The Qax said, "The Governor will remain conscious for some hours, although its sentience is diminishing already."

"Is there pain?"

"Our business is concluded here. Return to your craft."

Barely able to see through a sheen of ocean-stuff, Parz reached for the shelter of the flitter.

The GUT ship Hermit Crab swept backside-first through a powered orbit around the swollen cheek of Jupiter.

Michael Poole sat in the Crab’s clear-walled lifedome with the Virtual of his father, Harry. The ship was rounding the dark side of the planet now, and the GUT drive, blazing a mile beneath the transparent floor of the cabin, illuminated vast areas of that ocean of swirling cloud. Violet light was cast upward through the cabin, and Poole noticed how his father’s young, blond head had been given suitably demonic shadows in response.

"We’re making quite an entrance," Harry said.

"I guess so. If you like fireworks."

Harry turned to his son, his blue eyes boyishly wide with wonder. "No, it’s more than that. You’re the physicist, son, and I’m just a government functionary; and you’ll understand it all better than I ever could. But maybe the wonder of it doesn’t hit you with the same impact as a layman like me. We’re harnessing forces lost to the universe since the first few seconds after the Big Bang—"

"Essentially. Except that you’re talking about the first few fractions of a second…"

"GUT" stood for Grand Unified Theory, the philosophical system that described the fundamental forces of nature as aspects of a single superforce. The heart of the Crab’s GUT drive was a fist-sized chunk of hydrogen locked into a superconducting bottle and bombarded to creation physics temperatures. At such temperatures only the unified superforce could act. When hydrogen was bled from the bottle the superforce went through "phase transitions," decomposing into the four familiar forces of nature — strong and weak nuclear, gravitational, and electromagnetic.

And just as steam releases heat when it goes through a phase transition by condensing to water, so at each transition of the superforce a pulse of energy was emitted.

Poole said to his father, "The Crab uses GUT phase energy to flash comet ice to plasma; the superheated plasma is expelled through a superconducting nozzle…"

Harry nodded, peering down the mile of superstructure to the residual lump of comet that had brought them in from the Oort Cloud. "Sure. But it was that same phase transition energy, liberated during the cooling period after the Big Bang, which drove the expansion of the universe itself.

"That’s what seems so awesome, when you stop and think about it, Michael. We’ve spent a year scooting around the Solar System — and now we’re making Jupiter himself cast a shadow — and we’re doing it by harnessing the energies of creation itself. Doesn’t it make you wonder?"

Poole rubbed the side of his nose. "Yes, Harry. Of course it does. But I don’t actually think that sort of attitude is going to help us all that much, in the next few days. I’d rather not feel awed by the workings of our own drive, right now. Remember we’re going to be dealing with humans from fifteen centuries into the future… for all I know, with artificial life-forms, or with aliens, even."

Harry leaned closer to Poole and grinned. "Not all of us AIs are such terrible things, Michael."

Poole narrowed his eyes. "Push your luck and I’ll pull your plug."

Harry grumbled, "Maybe these superpeople from the future will be advanced enough to recognize the rights of AIs. Such as the right to continuous consciousness, for instance. Anyway, I know it’s all talk with you."

"If you don’t get your fingers out of my head, then I’ll shut you down talk or not, you old fart."

An alarm chimed through the lifedome. The Crab, sailing barely a thousand miles over a sea of purple clouds, was near its closest approach to the planet; and now the battered old ship swept around the limb of Jupiter and emerged into the light of the distant sun. Sol, shrunken by distance, lifted through layers of clouds at Jupiter’s flat-infinite horizon; for a few seconds there was a dazzling impression of the depth of the Jovian atmosphere as clouds cast thousand-mile-long shadows over each other. The cabin was flooded with brilliance. For a second Harry’s Virtual image retained the purplish shadows cast from the cabin floor by the drive. Then the processor caught up and when Harry turned his face to the sun his profile was highlighted in yellow.

Then, like a second, angular dawn, the Interface portal hurtled over the horizon toward them. Michael could see the firefly sparks of ships circling the portal, waiting for any new intrusion from the future. The Crab’s trajectory took her to within a few dozen miles of the portal; Michael stared out at the dazzling sky-blue of the portal’s exotic tetrahedral frame, let his eyes linger over those cool lines and be drawn effortlessly to the geometrically perfect vertices. The faces were like semitransparent panes of silvered glass; he could make out the watercolor oceans of Jupiter through the faces, but the cloud images were overlaid with a patina of silver-gold and were distorted, swirled around in a fashion the eye could not quite track, like visions in a dream. And every few seconds a face would abruptly clear, just for a dazzling moment, and afford Michael a glimpse of another space, unfamiliar stars, like a hole cut into Jupiter.

The Crab swept on and away from the artifact; it dwindled rapidly behind them like an abandoned toy.

"My God," Harry breathed. "I didn’t know how beautiful it was. I thought I could see stars in those faces."

"You could, Harry," Poole said softly. "It really is a gateway to another time, another place."

Harry leaned toward Michael. "I’m very proud of you."

Poole stiffened and pulled away.

Harry said, "Listen, what do you really think we’re going to find out here?"

"Aboard the craft from the future?" Poole shrugged. "Since they haven’t communicated with us apart from that single message from Miriam when they came through the Interface a year ago, it’s difficult even to extrapolate."

"Will humans still be recognizably human, do you think?"

Poole swiveled a glare at Harry. "And are we ‘recognizably human’? Look at us, Harry; I’m an AS immortal, and you’re a semisentient AI."

"Semisentient?"

"Superficially we look human enough, and we’d probably claim to be human, but I don’t know if a man of, say, a thousand years ago would recognize us as members of the same species as himself. And now we’re talking another fifteen centuries down the road…"

Harry wiggled his fingers in the air, pulling his face. "A third arm growing out of the center of the face. Disembodied heads, bouncing around on the deck like footballs. What do you think?"

Poole shrugged. "If gross modifications like that are efficient, or serve a purpose, then maybe so. But I don’t think any of that matters a damn, compared to what’s going on inside their heads. And what they’ve built."

"What about technology?"

"I guess I’d put singularity physics a long way up the list," Poole said. "The manipulation of spacetime curvature… We’ve already got a mastery of high-density, high-energy physics — that’s the heart of the GUT drive, and of the exotic matter that the Interface portals were built of. Exotic matter is mass/energy that is compressed to singularity densities, almost, so that the superforce emerges to bind it together — and then allowed to cool and expand so that the superforce breaks open in a controllable manner, to give us the negative-energy characteristics we want."

"And in fifteen more centuries—" Harry prompted.