"I'm trying," said Cheetah.

"You certainly are."

"Was that a shot?"

"Moi?" But then Kyle shrugged and smiled. "Actually, yes it was-good job catching it. You're making progress." But then Kyle shrugged and smiled. "Actually, yes it was-good job catching it. You're making progress."

"I certainly hope so. In fact-how's this?" Cheetah paused, apparently waiting until he had Kyle's full attention. "Julius Caesar wasn't just the great-uncle of Augustus-he was also the son of the Wicked Witch of the West, and like the Wicked Witch, he could be killed by water. Well, given that, Ca.s.sius and the rest of the republican conspirators decide that they don't need to off Big Julie with knives-they can do it far more cleanly with squirt guns. So they lay in wait for him, and when he comes down from the capitol, they open fire. Caesar resists, until he sees his best friend also shooting him, and with that, he utters his final words before falling down dead: 'H 'H2, Brute?' " Kyle laughed. Kyle laughed.

Cheetah sounded inordinately pleased. "You're laughing!"

"Well, it's pretty good."

"Maybe someday I will will get the hang of being human," said Cheetah. get the hang of being human," said Cheetah.

Kyle sobered. "If you do, be sure to let me know."

The stage lights were set up: three big lamps with Fresnel lenses on tripods, and barn doors to limit their beams. They were providing a constant source of power to the alien construct, letting it do whatever it was supposed to do.

And so far, all that seemed to be was to stay rigid. Heather could think of niche markets for such a product-a thought of Kyle darted through her mind-but she a.s.sumed that the aliens wouldn't have spent ten years just telling her how to make something stay stiff.

And yet, maybe that was indeed all the aliens had wanted to convey: a way to make materials stand up to great stresses, so that high-speed s.p.a.ceships could be built. After all, fast voyages between Earth and the Centaur's world would require substantial accelerations.

But that didn't make sense. If the Centaurs had ships capable of even half the speed of light, they could have sent a working model faster than they could have transmitted the plans. Granted, broadcasting information would always be cheaper than shipping physical objects, but it did make her question whether the stiffening was the point of the construct or just a byproduct of what it was really really intended to do. intended to do.

Heather sat and stared at it, trying to fathom its real purpose. She didn't like science fiction the way Kyle did, but they both loved the movie 2001: A s.p.a.ce Odyssey, 2001: A s.p.a.ce Odyssey, and she was haunted now by the final line spoken in that film: "Its origin and purpose," Heywood Floyd had said of the monolith, "still a total mystery"-although Heather always suspected it was the box the United Nations had come in. and she was haunted now by the final line spoken in that film: "Its origin and purpose," Heywood Floyd had said of the monolith, "still a total mystery"-although Heather always suspected it was the box the United Nations had come in.

She kept thinking about the missing data-about how big she should have made the construct. Maybe it was never intended to be built this large. The promised revolution in nanotechnology had never occurred, at least partly because quantum uncertainty made extremely small machines impossible to control. Perhaps the field generated by the tiles was supposed to overcome that; maybe the Centaurs had intended her to make the construct at a billionth of its current size. She sighed. You'd think they would have said said how big the d.a.m.ned thing was supposed to be. how big the d.a.m.ned thing was supposed to be.

Unless, she thought again, it was supposed supposed to be a matter of choice. She kept coming back to the idea of scale: a human would naturally build it at one size; an intelligent slug would have made it a smaller size; a sentient sauropod would have constructed it on a grander scale. to be a matter of choice. She kept coming back to the idea of scale: a human would naturally build it at one size; an intelligent slug would have made it a smaller size; a sentient sauropod would have constructed it on a grander scale.

But why make it human-sized? Why would the Centaurs allow the builders, whoever they might be, to construct it at whatever scale they wished?

Unless, of course, as Paul had suggested, the builders were meant to go inside it.

A silly thought; it probably had more to do with her memories of that garbage-can Concorde than with the object in front of her. Or maybe it was that darned Freudianism sneaking up again-Why, of course, Mein Frau, zometing always has to go inside ze tunnel.

It was a crazy notion. How would one go inside? Indeed, where where would one go? There were would one go? There were eight eight cubes, after all. cubes, after all.

In that cube there, she thought at once, mentally pointing at the third one along the shaft, the one with the four additional cubes attached to it. It was the only special cube, the only one with none of its faces exposed.

That one there.

She could unclip one of the projecting cubes-removing both of the panels that made up the concealed face-and clamber inside. Of course, if the power to the lamps went off, soon enough the whole construct would collapse and she'd end up on her a.s.s.

Crazy idea.

Besides, what did she expect? That the thing would take off, like that Concorde used to do in her imagination? That she'd be whisked across the light-years to Alpha Centauri? Madness.

Anyway, she probably couldn't remove one of the cubes with the structural-integrity field active. And with it off, the whole thing would collapse the moment she put any weight on it.

She moved over to the construct and grabbed the cube projecting from the right side. d.a.m.ned if it didn't come cleanly off when she pulled on it, the clamps that had been holding it there falling to the floor. And as she looked, she saw that the two panels that made up the inner face had come off, as if they had already bonded somehow, exposing the empty hollow of the central cube.

Heather put the cube she'd removed back on again, and it locked into place. She tried to pull it off once more and found that unless she pulled straight out, with no sideways motion at all, it wouldn't disengage. It was tricky, but she did manage to get if off again. She repeated the process a couple more times, and tried it with other cubes as well. They reconnected easily, regardless of the angle at which they were pressed in, but they all required a deft touch to remove; she'd been lucky the first time.

She removed the side cube again and looked at the hollow s.p.a.ce within. Actually, she should have made it a bit bigger-it looked like she'd be a tight fit. Not that she was really going to climb in, of course.

Heather looked at her desk, started toward it, stopped, then started again. Once she reached it, she removed a pad of paperite and a pen and began to write, feeling awfully silly: "I'm inside the third cube along the central shaft. Turn off the lights and keep the construct out of the sun and it will fall apart, releasing me."

She took a piece of tape from her desktop dispenser and stuck the notice to the wall.

And then she approached the cube again. It wouldn't hurt to climb in, she supposed, as long as she didn't reattach the cube she'd removed to gain access. She took off her shoes, rested her b.u.m on the edge of the central hollow, brought her legs up, and tucked herself inside, in a sort of sitting fetal position.

Nothing. Of course.

Except- That was strange.

Except that air air was coming through the walls. She held her palm near one of the flat surfaces and could feel a gentle breeze. The piezoelectric paint was doing more than providing structural integrity; it was either manufacturing air or cycling it through from outside. was coming through the walls. She held her palm near one of the flat surfaces and could feel a gentle breeze. The piezoelectric paint was doing more than providing structural integrity; it was either manufacturing air or cycling it through from outside.

Incredible.

It had to be cycling air through-that was the only sensible answer. The aliens surely couldn't have known what sort of atmosphere humans required.

Heather sagged back as much as the cramped quarters would allow. It was was indeed the only sensible answer-but it was also the most depressing one. She laughed at herself. She had indeed thought that maybe, just maybe, the aliens had told her how to build a starship-a starship that would whisk her away from Earth, away from all her troubles, and take her to Alpha Centauri. indeed the only sensible answer-but it was also the most depressing one. She laughed at herself. She had indeed thought that maybe, just maybe, the aliens had told her how to build a starship-a starship that would whisk her away from Earth, away from all her troubles, and take her to Alpha Centauri.

But if all it was doing was pumping air in from outside, it wouldn't make much of a s.p.a.ceship. She contorted herself inside the hollow cube so that she could get her nose up against the green substrate wall. She could feel the gentle breeze, but the air had no odor at all.

But if not a s.p.a.ceship, then what? And why the structural-integrity field?

She knew what she had to do. She had to reattach the removed cube while still remaining inside the central hollow. But surely she should tell someone first. Even with her "I'm inside the third cube" note, it could be hours, or days, before someone entered her office. What if she got trapped inside?

She thought about phoning Kyle. But that wouldn't do.

She didn't have any grad students of her own during the summer, but there always were a few milling about. She could grab one of them-although then she might have to share some credit with the student when she published her results.

And then, of course, there was the most logical name-the one she knew she'd been deliberately suppressing.

Paul.

She could call him up. He'd doubtless get credit anyway; after all, he'd manufactured the components from which the construct was made, and had helped her a.s.semble them.

Maybe, in its own crazy way, this was a perfectly reasonable excuse to call him. Not that last night had been a date or anything, not that any further contact was required.

She got out of the cubic hollow and crossed over to her desk, stretching as she did so, trying to get a crick out of her neck.

She picked up her handset. "Internal directory: Komensky, Paul."

There were a few electronic bleeps, then Paul's voice mail came on. "h.e.l.lo, this is Professor Paul Komensky, Mechanical Engineering. I can't come to the phone right now. My office hours for student appointments are-"

Heather replaced the handset. Her heart was fluttering a bit-she'd wanted to connect with him, yet felt a tinge of relief that she hadn't.

She felt warm, perhaps even warmer than the bright lights should have made her feel. She looked back at the construct and then over at her computer monitor. The Alien Signal Center Web page hadn't changed. There must be thousands of researchers working on the problem of what the alien messages had meant now that they were apparently over. She felt sure she had a good jump on everyone else-the lucky coincidence of Kyle having that Dali painting on his wall had let her leap ahead. But how long would it be before someone else built a similar construct?

She hesitated for another full minute, warring with herself.

And then- And then she walked across the room, hefted the cube she'd removed earlier and brought it closer to the construct. She then got one of the suction-cup handles Paul had given her and placed it over the center of one face of the cube-the face that consisted of two substrate panels sandwiched together. There was a little pump on top of the black plastic handle; she pulled it up and the unit clamped onto the cube. She then tried lifting the cube by the handle. She feared it would fall apart, but the whole thing held together nicely.

After one more moment of hesitation, she tucked herself back into the hollow and then, pulling on the suction-cup handle, she lifted the cube back up into place. It clicked easily into position, locking on.

Heather felt a wave of panic wash over her as she was plunged into darkness.

But it wasn't total total darkness. The piezoelectric paint shone slightly with that same greenish tinge that glow-in-the-dark children's toys gave off. darkness. The piezoelectric paint shone slightly with that same greenish tinge that glow-in-the-dark children's toys gave off.

She took a deep breath. There was plenty of air, although the close confines did make it seem stuffy. Still, even though she clearly wasn't going to suffocate in here, she wanted to be sure she could leave the construct whenever she wished. She splayed her hands and used them to try to push out the same cube she'd detached earlier.

Another wave of panic washed over her-the cube didn't want to give. The structural-integrity field might be sealing her in.

She balled her hands into fists and pounded on the cube again- -and it popped free, tumbling to the carpeted floor, the face with the suction-cup handle ending up on top.

Heather felt herself grinning sheepishly at her own panic. It probably was was a good thing that the construct wasn't a s.p.a.ceship-she'd have ended up making first contact with soiled panties. a good thing that the construct wasn't a s.p.a.ceship-she'd have ended up making first contact with soiled panties.

She got out, stretched again, and let herself calm down a bit. And then she tried once more, climbing back into the construct and using the gla.s.s handle to close what she was already thinking of as "the cubic door."

This time she just sat, letting her eyes adjust to the semidarkness and breathing the warm air.

Heather looked at the phosph.o.r.escent pattern on the panel in front of her, trying to make out any meaning in the design. Of course she'd had no way of knowing whether she'd oriented the construct the right way. She might have it on its side, or- Or backward. That is, she could be sitting in it backward. The confines were too tight for her to turn around with the door closed. She removed the cubic door, swung her legs outside, swiveling on her b.u.t.t. Once she was in place, facing the short end of the shaft instead of the long one, she pulled on the suction-cup handle to bring the cubic door-which was now on her right-into position.

She'd wrecked her night vision by opening the door again, so she sat waiting for her eyes to readjust.

And, slowly, they did.

In front of her were two circles. One was continuous, the other was broken into eight short arcs.

It came to her in a flash. The closed circle was "On," quite literally a completed circuit. And the broken circle was "Off."

She took a deep breath, then started to move her left hand forward.

"Alpha Centauri, here I come," she said softly, and pressed her palm against the closed circle.

18.

At first, nothing seemed to happen. But then Heather felt a sinking sensation in her stomach, as though she were in an elevator that was dropping rapidly down its shaft. A moment later her ears popped.

She smashed her fist against the stop b.u.t.ton- -and everything returned to normal.

Heather waited for her breathing to calm down. She tried the door, disengaging it slightly.

Okay: she could halt the process at any time, and she could get out at any time.

And so she resolved to try again. She closed her eyes, summoning inner strength, then pulled on the handle to reseal the door, and with an extended index finger, touched the center of the area on the panel in front of her circ.u.mscribed by the solid circle.

Heather's stomach dropped away from her again, and her ears, not yet recovered enough from the last time to pop, ached a bit.

And in front of her, the constellations of phosph.o.r.escent squares started shifting, moving, rearranging, as- As the unfolded hypercube she'd built began to close in on itself, moving ana ana or or kata, kata, collapsing into a tesseract, with Heather at its very heart. collapsing into a tesseract, with Heather at its very heart.

She felt herself twisting, and although the landscape around her was all just apparently random patterns of piezoelectric paint, it seemed that the design visible in her left peripheral vision was the same one she could detect in her right. The straight edges of the square panels were bowing in and out, now convex, now concave. Heather looked down in the dim light at her body and saw it stretched and flattened, as if someone had painted an image of her on paper, then pasted that paper to the inside of a bowl.

And yet, except for the undeniable feeling of rapid motion in her stomach and the pressure shifts in her ears, and now and again stars before her eyes-also, she knew, a phenomenon a.s.sociated with pressure shifts-there was no real discomfort. She could see her surroundings folding over and bending, and she could see herself doing the same things, but her bones were twisting without breaking.

The folding continued. The whole process took no more than a few seconds-judging by the runaway metronome of her heart pounding in her ears-but as it was happening, it seemed as though time were attenuated.

And then suddenly everything stopped moving. The transformation was complete: she was imprisoned in a tesseract.

No.

She fought for calmness. No, she wasn't imprisoned. At every step, she'd been able to stop the process, to escape. The aliens, whoever they were, wouldn't have gone to all this effort just to hurt her. She was still in control, she reminded herself. A willing visitor, not a prisoner.

But she felt there must be more to this than just the sensation of folding s.p.a.ce over on itself. Surely the Centaurs hadn't spent ten years telling humanity how to make a fancy amus.e.m.e.nt-park ride. There had to be more- And there was.

Suddenly, the tesseract exploded open, the panels breaking apart at their edges. It happened like sped-up film of a flower blooming with grace and absolute quiet.

The panels seemed to recede into infinity, each one racing away in a different direction. Heather found herself floating freely.

But not in s.p.a.ce.

At least, not in open s.p.a.ce.

Heather stretched out, extending her limbs. There was air to breathe and multicolored light to see by.

She looked down at her body- -and could not see it.

She could feel feel it-her proprioception was operating just fine. But she'd lost material form. it-her proprioception was operating just fine. But she'd lost material form.

Which made her think that the whole thing was a hallucination.

The air seemed no thicker than regular air, and yet she found she could swim in it, paddling with cupped hands or kicking with her feet.

It hit her: If the panels had receded, so had the stop b.u.t.ton. Adrenaline coursed through her. Dammit, how could she have been so stupid?

No. No. There's no such thing as an out-of-body experience. It had had to be a hallucination of some sort-meaning that she was still in the unfolded construct, still hunched over in that confined s.p.a.ce. to be a hallucination of some sort-meaning that she was still in the unfolded construct, still hunched over in that confined s.p.a.ce.

And the stop b.u.t.ton had to still be in front of her-a short distance ahead, to the right of center.