could see this entire volume all at once almost made sense when he thought of it as the bottom hyperface of the transparent window, but when he realized that every point was shared by the front hyperface of the opaque floor, any lingering delusions of normality evaporated.
With Poincare, delusions of normality were untenable from the start; even its outline confounded his old world notions of curvature and proportion. Orlando could see at a glance that the star's four-dimensional disk filled only about one third of the tesseract he imagined framing it—far less than a circle inscribed within a square—and this made some ill-adapted part of him expect it to sag inward as it arced between the eight points of contact with the tesseract. It didn't, of course. And since the polis had come close enough for the star's continents to he resolved, he'd been bedazzled. The borders of these giant floating slabs of crystallized minerals were intricate beyond the possibilities of three-dimensional nature; no wind-carved landscape, no coral reef could have been as richly convoluted as this silhouette of dark rock against glowing magma.
'Orlando?'
He moved slowly, consciously, thinking it through, following his body's suggestions but refusing to act on autopilot. Paolo was to his rear-left-dexter-gauche, and he turned first in the horizontal plane, then the hyperal. Orlando was blind to signatures, but his visual cortex had been rewired to grant five-dimensional facial cues the same significance as the old kind, and he recognized the approaching four-legged creature immediately as his son.
Bipeds in the macrosphere would have been even less stable than pogo sticks on Earth; with sufficient resources devoted to dynamic balancing, anything was possible, but no one in C-Z had opted for such an unlikely 5-body. Quadrupeds on a four-dimensional hypersurface had just one degree of instability; if the left and right pairs of feet defined orthogonal lines in the hyperal Plane, it created a kind of cross-bracing, leaving only the problem of swaying forward or backward—no more than bipeds faced on two-dimensional ground. Six-legged macrosphereans would be as stable as Earth's quadrupeds, but there was some doubt as to whether they could mutate into an upright species with two arms; eight limbs seemed to allow an easier transition. Orlando was more interested in the choices available to the Transmuters than the dynamics of natural selection, but like Paolo he'd opted for four arms and four legs. No centaur-like extensions to their trunks had been required; the hyperal space around their hips and shoulders provided more than enough room for the extra joints.
Paolo said, 'Elena's been looking at absorption spectra around the coastal regions. There's definitely some kind of local, catalyzed chemistry going on there.'
''Catalyzed chemistry'? Why isn't anyone willing to say the word 'life'?'
'We're on uncertain ground. In the home universe, we could say confidently which gases could only be present if they were biogenic. Here, we know which elements are reactive, but we're just guessing when it comes to whether or not they could he replenished by some inorganic process. There is no simple chemical signature that screams 'life.''
Orlando turned back to the view of Poincare. 'Let alone one that screams 'Transmuters, not natives.''
'Who needs a chemical signature for that? You just ask them. Or do you think they'll have forgotten who they are?'
'Very funny.' He felt a chill, though. As acclimatized as he was—able to stand four-legged in the middle of a penteract without collapsing into gibbering insanity—he couldn't imagine forgetting his own past, his own body, his own universe. But the Transmuters had been here a billion times longer.
Paolo said, 'My Swift-self says they've started inscribing a copy of the polis on the surface of Kafka.' There was resigned disgust in his voice; if the core burst turned out to be a misunderstanding, the digging of these giant trenches would go down in history as the crassest act of defilement since the age of barbarism. 'Models of the reconstruction robots still look dodgy, though. It's a pity the Transmuters didn't mention anything about the neutrino spectrum; a total energy dose for all particles at all frequencies is almost useless for predicting damage, and our own estimates are wildly uncertain, since we have no idea how or why the core's supposed to collapse.' He laughed dryly. 'Maybe they didn't expect anyone to try riding it out. Maybe they knew it would be unsurvivable. That's why they left us the keys to the macrosphere, instead of hints for building neutrino-proof machines: once it was too late to flee the galaxy, they knew this would be the only escape route.'
Orlando knew he was being goaded, but he replied calmly, 'Even if the core burst's unsurvivable, this doesn't have to be the end of the line. The vacuum here is made of four-dimensional universes. Even if it's impossible to break into them, there must be other singularities, other links already created from within. In all those universes, there must be other species as advanced as the Transmuters.'
'There might. They must be rare, though, or the place would be swarming with them.'
Orlando shrugged. 'Then if the whole Coalition has to make a one-way trip into the macrosphere, so be it.'
He spoke with defiant equanimity, but the prospect was almost unbearable. He'd always told himself that there'd be a way through: that he'd die in the flesh, with a flesher child to bury him, on a world where he could promise a thousand generations that no fire and no poison would rain from the sky. If the macrosphere was the only true sanctuary, his choice of futures came down to faking the entire fantasy in a 3-scape, or embodying himself in the alien chemistry of this universe and trying to raise a child on a world more surreal than anything in Ashton-Laval.
Paolo managed to display contrition on his altered face, visible to Orlando's altered eyes. 'Forget about one-way trips. If we can talk to the Transmuters at all, they're more likely to tell us that we misread everything. There was no warning, there'll be no core burst. We simply got it wrong.'
Probes were sent ahead to Poincare on fast, single-pass trajectories. Orlando watched the images accumulate, the curved stripes of instrument footprints barely scratching the star's hypersurface with medium- resolution topographic and chemical maps. Glimpses of the folded mountain ranges and igneous plains of the continents' interiors appeared strikingly organic to his old-world sensibilities; there were wind-blasted plateaus whorled like fingerprints, channels carved by lava flows more elaborate than capillary systems, plumes of frozen magma extruding spikes like riotous fungal growths. Poincare's sky was permanently dark, but the landscape itself was radiant with heat flowing up from the core, glowing at wavelengths analogous to near-infrared: on the border between the energy levels for lepton transitions and molecular vibrations. There were traces of rings and branched chains based on atom 27 in the absorption spectra of the atmosphere above much of the interior, but the most complex chemical signatures were found near the shores.
There were also tall structures clustered around the coastal regions that did not appear to be plausible products of mere erosion or tectonics, crystallization or volcanism. These towers were ideally placed to extract energy from the temperature difference between the magma oceans and the relatively cool interiors, though whether they were Poincare's equivalent of giant trees or some form of artifact was unclear.
A second wave of probes was placed in powered orbits, pushing themselves in against the outer rim of their angular momentum ridges so that engine failure would see them flung away into deep space, not crashing to the ground. Comparisons of scale with the home universe were slippery, but if the 5-bodies they'd chosen were used as measuring rods, Poincare's hypersurface could hold ten billion times as many denizens as the Earth—or conceal a few thousand industrial civilizations in the cracks between its putative forests and vast deserts. Mapping the entire star at a resolution guaranteed to reveal or rule out even a Shanghai-sized pre-Introdus city was a task akin to mapping every terrestrial planet in the Milky Way. The circular band of images collected by one probe as it completed one orbit of the hypersphere amounted to less than a pinprick, and even when the orbit was swept 360 degrees around the star, the sphere it traced out was about as significant, proportionately, as one shot of one location on an ordinary globe. As Carter-Zimmerman itself moved into a distant powered orbit, Orlando began to find the view from the Flight Deck overwhelming: too detailed and complex to take in, too distracting not to try. Every glance was like a blast of dense atonal music; the only choice was to shut it out, or to listen attentively and still tail to make sense of it. He considered further modifications to his mind; no native, no acclimatized macrospherean would respond to the sight of their world as if it were a drug-induced hallucination, less a vision than a mass-stimulation of networks signaling perceptual breakdown.
He had his exoself enhance his visual cortex further, wiring in a collection of symbols responding to various four-dimensional shapes and three-dimensional borders—all plausible primitive forms, likely to be no more exotic to macrosphereans than a mountain or a boulder was to a flesher. And the view of Poincare was tamed, parsed into this new vocabulary, though it remained a thousand times denser than any satellite view of the Earth or
