Twin cables ran over the debris and out over the Face. “We’ve laid cables across all the Lump’s Faces, and along the Edges,” Taft said with an ironic smile. “We’ve wrapped up this huge mystery like a birthday parcel, eh, Paul?” He opened up the car. It was a cylinder about forty feet long which clung like a glassy insect to its cables. Most of the hull was transparent, and it contained two rows of five large seats which were suspended from complex sets of gimbals. Taft helped Paul settle; straps were passed over his shoulders and around his waist, giving him a vicarious sense of security.

Taft took a seat near the front end of the car, before an instrument panel which centered on a small joystick. Taft pushed the stick forward and, with a jolt, the car began to pull itself along the cables.

They crawled out of the City’s dome of atmosphere. The sky’s deep blue faded, exposing hard stars. Spline ships drifted past the stars, diamond sharp.

The dark meteorite material grew sparse, and soon they were sailing smoothly over a glowing ocean. Occasional shadows, faint and miles across, washed from horizon to horizon.

Taft opaqued the hull, turning the car into a comfortable bubble of normality. Paul clung to his straps and settled into an uneasy sleep.

Light returned in a flood. Paul snapped awake… and screamed.

His chair had swiveled back on its gimbals. The nose of the car had tipped up through at least ten degrees. Outside, the Sugar Lump had tilted, too. He was falling backwards—

Green stood before him. “Paul. Stop it. You’re perfectly safe.”

His throat was tight; he gulped for breath. “What’s happening?”

He heard Taft laugh. “I’ve told the damn kid what to expect on this trip.”

“Then tell him again,” Green snapped. He turned and, clinging to handholds, made his way to the car’s small galley area.

Taft reclined comfortably in the drive chair. He was eating a small peach; gobbets of orange flesh clung to his beard. “I didn’t realize your memory continues to fail, mystery boy—”

“Skip it, Taft,” Green said casually.

Taft took another bite at his fruit. “Very well. Look, Paul, the surface on which the colony sits is utterly flat. The center of gravity of the Sugar Lump is somewhere beneath the center of the plane. The air we’ve been burning out of the meteorite material is attracted towards the center of gravity, so it clings to the middle of the plane as a kind of low dome. But now we’ve climbed away from the air and we’re being pulled back to the center of gravity. So your chair swivels until it points straight down to the center — but that means it’s at an angle to the plane’s local vertical. We seem to be climbing up an incline. By the time we get to the Edge we’ll appear to be climbing at almost forty-five degrees. See?”

Paul twisted in his chair until he could look back the way the car had climbed. The twin cables were geometrically perfect lines laid over a shallow, glowing slope. Thousands of miles distant, covered by a blue dome of air, the brownish meteorite debris lay splashed over the unblemished plane.

It looked as if the whole arrangement should slide off into space.

Paul shuddered and turned away. Green stood awkwardly on the tilting floor, sipping a coffee. “How do you feel? Better?”

Paul shrugged. “How should I feel? Commander, the Sugar Lump has been strong enough to withstand a major meteorite impact. Without so much as a scratch. How am I going to get through it?”

Green ran a hand over his closely-cropped, graying hair. “Paul, the Xeelee always build big. And tough. I’ll tell you about Bolder’s Ring sometime… what I’m saying is that the awe you feel won’t go away. But you’ll get used to it.

“And remember, you’re not a meteorite. You’re not trying to blast your way through.” He lowered his voice. “And that’s been Taft’s mistake. He’s fired off lasers, projectiles, particle beams — like a stream of little meteorites, yeah? And the success he’s had is precisely zero.

“You’re different, Paul.” Green leaned forwards, his expression a crumpled mixture of compassion and fascination. “You’ve this extraordinary talent. You’re not unique; I don’t want you to think that.” He smiled. “None of us has any doubts about your humanity… and all of us share your faculty, your quantum-mechanical way of seeing things, to some extent. Did you know that the dark-adapted eye, even without augmentation, can pick up a single photon? So straightforward human senses can perceive events at the quantum level. And there’s speculation that consciousness itself is a quantum process… What’s different about you is the strength of this — talent. The rest of us live here in the macro world, this smoothed-over mock-up of the truth. But sometimes you can see beyond the approximations and shams; you seem to be able to see right down to the fundamental level of quantum wave functions.” Green’s voice grew intense. “You see, Paul, in Taft’s Universe the surface of the Lump is certain to keep out a meteorite. But in your Universe nothing is certain.”

Paul twisted away. “I don’t want to be uncertain, Commander. I’m frightened. I don’t even know my real name.”

Green grasped his shoulders. “Look, Paul, you are a puzzle to us. There’s no point pretending otherwise. But the parts of the puzzle have to be connected. Where you came from must be connected with the way you are. And by doing this thing, by extending your talent to its limits, I believe you’re going to discover more than what the Xeelee are up to inside the Sugar Lump. I believe you’ll discover yourself.”

Paul found himself shuddering. He tried to concentrate on the straps around his waist, the reassuring hands on his shoulders.

“Yeah,” Taft said slyly. “Or maybe you’ll discover you’re nothing more than a vacuum diagram. What about that, eh, Paul?”

“A what?”

“Shut up, Taft.”

“Come on, Commander. If this is a revision class, then let’s revise it all.” Taft stepped up to stand before Paul, grinning, brittle with bitterness. “You told me how you took Paul up to the Spline fleet, put him through a crash course on how to be a human. Well, what about your quantum physics, Paul? Remember Feynman diagrams? Those cute pictures which show particles interacting, living, dying?”

“Taft…” Green growled.

“Well, now, here’s a remarkable little interaction. From out of nowhere pop three particles — a pion, a proton, and an antineutron. Of course conservation is violated all over the place — but thanks to the Uncertainty Principle nothing is absolute in this Universe. I presume that’s the concept our naval friend was groping for just now. And then the diagram closes up. The three particles recombine — they disappear back into the vacuum again, and conservation is reasserted. What a relief!

“But what really happens is that the antineutron is created at that final impact and moves back through time to initiate the creation of the other particles! Bizarre enough for you? And so this particular Feynman picture is a closed loop. A vacuum diagram. The particles come from nothing and return to nothing.” He grinned. “We’re here because we’re here because—”

Green raised one massive uniformed arm, pushed Taft away easily, muttered something Paul couldn’t hear.

Paul closed his eyes, hoping to make the incomprehensible Universe disappear into the vacuum from which it had sprung.

The approaching Edge was a knife-blade across the stars. The car climbed the one-in-one slope ever more slowly, finally stopping a hundred yards from the rim. “Come on, Paul,” Green said. “We walk from here.” Briskly he helped Paul seal himself into a light, one-piece pressure suit. “And go easy. Remember we’re that much further from the Lump’s center of mass; gravity is only about half what it is in the City.”