Diaspora

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.