“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.”