Could Cassiopeia look at the equations of relativity and see an implied universe of stars and planets and black holes? Could she look at the equations of quantum mechanics and see the intricate chemistry of living things?

Of course, that increased smartness must lead to a qualitative jump in understanding. A chimp didn’t think about things more simply than Malenfant did; it couldn’t grasp some of his concepts at all. There were clearly areas where Cassiopeia was simply working above Malenfant’s wretched head.

Cassiopeia had spent time trying to teach him about a phenomenon just a little beyond his own horizon — as chaos theory might have been to an engineer of, say, the 1950s. It was something to do with the emergence of complexity. The Gaijin seemed able to see how complexity, even life, naturally emerged from the simplest of beginnings: not fundamental physical laws, but something even deeper than that — as far as he could make out, the essential mathematical logic that underlay all things. Human scientists had a glimmering of this. His own DNA somehow contained, in its few billion bases, enough information to generate a brain of three trillion connections…

But for the Gaijin this principle went farther. It was like being given a table of prime numbers and being able to deduce atoms and stars and people as a necessary consequence of the existence of the primes. And since prime numbers, of course, existed everywhere, it followed there was life and people, humans and Gaijin, everywhere there could be.

Life sprouting everywhere, like weeds in the cracks of a pavement. It was a remarkable, chilling thought.

“Take me to your home,” he’d said one day.

Cassiopeia’s choice of a human label for her remote home was “Zero-zero-zero-zero,” the great sky map’s origin of coordinates.

I AM THE SUCCESSOR OF A REPLICANT CHAIN THAT EMERGED THERE, she’d said. She was descended from emigrants? Not exactly, because she’d continued. I RETAIN RECORDS OF ZERO-ZERO-ZERO-ZERO. Memories? Did each Gaijin come to awareness with copies of the memories of those who bore her — or constructed her? Were they, then, her memories, or a mere copy? IT IS POSSIBLE TO TRANSLATE TO ZERO-ZERO-ZERO-ZERO. THERE IS NO PURPOSE.

“I’d like to see it.”

THERE ARE RECORDS THAT—

“Your records only show me your world through your eyes. If we’re ever going to understand each other, you have to let me see for myself.”

There was a long hesitation after that.

FINALLY, she’d said then.

“What?”

THERE ARE MANY PLACES TO SEE. MANY WORLDS. BEFORE ZERO-ZERO-ZERO-ZERO.

“I understand. One day…”

ONE DAY.

But not today, Malenfant thought, as he opened his eyes to the light of a foreign Sun. Not today. Today, we are both far from home.

Cassiopeia provided him with an environment suit — a loosely cut coverall of what felt like a high-grade plastic. It had no zippers; he learned to seal it up by passing his thumb along the open seams. He lifted a hoodlike helmet over his head. There was a clear faceplate, a slightly opaque filter near his mouth.

There was no independent air supply, just one layer of fabric. The whole thing jarred with Malenfant’s intuition of the protection he would need to walk on an alien world. But Cassiopeia assured him it would be enough. And besides, the only alternative was his battered shuttle EMU suit, still with him, crammed into a corner of the lander, his only possession, long past its operational lifetime.

“Open the door. Please.”

The lander door dilated away. The world beyond was green and black.

The lander’s cabin floor was almost flush with the ground, and he stepped out, pace by pace, testing his suit. Gravity was a little more than Earth normal, comfortingly familiar, and the air pressure just a little higher than Earth’s sea level.

First impressions:

He was alone in an open forest, like park land. There were objects that were recognizably trees, about the size of Earth trees, and what appeared to be grass under his feet. Above his head a Sun sailed through a sky littered with high wispy cirrus clouds.

He closed his eyes. He could hear the soft hiss of wind over the grass, and a distant piping, for all the world like a bird’s song, and when he breathed in he filled his lungs with cool, crisp air.

It might have been Earth.

But when he opened his eyes, he saw a sky that was a lurid yellow-green. It was like a haze of industrial smog. The vegetation was a very deep green, almost black.

And he could smell chlorine.

His filter removed all but a trace of the chlorine compounds that polluted the atmosphere — including phosgene, toxic stuff humans had once used to slaughter each other. If not for his suit, this friendly looking world would soon kill him.

Chlorine: That was the big difference here. Most of Earth’s chlorine was locked up in the oceans, in the form of a stable chloride ion. This world seemed to have started out as roughly Earthlike. But something, one small detail, had been different: Here, something had pumped all that chlorine into the air.

He walked forward, over grass that crushed softly under his feet.

He reached a narrow valley, a rushing brook. There was a stand of trees nearby. The bed of the little stream was just a soft muddy clay, no sign of any rocks. The water was colorless, clear. He knelt down, stiffly, and dipped his fingers into the water. It was cold, its pressure gentle against his gloved hands.

WARNING. SOLUTION OF HYDROGEN CHLORIDE. HYPOCHLORIC ACID.

He snatched back his fingers. Like a swimming pool, he thought: Chlorine plus water gave a solution of acid and bleach. The weathering of any rocks here must be ferocious; no wonder only clays survived.

He straightened up to inspect a tree. He touched branches, leaves, a trunk, even a blossom. But to his gloved fingers the leaves felt slippery, soapy.

From a hollow in the tree trunk, at about his eye level, a small face peered out: the size and shape of a mouse’s, perhaps, but with a central mouth, three eyes arranged symmetrically around it. The mouth opened, showing flat grinding surfaces, and the little creature hissed, emitting a cloud of greenish gas. Then it ducked back into the hole, out of his sight.

The trunk didn’t feel like wood. He reached up and broke off a twig; it snapped reluctantly. The interior was springy, fibrous. The leaves, the tree trunk, were made of some kind of natural plastic — perhaps a form of polyvinyl chloride, PVC. If he could smell the blossom, it would surely stink like toxic waste.

It was like a grotesque model of a tree, a thing of plastic and industrial waste. And yet the breeze ruffled it convincingly, and sunlight dappled the green-black grass beneath.

In his ear, Cassiopeia, from orbit, began to lecture him about biochemistry. THE LIVING THINGS HERE ARE CONSTRUCTED OF CELLS — ANALOGOUS TO LIVING THINGS ON EARTH, TO YOU. THEIR METABOLISMS ARE NOT TOLERANT OF THE CHLORINE. BUT THEY HAVE EVOLVED SHIELDING AT THE CELLULAR LEVEL…

He interrupted. “There are trees here,” he said. “Grass. Flowers. Animals.” You see biochemistry. I see a flower, he thought.

There was a long silence.

It was the Gaijin way of seeing reality: from the equations of quantum mechanics, working up to a world. But that wasn’t the way Malenfant thought. Humans, it seemed, were better at broad comprehension than the Gaijin, quicker at abstracting simplicity from complexity. This object before Malenfant wasn’t a tree, because trees only grew on Earth. But it helped Malenfant to think in those terms, to seek patterns and map them back to what he knew.

The Gaijin, slowly, were learning to ape his thinking.

YES, came the reply. THERE ARE TREES.