Diaspora

Yatima said, “Blanca should he with us. Orlando should be with us.”

Paolo laughed. “Orlando would be miserable here.”

“Why? Traveling in any kind of scape he liked, with all the comforts of home…”

“You don’t know Orlando as well as you think.”

“No? Enlighten me.”

15. 5+1

Carter-Zimmerman polis. Swift orbit

85 803 052 808 071 CST

3 April 4953, 4:33:25.225 UT

A megatau before the cloning, Paolo finally managed to drag Orlando along to the Great Macrosphere Exhibition. A group of physicists had set up the scape, a long hall with an arched roof of leaded glass ribbed with wrought iron, packed with demonstrations of those features of the macrosphere that could be predicted with reasonable confidence. Although Orlando was determined to be part of the expedition, he seemed daunted by the prospect of confronting the exotic reality that the new C-Z clone would inhabit.

Paolo surveyed the hall. Less than a hundred citizens had decided to be cloned, but half the polis had been through the Exhibition. It was almost deserted now, though, and the angle of the light, cued to the number of visitors, gave an impression of late afternoon.

They approached the first exhibit, a comparison of gravity wells in three and five dimensions. The gridded surfaces of two circular tables had been made magically elastic in such a way that placing small spherical weights on them produced funnel-shaped indentations, with the effects of the gradient in each case mimicking the gravitational force around a star or planet in the different universes. The force diminished with distance as if it was being spread out over, respectively, an ever larger two-dimensional surface, producing an inverse-square law, or a four-dimensional hypersurface, yielding a visibly steeper inverse-fourth-power effect. It was a simplified pseudo-Newtonian model, but Paolo wasn’t about to scoff; he’d found Blanca’s rigorous six-dimensional space-time curvature treatment heavy going, and he’d skimmed over the hard parts where the Einstein tensor equation was derived by approximating the interactions between massive particles and virtual gravitons.

The exhibit said, “These diagrams show the pure gravitational potential, which always produces an attractive force.” A disembodied hand appeared and placed a small test particle at the edge of each well, with predictable consequences: both particles fell straight in. “Starting from rest, a collision is unavoidable. But if there’s any sideways motion, that alters the dynamics completely.” The hand placed a particle on the rim of the first well, but this time gave it a flick that sent it into an elliptical orbit around the central weight.

“The best way to see what’s really going on is to follow the body along its orbit.” The surface’s grid pattern began to spin, tracking the particle, and as it did the shape of the well changed dramatically: the center of the funnel inverted into a tall, steep spike, raising the weight above the surrounding surface. “In a rotating reference frame, the centrifugal force for a given amount of angular momentum acts like an inverse-cube repulsion.” Inverse-cube conquered inverse-square for small distances, so centrifugal force won out over gravity near the center; the star or planet from the bottom of the well was now high on a summit. The outer region of the funnel continued to slope down, though, so there was a circular trench around the spike where this initial fall in the surface reversed into a climb.

The patches of floor on which they were standing began to circle the table, tilting as necessary to keep them from overbalancing. Orlando groaned at the gimmick, but seemed amused in spite of himself. They caught up with the rotating reference frame, leaving the particle apparently moving only along a fixed, radial line. It rolled back and forth in the trench, cradled and confined by this hollow in the energy surface, the extremes of its elliptical orbit now revealed as nothing more than the farthest points it could reach as it tried to climb either the central spike or the gentler slope of the outer wall.

When the ride stopped, the exhibit offered them three chances to flick a particle into orbit around the second gravity well. Orlando accepted. The first two particles he launched spiraled down to a collision, and the third went skidding off the rim of the table. He muttered something about wishing he was deaf, dumb, and blind.

The exhibit transformed the surface to show the effect of centrifugal force. The inverse-fourth-power attraction of gravity was stronger than inverse-cube repulsion near the center, so even when the reference frame began to spin, the well remained a well. But further away, centrifugal force took over and turned the downward slope of the approach into an ascent. And where the ascent reversed and the surface plunged, in place of the first well’s circular trench there was a circular ridge. Compared to the three-dimensional universe, the entire potential energy surface was upside-down.

The exhibit spun them around with the reference frame. Then, its disembodied hand moving with them, it placed a particle on the outer slope of the ridge; unsurprisingly, it fell directly away from the center. A second particle, placed on the inner slope, fell straight into the well.

“No stable orbits.” Orlando picked up the particle that was rolling away and tried to balance it precisely on the ridge, but he couldn’t position it accurately enough. Paolo saw a flash of fear in his eyes, but he said wryly, “At least that means no Lacertas. Everything that’s going to fall together would have done it long ago.”

They walked on to the next exhibit, a model of the macrosphere’s cosmological evolution. As matter clumped together under mutual gravitational attraction from the initial quantum fluctuations of the early macrosphere, rotational motion either cut in at some point and blew the condensing gas cloud apart, or the process “crossed over the ridge” and the collapse continued unchecked. Star systems, galaxies, clusters and superclusters, all stabilized by orbital motion, were impossible here. But the fractal distribution of the primordial inhomogeneities meant that the end products of the collapse process had a wide spectrum of masses. Ninety percent of matter ended up in giant black holes, but countless smaller bodies were predicted to form, sufficiently isolated to survive for long periods, including hundreds of trillions with a stability and energy output comparable to stars.

Orlando turned to Paolo. “Stars without planets. So where will the Transmuters be?”

“Orbiting a star, maybe. They could stabilize an orbit with light sails.”

“Built out of what? There’ll be no asteroids to mine. Maybe they created a lot of raw materials with the singularity when they first crossed through, but for anything new they’d have to mine the star itself.”

“That’s not impossible. Or they could live on the surface, if they chose. That’s where any native life is expected to be found.”

Orlando glanced back at the model, which included something like a Hertzsprung-Russell diagram, plotting the evolving distribution of stellar temperatures and luminosities. “I wouldn’t have thought many stars would he cool enough. Except for brown dwarves, and they’d freeze completely in no time at all.”

“You can’t really compare temperatures. We’re used to nuclear reactions being orders of magnitude hotter than chemical ones, making them inimical to biology. But in the macrosphere they both involve similar amounts of energy.”

“Why?” Orlando’s gestalt still betrayed a sense of unease, but he was clearly hooked now. Paolo gestured at an exhibit further along, beneath a rotating banner reading PARTICLE PHYSICS.

The macrosphere’s four-dimensional standard fiber yielded a much smaller set of fundamental particles than the ordinary universe’s six-dimensional one. In place of six flavors of quarks and six flavors of leptons there was just one of each, plus their antiparticles. There were gluons, gravitons, and photons, but no W or Z bosons, since they mediated the process of quarks changing flavor. Three quarks or three antiquarks together formed a charged “nucleon” or “antinucleon,” similar to an ordinary proton or antiproton, and the sole lepton and its antiparticle were much like an electron and positron, but there was no combination of quarks analogous to a neutron.

Orlando scrutinized the table of particles. “The lepton is still much lighter than the nucleon, the photon still has zero rest mass, and the gluons still act like gluons… so what shifts the chemical energy closer to the nuclear?”

“You saw what happened with the gravity wells.”

“What’s that got to do with it? Ah. Same thing happens in an atom? Electrostatic attraction also goes from inverse-square to inverse-fourth, so there are no stable orbits?”

“That’s right.”

“Hang on.” Orlando screwed his eyes shut, no doubt dredging ancient memories of his flesher education. “Doesn’t the uncertainty principle keep electrons from crashing into the nucleus? Even if there’s no angular momentum, the attraction of the nucleus can’t squeeze the electron’s wave too tightly, because confining its position just increases its momentum.”

“Yes. But increases it how much? Confining a wave spatially has an inverse effect on the spread of its momentum. Kinetic energy is proportional to the square of momentum, making that inverse-square. So the effective 'force,’ which is the rate of change of kinetic energy with distance, is inverse-cube.”

Orlando’s face lit up for a moment with the sheer pleasure of understanding. “So in three dimensions, a proton can’t ever make an electron crash, because the uncertainty principle is just as good as centrifugal force. But in five dimensions, that’s not good enough.” He nodded slowly, as if coming to terms with the inevitability of it. “So the lepton’s wave shrinks down to the size of the nucleon. Then what?”

“Once the lepton’s inside the nucleon, it’s kink—pulled inward by the portion of the charge that’s closer to the center than it is itself, which is roughly proportional to the fifth power of the distance from the center. That means the electrostatic force stops being inverse-fourth-power, and becomes linear. So the energy well isn’t bottomless; outside the nucleon it’s too steep for the lepton to 'brace itself’ against the sides, the way an electron does in three dimensions, but inside the nucleon the sides curve together and meet in a paraboloid.”

They moved on to the first chemistry exhibit, which showed the paraboloid bowl at the bottom of the well, with a translucent electric-blue bell-shape superimposed over it: the lepton wave in its lowest-energy, ground state. Orlando reached in and touched it; it flickered into an excited state, breaking apart and deserting the center to form two distinct lobes, one of them color-coded red to indicate an inverted phase. After a few tau the whole wave flashed green, spontaneously emitting a photon, and fell back to its lowest energy level.

“So this is the macrosphere’s equivalent of a hydrogen atom?”

Paolo prodded the wave himself, trying to get it to the next highest level. “More like a cross between a hydrogen atom and a neutron. There are no neutrons in the macrosphere, but a positive nucleon with a negative lepton buried in it to cancel its charge makes a rough imitation of one. Blanca called it a 'hydron.’ If you try to join two of them together to make a 'hydron molecule’ you end up with something more like deuterium.” The exhibit, overhearing him, obligingly provided an animated demonstration.

Orlando exhaled heavily. “I don’t know how you can take this so calmly. Do you really trust anyone in C-Z to build an entire working polis according to these rules?”

“Maybe not, but if they get it wrong we won’t even know about it. I can’t see us shipwrecked in the macrosphere with the hardware disintegrating slowly beneath us. It’ll be all or nothing: a working polis, or a cloud of random molecules.”

“You hope. How are they even going to make molecules, if every chemical bond triggers nuclear fusion?”

“Not every bond does. If you throw enough hydrous together, the leptons fill up all the energy levels where they’re confined tightly within the nucleus, so the outermost ones end up protruding sufficiently to be able to bind two atoms together with a respectable separation between the nuclei. You have to fill up the first two levels completely, which takes twelve leptons—so every stable molecule needs to contain a few judiciously placed atoms of number 13 or higher. Atom 27 can form fifteen covalent bonds; it’s the closest thing in the macrosphere to carbon.” The exhibit showed them a three-dimensional shadow of a five-dimensional, sixteen-atom molecule: one atom of 27, joined to fifteen hydrons. Paolo said, “Think of this as a souped-up version of methane. If you knock off any of these hydrons and substitute a side branch, you can build all kinds of elaborate structures.”

Orlando was beginning to look besieged. As he glanced down the hall toward distant speculation on biochemistry and body plans, something caught his eve. “'U-star polymers.’ What does 'U-star’ mean?”

Paolo followed his gaze. “That’s just another crane for the macrosphere. U is the ordinary universe, and the star is mathematical notation for its ’dual space'-that’s a term used for all kinds of role-reversals. The universe and the macrosphere are both ten-dimensional… but one has six small dimensions and four large, the other has six large and four small. So they’re inside-out versions of each other.” He shrugged. “Maybe it’s a better name. 'Macrosphere’ captures the difference in size, but that hardly matters; once we’re there, we’ll be operating on roughly the same scale as any comparable lifeform. It’s the fact that the physics has been turned inside-out that will make all the difference.”

Orlando was smiling faintly. Paolo asked, “What?”

“Inside-out. It’s nice to know that’s the official verdict. It’s how I’ve felt about it all along.” He turned to Paolo, his expression suddenly, painfully naked. “I know I’m not flesh and blood. I know I’m software like every one else. But I still half believe that if anything happened to the polis, I’d be able to walk out of the wreckage into the real world. Because I’ve kept faith with it. Because I still live by its rules.” He glanced down and examined an upturned palm. “In the macrosphere, that will all he gone. Outside will he a world beyond understanding. And inside, I’ll just be one more solipsist, cocooned in delusions.” He looked up and said plainly, “I’m afraid.” He searched Paolo’s face defiantly, as if daring him to claim that a journey through the macrosphere would be no different from a walk through an exotic scape. “But I can’t stay behind. I have to be a part of this.”

Paolo nodded. “Okay.” After a moment he added, “But you’re wrong about one thing.”

“What?”

“A world beyond understanding?” He grimaced. “Where do you get that shit! Nothing is beyond understanding. A hundred more exhibits, and I promise you: you’ll be dreaming in five dimensions.”

16. DUALITY

Carter-Zimmerman polis, U*

Orlando stood outside the cabin and watched the last visible trace of his universe recede into the distance. The dome of sky above the Floating Island offered a pinhole view of the macrosphere, revealing only two faint stars; the station they’d built beside the singularity appeared just above the western horizon as a tiny, flashing white light, fading rapidly. The singularity itself was invisible at this distance, but the station’s beacon echoed the regular stream of photons emanating from it to mark its position.

If the team on Swift ever stopped creating those photons, the singularity would vanish from sight. A massless anomaly in the vacuum, small as a subatomic particle, it would he almost impossible to find. But then, if no one was sending, no one would be listening either, so there’d be no point scouring the vacuum for the home universe; any data blasted back at the singularity would trigger beta decays in Swift’s neutrons to no avail. Some people had expected the singularity to be surrounded by Transmuter artifacts, but Orlando hadn’t been surprised to find the region abandoned, given the absence of machinery on the other side of the link.

The beacon seemed to dim with unnatural speed, as if the polis was accelerating away wildly. Yet another manifestation of the inverse-fourth law: anything that spread out in all directions thinned more rapidly here. Orlando watched the reassuring pulse of light fade from view, then managed to laugh at his visceral sense of abandonment. It was possible to be stranded anywhere. On Earth, he’d once almost died of exposure less than twenty kilometers from home. Scale meant nothing. Distance meant nothing. They’d either make it back, or they wouldn’t and nothing this world could do to them could begin to compare to a slow death from cold and dehydration.

He addressed the scape. “Sweep the sky.” At any one moment, the ordinary view from the Island—a mere two-dimensional dome—could only encompass a narrow portion of the macrosphere’s four-dimensional sky. But the hemisphere could he swept across the sky, scanning it like a Flatlander scanning ordinary space by rotating the plane of vis slit-like view. Orlando watched the sparse stars come and go, far fewer than he’d have seen from Atlanta beneath a full moon. Still, it was remarkable that he could make out so many, when they were scattered so widely and their light was spread so thin.

A brilliant rust-red point of light appeared in the east, then faded rapidly as the view swept over it: Poincare, the nearest star to the singularity, their first target for exploration. It would take forty megatau to reach Poincare, but no one was tempted to freeze themselves for the journey; there was too much to think about, too much to do. Orlando braced himself. “Now show me U-star.” His exoself responded to the command, spinning his balls into hyperspheres, rebuilding his retinas as four-dimensional arrays, rewiring his visual cortex, boosting his neural model of the space around him to encompass five dimensions. As the world inside his head expanded, he cried out and closed his eyes, panic-stricken and vertiginous. He’d done this in sixteen dimensions to view the Orphean squid, but that had been a game, a dizzying novelty, like riding a comet or swimming with blood cells, adrenaline-pumping but inconsequential. The macrosphere was no game; it was more real than the Floating Island, more real than his simulated flesh, more real, here and now, than the ruins of Atlanta buried in a distant speck of vacuum. It was the space through which the polis sped, the arena in which everything he thought and felt was truly happening.

He opened his eyes.

He could see many more stars at once now, but they seemed more sparsely distributed; there was so much more emptiness to fill. Almost without thinking, he began joining up the dots, sketching simple constellations in his head. There were no striking figures here, no Scorpios or Orions, but a single line between two stars was a thing to be marveled at. His vision now stretched beyond its ordinary field in two orthogonal directions; Paolo’s friend Karpal had suggested calling them quadral and quintal, but with no obvious basis for distinguishing between them Orlando seized on the collective term: the hyperal plane.

Networks in his new visual cortex and spatial map attached a raw perceptual distinction to the hyperal directions, but it still required a conscious effort to make cognitive sense of them. They were definitely not vertical; that realization carried the most immediate force. The direction of gravity, of his body’s major axis, had nothing to do with them; if he was like a Flatlander seeing the world beyond his plane, that plane had always been vertical, and his slit-vision had now spread sideways. But the new directions weren’t lateral, either; unlike a vertical Flatlander, his “sideways” was already occupied. When he consciously divided his visual field into left and right halves, all the purely hyperal pairs of stars lay solely in one half or the other, just like all the purely vertical pairs. And whatever common sense dictated as the only remaining possibility, there was no sense of the sky having gained depth, of the stars looming toward him like a holographic image leaping out of a screen.

Orlando held these three negations in his mind at once. The hyperal plane was clearly defined by his anatomy, so long as he remembered that it was perpendicular to all three of his body’s axes.

One vaguely cruciform constellation lay almost flat in the hyperal plane: every one of the four stars shared roughly the same altitude above the horizon, and the same left-right azimuthal bearing, and yet they were not bunched together in the sky; the hyperal directions kept them as far apart as the stars of the Southern Cross. Orlando struggled to attach labels to them: sinister and dexter for the quadral pair, gauche and droit for the quintal. It was completely arbitrary, though, like assigning compass points to a fictitious map drawn on a circular piece of paper.

Several degrees away to the left-up-dexter-gauche he could see another four stars; these lay in the lateral plane, the plane of the “ordinary” sky. Mentally extending the two planes and visualizing their intersection was a very peculiar experience. They met in a single point. Planes were supposed to intersect along lines, but these ones refused to oblige. A quadral line running between the sinister and dexter stars of the Hyperal Cross pierced the vertical plane at right angles to both arms of the Vertical Cross… but so did the quintal line. There were four lines in the sky—or in his head—that were all mutually perpendicular.

And the sky still looked flat.

Nervously, Orlando let his gaze drop. Stars were visible below the horizon—not through the ground, but around it, as if he was standing on a narrow, jutting cliff, or a sharp pillar. He’d chosen to have no power to twist his head or body out of the usual three dimensions of the scape, though his eyes bulged literally out of his skull, hyperally, to capture a broad swath of extra information. He pictured a vertical Flatlander with two eye-circles, one above the other, suddenly made spherical, their axes still confined to swivel within the planar world but their lenses, their pupils, their field of view, protruding beyond it. As well as being a ludicrous anatomical impossibility, this compromise was now beginning to induce a giddy mixture of vertigo and claustrophobia. The Island had negligible width in the extra dimensions, and he could see clearly that the slightest hyperal movement of his body would send him plummeting into space like a drunken cosmic stylite. At the same time, the physical confinement that prevented this made him feel like he was wedged between two sheets of glass, or afflicted by some bizarre neurological disease that robbed him of the ability to move in certain directions.

“Restore me.”

His visual field collapsed to a relative pinhole, and for a moment he felt so infuriatingly diminished that he shook his head wildly, trying to cast off the blinkers. Then abruptly his vision seemed gloriously normal, and the macrosphere’s wide sky was like a fading memory of a disorienting optical illusion.

He wiped the sweat from his eyes. It was a start. A small taste of reality. Maybe he’d work up the courage eventually to wander a fully five-dimensional scape wearing a five-dimensional anatomy. Apart from the alarming possibility of glancing down and catching a glimpse of his own internal organs—like a Flatlander who twisted vis head out of the plane—unless he added two dimensions to his simulated flesh—he’d have the balancing skills of a paper doll, once he was free to fall quadrally and quintally.

But even gaining the anatomy and instincts to navigate five dimensions would only be scratching the surface. There’d always be more to adapt. In the flesh, he’d been scuba-diving dozens of times, but he’d barely been able to communicate with amphibious exuberants. The Transmuters had been here for at least a billion years or a roughly comparable period of macrosphere time, in terms of the rates of the most likely biochemical or cybernetic processes. Of course, they were sentient creatures in control of their own destiny, not beached fish required to have the right mutations in order to survive. They might not have changed at all. They might have clung like good realists—or good abstractionists—to simulations of the old world.

But over the eons, they might easily have decided to acclimatize to their new surroundings. And if they had, communication could prove impossible, unless someone, in the expedition was prepared to meet them halfway. Unless someone was prepared to bridge the gap.

The Flight Deck was crowded, making it a perfect environment in which to practice negotiating unpredictable obstacles, but Orlando found himself spending most of his time transfixed by the view. One entire wall of the penteractal scape was given over to a giant window, and the magnified image of Poincare behind it offered a perfect excuse to do nothing but stand and stare. Moving about in public 5-scapes still made Orlando intensely self-conscious, less out of any fear of falling flat on his face than from a strong sense that he could take no credit for the fact that he didn’t. His 5-body came equipped with numerous invaluable reflexes, as any real macrospherean body almost certainly would, but relying on these alien instincts made him feel like he was operating a telepresence robot programmed with so many autonomous responses that any instructions he gave it would be superfluous.

He glanced down at the bottom of the window. The most trivial details in a 5-scape could still be hypnotic; the tesseract of the window met the tesseract of the floor along, not a line, but a roughly cubical volume. That he 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 Swift.

But the Floating Island became unbearable, a straitjacket for his senses, a coffin with a nail-hole of sky. Every 3-scape was the same. Even with his three-dimensional vision fully restored, he couldn’t back out the new symbols without also losing his memories of Poincare, and he could feel their lack of stimulation constantly, an absence as oppressive as if the world had turned a uniform white.

He could choose to alternate between sets of symbols, one for 3-scapes and one for 5-scapes, with his exoself holding the untranslatable portion of his memories in storage. In effect, he would become two people, serial clones. Would that he so had? There were already a thousand of him, scattered across the Diaspora. But he’d come here to meet the Transmuters in person, not to give birth to a macrospherean twin who’d do it on his behalf. And the Diaspora’s clones would all willingly merge and return to the restored Earth—if that was possible—but what would become of a clone who’d go insane from sensory deprivation in a rain forest, who’d stand beneath a midnight desert sky and scream with frustration at the pinhole view?

Orlando stripped away the enhancements completely, and felt like an amnesiac or an amputee. He stared at Poincare from the Flight Deck, more stupefied and frustrated than ever.

Paolo asked him how he was coping. He said, “I’m fine. Everything is fine.”

He understood what was happening: he’d come as far as he could travel, while still hoping to return. There were no stable orbits here: you either approached this world at speed, grabbed what you needed, and retreated—or you let yourself be captured, and you spiraled down to collision.

“It’s a subtle effect, but everywhere I’ve looked the whole ecosystem is slightly skewed in their favor. It’s not that they dominate in terms of numbers or resource use, but there are certain links in the food chain—all of them ultimately beneficial to this species—that seem too robust, too reliable to be natural.”

Elena was addressing most of U-star C-Z, eighty-five citizens assembled in a small meeting hall: a 3-scape for a change, and Orlando was grateful that someone else felt like a rest from macrospherean reality. The detailed mapping of Poincare had revealed no obvious signs of technological civilization, but the xenologists had identified tens of thousands of species of plant and animal life. As on Swift, it remained possible that the Transmuters were hiding somewhere in a well-concealed polis, but now Elena claimed to have found evidence of bioengineering, and the supposed beneficiaries seemed to he camouflaged by nothing more than the modest scale of their efforts.

The xenologists had pieced together tentative ecological models for all the species large enough to be visible from orbit in the ten regions they’d singled out for analysis; microbiota remained a matter for speculation. The giant “towers,” now called Janus trees, grew along much of the coast, powered by the light shining up from the molten ocean. Each individual tree had a lateral asymmetry that looked utterly bizarre to Orlando, with leaves growing larger, more vertical and more sparsely distributed toward the inland side. The same morphological shift continued from tree to tree, between those directly exposed to the ocean light and the four or five less privileged ranks behind them. The leaves of the first rank were a vivid banana yellow on their ocean-facing hypersurface, and bright purple on the back. The second rank used the same purple to catch the waste energy of the first rank, and blue-green to radiate away its own. By the fourth and fifth rank, the leaves’ pigments were all tuned to hues of “near-infrared,” leaving them pale gray in “visible light.” These color translations were faithful to the ordering of wavelengths, but the visible/infrared distinction was necessarily arbitrary, since it was clear that different species of Poincare life were sensitive to different portions of the spectrum.

Because most of the leaves in this “canopy” were almost vertical, they obstructed the probes’ view far less than if they’d faced the sky, and random gaps in the foliage exposed considerable two-dimensional vistas. A dazzling range of forest-dwellers had been observed, from large, carnivorous exothermic flyers and gliders—all eight-limbed, if wings were counted—to patches of something like fungus apparently feeding directly on the trees themselves. The sheer volume of forest available for observation, and the lack of both diurnal and seasonal rhythms, had allowed the xenologists to deduce many life cycles relatively quickly; very few species reproduced in synchrony, and those that did were only in lock-step over small regions, so individuals of every species at every age could be found somewhere. There were young born live and self-sufficient, while others developed in everything from pouches to egg-like sacs in nests or hanging clusters, nodules under Janus bark, dead, paralyzed, or oblivious prey, and even the corpses of their parents.

Inland, the forest blocked the ocean light, but life spilled into the shadow. Some animals migrated away from the coast to raise their young, closely followed by predators, but there were also local species, starting with plants feeding on nutrients washed out of the forest. Poincarean life employed no single, universal solvent, but half a dozen common molecules were liquid at coastal temperatures. Rain rarely fell on the forest itself, and the major rivers flowing from the barren interior to be vaporized when they hit the magma ocean contained little organic material, but enough high-altitude dew ran down the Janus trees and found its way inland, enriched with debris, to power a secondary ecosystem comprising several thousand species.

Including the Hermits.

Elena summoned up networks of estimated energy and nutrient flows for predation, grazing, parasitism and symbiotic relationships. “The wider the analysis, the more the evidence mounts up. It’s not just that they have no predators and no visible parasites; they also face no population pressure, no food shortages, no disease, Every other species is subject to chaotic population dynamics; even the Janus trees show signs of overcrowding and die-offs. But the Hermits sit in the middle of all those wild swings, untouched. It’s as if the whole biosphere has been customized to shield them from anything unpleasant.”

She displayed a 5-image, and Orlando reluctantly switched his vision to view it properly. The Hermits, Elena explained, were limbless, mollusk-like creatures, living in stationary structures half excreted like shells, half dug our like burrows. They appeared to spend most of their lives inside these caves, feeding on hapless passers-by who fell into a slippery trench that led straight to the Hermits’ mouthparts. No carnivore had evolved the tools required to winkle them out, and though many species were smart enough to avoid the trenches, there were always plenty of victims. And of the six million Hermits observed from orbit, none had yet been seen either to breed, or to die.

Karpal was skeptical. “They’re just a timid, sedentary species that’s had good luck for the brief time we’ve been watching. I wouldn’t be tempted to extrapolate their lifespan to six million times the observation period; we’ve yet to see any significant temperature fluctuations in the crust, and when they come along they must cause havoc. We should shift our resources to the deserts; if the Transmuters are on Poincare at all, they’ll be as far away from the native life as possible. Why would they intervene on behalf of these creatures”

Elena replied stiffly, “I’m not suggesting that they did. The Poincareans could have engineered the whole setup for themselves.”

“Have you caught them doing anything remotely like biotechnology?”

“No. But once they’d put themselves in an invulnerable niche, why would they need to make any more changes?”

Orlando said, “Even if they’re intelligent enough to have done that, if their idea of utopia is spending eternity sitting in a cave waiting for food to slide down their throats, what are they going to know about the Transmuters? Ten thousand blazing star ships might have flown past Poincare a billion years ago, but even if the Hermits have been around that long, they’re not going to remember. They’re not going to care.”

“We don’t know that. Does Carter-Zimmerman on Earth look like a hive of intellectual curiosity? Can you tell what’s stored in the polis library from one glance at the protective hull?”

Karpal groaned. “Now you’re taking Orpheus to heart. One biological computer on one playlet in another universe hardly proves—”

Elena retorted, “One natural biological computer hardly proves that they’re common products of evolution. But why shouldn’t Poincarean life engineer them? No one objects to the notion that every technological civilization might undergo its own Introdus. If the Poincareans were skilled in biotechnology, why shouldn’t they create a suitably tailored living species, instead of a machine?”

Paolo interjected cheerfully, “I agree! The Hermits could be living polises, with the whole ecosystem as their power supply. But they need not have been built by native Poincareans. If the Transmuters arrived here and found no intelligent life, they might have tweaked the ecosystem to make a safe niche for themselves, then created the Hermits and migrated into them to while away the time in 3-scapes.”

Elena laughed uncertainly, as if she suspected she was being mocked. “While away the time until what"'

“Until something evolved here—a species worth talking to. Or someone arrived, like us.”

The debate dragged on, but no conclusions were reached. On the evidence, the Hermits might have been anything from random beneficiaries of natural selection to the secret masters of Poincare.

A vote was taken, and Karpal lost. The deserts were too vast to search, with no clear target. The expedition would concentrate its resources on the Hermits.

Orlando moved slowly across the luminous rock, grit registering painlessly on the sole of his single, broad, undulating foot. He felt naked and vulnerable outside his cave; twenty kilotau playing Hermit, riding this puppet on the hypersurface of Poincare, and he could empathize that much. Or perhaps he just preferred the view through the narrow tunnel because it helped cut the five-dimensional landscape down to size.

When he knew he was in sight of his neighbor, he extruded nine batons and performed gesture 17, the only sequence he hadn’t tried before. It felt almost as if he was spreading his hands and waggling his fingers, executing a fragment of sign language committed to memory without knowing its meaning.

He waited, peering down the tunnel into the pearly light of the alien’s multiply-reflected body heat.

Nothing.

Real Hermits left their caves almost exclusively for the purpose of building new ones; whether they outgrew the old ones, wanted a better food supply, or were moving away from some source of danger or discomfort remained obscure. Occasionally two naked Hermits crossed paths; nine megatau of ground-level observations by a swarm of atmospheric probes had yielded a grand total of seventeen such encounters. They did not appear to fight or to copulate, unless they managed to do so at a distance with secretions too subtle to detect, hut they did extrude several stalk-like organs up to twelve hypercylinders which Elena had dubbed “batons”—and wave them at each other as they passed.

The theory was that these were acts of communication, but with such a tiny sample of encounters to analyze it was impossible to infer anything about the hypothetical Hermitian language. In desperation, the xenologists had constructed a thousand Hermit robots and had them dig and excrete caves of their own, unnaturally close to real ones, in the hope that this would provoke some kind of response. It hadn’t, though there was still the possibility of a robot-Hermit encounter if one of the neighbors ever decided to leave and build a new cave.

Non-sentient software usually controlled the robots, but a few citizens had taken to riding them as Puppets, and Orlando had dutifully joined in. He was beginning to suspect that the Hermits were every bit as stupid as they seemed, which was more a relief than a disappointment; having wasted so much time on them wouldn’t be half as bad as being forced to accept that an intelligent species had willingly engineered itself into this cul-de-sac.

Orlando tried to look up at the sky, but his body was unable to comply; the infrared-sensitive hypersurface of his face could not he tilted that far. The Hermits—and many other Poincareans observed their surroundings by a form of interferometry; instead of using lenses to form an image, they employed arrays of photoreceptors and analyzed the phase differences between the radiation striking different points of the array. Limited to non-invasive observations of living Hermits and microprobe autopsies of other species’ corpses, no one really knew how the Hermits saw their world, but the color and spacing of the receptors supported one obvious guess: they could see by the thermal glow of the landscape itself. Heated by their bodies, their caves were slightly warmer than most surrounding rock, so they spent their lives cocooned in light. In his own cave, Orlando had adjusted the brightness he perceived until he found the ambiance vaguely comforting, but that was as far as he was prepared to go in finding Hermit experiences pleasurable. When small spiked octapods slid into his mouth, he turned and spat them out through the cave’s second tunnel. However stupid these creatures were, he wasn’t willing to slaughter them for the sake of empathizing with the Hermits, or to try to authenticate an act of mimicry that had probably been flawed from the start.

His exoself pasted a window of text into the scape, a weirdly disorienting intrusion. The two-dimensional object occupied a negligible portion of his field of view—in both hyperal directions it was slender as a cobweb—but the words still seized his attention as if they’d been thrust into his face in a 3-scape, blocking out everything else. When he scanned the window consciously to read the news, he felt a strong sense of déjà vu, as if he’d already taken in the whole page at a glance.

Swift C-Z had lost contact with them for almost three hundred years. On the macrosphere side, the link had never fallen silent: the stream of photons created by the singularity had stuttered straight from one data packet time-stamped 4955 UT, to another from 5242. But the citizens of Swift C-Z had just emerged from a long nightmare, wondering year after year if the reciprocal beta decays would ever resume.

Orlando jumped back to the Floating Island, the cabin, his 3-body. He sat on the bed, shivering. They weren’t stranded. Not yet. The room was familiar, comforting, plausible—but it was all a lie. None of it could exist outside the polis: the wooden floor, the mattress, his body, were all physically impossible. He’d traveled too far. He could not hold on to the old world, here. And he could not embrace the new.

He couldn’t stop shivering. He stared up at the ceiling, waiting for it to split open and allow the reality around him to come flooding in. Waiting for the macrosphere to strike like lightning. He whispered, “I should have died in Atlanta.”

Liana replied distinctly, “No one should have died. And no one should die in the core burst. Why don’t you stop bleating and do something useful?”

Orlando wasn’t fooled or confused for a moment—it was an auditory hallucination, a product of stress—but he grabbed the words like a lifeline. Liana would have goaded him out of self-pity; that much of her survived in his head.

He forced himself to concentrate. Somehow, the singularity had slipped—which meant the Transmuters’ long-neutron anchor, binding the home universe to macrosphere time, was losing its grip. Yatima, Blanca, and all the other dazzlingly brilliant experts in extended Kozuch Theory had failed to predict anything of the kind—which meant no one would know if, or when, or by how many centuries it might slip again.

But once or twice more could easily be enough to carry them right past the core burst.

The news might jolt the others into cloning the polis and searching for the Transmuters elsewhere. But even without another singularity slip they’d barely have time to visit two or three more stars. And while every instinct he possessed told him that the Hermits were dumb animals, every instinct he possessed was too far from the world that had shaped it to know gauche from droit.

Playing Hermit would never be enough to reach them. Riding a robot, reshaping his body image, crawling around on the hypersurface would never be enough. It was no use pretending that a single mind could embrace Earth and Poincare, U and U-star, three dimensions and five. Escape and crash. No one could bend that much; he had to break.

Orlando told his exoself, “Build a copy of the cabin. Here.” He gestured at one wall and it turned to glass; behind it, like an uninverted mirror image, the room was repeated in every detail. “Thicken it into a 5-scape.”

Nothing seemed to change, but he was seeing only the three-dimensional shadow.

He steeled himself. “Now clone me in there, in my 5-body, with all macrospherean visual symbols.”

Suddenly he was inside the 5-scape. He laughed, hugging himself with all four arms, trying not to hyperventilate. “No Alice jokes, Liana, please.” He had to concentrate to find the two-dimensional slice of the tesseract wall that revealed the adjoining three-dimensional cabin; it was like staring at a tiny peep-hole. His paper-doll original, the unchanged Orlando, pressed a hand against the glass in a vaguely reassuring gesture, trying not to appear too relieved. And in truth, in spite of the panic he felt, he was relieved himself not to be confined in that claustrophobic sliver of a world any more.

He caught his breath. “Now adjoin the robot’s scape.” The opposite wall became transparent, and behind it he could see the hypersurface of Poincare; the robot was still standing a few delta from the entrance to the real Hermit’s cave.

“Remove the robot. Clone me in there, with the Hermit body-image and senses, and Elena’s gestural language. And—“ He hesitated. This was it, the spiral down. “Tear out every symbol relating to my old body, my old senses.”

Ve was on the hypersurface. Through a floating four-dimensional window, he could see—with the xenologists’ best-guess Hermitian vision—the 5-cabin and its occupant, all the colors translated into false heat tones. The whole scene was obviously physically impossible: surreal, absurd. The 3-scape of the original cabin was too small and too far away to see at all. Ve looked around at the gently glowing landscape; everything appeared more natural now, more intelligible, more harmonious.

Elena had invented a gestural language for the Hermits’ batons; there was no pretense of capturing real Hermitian, but the artificial version did allow citizens to think in gestural impulses and images instead of their native tongue, and to communicate with their exoselves without violating the simulation of Hermit anatomy.

Ve extruded all twelve batons, and instructed vis exoself to duplicate the scape, then clone ver yet again with further modifications. Some came from the xenologists’ observations of other species’ behavior, some came from Blanca’s old notes on possible macrospherean mental structures, and some came from vis own immediate sense of the symbols ve required in order to fit this body and this world more closely.

The third altered clone of Orlando peered back down the tunnel of scapes, past vis immediate progenitor, searching in vain for a glimpse of vis incomprehensible great-grandparent. There was a world where that being had lived… but ve could neither name it nor clearly imagine it. With the symbols gone for most of the original’s episodic memories, the clone’s strongest inheritance was a sense of urgency, yet the edges of the lost memories still ached, like the vestiges of some plotless, senseless, unrecoverable dream of love and belonging.

After a while, ve turned away from the window. The Hermit’s cave itself was still beyond reach, but it was easier now to go forward than back.

Orlando paced the cabin, ignoring messages from Paolo and Yatima. The seventh clone had taken control of the robot nine kilotau ago, and almost immediately managed to persuade the real Hermit to leave its cave. They’d been miming and gesticulating at each other ever since.

When the robot finally left the Hermit to converse with the sixth clone, Orlando could see all the others watching intently; even the first clone seemed riveted, as if he was extracting some aesthetic pleasure from the five-dimensional baton-waving despite being blind to its meaning.

Orlando waited, his guts knotted, as the message passed up the chain toward him. What would happen to these messengers—more like children than clones—once they’d served their purpose? Bridgers had never been isolated; everyone had been linked to a large, overlapping subset of the whole community. What he’d done was an insane perversion of that ethos.

“There’s good news and had news.” His four-legged clone was standing behind the wall, face changing shape slightly as his head moved in unseen dimensions. Orlando stepped up to the glass.

“They’re intelligent? The Hermits—”

“Yes. Elena was right. They tweaked the ecosystem. More than we guessed. They’re not just immune to climate change and population swings; they’re immune to mutation, new species arising, anything short of Poincare going supernova. Everything’s still free to evolve around them, but they sit at a fixed point in the system while it changes.”

Orlando was staggered; that kind of long-term dynamic equilibrium was far beyond anything the exuberants of Earth had ever contemplated. It was at least as impressive as tying neutrons in knots. “They’re not… the Transmuters? Reduced to this?”

His clone’s shadow-face shimmered with mirth.

“No! They’re native to Poincare, they’ve never left, they’ve never traveled. But don’t ’took so disgusted.. They’ve had their age of barbarism, and they’ve had disasters to rival Lacerta. This is their sanctuary, now. Their invulnerable Atlanta. How can we begrudge them that?

Orlando had no reply.

The clone said, “But they do remember the Transmuters. And they know where they’ve gone.”

“Where?” Even the closest star might take too long to reach, if the singularity slipped again. “Are they in the desert? In a polis?”

“No.”

“Which star, then?” Maybe there was still hope, if they used all their fuel for a fast one-way voyage, and relied on signaling back to the station rather than returning physically.

“No star—or none that the Hermits could point to. They’re not in the macrosphere at all.”

“You mean… they found a way to enter another four-dimensional universe? To break in?” Orlando hardly dared believe it; if it was true, they could bring everyone through to the macrosphere, wait for the radiation to pass, then borrow the Transmuters’ trick to get back to the home universe itself—whether or not any robots survived on Kafka or Swift.

The clone smiled wistfully. “Not quite. But the good news is, the second macrosphere is four-dimensional.”