no doubt. Someone had transmuted these elements. Someone had deliberately weighed down this planet's atmosphere, in order to prolong its life.
13
SWIFT
Carter-Zimmerman polis, Swift orbit
85 801 536 954 849 CST
16 March 4953, 15:29:12.003 UT
Yatima rode the probe beside Orlando's, seeing both as sleek, finned cars about three delta long, hovering above Swift's flat red desert. The real probes were spheres half a millimeter wide, powered by the light of Voltaire, largely borne up by the wind but occasionally generating lift by spinning, moving forward by pumping atmospheric gases through a network of channels coated with molecular cilia. Even with elaborate piloting software, turning the car's steering wheel didn't always have the desired effect.
'Oasis.'
Orlando looked around. 'Where?'
'On your left.' Yatima hadn't turned yet, not wanting to sideswipe Orlando. It was unlikely that the probes themselves would touch, and it would hardly matter it they did, but one of the first things ve'd done after arriving from Konishi was hardwire a strong aversion to collisions into vis navigators. People in Carter-Zimmerman did not take kindly to other people trying to occupy the same portion of a scape.
Orlando swung his car around, and they headed for the oasis. It was a puddle of water a few meters wide —tens of kilodelta, at their current scale—trapped beneath a polymer membrane. Surface tension gently stretched the membrane into a convex mirror, reflecting an expanse of pale crimson sky that seemed to hover a few centimeters below the ground. Pure water boiled at around 60 degrees in Swift's thin atmosphere, so rain could only fall on the night side, but when enough run-off gathered on a patch of spores, the whole dessicated micro- ecology came back to life, and fought to hold on to the water for as long as possible. The membrane limited evaporation, and a mixture of other chemicals raised the boiling point by up to ten degrees, but by mid-afternoon of a 507-hour day only a fraction of the oases formed overnight remained. Still, Swift life could cope with being boiled dry at least as comfortably as most primitive Earth life could cope with being frozen.
Close up, they could see through the partially reflective surface into the dazzling world below. Broad helical carnivorous weeds shone in gold and turquoise; one swarm of mites avoiding their poisoned fronds were a deep, rich red, another were (pre-Lacerta Earth) sky blue. All Swift life made heavy use of sulfur chemistry; carbon dominated, but some primordial accident seemed to have pushed sulfur into sharing the structural role, and the intensity of the colors was one side effect.
'Maybe all of this was engineered from scratch,' Yatima mused. 'For decorative purposes. Maybe Swift was sterile and airless, and someone came along and built this ecosystem, molecule by molecule. Using heavy isotopes to make it last a little longer. Like sculpting in gold, to avoid corrosion.'
'No. Wherever the Transmuters are now, this must have been their native biosphere.' Orlando seemed grimly convinced, as if the alternative was too decadent and frivolous to contemplate. 'They would have substituted the isotopes slowly, feeding them into the existing atmosphere over millennia. It was a mark of respect that they didn't wrap their home in a protective sphere, or shift its orbit, or modify its sun. They slipped in a change at the lowest possible level, underneath the biochemistry.'
Yatima guided vis car over the puddle. Vivid green eels several millimeters long undulated by, much faster than the probe. A red-and-yellow twelve-legged spider walked upside-down on the membrane, picking out the flatslugs that lived embedded in it. Yatima didn't have much sympathy for the prey; they blithely fed on the protective polymers that almost every other species took the trouble to synthesize and excrete. Then again, it was a niche begging to be filled, and none of these creatures did anything with a conscious purpose.
'If they cared so much about their biological cousins, they can't have been expecting Lacerta. There's no sign of any built-in protection against a gamma ray burst.'
Orlando was unswayed. 'Maybe the only thing they could have done that would have made a difference were anathema to them. And they must have known that even if there were massive extinctions, they'd given the biosphere enough general resilience to recover.'
They'd found few fossils on Swift, so it was difficult to judge the extent to which life had been disrupted by the burst. Models showed that most of the existing species would have coped relatively well, but that was hardly surprising; they were the ones that had survived, not a representative sample of pre-Lacerta life. The heritable material here cycled between five different molecular coding schemes in successive generations; some species used a 'pure' scheme, all Alpha leading to all Beta, Gamma, Delta, and Epsilon, while others had mixtures o all five in every generation. Some biologists claimed to have identified a genetic bottleneck due to Lacerta, but Yatima wasn't convinced that anyone understood Swift's biochemistry well enough yet to say what a normal level of diversity would have been.
'So where are they now? Have they been swallowed by an Introdus, or scattered by a Diaspora? If you can read their minds about everything else, that ought to be an easy question to answer.'
Orlando replied with sublime confidence, 'Would I be here, if I thought I was wasting my time?' His tone was ironic, but Yatima didn't believe he was entirely joking.
They'd scoured the planet from orbit, looking for cities, for ruins, for mass anomalies, for buried structures. But a civilization as advanced as the Transmuters could have miniaturized their polises beyond any chance of detection. One faint hope was that since they'd bothered to intervene in the fate of Swift's organic life, they might show themselves at the oases now and then. Yatima wasn't optimistic. If they were still on the planet they could hardly be unaware of their visitors, but they hadn't chosen to make contact. And if they didn't want to be seen, they were unlikely to send big, clumsy, millimeter-wide drones plowing through these puddles. Yatima watched a rare translucent creature swim by beneath the probe, propelled by a jet of water it created by contracting its whole hollow body. Ve'd thought ve'd be prepared to study a world like this, patiently helping the biologists extract the kind of insights into evolutionary principles offered by even the most modest extraterrestrial biosphere. There were no spectacular new body plans or life cycles here, no strategies for feeding or reproduction that hadn't been tried out back on Earth, but at a molecular level everything worked differently, and there was a vast labyrinth of utterly novel biochemical pathways to be mapped. Yet the Transmuters made it almost impossible to care. Their absence—or their perfect camouflage—monopolized everyone's attention, transforming the intricate machinery of the biosphere into a very long footnote to a far more mesmerizing blank page.
Ve turned to Orlando. 'I don't think they're in hiding. How shy could they be, after giving the atmosphere a spectrum that screams, 'Civilization! Come and visit!' We only noticed it close up, but it wouldn't take a huge technological advance to spot it from thousands of light years away.
Orlando didn't reply; he'd been staring down into the puddle, and he continued to watch a swarm of crimson larvae molting, and eating each other's discarded skins. Yatima understood the stake he had in making contact with the Transmuters. By the end of the Diaspora, when his scattered clones had reconverged, the Earth would be habitable again—but he could never feel secure about returning to the flesh until Lacerta had been explained. Any Coalition theory was likely to remain as suspect as the original belief that Lac G-1's neutron stars would take seven million years to collide. But if the Transmuters had firsthand knowledge of the galaxy's dynamics on a timescale of millions of years—and were beneficent enough to transform this planet's atmosphere, atom by atom, just to save their distant relatives from extinction—surely they wouldn't begrudge an infant civilization a little information and advice on its own long-term survival.
'Okay.' Orlando looked up. 'Maybe the spectrum was meant to stand out like a beacon. Maybe that's the whole point. They could have preserved the atmosphere in a thousand other ways, but they chose a method that would get them noticed.'
