Schild’s Ladder

deforming, as if the whole vision was a reflection in liquid metal. He couldn’t even pin down the source of his conviction, the one regularity in all the busyness beneath them that struck him as the signature of artifice over nature. But all technology would be built from nature, here. Nothing entirely lifeless could endure.

He turned to Mariama. “This is not an oasis. It’s not a jungle. We’ve found the Signalers. This is their city.”

Chapter 17

The Sarumpaet circumnavigated the xennobe colony, reconnoitering, apparently unnoticed. Tchicaya kept the density of the probes low, lest the rain of inquisitive devices cross the threshold of perception?—?or some more sensitive, artificial means of detection?—?and alarm the denizens. He had no urgent need to study these creatures' internal anatomy, and the details of the colony itself were overwhelming enough.

Veins and bladders and sheets composed of thousands of different vendek populations defined the structure, separated by an intricate warren of tunnels through which the free vendeks of the Bright continued to pass. The probes identified changes in the winds as they flowed through the colony; specialized vendeks were diffusing out of a multitude of reservoirs and modifying the raw weather, killing off some species, supplanting them directly, or interacting with them to create new variants. To Tchicaya, this looked exactly like air-conditioning for physics: the Colonists could probably cope with all but the most extreme natural changes in their environment, but it made sense that they’d find it less stressful to delegate some of their homeostatic efforts to their technology.

Hundreds of vendek currents snaked out of the colony, presumably waste products from both the thing itself and its inhabitants. A few were so stable that they completely resisted the passage of both probes and sprites, and they appeared in the scape as gnarled black roots twisting away into the distance.

Tchicaya saw nothing to dissuade him from his earlier conclusion, though everything was open to alternative interpretations. Termite mounds had air-conditioning, ants had mastered agriculture, and the Colonists might not have needed to expend even as much effort as social insects to bring their home into existence; it was possible that they were mere symbionts, mindlessly tending some giant natural organism. Mariama remained cautious, but she did not choose to play devil’s advocate. They both had the same hopes now, and they both knew how easily they could be dashed.

They spent half a day debating the level of caution they needed to exercise. Whether these xennobes were the Signalers or not, they were likely to have far more potent defenses than the rabbit. It would be difficult to supervise any kind of complex interaction from too great a distance, though; if they hung back in their present orbit and sent down a drone, it would need to be largely autonomous.

The plan they finally settled upon was to send in a mobile form of their signaling banner, as large and obvious as they could make it, while following behind at a prudent distance. If the reception was violent, the tiny sprite-shadow of the Sarumpaet would be the less likely target.

If their mimicry of the signaling layer produced a promising reaction, they would move on to more complex exchanges, playing it by ear, hoping that the banner itself would prompt their hosts to respond in kind. Nothing the probes had revealed had offered any clues about the Colonists' preferred mode of interpersonal communication; sprites and other potential information-carriers flooded the colony, but plucking messages in an unknown language from all the influences modulating these carriers was beyond the standard Mediator software they’d brought through the border. Given time, Tchicaya would have happily observed the Colonists from a distance until everything about them, right down to the subtlest cultural nuance, was absolutely clear. He and Mariama could have descended from the sky expecting compliments on their perfect local accents and unprecedented good manners, like a pair of conscientious travelers.

It was not going to happen that way. The coming of the Planck worms would be unheralded, but the five percent error bars of the toolkit’s best statistical guess had already been crossed. If the sky rained poison right now, as they rushed through their rudimentary preparations, they would not even have the bitter consolation of knowing that they’d been ambushed by unforeseeable events.

They’d reached the end game, ready or not. They’d have to walk a knife edge between recklessness and caution, but they could not afford to take a single step back.

The signaling banner spiraled down toward the colony, twisting and fluttering like an airborne tent in a hurricane, but pulsing steadily from translucent to opaque. The Sarumpaet followed, close enough to maintain a probe image of the banner that was only a fraction of a ship-second out of date. The probes could also ferry instructions from the ship to the banner, enabling the signal to be modified on a similar time scale as soon as the need arose.

From the deck of the Sarumpaet, Tchicaya formed a rapid series of impressions of the crowded world below, none of which he believed was worth trusting. The density and animation of the creatures made him think of the bustle of markets of festivals, of riots. Of the crew of some ancient, oceangoing vessel battling a storm. In fact, all this violent swaying in the wind was probably about as exciting for the Colonists as a terrestrial animal’s endlessly beating heart. For all he knew, this was what they looked like at their most indolent.

He searched for any hint of a flickering shadow from the banner on the surface below, but between the shimmering of the sprites and the erratic geometry of all the objects involved, that was too much to expect. Perhaps it was fortunate that the nearsiders would not arrive with anything like the drama of an artificial eclipse; even if these xennobes did belong to the same species as the Signalers, different cultures could still have varying degrees of sophistication, and an overblown spectacle might have terrified a group for whom the search for life beyond the border was a barely comprehensible endeavor, something that only an obscure, deranged minority would even contemplate.

On the other hand, since the banner had no significant effect on the ground, it was possible that no one would even notice it. It wasn’t clear that any of the Bright’s inhabitants focused the sprites to form an image; the rabbit had been close enough to the banner it attacked to sense its presence through a drop in overall irradiation, like a chill on the skin. It made evolutionary sense to expect all mobile xennobes to possess a detailed knowledge of their surroundings, but a sufficiently unnatural object might still be as invisible to them as a burst of neutrinos to a human.

The banner came to a halt at a predetermined altitude: some twenty times the Colonists' typical body size. Tchicaya gazed down at the crowd, wondering how he was going to distinguish panic from indifference. The Colonists weren’t as shapeless as the airflowers; their network of vendek tubes bifurcated twice to give four distinct clusters of branches, and their geometry at any moment tended to reflect this. They looked like medical scans of the circulatory system of some headless quadruped, dog-paddling ineffectually in extremely rough seas. But if that intrusive probe image was unlikely to reflect the way they saw each other, by sprites alone they resembled tortured, mutilated ghosts, trying to break through into the world of the living.

Mariama said, “I think it’s been noticed.”

“Where?”

She pointed; a group of six Colonists had left the surface. As Tchicaya watched, they ascended rapidly, but as they grew nearer to the banner they slowed considerably. This cautious interest was not proof of anything, but it was an encouraging sign.

The Colonists surrounded the device, then began spraying it with a delicate mist of vendeks. “That’s cooperative sensing!” Mariama exclaimed. “One of them illuminates the object, the other looks at the transmitted pattern.”

“I think you’re right.” The group was arranged in pairs on either side of the banner, and the members of each pair took turns emitting the vendeks. The probes hadn’t encountered this species of vendek before; perhaps nothing inside the colony warranted the same kind of scrutiny as this alien object.

The Colonists retreated and formed a loose huddle away from the banner. “What now?” Tchicaya wondered. “How do you react to a mutated version of your own stratospheric beacon suddenly appearing on your doorstep?”

Mariama said, “I just hope they realize they don’t need to launch a new signaling layer in order to reply.”