distance—”

“Done,” the ColU said. “Colonel Kalinski, I now know we have traveled—or rather the Hatches have taken us—some three and a half billion years into the future. That is, after the epoch from which we set out.”

Beth, Mardina, Chu just stared at each other, and then into the slate hanging from Chu’s neck, as if the ColU’s mind resided there, as if behind a human eye.

But Stef understood immediately. “Yes, yes. So the collision is still a billion years away—”

“If it were to happen at all,” the ColU said enigmatically.

“I wonder what it must have done to cultures that emerged after our own, to have that hanging in the sky. Growing larger century by century. How many religions rose and fell in its light, awed and terrified?”

“We’ll never know, Stef Kalinski,” the ColU murmured.

“And, over three billion years—that’s presumably more than enough time for all the processes we’ve seen here on Per Ardua to have come about. For almost every trace of humanity to have eroded away. Even for species from two different star systems to find a way to evolve into one.”

Mardina looked around the strange sky. “I don’t understand. Three and a half billion years… It’s meaningless. Where is Terra? Where’s the sun?”

“I’m afraid I’m not sure,” the ColU said. “The sun and the Alpha Centauri system, the Centaur’s Hoof, were once near neighbors. But by now they will have wandered far from each other, as the Galaxy has turned on its axis. Earth, Terra, and the other planets will still orbit the sun. But Earth is probably lifeless; the sun, slowly heating, will have sterilized the inner planets—oh, as much as two or three billion years ago. But the aging sun has not yet entered its terminal cycle, the red giant phase when the sun will swell and swallow the inner worlds.”

Earth lifeless. Suddenly Stef shivered, despite the comparative warmth of her clothing. To be alone on this world was one thing. To be taken out of one reality stream and dumped in another was extraordinary. But to be stranded in a future so remote that Earth was dead, that presumably nothing like the humanity she had known could still survive…

“This is terrifying,” she murmured.

“Indeed, Colonel Kalinski,” the ColU said.

Chu was looking around the sky. “I rode on starships,” he said slowly. “I was held in slave pens. But when I passed windows, I glimpsed the skies of many worlds. And this is quite different. I mean, even aside from the approaching star storm, Andromeda. The stars seem more dim, more sparse.”

“That’s a good observation,” the ColU said. “Even in our time the great ages of star making were ending. Now there are fewer young stars, more aging ones.”

Chu asked, “And where are the other stars of the Centaur’s Hoof? They should be two brilliant lanterns in the sky.”

“Even Alpha Centauri has evolved with time,” the ColU said sadly. “Its stars were older than the sun. The brightest of the main pair will have lapsed into its red giant stage perhaps half a billion years ago, sterilizing any worlds in its own system, and its partner’s, before collapsing to a white dwarf—and Proxima will have become decoupled from its weakening gravity field. The lesser of the main pair would have had many billions of years left before it, too, entered its terminal phase. Smaller stars last longer. Proxima, the runt of the litter, would likely have lasted for six trillion years before running out of its carefully processed hydrogen fuel. But Proxima, now, is alone.”

“You say would,” Stef said. “Would have lasted trillions of years. And you seemed remarkably precise in your estimate of the date, given only a cursory look at this sky above us—”

“As I told you, I do have more information,” the ColU said. “About the future of the universe, gathered during the long years of my journey home to Earth in the Malleus Jesu. Subtle signs of times to come: evidence of titanic future events, smeared across the sky of the present. Events whose date I was able to estimate. Once I saw that Andromeda was so close, once I realized roughly what epoch this is, it was easy to deduce that they would have brought us, not to some arbitrary earlier point, but to this point in time. This most special time of all. With more observation, especially of the cosmic background radiation, I will be able to be more precise still—”

“They,” Stef snapped. “They brought us here. You mean the Hatch builders. Who Earthshine called the Dreamers.”

“The Dreamers—yes.”

Chu asked now, “And what is so special about this time, this future, this age?”

“Nothing.” The ColU sighed. “Nothing, save that it is the last age of all.”

“The End Time,” Stef said.

She saw Mardina place her hand on her belly, over her unborn child.

That was when Titus and Clodia came clambering up the slope. “Here you are. Camp discipline: leave a note before you all clear off next time.”

Beth said, “We’re stargazing. Looking at that.” She pointed up at Andromeda.

Titus snorted. “Who cares about lights in the sky? I’ve got something much more important to show you. Come see what we found!”

66

It was a walk of around three kilometers—two of Titus’s Roman miles.

They came down off the flank of the mountain and made their way along a dry, shadowed valley. The going was easy, even for Stef, who had walked little save around one campsite after another since the expedition set off. Titus and Clodia both carried torches of dry stems bundled up and dipped in pots of marrow; they burned, if fitfully. But the glow from Andromeda was surprisingly bright, especially from that brilliant central core. Billions of suns in lieu of moonlight, Stef thought idly.

And, as Titus had predicted, when she came to the structure Titus and Clodia had found, Stef too forgot the wonders of the sky. She even forgot, for a while, the ColU’s dark and still obscure mutterings about the End Time.

It was another ellipse, tilted like Andromeda in the sky—but this one, much longer than it was wide, was cut into the ground. And as Stef approached the cut she saw that in fact she was looking into a circular tube, a cylinder—no, a tunnel; it was big enough to be called that—several meters in diameter, that slid into the ground at a shallow angle, making this elliptical cross-section where it met the flat ground surface.

The ColU had his bearer, Chu, walk around this formation, studying it closely.

But Titus warned them all sternly not to step into the tunnel, onto the smooth, curved interior. “We were wandering around at random, hoping to find a convenient river or some such to carry us further on our way… Then we found a kind of way marker. Solid granite, and barely eroded.”

“We are all but beyond the terminator weather here,” the ColU said. “Weathering, erosion, will be slow. The marker, like this structure, could be extremely old.”

“Well, the marker had a distinctive arrow; you couldn’t mistake its meaning. Which led us straight to this.”

“Remarkable,” the ColU said. “Remarkable. And for us to have happened on such a structure so close to where we crossed the terminator—it cannot be chance; the cold side of this world must be laced with such constructs.”

“I don’t understand,” said Stef. She walked closer to the ellipse lip. “I see a tunnel.” She glanced back at their mountain for reference. “Pointing pretty much southeast—that is, away from the substellar—”

“And directly toward the antistellar,” the ColU said.

“A tunnel sloping down at a pretty shallow angle.” She took Clodia’s torch and held it up. The tunnel continued dead straight, into the ground, beyond the glow cast by the flickering torch. “Some kind of transport system?”

Titus grinned. “You philosophers haven’t spotted the most interesting thing about it. I told you to stay off the surface. Why? Because it is perfectly slippery—less friction than the smoothest ice, I would say. Though I can tell you it is no colder than the rest of the world—I touched it with my hand; I dared that. But if you were to step on it—” He took a pebble and set it carefully on the sloping surface of the cylinder. It seemed to rest still, just for a moment, and then began to slide into the mouth of the cylinder, picking up speed gradually until it disappeared into the shadows. “See?” Titus grinned. “You would fall on your backside and you would slither off out of sight, forever.”

“Not forever,” the ColU said. “Titus, I daresay you’ve tried this experiment a few times. When exactly did you drop your first rock down this shaft?”

“Actually it was a spare torch. I wanted to see how far it extended…”

They compared times. Titus always kept a careful check on times when marching or scouting. He had dropped the torch about an hour and fifteen minutes earlier.

“Good,” said the ColU. “We won’t have long to wait.”

Stef frowned. “Wait for what? This enigmatic manner of yours is irritating, ColU.”

“I’m sorry. When I was a mere farm machine, you know, people rarely listened to my speculations—”

“Spill it, tin man.”

“Colonel Kalinski, I think this is a gravity tunnel. It’s an old idea, dating back to contemporaries of Newton.”

“Never mind the history lesson. Just tell us.”

“Imagine a tunnel dug through the ground, in a dead straight line between two points on a planet’s curving surface. The tunnel is straight, but you can see that it will seem to dive down into the ground at one point, and then climb up again at the destination.”

Stef nodded. “I get it. So if you line the tunnel with a frictionless surface, and climbed on a sled—”

“You would slide down into the ground, reaching some maximum speed at the midpoint of the tunnel, until slowing to the other end. It would feel as if you had descended a slope and climbed another, but in fact you would have followed the tunnel’s straight line all the way. Do you see, Stef Kalinski? The passage is energy free, once the tunnel is cut. Powered by gravity alone. And if you built a network of tunnels, and made them durable enough—”

“You’ve built a transport system that could last a billion years.” Stef grinned at the audacity of it. “All but indestructible, and free. I love it. So the people who built this, whether they were our descendants or not, must have been pretty smart.”

The ColU said, “They may not have been people at all. This is Per Ardua. Remember we had evidence that there was a builder Culture that achieved planetary engineering. Maybe this is somehow a legacy of that.”

Titus was frowning. “I am trying to work this out. So my torch will have slid along this tunnel to the terminus. And then, with nobody to collect it—or so I presume—it will have started to slide straight back again. You say we must wait only a few minutes, ColU. Do you mean until my torch returns? But how can you know that? You don’t know how long this tunnel is…”

“It doesn’t matter,” the ColU said. “It’s an odd quirk of physics. The time the journey takes only depends on the density of the planet, the gravitational constant… Even if you could cut a tunnel right through the center of the planet—”

“Which would have been handy getting from substellar to antistellar,” Stef said drily.

“Even then, though you’d have reached much higher speeds at the midpoint, the journey time there and back would be the same.”

Titus said, “All this sounds like philosophical trickery to me. And how long is this magic transport time you predict, O glass demon?”

The ColU said, “Just wait… About this long.”

And, right on cue, a bundle of reeds came sliding up out of the mouth of the tunnel. As it slowed to a halt, Titus carefully reached down and swept it up with his one good hand. “Ha! A fine trick, demon. But now we have some planning to do. Come! Let us return to camp.”

The first trip through the gravity tunnel, Titus decreed, was to be made by sled, Beth’s cart, with the runners they had made to replace the axles and wheels on the undersurface. Of course they had anticipated having to drag the cart over farside ice, but Stef could see that this arrangement ought to work even better in the frictionless tunnel.

So they wheeled the cart the couple of miles to the tunnel mouth, established a temporary camp, spent a day fixing up the cart with its sled rails. They ate and slept, according to Titus’s stern orders.

Titus decreed that the first to take a trial trip through the tunnel would be himself with his daughter Clodia—and the ColU and Stef, who might be able to interpret the experience, and what they found on the far side. The pregnant Mardina, the baby’s father, Chu, and prospective grandmother Beth, would not be split up come what may; they would be staying behind.

They were evidently going to have to do some fancy work getting the crew loaded on at one end of the tunnel, and successfully off at the other before the sled started to fall back, without any outside help. Before they hauled the cart over to the tunnel Titus had them practice the art. They had most success with Titus and Clodia leaping out at the destination, carrying rope to tie up the cart, while Stef stayed in the cart cradling the ColU.

Then the cart crew bundled up in their warmest gear—they were after all going an unknown distance deeper into the chill of farside—and loaded food, water, blankets, material for a fire, and a few of their precious tools, onto the cart itself. Beth, Mardina and Chu had an easy enough time pushing the cart over the lip of the sloping tunnel, and held it steady while the passengers climbed aboard.

Then Titus ceremoniously lit a torch and held it aloft. “Onward, and into the unknown!”

The support crew let go of the cart. Slowly, almost imperceptibly, it began to slip down the slope.

Stef glanced back at the grinning, somewhat anxious faces of her companions. “It’s taking an embarrassingly long time to get going,” she said. “I feel like the King of Angleterre in his coronation carriage.”

“We will be in the dark soon enough,” the ColU said. “But remember, even if the torch were to fail, it is only forty minutes to complete the one-way trip to the far end.”

Now the mouth of the tunnel was all around them, swallowing them up, their speed gradually increasing. The dark was deepening now. The movement was utterly smooth, and entirely silent.

Stef felt a frisson of fear. “It’s like a roller-coaster ride. Magic Mountain at Disneyland. None of you have the faintest idea what I’m talking about, do you?”

Titus, cradling his torch with his burly body, was suspicious. “I don’t understand. We are moving quite rapidly already. And yet there is not a breath of wind.”

“As I anticipated,” the ColU said smoothly.

Stef snarled, “What now, ColU? I wish you’d be open with us.”

“I apologize, Colonel Kalinski. There could be no air resistance in here. Otherwise, you see, the friction would slow us; we might pass the midpoint but would not reach the tunnel end, and would slip back, eventually settling at the center, the lowest point. Human engineering designs based on this idea always imagined a vacuum tunnel.”

Titus took a deep breath. “We’re in no vacuum.”

“I think there is an invisible subtlety to the design. The air we breathe is carried with us—perhaps the tunnel air is held aside. Given time, Stef Kalinski, you and I could no doubt investigate the engineering. Whatever the detail, it must be robust to have survived a billion years…”

The dark was deep now. They didn’t seem to be moving at all, and Stef soon lost track of time. In the light of the torch, Clodia cuddled closer to her father.

Stef, unable to resist it, moved closer to the big Roman too.

Titus said, “I am sorry I do not have a hand for you to hold, Stef.”

She clutched his stump of an arm and rested her head on his shoulder. “This will do.”

“It won’t be long,” the ColU murmured, from the dark. “Just forty minutes. Not long.”

They emerged on an icebound plain.

Stef walked a few steps, away from the tunnel mouth and the disgorged cart. She swung her arms, breathing in deeply; the cold stung her mouth, and her breath steamed. “This is the far side, all right. Just the way I remember it.”

She looked around. Andromeda still hung huge and looming in a crystal-clear sky; there wasn’t a shred of terminator-weather cloud here. In the crimson galaxy light, the land seemed featureless, flat. But there was a peculiarly symmetrical hillock in the ice a few hundred meters away, like a flattened cone, or a pyramid with multiple flat sides—or like a tremendous jewel, she thought. Could it be artificial? There was no other feature in the landscape to draw her eye.

She walked that way, trying to place her booted feet on ridges in the ice to avoid slipping.

Inevitably Titus called after her. “Don’t go too far!”

She snorted. “I’m hardly likely to have marauding barbarians leap out at me, legionary.”

“You might slip and break your brittle old-lady bones. And with my single arm it would be a chore for me to have to carry you back to the cart and haul you home.”

“I’ll try to be considerate.”

The ColU called, “In fact, Colonel Kalinski, would you mind carrying my slate for a closer inspection? And if you could find a way to bring back a sample of that formation…” With surprising grace on the ice, Clodia jogged out to hand Stef the slate, and a small hammer from their rudimentary tool kit.

As Stef approached the pyramidal structure, she listened to the ColU’s analysis.

“I can deduce our change in position quite clearly from the shift in the visible stars’ position. Andromeda has shifted too of course, but that is too large and messy an object to yield a precise reading…”

The closer she got, the less like a geological formation the pyramid seemed. It was too precise, too sharply defined for that. She supposed there might be a comparison with something like a quartz crystal. But she had an instinct that there was biology at work here, something more than mere physics and chemistry. She took panoramic and close-up images. The pyramid looked spectacular and utterly alien, sitting as it was beneath a sky full of galaxy. Then she bent to chip off a sample from one gleaming, perfect edge.

Titus called, “How far have we traveled then, glass demon?”

“Not very far at all, Titus Valerius. Only a hundred kilometers—just a little more. That’s perhaps sixty Roman miles. Not very far—but that means we were never very deep under the surface. Two hundred meters at the lowest point, perhaps.”

With her sample of what felt like water ice tucked into an outer pocket, Stef headed carefully back to the group.

“Not very far, as you say, demon. But we know this tunnel is not the only one of its kind in the planet.”

“Quite so, legionary. There will be many such links, perhaps a whole network, perhaps of varying lengths.”

“Yes. And a way for us to go on, deeper into the dark. There must be another entrance close by—all we need do is find it. And then—”

“And then we can proceed in comparative comfort, if we’re lucky, all the way to the antistellar,” said the ColU. “For that central locus must be a key node of any transport network.”

Stef had got back to the cart, within which the ColU sat, bundled against the cold. “You want me to put some of this sample in your little analysis lab?”

“Yes, please, Stef Kalinski. Titus Valerius, let us consider. If this length of tunnel is typical, at sixty miles or so, and if we have a journey of less than six thousand Roman miles to complete to the antistellar—”

“We’ll need a hundred hops. And if each hop takes us two-thirds of an hour, as you said, that will take, umm…”

“Sixty, seventy hours,” Stef said. “I always was good at mental arithmetic. Even allowing for stops, and for hauling the cart between terminals, that’s only a few days.”

“It may be hard work,” Titus said. “But we will not freeze to death, or starve, or die of thirst on the way.” He nodded. “Excellent! But you know, Stef, I, Titus Valerius, anticipated that we would find some such fast road as this.”

“You did? How?”

“Because, if not, we would have encountered Ari Guthfrithson and the Inca woman walking back the other way. Would we not? For if we could never have mastered this world of ice on foot, and I suspect that is true, they could surely not. Clever fellow, aren’t I, for a one-winged legionary? Now then—Clodia, come with me. We will do a little scouting before we return. Let’s see if we can find the terminal of the next link, somewhere in the direction of the antistellar…” He glanced up at the sky, taking a bearing from Andromeda. “That way. Come now! And you, Stef Kalinski, you and your old-lady bones stay put in this cart.”

“With pleasure, legionary.”

As they walked away, she heard father and daughter laughing.

“It’s good to hear them happy,” Stef said. “Suddenly a journey that did look impossible has become achievable.”

“You too should be happy,” the ColU whispered.

“I should?”

“For the discovery you have just made.”

“What discovery? The pyramid?”

“It’s no pyramid, Stef Kalinski. It’s nothing artificial, and nor is it a merely physical phenomenon, as I’m sure you guessed. It is life, Stef Kalinski. Life. An ambassador, perhaps, from a colder world than this…”

As they sat huddled together in the cart, the ColU spoke of Titan, moon of Saturn.

Titan was a mere moon, a small world subsidiary to a giant, but a world nevertheless—and a very cold one. Its rocky core was overlaid by a thick shell of water, a super-cold ocean contained by a crust of ice as hard as basalt was on Earth. And over that was a thick atmosphere, mostly of nitrogen, but with traces of organics, methane, ethane…

“But it is those organic traces that made Titan so interesting,” the ColU said. “On a land of ice rock, where volcanoes belch ammonia-rich water, a rain of methane falls, carving river valleys and filling seas. And in those seas—”

“The probes found life. I remember the reports. Some kind of slow-moving bugs in the methane lakes.”

“Yes, life based—not on carbon, as ours is—but on silicon. Just as carbon-carbon bonds, the backbone of your chemistry, Stef Kalinski, can be made and broken in room-temperature water, so silicon-silicon bonds can be made in the cold methane of Titan’s lakes. A form of life not so very unlike ours superficially, but with a different biochemistry entirely—and very slow moving, low in energy, slow to reproduce and evolve. We found nothing but simple bugs on Titan, simpler than most bacteria—not much more complicated than viruses.

“But Titan is not the only cold world. Here at Proxima, while the Earth-like Per Ardua was the planet that caught all the attention—”

“Ah. Proxima d.”

“Yes. It was a Mars-sized world just outside the zone that would have made it habitable for humans, like Per Ardua.”

“So far as I know it was never even given a decent name. Nobody cared about it—or the other Proxima worlds.”

“They did not. But it was very like Titan—another common template for a world, it seems. And room for another kind of life.

“Stef Kalinski, Earthshine has spoken of a panspermia bubble, of worlds like Earth and Per Ardua linked by a common chemistry carried by rocks between the stars, worlds with cousin life-forms. But there could be other bubbles, worlds with different kinds of climate, different kinds of biochemistries, yet linked in the same way. Maybe one bubble could even overlap another, you see—for clearly a stellar system may contain more than one kind of world.”

Stef was starting to understand. “You always speak in riddles, ColU, whether you intend to or not. But I think I see. The sample I brought you—”

“The pyramid-beast over there has a silicon-based biochemistry very similar to that recorded on Titan, but not identical. Maybe it is a visitor from Proxima d, do you think? Somehow hardened to withstand what must be for it a ferocious heat, even here on Per Ardua’s dark side. As if a human had landed on Venus. But it is here, and surviving. And with more time still…”

“Yes, ColU?”

“Stef Kalinski, we have seen that, given billions of years, life-forms from across the same panspermia bubble can integrate, grow together.”

“The Earth ants in the Arduan stromatolite.”

“Exactly. Now, is it possible that given tens of billions, hundreds of billions of years, even different kinds of life could mix and merge? Your fast, quick kind, and the slow-moving Titanian over there? Could that be the next stage in the evolution of the cosmos itself? You already share a world, you see.”

“It’s a fantastic thought,” she said slowly. “But it’s never going to happen. Is it, ColU? Because this is the End Time, according to you. There will be no tens or hundreds of billions of years—”

“I’m afraid not, Colonel Kalinski. Here on the dark side I have been able to make quite precise assays of the sky: the state of the stars, the proximity of Andromeda—even the background glow of the universe as a whole, which contains warp-bubble clues to its future.”

“Hmm.” She looked up into the dark. “Well, it is marvelous seeing, for an astronomer. And you’ve come to a conclusion, have you?”

“I have. And a precise estimate of the time remaining.”

Stef felt chilled, as if she’d been given bad news by a doctor. “You’re going to have to explain all this to the others, you know. In language they can understand.”

“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…”

It took an hour before they were settled again.

When they took their places Beth thought they seemed calmer, more attentive—more ready to take in this strange news from the sky. The break had been a smart bit of people management by Titus Valerius, she thought. Who in the end hadn’t really needed a piss at all.

“So,” Titus said now, slurping the last of his tea, “as if the fate of this universe wasn’t bad enough, you have to talk about all the other ones.”

Stef smiled. “All right, Titus, I know we are leading you on a march you’d rather not be following… It’s all about logic, though. When all else fails, ask a philosopher. Sorry. Old physicist’s joke.

“Look, we all know from personal experience that other universes exist, with histories more or less similar to this one—or to the one into which each of us was born. And in my Culture our philosophers had predicted the existence of those universes. Our laws of nature were well founded, you see, but they did not prescribe how the universe had to be. Many universes were possible—an infinite number. It is just as our science would have predicted the sixfold symmetry of a snowflake, which comes from the underlying geometry of ice crystals, but within that sixfold rule set, many individual snowflakes are possible, all different from each other.”

“Universes as numerous as snowflakes,” Beth said. “That’s wonderful. Scary.”

Stef said, “But what are these universes? Where are they? You know that the science of my Culture was more advanced than in any other we’ve yet encountered—”

The ColU said, “And Earthshine would say that was because we had been the least deflected into efforts to build Hatches for his Dreamers.”

“We did have some models of the multiverse—I mean, of a super-universe that is a collection of universes. After centuries of study we never came to a definitive answer. We probably never got far out enough into our own universe to be able to map the truth.

“Still, we believed our universe had expanded from a single point, out of a Big Bang. Expanded, cooled, awash with light at first, atoms and stars and planets and people condensing out later. But our universe was like a single bubble in a bowl of boiling water, like a pot we put on the fire.” She gestured at the clay pot, within which water was languidly bubbling. “You see? There is a substrate, something like the water in the pot. And out of that heated-up substrate emerges, not just one bubble, but a whole swarm of them, expanding, popping… They are the other universes we’ve been visiting.

“And what’s inside those universes is going to be different, one universe to the next—a little or a lot. Some could differ wildly from the others, not just in historical details. Suppose gravity were stronger—I mean, the force that gives us weight. Then stars would be smaller, and would burn out more quickly. Everything would be different. And if gravity were weaker, there might be no stars at all. And of course some universes are going to be more similar than others.”

It seemed to be Chu who understood most readily. Not for the first time, Beth wondered what kind of scholar he might have become, given the chance. “All the universes we have seen are similar. They all have planets, suns, people. They even have the same people, up to a point.”

“Yes,” Stef said eagerly. “You’ve got it. When you think about it the differences are pretty small. I mean, whether Rome falls or not would be a big deal for us,” and she smiled as Titus scowled ferociously, “but from Per Ardua, say, you wouldn’t even notice it.”

The ColU said, “We believe that the Dreamers can somehow reach out to other universes that are—nearby. There is no good term for it. What is nearness in a multiverse? Beginning in one universe, they reach out into another that is similar, yet that contains a human Culture that is more—conducive—to Hatch-building. And we, our small lives, are swept along in the process.”

Beth found herself frowning. “But why? Why would they do that?”

Stef said, “We need to find that out. In fact I suspect Earthshine may already be learning that secret. What’s important now is that we know the multiverse exists. OK? We’ve been there. Now, the multiverse is big. Surely that’s true. But it can’t be infinite.”

Titus scratched his head. “Here we go again… Dare I ask, why not?”

“The trouble is, Titus,” the ColU said, “some scholars have always believed that nature does not contain infinities. Infinities are just a useful mathematical toy invented by humans, with no correspondence to reality. Unlike the number three, say, which maps on to collections of three objects: three people, three potatoes…”

Stef said, “Infinities can make sensible questions meaningless. Titus, start with the number one.”

“I think I can grasp that.”

“Add another one.”

“I have two.”

“Subtract one.”

“I have one again.”

“Add one.”

“Two.”

“Subtract one.”

“One!”

“Add one!”

“Two!”

“Subtract one!”

“One!”

She held up her hands. “OK, that’s enough. You get the idea. Now if I asked you to stop doing that after some finite number of steps—twelve or twenty-three or five hundred and seventy-eight—what answer would you get?”

“That’s easy. Either two or one.”

“Definitely one or the other?”

“Of course.”

“But if I asked you to go on forever, what answer would you end up with?”

“I—ah… Oh.”

“You see?” Stef said. “The answer can’t be determined. The question becomes absurd, once you bring infinity into it.”

Titus said, “I can feel my brain boiling like the water in that pot.”

“Physics—my philosophy—is about asking sensible questions and expecting sensible answers. About being able to predict the future from the past. When you bring in infinities, sensible questions have dumb answers. The whole system breaks down.”

The ColU said, “So the point is, the multiverse—the collection of the universes we visit—must be finite. Because nature won’t allow infinities.”

Mardina scowled. “Well, so what? What do I care if there is one reality, or ten or twenty or a million?”

Stef said, gently but persistently, “It matters because a finite multiverse has an edge. And if one of the member universes should encounter that edge…” She looked into the pot of water, and pointed out one largish bubble slowly migrating from the boiling center toward the side of the clay pot. “Watch.” When the bubble reached the edge, it popped, vanishing as if it had never existed.

The ColU said, “Given that one simple fact—that the multiverse must be finite—and knowing how old the universe is, or was in the age we came from—it has always been possible to make an estimate of how long the universe was going to last. How long it was likely to be before we hit the multiverse wall. Probabilistic only, but…”

Titus snapped, “How long, then?”

The ColU said, “My latest estimate, based on my inspection of the sky as far back as our time on the Malleus Jesu, is three and a half billion years after the age of mankind.”

Titus shook his head, growling under his breath. “An absurd number.”

“Not to an astrophysicist,” Stef said with a smile. “That is, a philosopher who knows the stars, Titus. In my Culture we were pretty sure that the universe was a bit less than fourteen billion years old. So why should the universe last longer than a few billion more? You see? Not trillions or hundreds of trillions of years, or beyond the age of proton decay… In my Culture we used to call this the Doomsday Argument. Why should the future be so dissimilar to the past? Shouldn’t we expect to find ourselves somewhere in the middle of its life span, not in its first few instants?”

Mardina was touching her belly again, as if trying to shield her baby from all this. “Three point five billion years. You’re saying the universe will die, three point five billion years after the year I was born. If I understand these numbers at all—that’s still an immense stretch of time.”

“Of course,” Stef said. “But here’s the catch, Mardina. We have been brought to the end of that stretch. That’s what we’ve determined—what the ColU has established definitively from his study of the sky.”

“It isn’t just the aging of the stars, the position of the galaxies,” the ColU said. “That would be enough for a rough estimate. There are also distortions in the background glow of the sky, the fading relic of the Big Bang explosion. Distortions caused by events from the future.”

Titus tapped the pot with a fingernail. “Because of the proximity of this wall of yours.”

“Which is a tremendously energetic horizon that sends back signals, back through time. Signals that show up as distortions in the background radiation. That is why I am able to be so precise. This, the age in which we find ourselves, is the End Time—”

“I don’t want to hear it.” Mardina stood, suddenly, pulling away from Beth, the weight of her blankets almost making her stumble into the fire. “I don’t want to hear any more.” She clamped her hands over her ears, and stomped out.

Beth half rose. “She needs her boots, her cloak, if she’s going out there—”

“No.” Chu was already on his feet, and grabbing his own boots. “Let me. It is our problem.”

Beth nodded to the rest. “Let him go. It will be harder for them, to be so young, to have to face this. We must let them find their way.”

Beth longed to go after her daughter, but she made herself sit still. “You’re a wise man, Titus Valerius.”

He smiled, looking tired. “No. Just an old one, and a survivor. So, Collius. Here we are in the far future, as I understand it. How long until we encounter this—edge?”

The ColU said simply, “A year. No more.”

Titus nodded. “And what then? What will happen?”

Stef said, “A wall of light.”

Titus heaved a huge sigh. “Very well. From the ethereal to the practical. Shall we consider our route for tomorrow? And then we all need sleep, if Morpheus grants it tonight.”

68

The antistellar was the place where all the gravity-train tunnel mouths converged.

At the final destination, as the rest of the party went through the by-now practiced routine of grappling their sled-cart out of the frictionless tube, Stef walked forward, away from the tunnel. The ice under her booted feet was concrete-hard but ridged, crumpled, wind-scoured—evidently old—and was not slick, maybe it was too cold for that; the footing was good. Once, back in her original timeline, she’d skimmed in space over the polar caps of Mars, which were very old accretions of water ice, the deepest layers perhaps a couple of million years old. The ice under her feet now might be a thousand times older than that. She really had been brought to an antique time, an old universe.

And the dark-side cold itself—she seemed to remember that too, from her first experience here. This point furthest from the warmth of the star was the center of a hemisphere of endless night, of ice and dark. Yet there was a limit to the cold, even here; some warmth at least washed around the world from the day side. It was evidently a survivable cold. Still, her breath steamed, and the frigid air plucked at her lungs and nose and eyes.

As she walked she could clearly see, by the light of an Andromeda reduced to a bloated sunset sitting on the horizon, more tunnels, dark gashes in the ground: a network of tunnels lacing this chill hemisphere of the planet, and all converging here, at the antistellar, at this point of geographic symmetry.

And at the precise antistellar point itself, the place all the tunnels seemed to be pointing to—something was there, a kind of flattened dome from which came a glow of pale light, with structures dimly visible within.

Earthshine: it had to be him.

Stef walked back to her companions. By now they had the cart set up on its runners, ready for the final haul over the ice to the dome. The ColU was in its pack on Chu’s back. Mardina, more visibly pregnant every day despite her layers of cold-weather clothing, stood at Chu’s side, their gloved hands locked together, breath wreathed around their faces.

Titus grunted, pointing to the dome. “So our long journey is over—and there is the obvious destination. We should be ready to defend ourselves.”

The ColU said now, “You may be right, legionary. But consider this. Earthshine needs no such shelter as that dome, whereas you do need shelter. Perhaps the dome itself should be seen as a gesture of welcome.”

Titus nodded cautiously. “I see your reasoning. But consider this, in turn. If we would be welcome, so would Ari and Inguill have been, if they got this far. We should be prepared for whatever they are up to in there. Also, if Earthshine, or his image, could walk around on this ice butt-naked—”

Beth laughed. “Titus, he could fly through the air if he wanted to.”

“Then why isn’t he here now? I’m quite sure he’s as aware of us as we are of him. Why not come out and see us?” Titus glanced around at the group. “It’s clear that there’s much about this situation that we don’t yet understand. We go to the dome. It’s the obvious destination. The only destination. But we go in with our hands open in gestures of peace and friendship, and our weapons sheathed at our backs. Agreed?”

Stef shook her head. “You’re a terrible cynic, Titus Valerius. And I’d like to see you in a knife fight; you’re like an overweight panda in that cold weather gear… But you and your instincts have kept us all alive this long. Agreed.”

They formed into a loose party, with Titus, Chu, Clodia and Beth hauling the cart toward the dome, and Mardina walking with Stef at the rear. Titus and Chu were in the front rank, and Stef could see their pugio daggers tucked in the back of their belts, glittering in Andromeda light.

Mardina linked her arm through Stef’s, and they walked cautiously together. Stef peered up. “That sky isn’t what it was when I came this way before, with your grandfather Yuri, in that other timeline. It’s been so long, the stars have swum around the sky, or aged and changed, the constellations have all melted away. I thought I would still be able to see her, though, up at the zenith. Brilliant she was, and as we walked to the antistellar we saw her steadily rise in the sky unlike any star.”

“‘Her’? Who are you talking about, Stef?”

“A creature called Angelia. A creation of my father.”

“Another artificial person, then. Like the ColU, like Earthshine.”

“Yes. Actually she was also a kind of ship. She and her lost sisters… I got to know her. I don’t suppose she could have survived this long. Why, in a billion years or two her very substance would have sublimed away, probably.”

Mardina squeezed her arm. “We’re in another history. She was probably never here at all.”

“Maybe not,” Stef said with a bitterness that surprised her. “Just another story, erased by the Dreamers’ meddling.”

“No, not erased. Not as long as you remember her.”

Stef felt unreasonably touched. She patted Mardina’s hand. “You’re a good person, Mardina.”

Mardina laughed. “Despite my great-grandfather being a criminal mastermind downloaded into a box of metal and glass?”

“Yes. That’s quite a legacy, isn’t it? But Yuri at least was a good man too, your grandfather—I can tell you that much. And you’re going to make a fine young mother.”

But that was the wrong thing to say. Stef could feel Mardina stiffen.

“Well, there’s not going to be the time to find out, is there? Not if the ColU is right that all this,” and she gestured at the starry sky, “is about to roll up like a closing scroll.”

Stef could think of nothing to say.

She was relieved when Titus, in the van of the party, reached the translucent wall of the dome.

69

The dome was perhaps fifty meters across, Stef estimated as they walked around it, maybe ten meters tall at its midpoint, the highest point. Its skin was reasonably clear, translucent, and she saw no signs of support, no framework, no ribbing.

Titus glared in through the wall, as if he were scouting out the war camp of a bunch of unruly barbarians. Well, perhaps that wasn’t so far from the truth. He pointed out structures within the dome, piles of matériel. “That looks like what might have brought Ari and Inguill here.” A sled, much smaller and cruder than theirs, with heaps of garments and blankets roughly dumped around it—heavy coats, thick boots.

“And that object in the center, a kind of pillar in the middle of a mesh framework—”

“I believe that is Earthshine,” the ColU murmured. “His support unit anyhow. But evidently heavily modified, for some purpose. And, over there…”

They could all see what it meant. At one side of the dome was a Hatch emplacement, set into the rocky floor.

Stef cupped her hands around her eyes and peered in through the wall, trying to see better, cursing the vapor that rose up from her breath. A Hatch like any other Hatch. Just like the one she’d been brought to on Mercury, the first she’d seen—like the one Dexter Cole had found here on Per Ardua, right here at the antistellar— just like the Hatches she’d seen on worlds of other stars. All of them were alike, just a rectangular panel a few meters across set in the ground, the fine circular seam that marked the position of the lid. Crude functional simplicity.

Yet these simple gadgets were responsible for altering history itself, for adjusting the destinies of billions of souls. Stef was a physicist, and she’d been studying Hatches most of her adult life. Still, they made her shudder.

And on this particular Hatch that lid gaped open.

“So,” the legionary snapped. “Now what? Do we cut our way in?”

Clodia pointed. “Either that, Father, or follow the arrow on the wall.”

They came to a doorway, a blister that protruded from the smooth dome wall.

Titus said, “This door has a handle; that’s simple enough.” He squinted through the wall. “And a second door within.”

“I think it’s a kind of airlock,” Stef said, surveying the dome again. “This structure has no internal skeleton. Has to be air pressure holding it up. Se we need to go through these double doors to avoid letting out all the inner air, and the warmth.”

Titus said sourly, “I have served on starships, you know; I do know what an airlock is. Not that I was expecting to find one here. The practicalities concern me more. Such as, I doubt if this lock could take more than three of us at a time. Two, if laden with baggage. We’ll have to be separated to enter.”

“I sincerely doubt there will be any threat,” Stef said briskly. “Legionary, you can see through the wall. There is only Earthshine… Even Ari and Inguill are nowhere in sight. I think we can take the risk, don’t you?”

“And I for one,” said Beth, “am keen to get out of this cold, for the first time in weeks.”

“Lead us, Titus Valerius,” Stef said.

It proved simple enough for Titus and Clodia to cycle through the airlock. Experimenting, Titus found there was a simple fail-safe. “The inner door won’t open unless the outer one is firmly shut,” he boomed, his voice muffled by the thick dome wall. “The air within is warm and moist.” Still inside the airlock, he pressed his hand against the material of the dome. “This is pliant, yielding a little, but evidently thick and strong. It will be interesting to see how it withstands the blade of my pugio—”

“Not now, Father,” Clodia said. “Come on.” She led the way through the airlock’s inner door and into the interior of the dome, pulling open her heavy clothing as she walked.

Stef took Mardina’s hand, and they both stepped into the airlock together, leaving Chu and Beth unloading stuff from the sled. Mardina closed the outer door, and Titus opened the inner for them—and, just as Titus had described, warm, moist air gushed over them. Stef took deep, shuddering breaths, already feeling warmer than she’d been since crossing the terminator.

She walked out of the lock and stood by Titus. Mardina followed, more uncertainly. The dome itself was a silvery, translucent roof that excluded the sky, lit by small hanging lamps. Even Andromeda was reduced to a washed-out crimson glow. The ground was bare rock, blackish like some kind of basalt, scraped and grooved—presumably by the action of ice across millions of years. Stef looked over at the central clutter of gear. There was Earthshine’s support unit, clearly identifiable, embedded in a nest of other equipment. There was no sign of Earthshine’s avatar projection.

Titus said, “The air smells—funny. Like a ship. Or a factory.”

Stef’s senses were dulled by age, but she agreed. “I smell ozone. No scent of people, or not much—”

Mardina wrinkled her nose. “Maybe my nose is sharper. I can smell a hint of sewage. Yuck. Not unlike what we smell like in the mornings, after a night under the canopy. They are here, then. My father and Inguill.”

Titus snapped, “Well, we can’t hover by the door all day. Clodia! With me. We will organize the work of moving our equipment in. Beth and Chu have made a start.”

“Bring in the ColU first,” Stef suggested. “It will help us make sense of all this…”

Soon the ColU was set on a heap of grubby blankets just inside the lock, and Mardina had hung its sensor unit around her own neck.

Then, as the pile of their belongings gradually accumulated inside the lock, a puddle forming at its base as residual ice melted in the warmth, Stef and Mardina approached the Earthshine unit.

The processor pillar stood at the center of what looked like a sculpture of a spider, itself a few meters tall, with angled rods hinging from the central unit and plunging into the rocky ground. The rods seemed to Stef to be made of some kind of ceramic, milky and smooth. The pillar itself had long lost the wheels Beth had described, on which it had rolled around the planet. Stef could see that the casing of the support unit had been broken open, much of its innards removed or redeployed.

Because of the framework of rods, they could get no closer than a few meters from the central unit. Beyond the support unit Stef made out what looked like a manufacturing area of some kind, with various devices littering the ground—devices of an uncertain function, but an oddly smoothed-out appearance. The materials used seemed to be similar to the ceramic-like substance of the spider legs.

And beyond that, set in the ground, that open Hatch.

Stef faced the support unit. “Earthshine. Are you in there?”

“You took your time.”

The voice sounded as authentic as ever, but there was still no sign of a virtual human body, any of his “suits” as he’d once called them, Stef recalled.

Mardina said, “Hello, Great-grandfather. We did come as fast as we could. Given that you abandoned us in the first place…”

“Mardina, I can see you, even if I’m not much to look at. Come closer, child… My word. You’re pregnant!”

Mardina blushed.

“The dynasty continues,” Stef said drily.

“If only for now. Who is the father?”

“Chu Yuen,” said the ColU, speaking from the slate at Mardina’s neck—and, perhaps, directly to Earthshine by other means, Stef thought. “You recall, the slave from the Rome-Xin Culture who is my bearer. An intelligent boy, evidently of good stock, even if he did fall on hard times.”

“A good father, then. I look forward to getting to know him better. And I already know you too well, ColU.”

“I told you on Mars—on that other Mars—that I would hunt you down, wherever you fled.”

“And so you have. Well done. Perhaps you will do me the courtesy of listening to what I have discovered here…”

Stef was starting to feel dizzy. “I’m too hot, damn it, after months of being too cold.” She began to pull ineffectually at her outer coat.

At a call from Mardina, Beth and Chu hurried over with blankets from the cart, and heaped them up on the rocky ground. Beth helped Stef remove a few layers of clothing, and Chu handed her a canteen of water, brought in from outside—icy, but refreshing—and they sat her down on the blankets. Beth and Mardina sat with her, and soon Stef felt a lot more human. She refused food, however. “If I never eat another mouthful of freeze-dried potato, I won’t be sorry.”

Earthshine said, “I of course need no food of that sort. But since the arrival of the others, one of my fabricators has been devoted to manufacturing human-suitable food from the raw materials of the environment—broken-up rock, organics filtered from the ice.”

The others. It was the first time he had mentioned Ari and Inguill, even tangentially.

“A fabricator.” Mardina frowned. “What’s that?”

“Advanced technology from our own timeline,” the ColU said. “A device that can take apart matter at the molecular level, or even below, and assemble it into—well, whatever you desire. It’s slow but effective. My own physical frame once contained such machines. Once Earthshine and his two brothers, artificial intellects as powerful as him, lurked in holes in the ground, on Earth. And they were surrounded by fabricators and other gadgets, like miniature factories, that used the raw materials of the planet to supply them with all they needed—materials for maintenance, energy.”

Earthshine said, “I carried such gadgets with me in this support module. Now, here, I have broken them out and have put them to work. Everything you see here, the dome, this framework around me, has been manufactured from local materials, the rocks, the ice. Over on the far side of the dome I have created a pond, a body of standing water, to refresh the air. As for energy, though I have an internal store of my own, I have plumbed the planet itself for its inner heat. Manufactured drills to penetrate the surface rock layers…”

Stef asked, “Why did you build all this?”

“I came here because of the Hatch, Stef. To study it, and its makers. That’s why we were brought to this planet in the first place, to this epoch—what other reason could there be? That’s what I’ve been doing since I got here, primarily. But I always expected you, some of you at least, to follow. So I prepared this habitat.”

“Generous of you—”

“Although I did not expect those others to be the first of the group to come here.”

Mardina pushed herself to her feet. “‘Those others.’ You mean my father and the Inca woman, don’t you? You keep hinting they’re here, but I don’t see them. Well, there’s only one place they can be.” She set off toward the open Hatch.

Beth called, “Be careful, Mardina.”

But Mardina didn’t slow her pace.

Stef said now, “This frame you’ve put up around yourself, Earthshine. You’ve rooted yourself into the ground. Is this part of your thermal energy mine?”

“Oh, no,” he said now. “You’ll see that outside—a few panels flush to the ground, deep bores beneath. All this is to achieve a more intimate kind of contact.”

Beth asked, “Contact with who?”

“The Dreamers,” the ColU said suddenly. “You’re trying to talk to the Dreamers, aren’t you?”

“This ancient world is infested with them,” Earthshine said. “Well, I imagine it always was. ColU, it is as if I have dropped an antenna into a brain. And I think—”

“Yes?” The ColU sounded breathless, eager.

“I think I hear their thoughts…”

And Stef Kalinski heard a gunshot.

70

Mardina, who had been approaching the open Hatch, threw herself down on the ground.

Chu and Titus were with her faster than Stef would have believed possible. Sprawling, they grabbed Mardina by the arms, slithered back along the ground, and delivered her to Stef and Beth. Beth took her pregnant daughter in her arms.

To Stef, Mardina looked shocked, furious.

“I’m not hurt, Mother. Really, I’m not. I heard the shot—I thought I saw something fly past me—I dropped to the ground—I guess it was a warning shot. I can’t believe he did it. My father.”

Beth stroked her head. “Frankly, love, you and I always meant less to Ari than his ambition.”

“I’ll give them a warning shot,” Titus yelled. With gladio in his good hand, he approached the pit. Chu, too, followed the legionary, a dagger in his hand, looking coldly furious. It was after all his lover and the mother of his baby who had been shot at. That quiet intensity seemed to have burned away the last of his slavish deference, Stef thought.

Titus called, “You, Inguill, quipucamayoc! Ari the druidh!”

“Come no closer, legionary!” It was undoubtedly Ari’s voice, Stef could hear, though it sounded strained, weak. “We are protecting our property… We have rights of priority that…” He broke up in coughing.

“Wait, legionary,” Stef called. “Let’s see if we can talk our way out of this.”

“Talk? Ha! And who in Hades gave them a ballista?”

“It was manufactured here,” Earthshine said. “Using a fabricator. I was naive—I showed them how to operate the fabricator with voice commands. It uses an electrical charge to drive a projectile of—”

“And who fires a ballista in a dome like this?”

“The dome material is self-sealing,” Earthshine said, still more softly. “In that regard at least we are secure. Besides, the outside air is breathable, if cold. We are in no danger.”

Stef got stiffly to her feet. “I don’t understand any of this. What property do they think they own? What do they mean by priority?” She draped a blanket over her shoulders and began to shuffle toward the pit.

“Stef Kalinski,” Titus said, “stay back!”

“Oh, nonsense, legionary. Somebody’s got to deal with this. At least I won’t be missed if I get shot. And when it comes to Hatches, I’m the expert, remember.”

“Take me,” the ColU said urgently. “The slate, an earphone…”

Beth ran up to hand her the slate, which Stef hung around her neck. It felt inordinately heavy. “Now, then…”

Feeling neither brave nor scared—maybe she was just too old to be bothered anymore—Stef neared the pit. The material of the emplacement panel felt very eerie under her feet, smooth, alien, neither hot nor cold.

“Ari Guthfrithson! Inguill! It’s me—Stef Kalinski. I’m coming to talk to you. Shoot me if you must, but try not to hit your pregnant daughter at least, Ari…”

She came to the lip of the open pit. Ari and Inguill were sitting together at the base, huddled against a wall—near a rounded doorway, she noticed. If this was a typical Hatch, that door would lead to a transitional chamber, with another door beyond leading to—somewhere else. But for now the door was sealed shut, featureless save for a seam in the wall.

Ari and Inguill, their knees up against their chests, wore filthy remnants of the clothes of their cultures, Ari his druidh’s gown, Inguill in her formal attire as a quipucamayoc. They were surrounded by the basics of living, a heap of grimy blankets, piles of food—tired-looking vegetables, what might be dried meat—and simple buckets in which slopped piss and watery shit. The source of Mardina’s sewage smell, then. They looked impossibly skinny, even skeletal, in their loose clothing. Stef saw glossy, dead-looking patches of skin on Ari’s cheeks, his forehead. Frostbitten?

But in two bony hands Ari held a convincing-looking gun, pointing it out of the pit at her. “No closer, Stef Kalinski.”

Stef held her empty hands in the air. “I’m no threat to you, Ari. I never was… Can I lower my hands? I’m kind of tired, and only just got over a dizzy spell.”

He nodded curtly.

“Thank you. Mind you, I’m a picture of health compared to you. You should have waited for us, you two. Traveled with us.”

“You are all fools,” Inguill snapped. “And we got here first. Which was the whole point.”

Stef leaned down, cautiously. “So why in heaven’s name are you sitting in that hole?”

“We’re waiting for Earthshine to let us in,” Inguill said. “Through that door. We know he can open it; we’ve seen it… We want to go through the Hatch. We want to be first.”

“And now you’re mounting a sit-down strike? But why? After plodding all that way across the ice muttering to each other, do you even remember anymore?”

Ari raised his gun; it wavered uncertainly. “You won’t trick us out of here.”

“I’ve no intention to. Believe me, I’ve been through enough Hatches; you’re welcome to this one. But, look—will you let me bring you some fresh food, at least? Or one of the others. And how about I get the legionary to take out those slop buckets for you?”

“Not Titus,” Inguill snapped.

“Chu, then.” Stef looked directly at Ari. “Who is the father of your grandchild.”

The gun lowered at last. “I heard you speak of this… It’s true, then?”

“I’m afraid so. Look, I’ll go get help. Don’t go away, now.”

As she walked away she heard Inguill’s ranting voice. “We won’t be tricked, Stef Kalinski! We won’t be tricked!”

With Ari and Inguill fed, and their slop buckets emptied out of the airlock, Titus’s group gathered, sitting on heaped blankets and bits of Earthshine’s equipment, before Earthshine in his spidery cage. They had hot drinks and portions of food manufactured by Earthshine’s fabricators, bland but nutritious.

Beth had spoken to Ari. But Mardina had refused even to look at her father, who had taken a shot at her.

“I fear they are no longer sane,” Earthshine whispered.

“Oh, you don’t say,” Stef said drily.

“They have developed an obsession with the power they perceive to lie beyond the Hatch. That was why they abandoned the rest of you, stole your equipment… Why they abandoned the history they had been born into. Even abandoned you, Mardina, Beth. Why, the trek here itself nearly killed them, but they would not be stopped.”

Beth grunted. “I’m not surprised at that. Whatever other qualities he’s got, Mardina, your father is not a practical man.”

“And Inguill was a bureaucrat,” Stef said. “In her culture. A wily one, a very clever individual, but not prepared for such a journey. Whereas we had a Roman legionary to lead us. Perhaps neither of them truly imagined what it would be like. But once they had set off—”

Earthshine said, “They were driven on by pride and greed. Their obsession with the antistellar, with the Hatch they expected to find here. They clung to that dream, even though they left behind their health, even their sanity.”

Titus snapped, “What is this dream?”

“I think they believe,” the ColU said, “that the Hatch will give them the power of gods. The power to remake worlds. After all, they’ve seen it happen—we all have, more than once.”

Stef nodded. “And maybe the deep shock of those experiences has taken a toll on them, more than we realized.” She closed her eyes, looking inward. “A toll on the rest of us too.”

“In a way, I admit,” said Earthshine now, “we aren’t so dissimilar. I was outraged by what I saw as the meddling of the Dreamers in our histories, as it gradually unfolded. I struck at Mars, a Mars, to attract their attention. Well, it worked. I was brought here. I intended to challenge them again. And above all to try to understand…”

Stef prompted, “Earthshine, Ari said you had control of the Hatch in some way.”

“In a sense, I do. The Hatches have always chosen who they will respond to.”

“That’s true,” Beth said. “I remember the first Hatch I ever saw, at the substellar. It—developed—grooves in its upper surfaces, for builders to lie in, like keys in locks.”

Earthshine said, “With humans, handprints are commonly used. Here, the builders evidently sensed something of my presence. In my case the interface is electromagnetic, not physical contact. Not visible. But when I sent it a certain message—echoing a signal I received—the Hatch opened, the great lid.”

Stef pressed, “And then the second door, to the next chamber?”

“I have explored the second chamber,” Earthshine said. “Or at least I have sent secondary units in there. I believe I know what lies beyond the next door—and on the far side of this Hatch itself. But I have yet to open that final door. I have constructed a probe. You might be interested in the details, Stef. A sphere, of material of very high heat capacity. I hope it will last a measurable time, even as much as a nanosecond.”

Stef tried to imagine this. “What are you saying, Earthshine? What lies beyond that door?”

Earthshine whispered, “The ColU knows—or suspects.”

“The boundary,” said ColU. “The edge of the multiverse. The death of the future. Yes. That is what they would bring you here to show you. So that you could understand…”

“There need be no spatial deviation, you see,” said Earthshine. “You need not travel across space to reach it. And you need journey only a short distance into the future. After all, the event will occur everywhere, simultaneously. On every world.”

The ColU said, “We must compare our estimates of the time remaining.”

The humans absorbed this terrible conversation in silence.

Stef said at last, “And that’s what you’ve told Ari and Inguill they will walk into, if—”

“If they are in the second chamber when the Hatch opens, yes. But they won’t listen, Stef. They don’t believe me. They believe that the Hatch will fulfill their dreams of power and wealth.”

Titus shook his head. “Then what are we to do?”

Stef sighed. “I suggest we try to get Ari and Inguill out of there. After all, you are family, Beth, Mardina. You might get through where Earthshine couldn’t. And then—”

“And then,” the ColU said, “we must consider how best to use the time remaining to us.”

Mardina rested her hand on her belly, dropped her head, and reached blindly for Chu.

71

The group spent two full days trying to coax Ari and Inguill out of the pit. Beth tried the hardest, tried to get through to the man she’d almost married. Even Mardina reluctantly consented to speak to Ari, about the baby she was carrying, his grandchild.

Neither basic human appeals, nor Earthshine’s cold logic about what must lie beyond the Hatch door, made any difference. Ari did seem anguished about the fate of the baby. But nothing would change his mind, nor Inguill’s, who babbled about the power of Inti, the Inca sun god. They were both convinced of only one thing: that Earthshine was trying to keep them from—well, from glory, Stef supposed.

Titus remarked, “No mortal should seek the power of a god. It would burn him in a flash.”

The ColU seemed to agree. “But who are we to stop them, Titus Valerius?”

At last, they gave up. Earthshine agreed to open up the Hatch for them.

The group gathered at the lip of the pit to see the outcome.

In response to Earthshine’s invisible signal, the door to the Hatch’s middle chamber swung back at last. In that chamber Stef could see the “probe” Earthshine had mentioned, a fat ceramic sphere sitting on the chamber floor.

Ari and Inguill stepped through, moving gingerly, helping each other. At each step of the way, Earthshine paused to allow them to reconsider, to pull back.

But at last they pulled the door closed behind them, without a backward glance, and they were gone.

“I gave them a control,” Earthshine said. “To emulate the signals I use to communicate with the Hatch. A simple handheld thing… And I found a way to send signals through the emplacement substrate, so I will know, from my probe, when the final lid is opened.”

Stef was intrigued. “You sent signals through Hatch substrate material? That’s more than we ever managed, in the years I spent studying Hatches and kernels on Luna and Mars—”

“They are gone,” Earthshine said simply.

When it was safe, Earthshine opened the second door once more. The central chamber, with its door firmly closed once more, seemed entirely undamaged to Stef, and was entirely empty.

Earthshine said that his probe had after all lasted a healthy fraction of a nanosecond, and it had learned a good deal about the nature of the “multiverse boundary.” It and the ColU immediately locked into a silent, high-speed electronic communication about the new data.

And Clodia and Chu, exploring the Hatch, found something new: grooves to take human hands, on the inner side of the Hatch’s second door. Three pairs of them.

“That,” the ColU said enigmatically, when it was told, “deserves further consideration.”

72

Earthshine said, “I believe that the Dreamers have spoken to me as they have spoken to none other of our kind. And by ‘our kind’ I mean complex life-forms, equivalent to your own multicellular nature, although the details differ from world to world, biosphere to biosphere… That sounds arrogant, I know. Even grandiose.”

Stef said skeptically, “I’ll say. Of all that vast cosmic host—”

“Yet I am unusual, for them. I am a product of human technology, of course. And yet I think that humanity itself, all of our biosphere above the level of the single-celled creatures, is a kind of technology to them. Created for a purpose, you see, or at least modified. But I am a secondary creation—as if one of my fabricators produced, not a copy of itself, but an entirely new design of its own. As such I am perhaps of—interest—to them. And I am not entirely under their control.”

“As we are?” Stef asked sourly.

“Well, aren’t you?”

Titus grunted. “This all sounds too philosophical to me. What am I, a Greek?” He, Stef, Beth, the ColU, the elders of this tiny antistellar colony, sat in a loose circle, beside the comfort of an open fire burning on a hearth of stone slabs, in the shadow of the strange spider-like structure that encompassed Earthshine’s support unit. Now Titus dipped his clay mug into the slowly boiling bowl of tea on the fire. “Face it, Earthshine. You got the Dreamers’ attention because you smashed Mars to pieces, and murdered a whole world of these clever animalcules in the process. That would get most people’s attention.”

“Well, that’s true. And that of course was the intention.”

“And so they brought you here,” said the ColU, a glittering mass of technology set on a blanket away from the fire. “They guided you through their Hatch network to this place. And—”

“And they spoke to me,” Earthshine said, cutting in. “They told me their story. If that term is adequate for such a biography… In a way, you see, it is the story of life, in this universe.”

“Tell us, then,” Stef said, leaning forward, swathed in a blanket. “Tell us, Earthshine.”

“From the beginning, even when the universe was still very young, there was life.

“Life self-organized, from collections of more or less simple chemicals, blindly following the laws of chemistry and physics, guided by mathematical rules evidently inherent in reality. Microbial life, single-cell life, viral life… Some scientists used to think life could have emerged even when the Big Bang glow was still bright, and the whole universe was warm enough to be one big habitable zone.

“On worlds with similar surface conditions, similar kinds of life emerged. Earth and Per Ardua, for example. But life spread, too, as rogue comets and asteroids blasted the surfaces of the young worlds, and handfuls of bugs buried deep in rock fragments survived chance journeys between the planets, and, more rarely, between the stars. Panspermia bubbles formed, worlds with similar conditions hosting related forms of life, sharing common origins. Across the Galaxy such bubbles jostled, and even permeated; worlds of warm-Earth life could share stellar systems with worlds of cold-Titan life, as you’ve seen for yourselves.

“And life spread inward too, down into the guts of the worlds, following deep water flows, mineral seeps, leaks of heat energy, radioactivity… The interiors of worlds, too deep even for the immense bombardments of the young cosmos to do any damage, were warm, safe cradles in those early days, and life got down there pretty quickly—on Earth we found deep bugs all over the world, all of similar species. The deep rock is a static shelter, though, and relatively starved of energy. Life was slow to spread, even slow to procreate. To survive on such thin resources, living things learned to repair rather than to reproduce. But gradually a kind of complexity grew and spread, as the microbes gathered themselves into mutually supportive colonies, and the colonies combined into supercolonies.

“A threshold was passed. Consciousness emerged.

“On Earth, and on Per Ardua, most of the biomass of the planet—most of its weight of living stuff—dwells in the deep subsurface rocks. For most of their history, humans never even suspected it existed. And it is aware, a constellation of huge, slow minds. These are the Dreamers. They remember their birth, when the universe was young.

“And world after world woke up…”

The story was told in fragments, day by day, amid intense interrogation by Stef and the others.

As the weeks and months passed since their arrival at the antistellar point of Per Ardua—as the deaths of Ari and Inguill faded in the memory—the audience around Earthshine came and went. They all needed to sleep and eat; they all had chores to do with the maintenance of the colony that kept them all alive—and they were all determined to support Mardina through her pregnancy. That drew even the ColU away from Earthshine, and its slow, sometimes rambling monologue.

But they listened, and they questioned Earthshine on confusing details from their different viewpoints. Gradually a kind of summary of the story was emerging, one that they could all grasp, one way or another.

And in the midst of cosmic strangeness, human life went on.

As Mardina’s pregnancy approached its full term, she became ever heavier, ever more slow moving. At least she felt she had good support, isolated as she was here. The ColU had been specifically instructed in childbirth procedure to support the growth of the original ISF colonies, and Earthshine’s fabricators were capable of synthesizing any medicinal support she needed. She had at her side wise women in her own mother and Stef Kalinski. And Chu was turning out to be a doting parent-to-be. Only Clodia remained a problem for now, her residual jealousy over Chu getting in the way—and, perhaps, Mardina thought, Clodia’s resentment at having her own ambitions to be a soldier thwarted. It was a shame that the comradeship they’d built up on Yupanquisuyu was gone now—or maybe they’d just grown out of it, she thought.

No, Mardina couldn’t complain about the support she had, even if she would have preferred to have Michael the medicus on hand, or better yet, a fully equipped Brikanti hospital.

Still, as time passed, she felt less and less enthusiastic about work. Even about moving around too much.

And, in a dome where there wasn’t a lot of entertainment, she found the slow processes of the fabricators’ labor an increasing distraction. One morning Mardina found one little gadget, no larger than a loaf of bread, sitting in a pool of ground-up Arduan rock, which in turn it was processing into machine parts that it gathered in neat heaps. She knelt to watch it, rapt.

Chu said, “It is proceeding faster than I imagined.”

“This one’s actually making a copy of itself.”

“I suppose it is giving birth, in a way. Bit by bit.”

Mardina, sitting on a heap of blankets, rubbed her belly. “I wish I could do it that way. Take out this little monster one limb at a time and then assemble it on the floor.”

“You don’t mean that.”

“No, I don’t suppose I do. But if these machines keep this up, we’ll start to become a real colony. Titus wants to call it ‘Nova Roma.’”

But Chu did not smile. “It is a shame that we will have so little time to enjoy what we build.”

Mardina flinched; it wasn’t the kind of thing Chu usually said. She looked down at the solidity of the rocky floor, and up at the star-strewn sky beyond the dome, and she reached for Chu’s hand. “We can’t think like that.”

“No. I am sorry. For even if what the mechanical sage says is true, it is up to us to behave as if it is not so.”

She tried to absorb that. Then she stirred. “Come on. Help me up; I’m getting stiff. Time for my exercise, a couple of tours of the dome…”

“From the beginning the great communities of Dreamers apprehended something of the universe around them.

“They sensed the early battering of their worlds by the debris of planetary formation. They were tugged by the subtle tides exerted by their worlds’ parent stars and sister planets. They could feel the slow geological evolution of their host worlds—an evolution shaped from the beginning by life itself; there’s evidence that the presence of life on a planet like Earth, for instance, even helps stabilize the formation of continents.

“Even multicellular life, when it evolved—infrequently, sporadically—served as a kind of sensory mechanism for the living worlds.

“For some worlds, given the right conditions, with an atmosphere reasonably transparent to the parent star’s radiation, energy could pour down from the sky onto the land and into the upper layers of the oceans, and the familiar miracles of complex life could come about. Photosynthesis, a chemical means to exploit the energy of stellar radiation. Grand rebuildings of oceans and atmospheres through the injections of such gases as oxygen or methane. The evolution of secondary forms of life—like Earth’s animals—to feed off those products. But the outer layers of complex planetary life, so important to creatures like humans, were all but an irrelevance to the Dreamers. They only ever amounted to a trivial fraction of any world’s total biomass. And the complex creatures were usually not even aware of the noostrata that permeated the rocks beneath their feet.

“Yet, through the frantic reactions of the complex forms, ‘animals’ and ‘plants,’ to external events like asteroid strikes or stellar flares or supernova explosions, the Dreamers came to know the universe in more detail.

“I think even then, far back in cosmic time, the Dreamers began to get the first hints of the approach of the End Time.

“And then there was communication, between Dreamer worlds.

“The complex forms, in their haphazard way, built spacecraft, or infested comets and other wandering bodies, and began a new kind of contact, supplementing natural panspermia, the slow drift of impact-loosened rocks. Panspermia had always been a way for the worlds to be linked to each other. A package of living things and genetic data is a kind of communication, a message from one minded world to another. With the coming of complex life and interstellar travel, that process remained random, without central direction, but did become more frequent.

“From the beginning, the living worlds had been aware of each other’s existence. Now, slowly, sporadically, imperfectly, they began to talk.

“Imagine a community of minded worlds, then. All different in detail, yet all with fundamental similarities, engaged in a slow, chance conversation. They shared ideas, perceptions. Some grew in stature, while others became more inward-looking. They were all effectively immortal, of course—and they were stuck with each other. I imagine them as like a college of bickering professors, locked in decades-long rivalries. But in the case of the Dreamer worlds, aeons-long. Not quite immortal, though; in a dangerous universe, whole worlds can be lost, sometimes, and all their freight of life and mind with them.

“But this slowly developing community was disrupted by the freak emergence of one mutant world.

“The human categorization of complex creatures into ‘animal’ or ‘vegetable’ is too simple. Anthropocentric. Even on Per Ardua, the builders were animals that photosynthesized.

“Well, then. Consider a world in which every complex organism, every plant and tree, every creature, motile or not, is, if not sentient itself, then a sense organ for a larger mind. Every flower is like an eye or an ear on the world. Sensory impressions chatter down tendrils like nerves, and feed into root masses of huge complexity: aged vegetable brains. And these in turn, on this world, speak directly to the true minds of the planet, the Dreamers in their deep rocks. This world was called Alvega in some human Cultures.”

Stef wondered how Earthshine could possibly know that.

“All this came about because of a peculiar origin of life on this one particular world. On many worlds there can be several origin events; but on most worlds, like Earth or Per Ardua, a single design, a single DNA-like coding system controlling a single protein set—or the equivalent in different biospheres, like the Titans—emerges as dominant, and usually quite quickly, with small advantages quickly becoming overwhelming. But not on Alvega. Here, two quite different and inimical biospheres battled down long ages for control, even after the emergence of complex life. When the long war was won, the winner had become by necessity much more closely integrated than most worlds, with the complex surface florescence feeding directly into the Dreamer communities below.

“On this world, then, the Dreamers were much more engaged with the external universe—and they had the means to achieve direct contact with others like themselves, for their complex partners on the planetary surface were, uniquely, entirely under the Dreamers’ control.

“From Alvega a new wave of emissaries were sent out, in interstellar craft not unlike huge trees, their mission to link one world with another.

“It took many hundreds of millions of years for the new living technology to spread across the Galaxy. But, gradually, one world after another, isolated Platonic Dreamers woke to the possibility of community, of deep and rapid communication with others of their kind.

“There was a new urgency now—if you can ever call a billion-year-program ‘urgent.’ The value of complex life was seen for the first time, and panspermia of a new kind became intentional. Across the panspermia bubbles, waves of modification were sent out, so that worlds that had not known photosynthesis were raised to that level, and then living complexity became possible on worlds suddenly rich with the energy provided by oxygen or methane, or other reactive chemicals. Creatures like plants, creatures like animals, new kingdoms of life blossomed on world after world—”

“I knew it,” the ColU breathed. “I found this, even on Per Ardua—the first world beyond the solar system reached by humans. The coincidences of timing. Photosynthesis appeared on Per Ardua two billion years before humans showed up, just as on Earth. And the first complex creatures appeared on both worlds with quite precise coincidences of timing: five hundred and forty-two million years before humanity on Earth, the same on Per Ardua. I measured this. I knew it! I remember speaking of this to your mother and father, Beth Eden Jones. Not that they understood the implications, not then. Well—nor did I. Not then.”

“The coincidences were real,” Earthshine said. “I have no detail on how this was done, what kind of agency they used to trigger a complexity explosion on Earth, say. I imagine farmers striding across the stars… But these events are indeed evidence of a deep, Galaxy-wide bioengineering on multiple worlds, by communities of Dreamers who were becoming more knowledgeable, more communicative—and more willing to intervene in the destiny of life.

“And as they grew in power and understanding, and as they learned more of the universe around them, so they developed a new urgency. Because—”

“Because they became aware of the imminence of the End Time,” Stef whispered.

“Yes. Even the Dreamers, who, huddled in the deep rock, might survive even the supernova detonation of a parent sun, could not survive that.

“And so they laid their plans.”

They might be a short-lived colony, but they were a busy colony.

They all had projects of one kind or another—well, Stef thought, there were so few of them, there were always plenty of chores to do, ranging from stitching ripped clothing or fixing a leaking boot to supervising the synthesis of some new component by the clattering fabricators.

Mealtimes were the only occasions when they all gathered together, breakfast, lunch, supper. That included Earthshine, for they always sat around his spidery framework. The ColU too. Titus had mandated that from the beginning, once they had got over the loss of Ari and Inguill. They were too small a group to be able to afford to break up into cliques or factions. Stef supposed this was another relic of Titus’s field experience, presumably dating from when he had had to lead small isolated parties, scouts maybe, on long expeditions. She applauded his leadership.

It was unfortunate, though, that he always used language like “lancing boils” or “spilling the pus” to describe the process of talking out their problems. Especially when she was trying to force down the freeze-dried potato or fabricated slop that passed for food here.

And she tried not to let her dissatisfaction with the food distract her from listening to Earthshine’s long, complex account.

“So. After the complexity waves. That was when they started to build the Hatches,” Stef prompted.

“That was when,” Earthshine agreed. “I don’t know where, how, when the technology emerged. But a Hatch link is essentially a communications technology optimized to fit within the limits of the universe in which we find ourselves.”

“Limits? What limits?”

“To begin with, lightspeed. That seems to be a fundamental physical barrier—just as Einstein predicted all those years ago. And the other—”

“The end of the universe,” the ColU said.

“A wall across the future. And very close in time, to such long-lived beings. There was never a sense that the minded worlds, or that any of the Dreamers—or any of us—could survive that final limit. But they felt the urgency to talk, to communicate—to share as much as they could, to make the most of the time available.

“But here were these vast minds, dependent for their communication on the slow trajectories of crude starships, or on the still slower drift of rocks from star to star. It is as if Einstein and Newton, two tremendous intellects, both under sentence of imminent death, were able to communicate only by means of Morse code tapped out on a cell wall… They had to do better.”

“And the Hatches were the way,” Stef said.

“Yes. The Hatches are something like wormholes, flaws in space-time connecting one event to another. As you know, Stef, theoretically, wormholes can even link different universes—different cosmoses drifting in the great hulk of the multiverse. Any transition would be limited by lightspeed—”

“But with a Hatch, one can step from Mercury to Per Ardua, say, four light-years apart, in no more than four years.”

“Exactly. It is the best one can do. But to build such engines, rips and twists in space-time, requires huge amounts of energy, as you can imagine. Where is such energy to come from?”

“The kernels,” Stef said immediately. “Which are also like wormholes, through which energy pours. That was basically a lure—right? The cheese that baited the trap, into which we clever tool-making apes thrust our greedy paws. And all the time the true purpose was to get us to build those damn Hatches.”

“True, although you never got that far, did you? You saw that kernels were associated with Hatch emplacements, of course. But, Stef, you never understood how the presence of kernels facilitates the setting up of a Hatch in the first place. You never even discovered the process by trial and error, as did the Romans, the Incas.

“Stef, there is actually only one kind of technology here. Kernels are Hatches; a Hatch is a specialized form of kernel. The Hatches emerge when a kernel field is perturbed by an energetic event—I imagine it is almost an organic process, a self-selection, as a single tree will emerge from a grove of saplings.”

“Maybe. But what about the energy? For all the decades I spent studying those beasts, we never came close to understanding where that energy came from.”

“True,” said Earthshine. “And I was never allowed access to kernels and Hatches to study them for myself. I had to rely on your work, at secondhand. How much time was wasted!”

“We guessed stellar cores, supernovas, gamma ray bursters, quasars—”

“Wrong, wrong and wrong again. Remember, Stef, both kernels and Hatches are forms of wormholes. As we have experienced ourselves, a wormhole can link events separated by space and by time. We walked through a Hatch from the Mars of Inguill’s Inca era, the human age, to—this, a world light-years distant and well over three billion years separated in time.”

“Yes,” said Stef. “But these wormholes aren’t as they were predicted by our own science, by relativity. They were rips in space and time held open by impossible kinds of antigravity… You could have traveled faster that light through Einstein’s wormholes. And you could have dragged such a wormhole around with a sublight ship to make a functioning time machine. But this is different. Kernel/Hatch wormholes are sublight. But they can link different universes. And so you could connect the present of one universe to the past or the future of another…” The pieces of the puzzle moved around inside her head. “That’s it. If you’re right about the nature of the multiverse, then all the universes in our local ensemble share the same future, if you look ahead far enough…”

“They all must face the End Time,” the ColU said.

Earthshine said, “And that, Stef, is the answer to where a kernel’s energy comes from. Not from some quasar, from some point distant in space. It comes from a point distant in time—”

“The future.” Stef saw it now. “The End Time itself.”

“Yes. You have it. The End Time will be a hugely energetic event. The Dreamers have tapped into that very energy, using the kernels, in order to build their Hatch network. Now, we multicellular toy-creatures are allowed to play with the technologies, to build our kernel-driven starships and to wage our wars, but—”

“But it’s all secondary to the true purpose,” Stef said, “which is for the Dreamer worlds to be linked to each other. You know, my father saw this, right at the beginning. He sensed that whoever was giving us kernels—he never lived to learn about Hatches—had some agenda of their own.”

“He was right. Humans, however,” Earthshine said softly, “could never resist such deadly toys. Even if they were powered by the energies of Ragnarok itself.

“So the Hatch network spread. So the worlds were linked, as never before; so they learned and grew.

“But that’s not the end of the story. For even this was not enough. The time left, mere billions of years, seemed horribly short to such minds as the Dreamers. And so, having intervened several times before in the destiny of life in the Galaxy, now they intervened again. Seeking to find a way to have us serve their needs even more completely…”

As the final months passed, Titus Valerius led many expeditions back to the nearside of Per Ardua. Given the gravity-tunnel network, the terminator was only days away; they always needed supplies, so why not travel back?

Titus didn’t retrace the journey that they had made to get here every time. He and his companions took the chance to explore the rest of the branching gravity-train system that fanned out across the dark face of Per Ardua, and to study different regions of the terminator and the edge of the star-facing side. This amounted to a kind of inspection of the tunnel system itself, of course, and Titus did report a few breakages, even collapses, times they had had to come back the way they’d traveled and find another way. The tunnel system was tremendously ancient and wonderfully robust—Stef joked in the silence of her head that it had kept working almost to the end of the universe itself—but nothing was perfect, it seemed.

Titus never forgot his primary purpose. Each time he returned, he would faithfully deliver a sled full of root vegetables and fruit, plus anything exotic he found, such as, once, a box of what looked and tasted like peaches.

But he also brought home specimens he thought might be of interest to the ColU or Earthshine. The ColU had specifically asked for samples of stems of any kind, the rod-like forms that had once been the fundamental unit of complex life on Per Ardua. And once Titus brought back a miniature stromatolite, a cylinder maybe a meter and a half tall, half a meter wide. He and Chu dragged this thing home strapped to the bed of the sled with ropes.

They had already given over part of the dome to a “Per Ardua garden,” where the ground-up rock floor had been laced with native soil, and the ColU was growing his stem samples and other native forms. Here they planted the stromatolite, bedding it deep in the worked ground. Not even the ColU had any experience of transplanting stromatolites before, and the little community spent some days fretting over the health of its new arrival before the stromatolite seemed to flourish, with its bronze-colored carapace acquiring a new sheen. It was another example of the integration of life, Stef supposed, of living beings from different stars working together: humans from Earth tending a stromatolite from Per Ardua.

And it was the lack of time in this doomed universe for integration, of biospheres and cultures and minds, that had driven the Dreamers to attempt their most radical rebuilding.

“Even humans had such fantasies,” Earthshine said. “Of cultures crossing the stars and coming together. Perhaps there would be conflict at first, but in the end there would be integration. A Galaxy united under a common civilization—imagine it.”

“I remember some of the scientists’ dreams,” Stef said. “Perhaps if mind could encompass the universe, it could change its destiny. Save it from a Big Crunch, or a Big Rip. Make the universe better than nature intended.”

“Or at least,” the ColU said, “mind, by filling the universe, could observe it. And thereby make its existence worthwhile.”

“But there is no time for any of this,” Earthshine said now. “No time! Not in a universe with such a short life span, and constrained by lightspeed. Even a single Galaxy is too large, the Dreamers concluded, to be united in such a time. The Dreamers grew restless—though that’s an odd word to apply to billion-year-old minds. They wanted more time. But there was no more to be had, not in the future.”

“Ah.” Stef nodded. “I think I see where this is going. To gain more time, they started to reach, not into the future—but into the past.”

“You have it. Remember, the Dreamers were becoming masters of wormhole technology; they had kernels and Hatches. By tapping the End Time event itself they had an effectively infinite energy supply. Now they began to reach out, not across time and space in this universe, but to other universes entirely. Universes with different histories.”

Stef laughed. “Of course. I see it now. Suppose you’re dissatisfied that humans in my reality sheaf, the UN-China Culture, didn’t even start to work with Hatches until the twenty-second century. You wish it had been earlier. Well, then, you simply pluck another copy of the universe from the tree of possible realities, one where we did get to the Hatches earlier.”

Mardina nodded. “I see—I think. Which happened to be a history in which Rome survived, as it did not in your history.”

“That’s it,” Earthshine said. “So the destiny of the human race is altered fundamentally. Billions who might have lived were never born at all. Billions more rise up to take their place. And those billions strive to extend the Hatch network, long before it would have happened in the earlier reality—for that, you see, was the point.”

Titus frowned. “But if this is true, what of the other histories, other realities? Are they simply discarded, like—like early drafts of a note of command?”

“Not discarded,” said Earthshine. “They all continue to exist, out there, somewhere in the multiverse. And all, incidentally, will be terminated at the End Time; they are too closely related to be spared. But there is only ever one universe that is primal. As if it is more real than the rest. And before the Dreamers’ meddling, the primal universe would have been the most logical, the most neat, the most self-consistent in terms of causality. Self-consistent as the others were not.

“Magnificent it may be, but this project of the Dreamers is—untidy. Only the original primal universe was clean in a causal way, where for every effect there was a cause, neatly lined up in an orderly history. No anomalies, no miracles. But the fresh universes these creatures have selected are less optimal. They have rough edges. Effects preceding causes. Effects with no cause. Trailing threads. Threads to be picked out by the likes of me… You might even find gross violations, I suppose. Absurdities. For example, a universe where Julius Caesar never lived—but where a mass of evidence, documents and monuments, happened to be found that described his nonexistent career. Effects without cause.”

“And we found some of those threads,” Stef said. “So did Ari, with his remains of the Drowned Culture. And Inguill with her mission patch from a flight to Mars that never happened.”

“But all of this is an irrelevance, to the Dreamers. All they care about are the Hatches we build for them. And in each new reality we follow a cultural and historic logic that, yes, enables us to reach the stage of building Hatches ever earlier.

“And so in each successive draft of cosmic history, the Dreamers’ network of interconnectivity and communication reaches back, deeper into time, deeper into the past. The number of thoughts they are able to share grows, and their apprehension of the universe grows deeper, in space and time. The Dreamers are essentially contemplative. If the universe is to be brief in duration—well, it is beautiful nonetheless, and deserves to be apprehended to the full. To be appreciated, to be studied and cherished, from beginning to end.”

“It is monstrous,” the ColU said. “It is magnificent. As if the universe itself, a finite block in space and time, is a kind of garden. A garden of which every square centimeter is to be tended, made as beautiful as possible, all the way to the back wall, so to speak. I am a gardener, or was; I can see the appeal of a cultivated cosmos. And all of it contained by the walls of birth and death.”

“But the price of all this is raggedness,” Stef said, dissatisfied on a profound level. “A universe of holes and patches, where scientific inquiry doesn’t necessarily make sense. And how far would they go to get to build their empire of the Hatches? Maybe in some realities mankind was eliminated altogether, and replaced by some other clever creature. Rats, maybe. Smart rodents burrowing through the multiverse like it was some roomy loft…”

Earthshine said, “And all of it, tidy or otherwise, doomed to incineration when the End Time comes. You see it now. We never mattered. We really are just a kind of technology to the Dreamers—created by their uplift programs and then modified for a purpose. In fact I suspect the Dreamers don’t really believe we are intelligent at all. We are too small; there were always too many of us, getting in each others’ way. To them we are more like social creatures, industrious creatures who blindly build things. Like ants or beavers.”

“Or builders,” Beth said.

“Or road-laying legionaries,” Titus said. “And given some of the lads I’ve worked with in my time, they might have a point.”

One morning Beth came to find Stef. She was grinning widely. “There’s something you need to see. As one veteran Per Arduan to another.”

She led Stef over to the ColU’s small Arduan garden. The ColU itself sat on a chair by the garden, roughly made by Chu from Arduan tree-stems. “Colonel Kalinski,” it said. “Look what I did.”

Beth took Stef to the edge of the worked soil. Reed-like stems grew in the earth in the shadow of the dwarf stromatolite, and in a shallow, marshy puddle.

Beth said, “Remember scenery like this? The ColU says it believes that the stems we see today are descendants of those of our time, of the first colonies. And it was those stems that bundled up to make builders. The ColU thinks the genetic potential to create builders is still in there somewhere; all he needs to do is cross-breed enough samples to restore the native stock.”

Stef thought that over. “You won’t have time, ColU. There are only months left—”

“I know, Stef Kalinski. But you’ll forgive me for trying even so…”

“I asked the ColU to do this,” Beth said. “The builders saved my life, and my parents, when we migrated with their lake—even if they didn’t know it. I always felt guilty about how the builders kind of got shoved aside when humans came pouring through the Hatch to Per Ardua. I wanted us to at least try.”

“The ColU hasn’t succeeded, though, has it?”

“No, but it’s made some progress. Come see. Take a closer look. Just don’t get freaked out the way my father always said he was, when he first discovered these things…”

Curiosity pricking, Stef stepped forward to the edge of the pond and bent to see. The artificial pond was shallow, and its base was covered with mud, thick with lichen, from which the stems were growing. The stems themselves came up to her waist. They were an unusual kind, darker, flatter, more like blades than the usual tube-like structures, yet still substantial, still no doubt filled with marrow.

She crept closer, right to the water’s edge.

And on every stem, facing her, growing from the muddy pond scum, a single eye opened.

Earthshine said, “It was you, Stef, who first brought the Dreamers to my attention, in a sense. At least, their history-meddling. For your personal history was tinkered with in a minor way when you first opened that Hatch we found on Mercury—”

“And suddenly I had a sister I didn’t remember. Suddenly my memory didn’t fit the facts of the universe as it existed.”

“In retrospect, that was a classic loose end. An effect with no cause, in a universe that was now nonperfect, its causality become ragged. Or rather, more ragged.”

“And later you found another loose end. The grave of my mother—”

“Which still recorded she’d only had one daughter. Even as the second daughter stood there looking at the stone. And later, as you know—now I knew what to look for—I found more evidence of meddling. More evidence of lost timelines.”

“The Drowned Culture.”

“From these traces I deduced the existence of the Dreamers. Oh, not their nature, the fact that they were ensconced in the hearts of the rocky worlds. That came later. But I knew they were there, meddling, tinkering… In my fancy, I identified them with Loki, the trickster god of the Norse. Well, in the myth, Loki’s actions brought on Ragnarok, the final war—and in the course of that war, another god, Heimdall, finally killed Loki himself. Was that to be my role? That was what I began to believe.”

“And you did try to kill them,” Stef said. “Or at least you made a start. You used Ceres to hammer Mars. Even much of the subsurface life, the Dreamers, must have been destroyed in that action. But what were you thinking? Would you have roamed the Galaxy smashing one world after the next, trying to eradicate bugs hidden kilometers deep?”

“I would probably have come up with a better strategy,” Earthshine said evenly. “Consider this. Each infested world is isolated, biologically, in its deepest layers. Isolated, and therefore vulnerable to an engineered virus, perhaps, a bacteriophage… It might take a thousand years or a million, but such an agent could rip through the noostrata of such a world, and—behead it. Yes, there are many such worlds, but they are connected by the Hatch network—and again, that’s a weakness. Perhaps some agent could be delivered through the Hatches themselves, targeting the destination world, before moving on…

“This is a sketchy scheme. The point is that every life-form has vulnerabilities, and every community is made vulnerable by interconnectedness. Given time and motivation, I believe that I, or another, could find a way.” He said softly, “It may not have taken much effort. In Norse myth, Loki killed Baldr, favorite child of the gods, with an arrow made of mistletoe. A single arrow. Perhaps I wasn’t even the first to try.

“But that initial assault on Mars—call it a spasm of rage—was enough for me to attract the Dreamers’ attention. Enough for them to send me here, with the rest of you as a presumably unintended consequence. I think they wanted me to see this, you see. The End Time. I think they wanted me to understand what they were trying to do—and to make sure I gave up my efforts to hinder them.

“And I did understand. In any event I would not try to harm them now—that ambition is gone. I feel—honored—to have had my strength recognized, at least. And to have been brought to this place. To Ultima.”

Titus frowned. “Ultima?”

“You know, every starfaring culture we found had a legend of Ultima, the furthest star. Even the Incas you met spoke of Kaylla, nearest star, and Karu, furthest. Perhaps alien minds frame such ideas too. We were all surprised to be delivered to Proxima, the nearest star to the sun. But in the end, you see—”

“Every star is Ultima,” Stef said. “Every star is the last star. For all the stars will encounter the End Time in the same instant.”

Titus looked around the group. “So,” he said, “that’s the story told. All we need to do now in the time left is sit around and wait for the end. Is that it?”

Beth, impulsively, embraced Stef. “If so, there are worse places to be. And worse people to be with.”

And then the ColU coughed, making them all stare.

“A polite interruption,” said Stef. “What do you have to say, ColU?”

“Just that the situation may not be quite so simple. Perhaps we have—an option. If not hope.”

“An option? What do you mean?”

“Do you recall that when Ari Guthfrithson and Inguill foolishly lost their lives in the Hatch—”

Mardina’s scream filled the dome.

Chu called, “It is time! The first contraction!”

The conversation broke up. Falling into a much-practiced routine, the group hurried to Mardina’s side.

73

After the birth, the baby grew healthy and happy, a little girl who absorbed all their attention, soon repaying in smiles.

But the time they had left dwindled, from months, to weeks, and at last to days.

Earthshine said he was calling a group conference, by the Hatch. He had matters to discuss.

Titus just grunted at this news. “In any other circumstances, that might sound ominous.”

Of course, they would all come; they would do as Earthshine asked. They were nothing if not a team by now.

But first, this morning, as every camp morning, Mardina, Beth and baby Gwen took a walk around the growing colony.

They gravely inspected the rows of terrestrial plants, sprouting from carefully manufactured and tilled soil, under ever-extending banks of sunlight lamps constructed in turn by an army of fabricators. And as they walked past the banks of Arduan green there was a soft rustle: the sound of eye-leaves turning to watch them go by. At the wall of the dome, they peered out to see the farther extensions of the colony beyond, scars in the ground where more fabricators were toiling to turn Arduan rock into soil, the slumped form of a second dome yet to be inflated—and it probably never would be, Mardina thought. The vision of an hourglass coalesced in her head, to be firmly pushed away.

Cradled in Mardina’s arms, bundled in a blanket, little Gwen gazed around at whatever she could see. She was three months old now. Her hair looked as if it would be crisp black, a legacy of her grandmother, Mardina Jones, and she had dark eyes, like her father’s. And those eyes were wide and seemed full of wonder, gazing at this world of marvels into which she had been thrust. Even if, and Mardina couldn’t help the thought, it was a world that would betray her long before she could hope to understand why. Just months old. Just days left to live…

“We’re doing well,” she said aloud, to distract herself from her own thoughts. “The colony, I mean. Given we started from nothing but the gadgets in Earthshine’s support kit.”

Beth said, “I grew up a pioneer, with my parents, alone on this world. It’s pleasing to build stuff, isn’t it, to bring life and order to a world—to make it right? Just as the builders always did. Maybe we’ve got more in common with them than people ever understood.”

“Even if we’re running out of time,” Stef said.

“But that was always true, I suppose,” Beth said. “Time for people, for worlds, for the stars. You just have to do the best you can in the here and now.”

Mardina hugged her baby. “But it all seems so solid. So real, so detailed. That big old galaxy sprawling across the sky. The way Gwen’s hair feels when I brush it. It’s hard to believe…”

Beth waited for her to finish.

“If I don’t speak the name of this thing, it still feels like it isn’t real. Does that make any sense?”

The ColU spoke to them now, whispering in their earphones. “It makes plenty of sense, Mardina Eden Jones Guthfrithson. The power of names: probably one of the oldest human superstitions, going back to the birth of language itself. To deny a name is to deny a thing reality. And yet now it is time to name names. I am sorry to disturb you. Earthshine is ready for us…”

Once more they gathered around Earthshine’s support unit, under its spidery tree of extensors, his connection with the dirt and rock of Per Ardua and the legions of Dreaming bugs that infested it. They sat on heaps of blankets, and low benches made from the remains of the ramshackle sled Ari and Inguill had towed here.

In the crib Titus had made, Gwen wriggled and gurgled, half asleep and content for now.

“Only three,” Earthshine said.

Titus frowned. “What’s that?”

“Call it a headline. A key point. A summary, perhaps. For all that I myself have human origins, for all I infested the human world for decades, I still find myself clumsy when delivering ambiguous news. But if you remember this in what follows, it may help. Only three.”

Titus growled, “No doubt you’ve brought us here to speak of what’s to become of us.”

“And how we must respond, yes. You know that we have only a few days left, now. And there are preparations we must make.”

Only a few days. A few days, before Mardina would have to lose Gwen. She felt as if a pugio were twisting up her guts at the thought of it.

And Titus laughed sourly. “What preparations? Myself, I plan to get blind drunk, and sleep through the twilight of the gods—”

“You will not,” snapped Clodia. Sitting behind him, she grabbed his hand. “You’ll be right here with me, Father; that’s where you’ll be.”

Titus seemed to calm quickly, as if suddenly remembering he wasn’t trying to motivate a bunch of recalcitrant legionaries. “Of course I will, child.” He wrapped his stump of an arm around her shoulders. “Of course I will.”

Stef said now, “But Titus asked a good question, Earthshine. What meaningful preparations can we make? I think it’s time to stop being enigmatic. Tell us straight what’s on your mind.” She scowled. “Or is this some cruel trick?”

“No,” he said earnestly. “Not a trick. It is a sliver of hope. Listen, please. We have discussed this many times. You do understand what is to happen? This universe—and all those near it in the multiverse, near in probability space—this universe will intersect a boundary, the edge of the multiverse itself. In essence, time will cease. The End Time—that is a literal description.”

The ColU unit was sitting on a blanket, an honorary human among humans. It said, “Imagine that the whole of this world is a simulation, supported in the memory banks of some vast computer—the way Earthshine can project a simulation of a human body. When the boundary comes it will be as if that simulation is frozen. Paused. You would not feel anything. But your stories would be ended, as cleanly as if you had paused some projected virtual show, and never restarted it, leaving the characters in limbo.”

“Except,” Earthshine said, “we know it won’t be as simple as that. It won’t be a perfectly sharp cutoff. Everything in nature is uncertain—everything is smeared. And so will be the multiverse boundary.”

Stef said, “Which is why the kernels work. They are wormholes connecting us to the boundary, and what we find there is a huge outpouring of energy.”

“That’s it,” Earthshine said. “Every particle in the universe follows a world line, a kind of graph threaded through space-time. And every world line, every particle, must end at the multiverse boundary. In that way it’s like an event horizon—like the edge of a black hole, but a black hole absorbs. This is like a tremendous mirror, or a furnace, if you like, where every last grain of creation will be thermalized—burned up as heat energy. And as the energies of all the terminating particles pile up there, indeed are reflected back, there will be a last infernal carnival of creation, as that energy nucleates into new particles, which will immediately be swept over by the advancing boundary…”

The ColU said now, “These huge energies have already had an influence on our universe, observable effects. These were distortions I detected in the cosmic background radiation, as if our universe is recoiling from what is to become of it. That was how I was able to calculate the timing of this event, roughly, long before we got here.”

Earthshine said, “The important point now is that the boundary is smeared, just a little. The destruction it brings will not be quite instantaneous. And that gives us a sliver of an opportunity—”

“No,” Beth said, suddenly understanding. “The Dreamers. It’s given the Dreamers an opportunity, to help us.”

“You understand, Beth Eden Jones,” the ColU said. “You always did have a good intuition about Hatches.”

Mardina frowned. “What are you talking about?”

“The Hatch,” Beth said, and she took Mardina’s hands. “Remember? After Ari and Inguill went through, and Earthshine’s probe. After we opened it again, the Hatch had changed. It’s just like the first Hatch I ever saw, with my father, at the substellar. Buried in the jungle. Grooves appeared in its surface. I was the first to understand—they were grooves to hold the bodies of builders. And when the builders climbed into the grooves, it was like putting a key in a lock. You see?”

“Ah,” Titus said. “And now, in the doorway, when our Hatch was opened up for Ari and Inguill—recesses for hands. Human hands.”

“I think the Dreamers are telling us something,” Earthshine said. “On some level they know we’re here. I always have the impression that they can’t see us clearly—they don’t understand us, or our nature, or not sufficiently. But they know we’re here.”

Beth said eagerly, “Yes, that’s it. They’re saying we can go through the Hatch. Through to—”

“The past,” Earthshine said gravely. “It must be someplace else in space, some other world, another history. But it has to be the past, from this point, for there’s no future. And there is plenty of past to choose from. Seventeen billion years of it…”

Chu frowned. “How could you even know where you were? In space or time.”

“Good question,” Earthshine said. “If the travelers remain on Per Ardua, perhaps we could prepare maps of the stars, at different epochs. Even of the position and size of Andromeda. But if you translate through space as well as time… Well, these are details. The journey is the thing.”

Mardina clutched her baby, who stirred and gurgled. “Then there’s hope.”

But Stef said gravely, “Only three. Remember? That was how he opened this conversation. Only three. Only three of us can do this, pass through the Hatch. Is that what you mean, Earthshine?”

And suddenly the group seemed an enormous crowd: Mardina and her baby, sitting between Chu and her mother Beth; Titus with his daughter clutching his one good hand; Stef sitting alone—and the ColU and Earthshine, two artificial people. Seven of them, or nine, depending on your definition. Of whom only three could survive.

“Why?” Mardina found her voice came out as a snarl. “Why only three?”

Earthshine sighed. “I suspect it is simply because of the world we sit in. Per Ardua. The records show that the builders, using Hatches—”

“Ah. I remember,” Beth said. “The builders did everything in threes. Their bodies had triple symmetries—three legs. They moved in groups of three, or threes of threes—nine, or twenty-seven.” She laughed, bitterly. “These Dreamers of yours can’t tell how many we are, Earthshine! They can’t tell the difference between us and builders!”

“Which only shows how remote they are from us,” Earthshine said. “Yet they are trying to be—kind.”

Titus growled, “And so we have the game before us—the battlefield set out, and we can’t change that. Three to go through, six to remain. And we must decide which three, right now.”

Mardina saw people pull back, as if more shocked by that pronouncement than by Earthshine’s revelations. As for herself, she clutched her baby harder. The sting of hope in her chest was more painful than the despair.

Stef looked small and frail, a blanket over her shoulders. But she said firmly, “Titus, it’s too soon. We have a little time left, time to think.”

“No. In war I have seen similar situations. Some must die so the others can live. We decide this now, and we stick to the decision. Otherwise we will tear ourselves apart. Perhaps literally; we might destroy each other, fighting for a place. Why, I remember once on campaign—”

“We would not do that,” Clodia said.

“We might,” Stef said ruefully. She turned to Mardina. “You, Mardina, and the baby. If nobody else—you. You two are the future of this peculiar little extended family of ours. Of course you must live.”

Mardina felt tears well. “But—”

“No.” Titus held up his hand. “No arguments. Of course she is right; we would not be human if we chose otherwise.”

The ColU said, “I am not human at all, and I concur. And as for myself and Earthshine, we should be ruled out. We are created beings, created to serve humanity. And how better can we serve humans now than by saving as many of you as we can? But I speak for myself. Earthshine, your origin is more complicated than mine—”

“Oh, I’m staying right here,” Earthshine said. “I want to see the End Time firework display. Seventeen billion years in the making—I wouldn’t miss it for the world.” He seemed to think that over. “Ha! I made a joke.”

“And I of course will stay,” Stef said. “I’ve done my Hatch-hopping, and I’m too old for babies. Too old even to babysit. And, yes, I admit I’m curious too about the End Time. An entirely novel physical phenomenon. We should work up an observation suite, Earthshine. Do some decent science. Perhaps there will be time to debunk a few theories before the lights go out.”

“I look forward to it, Stef Kalinski.”

Titus growled, “I, of course, will stay. After all, you would probably all be dead before the End Time anyhow if not for my organization and leadership.”

Stef smiled. “I won’t deny that, Titus Valerius.”

Clodia clutched her father, burying her head against his chest.

“So,” Stef said now. “That leaves three candidates for one place.”

Again there was a dismal silence as they shared looks. The remaining candidates were Beth, mother of Mardina. Chu Yuen, father of the baby. Clodia, who was younger than Mardina herself.

Clodia spoke first. “It must be Chu,” she whispered. “The baby needs her father. And Mardina will need Chu’s strength and wisdom. Take Chu, not me.”

Her father embraced her. “Good girl. We will be together. Romanitas to the end.”

“She’s right,” Beth said impulsively to Chu Yuen. “Of course it must be you. You’re the father. You’re a good man, Chu. And you’re much stronger than I ever could be—”

Mardina broke down completely now. With her baby in her arms she stumbled over to Beth. “No! Mother, I can’t be without you.”

“Yes, you can.” Beth took her by the shoulders, and held her, looking into her daughter’s face. “You can do this. You must—you will. My father, Yuri, used to speak of doors he passed through in his life. He fell asleep on Earth, woke up on Mars, and wound up on Per Ardua, light-years from home and a century out of his time. Just another door opening, he would say. You go through it and deal with what you find.”

“When he died,” the ColU said, “he said the same thing, even at the end. I was with him, in deep space… Just another door, he said.”

Mardina gasped, “But what about you? Mother, what about you?”

“I’ll be fine. Don’t worry about me. I won’t be alone.”

“You will not,” the ColU said. “Just as I attended your father’s death, Beth Eden Jones, so I was there at your birth. I will be honored to have your company now.”

Stef let out a deep breath. “I admit, right now I could use a hug. But I’ll wait my turn. So, Earthshine, you got your news out, and the decision is made.”

“And we have a lot of work to do,” Earthshine said gravely.

74

Time ran down quickly after that.

Stef Kalinski found herself counting down landmarks. Things she’d never see again, or do again. A last shower, in the crude lash-up they’d set up at one end of the dome. A last dinner with the group. The last time she flossed what was left of her teeth…

Suddenly it was the final time there would ever be a tomorrow.

They had taken to sleeping in separate little huddles around the dome, Chu with Mardina and the baby, Titus close to his daughter. That last night, by unspoken consent, they pulled their sleeping gear together in a rough circle close to Earthshine’s static installation. The last nine, including Earthshine and the ColU, alone on this world—perhaps the last humans in the universe—gathered together in a dome illuminated by low-level lights, and the sunset glow of Andromeda.

Stef surprised herself by sleeping pretty well, for an old buzzard, she told herself. It was almost a comfort to be woken a couple of times by the baby’s demands to be fed, and the murmuring of Beth as she helped her daughter. Stef smiled in the dark. Poor Mardina still had her duties to perform, end of the world or not. Who would be a mother?

Actually Stef would, right now.

When she woke, there were only hours left.

In the dome morning, after a subdued breakfast, the first order of the day was to get Chu, Mardina and the baby installed in the Hatch.

Earthshine had created a protective sphere, like the one in which he’d encased his probe to the End Time: a thick heat-absorbent shell that, he believed, had kept the probe functioning for fractions of a nanosecond, while Ari Guthfrithson and Inguill had been immediately destroyed. Maybe it could help now, in this new transition—and the ColU had agreed that it could do no harm.

The shell, scaled up to take humans, was like a big smooth egg, the cross-section of its shell thick—it had taken a squad of fabricators some time to construct. It looked scary, the threat it embodied was scary, and Mardina and Chu looked suitably anxious as they wriggled their way into the tight interior, with their packs of tools and clothes and food and water and baby stuff—even pressure suits, improvised from the Mars gear Beth had brought with her. With all that stuff crammed in, there was barely room to move. But the young family would just sit out the remaining time in the shell. Earthshine said it was confident the Dreamers would take care of their destiny from that point on; no more need for palm prints in indentations in doors.

Then it was time to seal the shell, and close up the Hatch. Time for Beth to say goodbye to her daughter, the others to lose their friends.

Stef had always had a feeling she was going to have trouble getting through this part of the day without making a fool of herself, and so she said her farewell with a quick hug of Chu and Mardina, a last stroke of the baby’s smooth and untroubled forehead. Then she took herself away from the sundered family.

She set off around the dome, on a last round of chores. She checked the lights and heating that excluded the Per Arduan farside cold and dark, preserving the banks of green growing things they cultivated here.

And she found Clodia.

The Roman girl was carrying cans of water, and packets of plant food synthesized by Earthshine, some for the potatoes and beets and other terrestrial imports, some for the Arduan plants. As she worked her way along the rows of young eye-leaves, Stef saw that Clodia was smiling.

Stef joined her. “This place is pretty neat and tidy.”

“That’s my father for you. He’s been preparing for the end of the world like it is an inspection by Centurion Quintus Fabius.”

Stef laughed.

“Meanwhile,” Clodia said, “I don’t see why these should go hungry. Even today.”

“No indeed. Look, the eye-leaves are turning to follow you.”

“They always do. Every day. I make sure I don’t walk too fast, so they can track me.”

“Considerate. And you always smile at them?”

Clodia shrugged, as if embarrassed. “Why not? I never saw a builder, only pictures of them. But I see those eyes looking at me, and I don’t know what kind of mind lies behind them. I never knew anybody who didn’t feel better for being smiled at, did you?”

“I suppose not…”

Stef was aware of time passing. They had all said resolutely that they didn’t want a countdown, but on this last day Stef couldn’t help have at least a rudimentary sense of the hour. And she knew—

A horn sounded, a signal Earthshine had insisted on.

“Come on. Let’s get back to your father.”

Once again the group gathered beside Earthshine’s spidery enclosure. A fire had been lit, though it wasn’t cold in the dome; its crackling was comforting, and a bowl of water was bubbling to the boil.

Titus was squatting on a bench, with a mug of what looked like beer in his one hand. Stef knew he had been experimenting with home brewing; he said that all legionaries learned such skills on long marches away from home. Stef herself had assiduously avoided any contact with the stuff.

Clodia helped herself to a mug of tea and went to sit by her father, on blankets at his feet, and cuddled up against his legs. Now Stef could see Clodia’s eyes were puffy, her cheeks streaked, as if she’d been crying. Stef cursed herself for not noticing before. Crying over what, the coming end for her father, the loss of her own military dreams? If so, at least she seemed calm now. That was the gardening, Stef thought. Nothing calmed you quite so much as cultivating your garden. Even when it didn’t have eyes to look back at you.

Beth was sitting alone, wrapped in a blanket—no, not alone, Stef realized; she was close to the winking unit of the ColU, her friend from childhood. Beth had seemed unable to move far from the Hatch since it had been closed over Mardina and Chu and Gwen. Stef found it hard to blame her, and nobody was of a mind to force her away. But now Beth was clutching a kind of crude doll to her chest: Mister Sticks, a toy from her own childhood, made for her by the ColU when it still had a body and manipulator arms to do it. This copy had been made from dry Arduan stems by Clodia, under the ColU’s strict instructions.

Stef poured out two mugs of tea, and carried them over to Beth. “May I join you?”

“Why not?” Beth’s voice was bleak, empty. But she responded reflexively when Stef handed her the tea, moved along her bench a little, and let Stef sit down. Stef pulled a blanket over her own shoulders, and reached under layers of cloth until she found Beth’s hand.

“So we are all here,” Earthshine said. “I take it you don’t want a countdown—”

Titus snapped, “No, we do not!”

“Very well. But, Stef, you may wish to have your slate to hand.”

“Damn.” She’d forgotten about that. Just as they’d decided, she and the ColU and Earthshine were going to keep monitoring the science of this event, as long as they could. She had to rummage under her blanket in her capacious pockets until she found the slate, dug it out and wiped its surface clean of bits of lint with a corner of her blanket. Here was another survivor, she thought, another relic of a different universe. She wondered where she’d first picked it up. Mars? The moon? Never imagining that it would still be here with her now, in such a place, in such a time.

The screen lit up with displays: simple counts, graphics. She scanned the material quickly, immediately understanding the most basic implication. “There’s a radiation surge. It’s already started, then.” She felt dismay at the first real physical proof of the end: that it was real after all, just as Earthshine had predicted, despite all their efforts to believe otherwise.

“In a sense, yes,” said the ColU. “Already we’re seeing high-energy radiation, heavy nuclei—rather like cosmic rays. A flood of it coming backward in time. And pretty bad for your health, by the way.”

She had to laugh. “What, we’d all be dead of radiation poisoning in a year? Remind me not to renew my life insurance.”

“It’s going to ramp up from here. Soon we’ll be seeing exotic nuclei, elements nobody ever saw before—or named. Stef Kalinski, you’ll be the greatest discoverer of exotic physics that ever lived.”

“Yeah… So how are you feeling, ColU? Do you understand what is about to happen to you?”

“Yes, Stef Kalinski. I am to be turned off at zero.”

“Well, that’s close enough.”

“It may be easier for artificial intelligences to understand than humans, organic creatures, in fact. The possibility that consciousness may terminate, suddenly: anybody fitted with an off switch knows all about that.”

Beth stroked its shell. “Good luck, ColU. And thank you.”

“Thank you for loving me,” the ColU said, to Stef’s surprise.

The dome lights flickered once, twice, and failed.

Even Stef’s slate went down. She patted its surface, and set it aside. The end of science.

The ColU said, “That’s probably the radiation. Earthshine and I have hardened power units. We should keep functioning a little longer.”

Now the only glow came from the sky, from the sprawl of Andromeda—a tremendous galaxy doomed to destruction just as was her own feeble frame, Stef thought. Her friends were shapes in the dark around her. And as her eyes adjusted Stef began to see the stars above.

Earthshine whispered, “The wolves that have always chased day and night through the sky are catching them at last…”

Under the blanket, Beth’s fingers tightened on Stef’s.

Stef heard Titus take a long, satisfying draft of his beer. Then he said, “You know, this reminds me of a time on campaign when…”