Stephen Baxter - Origin

The Nutcracker child gurgled, her eyes shining. She seemed enchanted by the turning wheels, as if the whole display, surely a thousand miles across, was no more than a nursery mobile.

“Blue rings,” Nemoto breathed.

Emma squinted, wishing her eyes would dark-adapt faster. “Like the Wheel, the portal I fell through to come here.”

Nemoto said, “This technology has a unifying, if unimaginative, aesthetic.”

“It is the world engine,” Mane said simply.

Emma saw the turning wheels reflected in Mane’s broad, glistening eyes. “What is a world engine?”

“Can you not see? Look deeper.”

“…Ah,” Nemoto said.

At the heart of the turning rings, there was a world.

It was like Earth, but it was not Earth. Turning slowly in the light of an off stage sun, it was wrapped in a blanket of thick, ragged cloud. Emma glimpsed land that was riven by bright-glowing cracks and the pinpricks of volcanoes. Plumes of black smoke and dust streaked the air, and lightning cracked between fat purple clouds.

“Not a trace of ocean,” Nemoto murmured. “Too hot and dry for that.”

“Do you think it is Earth? — or any of the Earths?”

“If it is, it is a young Earth, an Earth still pouring out the heat of its formation…”

“The sky,” Mane said, her voice quavering, “is full of rock.”

Emma glanced up.

…And for an instant she saw what the Daemon saw: a different point of view, as if she were standing on that burnt, barren land, on bare rock so hot it glowed, close to a river of some sticky, coagulating lava. She looked up through rents in fat, scudding clouds — into a sky that was covered by a lid of rock, an inverted landscape of mountains and valleys and craters.

She gasped, and the vision faded.

Emma saw again the hot young world, and another beside it now, a Moon-like world, evidently cooler than Earth, but large, surely larger than Mars, say. The two planets sat side by side, like an orange and an apple in a still-life.

But they were approaching each other.

“I think we are watching the Big Whack,” Nemoto murmured. “The immense collision that devastated young Earth, but created the Earth-Moon system…”

The planets touched, almost gently, like kissing. But where they touched a ring of fire formed, shattering the surface of both worlds, a spreading splash of destruction into which the smaller body seemed to implode, like a fruit being drained of its flesh.

“The collision took about ten minutes,” Nemoto said softly. “The approach speed was tens of thousands of miles per hour. But a collision between such large bodies, even at such speeds, would look like slow motion.”

A vast fount of material, glowing liquid rock, gushed into space from the impact. Emma glimpsed the impacting planetesimal’s grey curve, a last fragment of geometric purity, lost in the storm of fire. A great circular wave of fire spread out around the Earth from the impact point.

A ring of glowing light began to coalesce in Earth orbit. As it cooled it solidified into a swarm of miniature bodies. And then spiral arms formed in the glowing moonlet cloud. It was a remarkable, beautiful sight.

“This is how the Moon was born,” Nemoto said. “The largest of those moonlets won out. The growing Moon swept up the remnant particles, and under the influence of tidal forces rapidly receded from Earth. Earth itself, meanwhile, was afflicted by huge rock tides, savage rains as the ocean vapour fell back from space. It took millions of years before the rocks had cooled enough for liquid water to gather once more.”

“You know a lot about this stuff, Nemoto.”

Nemoto turned, her face underlit by the glow of Earth’s violent formation. “A few months ago a new Moon appeared in Earth’s sky. I wanted to know how the old one had got there. I thought it might be relevant.”

Emma glanced at Mane. The Daemon stood with her knuckles resting lightly on invisibility. Her eyes were closed, her face blank. Julia’s eyes were closed too.

“What do they see?” she whispered to Nemoto. “What do they hear?”

“Perhaps more than this show-and-tell diorama. Manekato said this place, this tunnel in the Moon, was information-rich. Julia is as smart as we are, but different. Manekato is smarter still. I don’t know what they can apprehend, how far they can see beyond what we see.”

“…Hey. What happened to the Earth?”

The glowing, devastated planet had blown apart. Fragments of its image had scattered to corners of the chamber — where the fragments coalesced to new Earths, new Moons, a whole family of them. They hung around the chamber like Christmas-tree ornaments, glowing blue or red or yellow, each lit by the light of its own out-of-view sun.

Other Earths:

Emma saw a fat, solitary world, banded with yellow cloud.

Here was another cloud-striped world, but the clouds swirled around a point on its equator — no, it was a world tipped over so that its axis pointed to its sun, like Uranus (or was it Neptune?).

Here was an Earth like Venus, with a great shroud of thick clouds that glowed yellow-white, nowhere broken.

Here was a world with a fat, cloud-shrouded Moon that seemed to loom very close. This Earth was streaked by volcanic clouds. It lacked ice caps, and its unrecognizable continents were pierced by shining threads that must have been immense rivers. This world must be battered by the great tides of air, water and rock raised by that too-close companion.

Most of the Earths seemed about the size of Earth — of the Earth, Emma’s Earth. But some were smaller — wizened worlds that reminded her of Mars, with huge continents of glowering red rock and brooding weather systems squatting over their poles. And some of the Earths were larger. These monster planets were characteristically wreathed in thick, muddy atmospheres and drowned in oceans, water that stretched from pole to pole, with a few eroded islands protruding above the surface, rooted on some deep-buried crust.

The Moons varied too. There seemed to be a spectrum of possible Moons. The smallest were bare grey rock like Luna, those somewhat larger cratered deserts of crimson rock more or less like Mars. Some were almost Earth-like, showing thick air and ice and the glint of ocean — like the Red Moon itself. There were even Earths with pairs of Moons, Emma saw, or triplets. One ice-bound Earth was surrounded, not by a Moon, but by a glowing ring system like Saturn’s.

Emma looked, without success, for a blue Earth with a single, grey, modest Moon.

“The Big Whack collision shaped Earth and Moon,” Nemoto murmured. “Everything about Earth and Moon — their axial tilt, composition, atmosphere, length of day, even Earth’s orbit around the sun — was determined by the impact. But it might have turned out differently. Small, chance changes in the geometry of the collision would have made a large difference in the outcome. Lots of possible realities, budding off from that key, apocalyptic moment.”

“What are we looking at here? Computer simulations?”

“Or windows into other possible realities. It is a glimpse of the vast graph of probability and possibility, of alternates that cluster around the chaotic impact event.” Nemoto seemed coldly excited. “This is the key, Emma Stoney. The Big Whack was the pivotal event whose subtly different outcomes produced the wide range of Earths we have encountered…”

Emma barely understood what she was saying.

Julia grunted. “Grey Earth,” she said. She was pointing to the tipped-over, Uranus-like Earth.

Emma said, “Where you came from.”

“Home,” Julia said simply.

Nemoto said, “I recognize that one.” She pointed to the fat, solitary Earth, banded by Jupiter-like clouds. “A Moonless Earth, an Earth where the great impact did not happen at all. It may be the Earth they call the Banded Earth, which seems to be the origin of these Daemons.”