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.”