Incandescence

The tunnel snapped into focus, decorated with elaborate patterns where the fungus in all its variety grew. Despite the strangeness of the view, the new system felt right: Rakesh knew where he was now, how to move, and what to expect to see when he did. It was unsettling to be reminded that vision was a highly refined form of knowledge, a set of propositions about the world that needed to be deduced, not some passive stream of data that simply flowed into his skull as effortlessly as light into a camera.

They set out along the tunnel, which loomed over them like some monumental feat of engineering. It was only about two centimeters wide, but Rakesh had no way of knowing whether its builders would have viewed it as a cramped passageway, a great highway, or something in between.

They'd chosen not to use the avatars' vibration sensors as their primary mode of perception, but that didn't stop them picking up a faint but rising beat conducted through the tunnel wall. "Should we go and explore that?" Parantham asked.

Rakesh said, "It sounds as if it's coming toward us already."

A giant creature came scurrying around a bend in the tunnel. It was moving on twelve legs like a busy arthropod, about a millimeter across. Their mode of vision rendered it translucent, revealing hints of membranes and chambers flexing and contracting within.

When it changed course to charge straight toward them Rakesh suppressed the urge to flee; their avatars were extremely robust, and in any case easily replaced. The creature halted and inclined the axis of its body toward him; it seemed presumptuous to assume that it was lowering its face, when Rakesh could make no immediate sense of the complex mass of bristles, knobs and tendrils that confronted him. A cluster of these organs suddenly sprang forward and made contact with his avatar, wrapping it and holding it firmly; he steeled himself for the shock of being vicariously swallowed, but after a moment the creature unwrapped him and disengaged. It stood motionless for a second or two, as if pondering the need for another taste, then it turned away and continued down the tunnel, as rapidly as it had approached.

Parantham said, "We should follow it."

"Yes."

The avatars had small fusion-powered ion thrusters attached like backpacks; with no gravity or air resistance to overcome, catching up with the creature and flying a few centimeters above it was easy. Having dismissed them as inedible once, the creature seemed untroubled by their presence, if it was aware of them at all.

The creature had shed cells on Rakesh's avatar, and he had the nanomachines sequence them as he flew. They shared the fungus's vacuum-hardening traits, and a large proportion of its other genes, both natural and introduced.

Parantham said, "I'd like to run a morphogenetic model. What do you think?"

"Coarse-grain it, and I think that would be ethical." Software could take the genome and use it to simulate a growing embryo. A fine-grained simulation would necessarily experience everything that a real organism would, but a coarse-grained simulation could provide information about the range of generic experiences that were possible, without anyone actually experiencing them.

"All right."

In a spare corner of Parantham's mind, a sketch of the virtual creature took shape. While Rakesh watched the adult below him scurrying along, pausing now and then to graze on patches of fungus, a second viewpoint showed him an annotated diagram of the developing embryo in its egg case. As morphogen gradients washed over the dividing cells, eight distinct segments formed, the middle six slowly sprouting a tightly folded pair of legs each. Mouthparts, excretory and reproductive organs were whittled out of the growing mass of cells. The developing nervous system was extremely simple, and by the time the egg hatched it was close to hardwired: a handful of innate drives and reflexes would enable this creature to move, feed and mate, but it had no potential to do anything more complex.

Like all DNA-based life it was Rakesh's distant cousin, but it was unlikely to be a direct descendant of whoever had built this ark.

"It doesn't use infrared at all," Parantham observed. "It listens for sounds conducted through the tunnel wall."

"So how did it home in on me when I was standing stock still?" Rakesh examined the model's results more closely. "Aha. Resonances set up by its own footsteps. A kind of sonar, after all." It was impossible to say exactly how this creature's natural ancestors had lived, but the engineered traits it possessed were extensive and ingenious. The Arkmakers might not have had the technology to locate, let alone reach, another planet like their own, but they had worked hard to adapt life to their new environment.

"So where are its designers?" he asked Parantham.

"Be patient," she replied. "We've barely scratched the surface."