The devices and human-analogues had been tiny, like finely jewelled toys.
The human-analogues and their devices swarmed to a magnetic pole of the neutron star, and great machines were erected there: discontinuity-drives, perhaps powered by the immense energy reserves of the neutron star itself.
Slowly at first, then with increasing acceleration, the neutron star — dragging its attendant companion, ring and planets with it — was forced out of its parent galaxy and thrown across space, a bullet of stellar mass fired at almost light speed.
“A bullet. Yes.” In the pod, Uvarov mused. “An apt term.”
Lieserl stared at the swirling, unresolved pixels inside the Virtual image’s clear tetrahedral frame. “I wonder if there are still people in there,” she said.
Mark frowned. “Where?”
“People-analogues. Inside the neutron star. I wonder if they’ve survived.”
He shrugged, evidently indifferent. “I doubt it. Unless they were needed for maintenance, they would surely have been shut down after their function was concluded.”
Shut down… But these were people. What if they hadn’t been “shut down”? Lieserl closed her eyes and tried to imagine. How would it be, to live her life as a tiny, fish-like creature less than a hair’s-breadth tall, living inside the flux-ridden mantle of a neutron star? What would her world be like?
“A bullet,” Uvarov said again. “And a bullet, fired by our forebears — directly at the heart of this Xeelee construct.”
She opened her eyes.
Mark was frowning. “What are you talking about, Uvarov?”
“Can’t you see it yet? Mark, what do you imagine the purpose of this great engineering spectacle was? We already know from the Superet data, and the fragments provided to us by Lieserl — that the rivalry between humanity and Xeelee persisted for millions of years. More than persisted — it grew in that time, becoming an obsession which — in the end — consumed mankind.”
Lieserl said, “Are you saying that all of this — the discontinuity engines, the hurling of the neutron star across space — all of this was intended as an assault on the Xeelee?”
“But that’s insane,” Mark said.
“Of course it is,” Uvarov said lightly. “My dear friends, we’ve plenty of evidence that humanity isn’t a particularly intelligent species — not compared to its great rivals the Xeelee, at any rate. And I have never believed that humanity, collectively, is entirely sane either.”
“You should know, Doctor,” Mark growled.
“I don’t understand,” Lieserl said. “Humans must have known about the photino birds — damn it, I told them! They must have seen what danger the birds represented to the future of all baryonic species. And they must have seen that the Xeelee — if remote and incomprehensible — were at least baryonic too. So the goals of the Xeelee, if directed against the birds, had to be in the long-term interests of mankind.”
Uvarov laughed at her. “I’m afraid you’re still looking for rational explanations for irrational behavior, my dear. Lieserl, I believe that the Xeelee grew into the position in human souls once occupied by images of gods and demons. But here, at last, was a god who was finite — who occupied the same mortal realm as humans. A god who could be attacked. And attack we did: down through the long ages, while the stars went out around us, all but ignored.”
“And so,” Mark said grimly, “we fired off a neutron star at the Ring.”
“A spectacular gesture,” Uvarov said. “Perhaps humanity’s greatest engineering feat… But, ultimately, futile. For how could a mere neutron star disrupt a loop of cosmic string? And besides, the Xeelee starbreaker technology was surely sufficient to destroy the star before — ”
“But it didn’t work,” Lieserl said slowly.
Mark had been staring at the sensor ’bot; the squat machine had come to a halt before the chair, its sensor arms suspended in the air. “What do you mean?”
“Think about it,” she said. “The neutron star is heading away from the site of the Ring. And it’s clearly not been disrupted by starbreakers.”
“Yes. So something went wrong,” Uvarov said. “Well, the precise sequence hardly matters, Lieserl. And — ”
It happened in a heartbeat.
The light died. The ancient structure was flooded with darkness.
Louise and Mark left the improvised hospital and found an abandoned house. The house was bereft of furniture, its owners gone to live in the zero-gee sky (but, of course, the zero-gee dwellings were gone now, Louise noted morosely, swept out of the sky by the cosmic string incursion).
Mark quickly created a Virtual diagram in the air: a geometrical sketch of lines and angles, lettered and arrowed.
Louise couldn’t help but smile. “Lethe, Mark. At a time like this, you give me a diagram Euclid would have recognized.”
He looked at her seriously. “Louise, working out the spacetime geometry of a cosmic string is a hard problem in general relativity. But, given that geometry, all the rest of it is no more than Pythagoras’ theorem…
“As near as I can figure out, this is what Spinner is up to.” There was a pair of tubes in the air, glowing electric blue, like neon. “We are flying around a pair of cosmic strings. Now, here are the angle deficits of the strings’ conical spacetimes.” Wedges of air, like long cheese slices, were illuminated pale blue; one wedge trailed each string length.
“Okay. Here comes the Northern.” The ship was represented by a cartoon sketch of a sycamore seed in black. “You can see we’re traveling on a curving path around the string pair, going against the strings’ own rotation.”
Now the seed arced into the wedge-shaped angle deficit glow of one of the strings. As soon as it had entered the boundary it vanished, to reappear instantly at the far side of the deficit.
Mark snapped his fingers. “See that? Faster-than-light traveclass="underline" a spacelike trajectory right across the deficit.”
Now the little ship-model came arcing back and flickered through the second string’s angle deficit. “Louise, the strings are traveling just under the speed of light — within three decimal places of it, actually. Spinner has the Northern traveling at a little over half lightspeed. The turning curves, and the accelerations, are incredible… The domain wall inertial shielding seems to be working pretty well, although there’s a little leakage.”
Louise nodded. “Right. Which is why the Northern is complaining.”
“Yeah. Louise, the Northern wasn’t designed for this — and neither was our bastardized lash-up of Northern and nightfighter. But there’s nothing we can do. We’ll just have to pray the whole mess holds together until Spinner-of-Rope finishes her joy-riding…
“Anyway, the trajectory she’s following is quite precisely machined… We’re passing from side to side of the string pair in light-minutes, but we’re crossing light-years thanks to the spacelike savings. Louise, I think Spinner-of-Rope is assembling closed timelike curves, from these spacelike trajectories.”
Louise stared at the seed-craft; she felt an impulse to reach out and pluck it from the air. “But why, Mark? And how?”
“I know what a closed timelike curve is,” Spinner said. Again she dragged the ship to a halt and whirled its nose around toward the string; although she was still shielded from the impossible accelerations she felt herself gasp as the Universe lurched around her. “The original mission of the Great Northern, with its wormhole, was to follow a segment of a closed timelike curve…”