Stephen Baxter - Timelike Infinity

"Well, I’m sorry you don’t approve," Harry said defiantly. "But it’s honest. I’m still human, son."

Michael shook his head, impatient with the sudden jumble of emotions he found stirring inside him. "The hyperdrive," he said sternly. "All right, Harry. How many dimensions does spacetime have?"

Harry opened his mouth, closed it again. "Four. Three space, one time. Doesn’t it? All wrapped up into some kind of four-dimensional sphere—"

"Wrong. Sorry, Harry. There are actually eleven. And the extra seven is what allows the hyperdrive to work…"

The grand unified theories of physics — the frameworks that merged gravitation and quantum mechanics — predicted that spacetime ought to assume a full eleven dimensions. The logic, the symmetry of the ideas, would allow little else.

And eleven dimensions there turned out to be.

But human senses could perceive only four of those dimensions, directly. The others existed, but on tiny scales. The seven compactified dimensions were rolled into the topological equivalent of tight tubes, with diameters well within the Planck length, the quantum limit to measurement of size.

"Well, so what? Can we observe these compactified tubes?"

"Again, not directly. But, Harry, looked at another way, the tubes determine the values of the fundamental physical constants of the universe. The gravitational constant, the charge on the electron, Planck’s constant — the uncertainty scale—"

Harry nodded. "And if one of these tubes of compactification were opened up a little—"

" — the constants would change. Or," said Michael significantly, "vice versa."

"You’re getting to how the hyperdrive works."

"Yes… As far as I can make out, the hyperdrive suppresses, locally, one of the constants of physics. Or, more likely, a dimensionless combination of them."

"And by suppressing those constants—"

" — you can relax the compactification of the extra dimensions, locally, at least. And by allowing the ship to move a short distance in a fifth spacetime dimension, you can allow it to traverse great distances in the conventional dimensions."

Harry held up his hands. "Enough. I understand how the hyperdrive works. Now tell me what it all means."

Michael turned to him and grinned. "Okay, here’s the plan. We enter the Interface, travel into the wormhole—"

Harry winced. "Let me guess. And then we start up the hyperdrive."

Michael nodded.

The Interface portal was immense over them, now; one glimmering pool of a facet filled Michael’s vision, so close that he could no longer make out the electric blue struts of exotic matter that bounded it.

"Three minutes away," Harry said quietly.

"Okay." As an afterthought Michael added: "Thanks, Harry."

"Michael — I know this won’t, and mustn’t, make a damn bit of difference — but I don’t think there’s any way I can survive this. I can’t function independently of the Spline anymore; I’ve interwoven the AI functionalities of Spline and Crab so much that if one fails, so must the other…"

Michael found himself reaching out to the Virtual of his father; embarrassed, he drew his hand back. "No. I know. I’m sorry, I guess. If it’s any consolation I’m not going to live through it either."

Harry’s young face broke up into a swarm of pixels. "That’s no consolation at all, damn you," he whispered distantly.

The Interface was very close now; Michael caught fugitive reflections of the Spline in that great, glimmering face, as if the facet were some immense pool into which the warship was about to plunge.

Harry crumbled into pixel dust, re-formed again, edgily. "Damn those drones," he grumbled. "Look, Michael, while there’s enough time there’s something I have to tell you—"

The intrasystem freighter settled over the battered, gouged-out Spline eyeball. Cargo bay doors hung open like welcoming lips, revealing a brightly lit hold.

The eye bumped against the hold’s flat ceiling, rebounding softly; a few yards of chewed-up optic nerve followed it like a grizzled umbilical remnant, wrapping itself slowly around the turning eye. Then the hold doors slid shut, and the eye was swallowed.

In an airlock outside the hold, Miriam Berg pressed her face to a thick inspection window. She cradled a heavy-duty industrial-strength hand laser, and her fingers rattled against the laser’s casing as the hold’s pressure equalized.

She cast her eyes around the scuffed walls of the hold with some distaste. This was the Narlikar out of Ganymede, an inter-moon freighter run by a tinpot two-man shipping line. She knew she shouldn’t expect too much of a ship like this. The D’Arcy brothers performed a dirty, dangerous job. Normally this hold would contain water ice from Ganymede or Europa, or exotic sulfur compounds excavated with extreme peril from the stinking surface of Io. So that would explain some of the stains. But sulfur compounds didn’t scratch tasteless graffiti onto the hold walls, she thought. Nor leave sticky patches and half-eaten meals all over — it seemed — every work surface. Still, she was lucky there had been even one ship in the area with the capacity to come and pick up this damn eyeball so quickly. Most of the ships in the vicinity of the Interface portal were clean-lined government or military boats — but it had been the D’Arcy brothers, in their battered old tub, who had come shouldering through the crowd to pick her up from the earth-craft in answer to the frantic, all-channel request she’d put out when she’d realized what Poole was up to.

She watched the Spline eyeball bounce around in the hold’s thickening air. It was like some absurd beachball, she thought sourly, plastered with dried blood and the stumps of severed muscles. But there was a clear area — the lens? — through which human figures, tantalizing obscure, could be seen.

Michael…

Now a synthesized bell chimed softly, and the door separating her from the hold fell open. Towing the laser, Berg threw herself into the eyeball-crowded hold.

The air in the hold was fresh, if damn cold through the flimsy, begrimed Wignerian one-piece coverall she’d been wearing since before the Qax attack. She took a draught of atmosphere into her lungs, checking the pressure and tasting the air -

"Jesus."

— and she almost gagged at the melange of odors that filled her head. Maybe she should have anticipated this. The gouged-out Spline eyeball stank like three-week-old meat — there was a smell of burning, of scorched flesh, and subtler stenches, perhaps arising from the half-frozen, viscous purple gunk that seemed to be seeping from the severed nerve trunk. And underlying it all, of course, thanks to her hosts the D’Arcys, was the nose-burning tang of sulfur.

Every time the eyeball hit the walls of the hold, it squelched softly.

She shook her head, feeling her throat spasm at the stench. Spline ships; what a way to travel.

After one or two more bounces air resistance slowed the motion of the sphere. The eyeball settled, quivering gently, in the air at the center of the hold.

Beyond the Spline’s clouding lens she could see movement; it was like looking into a murky fishtank. There was somebody in there, peering out at her.

It was time.

Her mind seemed to race; her mouth dried. She tried to put it all out of her head and concentrate on the task in hand. She raised her laser.

The D’Arcys, after picking her up from the earth-craft, had loaned her this hand laser, a huge, inertia-laden thing designed for slicing ton masses of ore from Valhalla Crater. Callisto. It took both hands and the strength of all her muscles to set the thing swinging through the air to point its snoutlike muzzle at the Spline eyeball, and all her strength again to slow its rotation, to steady it and aim. She wanted to set the thing hanging in the air so that — with any luck — she’d slice tangentially at the eyeball, cutting away the lens area without the beam lancing too far into the inhabited interior of the eyeball. Once the laser was aimed she swam over to the eyeball; pressing her face as close to the clouding lens as she could bear, she peered into the interior of the ball. There were two people in there, reduced to little more than stick figures by the opacity of the dead lens material. With her open palm she slapped at the surface of the lens — and her hand broke through a crustlike surface and sank into a thick, moldering mess; she yanked her hand away, shaking it to clear it of clinging scraps of meat. "Get away from the lens!" She shouted and mouthed the words with exaggerated movements of her lips, and she waved her hands in brushing motions.