Schild's Ladder (37 page)

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Authors: Greg Egan

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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.”

“Maybe we should try to make a more obvious proxy,” he suggested. “Something that resembles one of their bodies.”

“How would we decide which features to include, and which to leave out? We don't even know the difference between their communications signals and their waste products. We'd probably come up with the equivalent of a glove puppet of a monkey that smelled exactly like human excrement.”

She had a point; even the six Colonists high above the din—and/or stench—of the colony were now bathed in a confusing fog of vendeks, and it was beyond the
Sarumpaet
's resources to untangle their functions and meaning.

Tchicaya felt a sudden stab of pessimism. He believed he'd finally reached the people he'd come to find—but he had days, at most, not only to describe the Planck worms to them, but to reach a level of communication and trust that would enable them to work together to deal with the threat. However many subtleties, abstractions, and courtesies he omitted along the way, even conveying the core of the message was beginning to seem hopelessly ambitious.

He said, “Maybe we should change the signal right now, instead of waiting for them to reply? Just to make it clear that the banner's not passive?”

Before Mariama could respond, the Colonists began regrouping around the banner. In unison, they released a stream of vendeks, denser than before; in the probe image, it looked as if the six veined bodies were blowing soap films. The individual sheets met at the edges and merged, forming a bubble, enclosing the banner.

The Colonists retreated again, then sprayed a new mixture at the bubble. It began to drift after them, down toward the surface.

Mariama said, “They've grabbed it! They're towing it!”

The wall of the bubble was passing sprites, but it resisted the
Sarumpaet
's probes—the only means they had to get instructions to the banner. They'd lost control of the device completely, now; they couldn't even reprogram its message, let alone command it to try to break out of its cage.

“We could make another one,” Tchicaya suggested. “Right in front of their eyes.”

“Why not see what they do with this one?”

“You think we should follow it?”

Mariama nodded. “They might release it from the container, once they've got it where they want it. They might even have their own signaling device down there.”

Tchicaya was not convinced. “If they think it's just a message in a bottle, they're not going to talk back to it. And if we can't regain control of it, the last place we want to try scribing a new one is in the middle of some chamber down there.”

“We'll only find out what they think it is if we go after it,” Mariama replied. “Besides, we initiated contact
with this object
. We should stick to that, follow through with it, or we risk confusing them.”

That did make sense. They had to be flexible, or they'd end up chasing their preconceptions down a
cul-de-sac
, but they also had to try to be consistent. Changing tack every time they feared that they might have been misinterpreted could bury any message beneath all the distracting shifts in strategy.

Tchicaya said, “All right, we'll follow it!” He instructed the
Sarumpaet
to pursue the purloined banner.

As they descended, it finally struck him just how extraordinary a sight they were witnessing. The banner was still flashing out its programmed sequence from within its container; the Colonists hadn't damaged it at all.
Towing
anything without destroying it, here, was a feat akin to putting a tornado on a leash. There were no simple analogs of the notions of pushing or pulling something, let alone any reason to expect it to respond by moving as a whole—like a nice near-side object made from atoms bonded together into a mildly elastic solid. You couldn't even rely on the local physics to
permit
something to behave, in uniform motion, as it had when it was stationary, however gently you conveyed it from one state to the other.

He turned to Mariama. “This is proof, isn't it? They have to be more than animals, to be able to move it like that.”

Mariama hesitated, no doubt pondering the evolutionary advantages of a delicate touch when kidnapping other species of xennobe to fill with your parasitic young.

But she said, “I think you're right. I've been giving them the benefit of the doubt until now, but I think they've finally earned it.”

The six Colonists touched down on the surface and proceeded along a narrow path that opened up in the throng ahead of them. The bubble appeared to be following a vendek trail laid by its creators, and the
Sarumpaet
stayed close enough behind it to avoid the crowd as it reclaimed the ground in the wake of the procession. Rather than rendering the flight deck in proportion to the ship's actual physical dimensions, the scape was constantly making choices of scale to keep the view of their surroundings intelligible, and the Colonists on either side of the ship appeared roughly as large as giraffes. Absurd as it was, Tchicaya found it difficult to suppress the feeling that they might look in through the hull and see him standing on the deck gazing back at them; he kept wanting to avert his eyes, so as not to risk frightening or provoking them.

Close up, the ship's probes revealed more of the Colonists' anatomy. Dwelling on the crude, wind-blown X of their overall shape was pointless; everything that mattered was in the vendek mixtures locked in the network of tubes. The toolkit struggled to annotate the images, hinting at the subtlety of the vendekobiology and the complexity of the network's topology. Tchicaya could only take in a fraction of what the toolkit was managing to glean, but the Colonists were manipulating their internal physics with as much precision as any animal controlling its biochemistry, juggling pH or glucose concentrations.

He caught Mariama's eye, and the two of them exchanged giddy, fearful smiles. Like Tchicaya, she was enraptured by the beauty and strangeness around them, but more painfully aware than ever of the vast gulf they'd have to bridge in order to protect it. The closer they came to the possibility of success, the more vertiginous the fall if they lost their grip. To be overrun by Planck worms in the honeycomb would have meant nothing but a bleak local death; here, they would be witnessing a whole world dying.

The procession entered a tunnel, angled steeply down into the colony's interior. As the density of sprites dropped, the scape experimented with the other ambient information-carrying vendeks. No single species could come close to matching the details of the probe images, but taken together they provided a fair description of the surroundings. From the Colonists' point of view, the Bright might well have been horribly misnamed; the conditions down here stood a far better chance of providing useful illumination, and the colony could have been perceived to lie in a somber landscape of permanent twilight.

Out of the full force of the wind, the geometry of both the Colonists and their architecture became more stable. The walls of the tunnel were formed from a basic layer population, but hundreds of other structures adorned them. Apart from the “air-conditioning” and “light sources,” Tchicaya couldn't guess what purpose most of the structures served. They looked too complex to be decorations, but mere endurance required sophistication here; the air-conditioning wasn't perfect, and anything incapable of responding to the weather risked being scoured away by the Bright.

The tunnel branched; the procession veered left. The air-conditioning was becoming more aggressive about removing impurities; the ship and the toolkit had to work harder than ever to keep the hull intact and the probes viable in the presence of all the new cleaning vendeks. Tchicaya had contemplated a number of unpleasant fates since the anachronauts had blown him out of the
Rindler
, but being scrubbed from the environment like an unwelcome speck of dust was one of the most insulting.

After a second fork, and a section that zigzagged and corkscrewed simultaneously, the tunnel opened out into a large cave. The physics here was more stable than anything they'd seen since the honeycomb; the weather had not been banished, but the turbulence had been subdued by an order of magnitude compared to the open Bright.

A stream of vendeks crossed the cave, rendered pitch black by the scape for most of its length, where the probes found it impenetrable. Near the center, the stream mingled with the surrounding free vendeks, expanding and becoming diluted before contracting back to its original width and continuing on its way. The probes could enter this region, which they portrayed as a sphere of gray fog; not all of them were coming back, though, and those that did reported that they'd almost lost control over their trajectories. Moving through the Bright had been difficult from the start, but some extreme, systematic distortion here was interfering with their attempts to navigate.

The toolkit collated all the evidence and reached its own conclusion. “There's curvature engineered into the graphs here. You can invade these vendeks where the current opens out, but in the process they reorient your time axis.”

It took Tchicaya a moment to digest this. Patterns in a quantum graph persisted by replicating themselves in future versions of the graph, but “the future” could only be defined by the orientation of the pattern itself. If you sliced the space-time foam one way to find a graph with vendek A in it, but needed to take a slice at a different angle to find vendek B, the two vendeks would see time as lying in different directions, and mere persistence, on their own terms, would put them in relative motion.

So “reorient your time axis” was toolkit-speak for “change your velocity.” The vendek current couldn't sweep anything along the way a river did, with pressure and momentum, but it could twist the local definition of being “stationary” progressively further away from its original orientation. In a sense it was like ordinary gravity, but on the near side the symmetries of the vacuum imposed a rigid austerity on the possibilities for space-time curvature. Here, the curvature had been tailored on the spot, woven directly into the graphs by the choice of vendeks.

“These people engineer space-time the way we do polymer design,” he marveled. “Choose the right monomers, get their shape and reactivity right, and you can create whatever properties you desire.”

Mariama smiled. “Except that they're more like microbes than monomers. Everything comes down to breeding and blending the right vendeks.”

“So what is this? A waste-disposal system?” If they wanted to toss the banner away, they could have done that from the surface with their towing bubble, but this accelerated sewer might send it further, faster.

The Colonists had paused at the entrance to the cave, but now they began to move along a shallow spiral, inching their way down toward the velocity gradient. They weren't discarding the banner in the black river. They were going with it.

Tchicaya groaned. “I know what this is! We saw the rest of it, from the outside. It's a transport system. We're on the entry ramp to a highway.”

Mariama agreed. “Maybe this whole place is just a tiny outpost, and the artifact is such a big deal that they're rushing it straight to the nearest expert.”

The conga line of Colonists was winding its way toward the axis of the cave, actively fighting the effect of the black vendeks in order not to get dashed against the wall where the current exited. The
Sarumpaet
was still obediently following the towing bubble; if they wanted to break away from the convoy, they'd have to do it in the next few seconds.

There was no way of knowing how long the journey would take. They'd seen this highway disappearing into the haze, into the depths Xof the far side. This outpost was where the danger would strike first, where the people needed to be told what was coming so they could fight it, or evacuate.

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