Pressure shifts; stars before her eyes.
Then the walls of the construct receded again into nothingness, and Heather felt once more as though she were floating, her body invisible.
Below her, the strange ground curved away as if she were viewing an unknown part of Earth from a great height.
Above, the sky curved away in the opposite direction—but no, it wasn’t the sky. Rather, it was another world, a world of distinct geography. It was as if two planets were orbiting very near each other, in defiance of celestial mechanics, and Heather was floating down the doubly concave corridor between them. In the distance far, far ahead, there was a maelstrom of gold and green and silver and red.
Her heart was racing. It was incredible, overwhelming.
She fought for sanity, grasped at reason, trying to interpret it all.
Heaven above and hell below?
Or perhaps the two hemispheres of a brain, with her riding along the corpus callosum?
Or maybe she was sliding down the cleavage of some colossal Earth Mother… ?
Yin and yang, broken apart, with one of them turned around?
Two mandalas?
None of those seemed right. She decided to try a more scientific approach. Were the spheres of equal diameter? She couldn’t tell; when she concentrated on one, the other faded away—not just into her peripheral vision, but as if its actual reality required her concentration.
She was literally shaking with excitement. It was like nothing she’d ever experienced before. For the first time, she understood what the phrase “mind-blowing” actually meant.
She wondered if she were seeing the Centauri system. It consisted of three suns, after all—bright and yellow A; dimmer, orange B; and tiny, cherry-red Proxima. Who knew what dance planets would undergo in such a system?
But no; the spheres weren’t planets. Nor were they twin suns. Rather, she felt sure, they were realms—specific spaces, but not really solid. What she’d first taken to be lakes reflecting sunlight on the surface of one of them were in fact tunnels right through, revealing the multicolored maelstrom that made up the backdrop to everything.
Heather found that her throat was dry. She swallowed with effort, trying to calm herself, trying to think.
If the construct had really folded into a hypercube, then she was perhaps now in a four-dimensional universe. That could explain why objects disappeared if she didn’t look at them directly—they were slipping not just left and right out of her field of view, but ana and kata as well.
Heather was stunned, shell-shocked, unsure of what to do next. Try to fly up to the orb above? Down to the one below, perhaps taking a journey through one of the tunnels that permeated it? Or move ahead to the maelstrom?
But soon her choice was made for her. Without her exerting any effort, she seemed to be floating up toward the overhead sphere—or, perhaps, the sphere was coming down toward her. She couldn’t tell if the breeze she felt was due to her own movement or was just the air-circulation system inside the construct.
As she floated upward, she was startled to see what looked like a mouth open upon the sphere above her and a long, iridescent snake shoot out of it and drop down past her, connecting with the sphere below, where it was promptly swallowed by another mouth. As she continued her ascent, two more snakes made the downward journey from above, and one leaped up past her from the lower sphere to the upper one.
Although they were unlike anything she’d ever seen before, she felt sure, somehow, that the spheres and snakes were organic—they had the look of biology, the slick wetness of life, the irregularities of something grown rather than manufactured. But whether they were separate life forms or just organs within a bigger creature, she had no way to tell. The maelstrom backdrop might be the far reaches of space—or some sort of containing membrane.
Her heart was still hammering; the idea that some or all of this was alive frightened her. And as she got closer to the surface of the upper sphere, she could see that it was gently expanding and contracting—either pumping or breathing. The dimensions were fantastic; assuming that she was still 164 centimeters tall, the sphere must be dozens, if not hundreds, of kilometers across. But then again, perhaps she’d shrunk to a tiny fraction of her original size and was now on some fantastic voyage through the anatomy of a Centaur.
Indeed, perhaps that was the purpose! Many SETI researchers had suggested that actual, physical travel between stars would always be impractical. Perhaps the Centaurs had merely sent a detailed record of what they were like inside so that humans could reconstruct one of them from local material.
She continued to rise higher and higher—which made her think about gravity. She had a sense of up and down, and she felt as though she were moving to a greater altitude. But if she were truly weightless, then such sensations had no real meaning.
Up or down? Rising or falling?
Perspectives. Perceptions.
In a class on the psychology of perception years ago, Heather had been introduced to the Necker cube: twelve lines making up the skeletal view of a cube, as seen from an angle:
If you stared at it long enough, it seemed to bounce between being a cube angling off toward the upper left and one angling toward the lower right, each square panel popping between being the one in the foreground and the one in the background.
She closed her eyes, and—
— and after a second, saw the inside of the construct. That method wouldn’t do to reorient herself. She opened her eyes, but the same sphere seemed to be overhead. So instead, she pulled in her focus, looking at an imaginary object only centimeters in front of her nose. The background became blurry. After a few seconds, she let her eyes relax, returning to infinity focus.
And indeed, her perspective had now flipped. The closest sphere now appeared to be beneath her feet. She rather suspected that with an effort of will, she could make it appear to her left or right, or front or back, or—
Or kata or ana?
If her mind could only deal with three pairs of directions at once, and if there really were four to choose from here, then she simply was failing to see one of the pairs. But surely there was no absolute hierarchy, no sense in which length had any more claim to being the first dimension than did height or depth.
She defocused her eyes again and tried to clear her mind.
When she refocused, everything was the same.
She tried once more, this time also blinking her eyes but making sure not to keep them closed long enough to switch back to the interior of the construct.
And then the blurry background did seem to shift—
And she refocused once more.
And suddenly, incredibly, everything was different. Heather gasped.
The spheres were now two great bowls joined at their rims—as if Heather were now inside a giant ball, everything turned inside out.
The inner surface of the ball now seemed to be granular, almost like the surface of a star—again, she thought perhaps she was somehow seeing a vision of the Centauri system, despite the pulsing biological feel it all had.
She now seemed to be drifting backward—another perspective shift. She rotated around, swimming through space, so that she was facing in the direction of apparent movement. As she got closer to the surface, she saw that the granularity was made up of millions of hexagons, packed tightly together.
As she watched, one of the hexagons began to recede away, forming a long, deep tunnel. As it elongated, Heather could see its sides grow slick, then iridescent—and she realized that from her new perspective, she was seeing one of the snakes from the inside. Eventually the tunnel pinched off, presumably as the snake broke free from the surface.
At last she was within a few hundred meters of the vast, curving wall.
She was woozy, disoriented—as if she’d spun around on her heels over and over again, making herself dizzy. She was dying to explore some more, but—God damn it, what an unfortunate intrusion of reality! She had to urinate. She hoped that when she next returned, it would be back here, at this spot, not at where she’d begun from. It would be awkward making progress in her explorations if she always entered this wondrous realm at the same place.
She closed her eyes, waited for the vision of the construct to appear in her mind, touched the stop button, and staggered out into the oddly angular world she called home.