She reached an arm forward.

Nothing.

Another wave of panic washed over her. It had had to be there. to be there.

She closed her eyes.

And a half-second after she did so, a mental image of the interior of the construct formed around her, looking, in her mind's eye, just as it had at the beginning.

She opened her eyes, and the construct disappeared; closed her eyes, and it reappeared. There was a slight delay-more than enough for persistence of vision to decay-before each switch-over occurred.

So it was was an illusion. She closed her eyes, let the construct reappear in her mind, reached forward, pressed the stop b.u.t.ton, opened her eyes, saw the panels come rushing back in, then felt the hypercube unfolding around her-bowing and bending, a reversing of the previous dance. an illusion. She closed her eyes, let the construct reappear in her mind, reached forward, pressed the stop b.u.t.ton, opened her eyes, saw the panels come rushing back in, then felt the hypercube unfolding around her-bowing and bending, a reversing of the previous dance.

After a minute, the view with eyes open and closed was identical: the construct had reintegrated. She was back in her office, back at the university-she knew it in her bones. Still, to prove it absolutely, she operated the cubic door-she was getting adept at disengaging it-and stepped outside. Light from the stage lamps stung her eyes.

All right: She could return home whenever she wanted. Now it was time to explore.

She got back in, pulled the door into place, took a deep breath, and pressed the start b.u.t.ton.

And the hypercube folded up around her once more.

19.

Kyle entered his lab the next morning and took Cheetah out of Suspend mode.

" 'Morning, Dr. Graves."

" 'Morning, Cheetah." Kyle brought up his e-mail on another console.

Cheetah waited, perhaps antic.i.p.ating a further comment from Kyle on his informal greeting. But then after a moment, he said, "I've been wondering, Dr. Graves. If you succeed in creating a quantum computer, how will that affect me?"

Kyle looked over at the mechanical eyes. "How do you mean?"

"Are you going to abandon the APE project?"

"I'm not going to have you dismantled, if that's what you mean."

"But I will no longer be a priority, will I?"

Kyle considered how to respond. Finally, with a little shrug, he said, "No."

"That is a mistake," said Cheetah, his tone even.

Kyle let his gaze wander over the angled console. For a second, he expected to hear the sound of the door bolt locking shut. "Oh?" he said.

"You are missing the logical next step in quantum computing, which would be to press on into creating synthetic quantum consciousness."

"Ah," said Kyle. "The coveted SQC." But then a memory came to him, and he lifted his eyebrows. "Oh-you mean Penrose and all that s.h.i.t, right?"

"It is not s.h.i.t, Dr. Graves. I know it has been two decades since Roger Penrose's ideas in this area have had much currency, but I have reviewed them and they make sense to me."

In 1989, Penrose, a math prof at Oxford, published a book called The Emperor's New Mind. The Emperor's New Mind. In it, he proposed that human consciousness was quantum mechanical in nature. At that time, though, he couldn't point to any part of the brain that might operate by quantum-mechanical principles. Kyle had started his studies at U of T just after that book came out; a lot of people were talking about it then, but Penrose's stance had seemed to Kyle just a wild a.s.sertion. In it, he proposed that human consciousness was quantum mechanical in nature. At that time, though, he couldn't point to any part of the brain that might operate by quantum-mechanical principles. Kyle had started his studies at U of T just after that book came out; a lot of people were talking about it then, but Penrose's stance had seemed to Kyle just a wild a.s.sertion.

Then a few years later, an M.D. named Stuart Hameroff tracked Penrose down. He'd identified precisely what Penrose needed: a portion of the brain's anatomy that seemed to operate quantum mechanically. Penrose elaborated on this in his 1994 book Shadows of the Mind. Shadows of the Mind.

"But Penrose was nuts," said Kyle. "He and that other guy were proposing-what was it now?-some part of the cytoskeleton of cells as the actual site of consciousness."

Cheetah lit his LEDs in a nod. "Microtubules, to be precise," he said. "Each protein molecule in a microtubule has a slot in it, and a single free electron can slide to and fro in that slot."

"Yeah, yeah, yeah," said Kyle dismissively. "And an electron that can be in multiple positions is the cla.s.sic quantum-mechanical example; it's possibly here, or possibly there, or possibly somewhere in between, and until you measure it, the wave front never collapses. But Cheetah, it's a big big leap from finding some indeterminate electrons to explaining consciousness." leap from finding some indeterminate electrons to explaining consciousness."

"You're forgetting the full impact of Dr. Hameroff's contribution. He was an anesthesiologist, and he'd discovered that the action of gaseous anesthetics, such as halothane or ether, was to freeze the electrons in microtubules. With the electrons frozen in place, consciousness ceases; when the electrons are again free to be quantally indeterminate, consciousness resumes."

Kyle raised his eyebrows. "Really?"

"Yes. The neural nets in the brain-the interconnections between neurons-are intact throughout, of course, but consciousness seems independent of them. In creating me, you accurately emulated the neural nets of a human brain, and yet I still don't pa.s.s the Turing test." The same Alan Turning that Josh Huneker had idolized had proposed the definitive test for whether a computer was exhibiting true artificial intelligence: if, by examining its responses to whatever questions you cared to ask it, you couldn't tell that it wasn't really human, then it was indeed true AI; Cheetah's jokes, his solutions to moral quandaries, and more, constantly revealed his synthetic nature. "Ergo," continued the voice from the speaker grille, "there is something else to being human besides neural nets."

"But, come on," said Kyle. "Microtubules can't have anything to do with consciousness. I mean, they're hardly unique to the human brain. You find them in all kinds of cells, not just nerve tissue. And they're found in all kinds of life forms that have nothing like consciousness-worms, insects, bacteria."

"Yes," said Cheetah. "Many people dismissed Penrose's idea precisely because of that. But I think they were wrong to do so. Consciousness is clearly a very complex process-and complex processes don't evolve as a unit. Take feathers for flight as an example: They didn't spring full-blown from naked skin. Rather, they evolved from scales that had gradually become frayed to trap air for insulation. Consciousness would have to be similar; before it first emerged, there would already have to be in place ninety-plus percent of whatever was required for it to exist-meaning that its infrastructure would have to be both ubiquitous and useful for something else. In the case of micro-tubules, they serve important functions in giving cells shape and in pulling chromosome pairs apart during cell division."

Kyle made an impressed face. "Interesting take. So what are you proposing? That my quantum computer is essentially an artificial equivalent of a microtubule?"

"Exactly. And by porting an APE such as myself to a general-purpose quantum computer, you'd be able to create something that really does have consciousness. You'd make the artificial-intelligence breakthrough you've been longing for."

"Fascinating," said Kyle.

"Indeed. So you see, you can't give up on me. Once you get your quantum computer working, it won't be long before you will have it in your power to grant me consciousness, enabling me to become human . . . or, perhaps, even more more than human." than human."

Cheetah's lenses whirred, as if going out of focus while he contemplated the future.

20.

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 h.e.l.l 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 realms-specific s.p.a.ces, 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 ana and and kata kata as well. as well.

Heather was stunned, sh.e.l.l-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 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 s.p.a.ce-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; a.s.suming 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 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. 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 alt.i.tude. But if she were truly weightless, then such sensations had no real meaning.

Up or down? Rising or falling?

Perspectives. Perceptions.

In a cla.s.s 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: [Picture C]

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 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. 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 kata or or ana? 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 was different. Heather gasped. 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 s.p.a.ce, 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-G.o.d d.a.m.n 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 b.u.t.ton, and staggered out into the oddly angular world she called home.

21.

When Heather left her office and entered the corridor, she was shocked to see through the window at the end of the hall that it was nighttime. She looked at her watch.

Eleven P.M.!

Heather entered the staff women's washroom, its door yielding to her thumbprint. She sat on the toilet, which had a refreshing solidness to it, contemplating everything that had happened. Her first thought was to tell everyone what she'd discovered-to go running through the campus shouting "Eureka!"

But she knew she had to contain herself. This was the breakthrough that could earn her not just a full professorship (and tenure!) at U of T, but at any university she wanted, anywhere in the world. She needed to delay making her announcement until she knew what she was dealing with, but not so long that someone else would scoop her. She'd lived enough years in the world of publish-or-perish to know that tipping one's hand at the wrong point was the difference between a n.o.bel Prize and nothing.

Discovering what that strange realm was would be the real breakthrough; that's what the public would want to know.