The separation of color would be minute, but the effects would be dramatic: the two orbiting, polarized cores would generate powerful jets of mesons, which would act to brake the neutron stars' orbital motion a kind of nuclear analogue of gravitational radiation, but mediated by the strong force and hence much more energetic. The mesons would decay almost at once into other particles, but this secondary radiation would be very tightly focused, and since the view from the solar system was high above the plane of Lac G-1's orbit the beams would never be seen head-on. No doubt they'd become spectacularly visible once they slammed into the interstellar medium, but after only 16 days they'd still he traveling through the region of relatively high vacuum that the neutron stars had swept clean over the last few billion years.

The whole system would be like a giant Catherine wheel in reverse, with the fireworks pointing backward, opposing their own spin. But as they bled away the angular momentum that kept them apart, gravity would draw them tighter and they'd whip around faster. The nanosecond glitches in the past might have involved small pools of mobile quarks forming briefly, then freezing back into distinct neutrons again, but once the cores melted completely it would be a runaway process: the closer the neutron stars came to each other, the greater their polarization, the stronger the jets, the more rapid their inward spiral.

Karpal knew that the calculations needed to test this idea would be horrendous. Dealing with interactions between the strong force and gravity could bring the most powerful computer to its knees, and any software model accurate enough to he trusted would run far slower than real time, making it useless for predictions. The only way to anticipate the fate of Lac G-1 was to try to see where the data itself was heading.

He had the analysis software fit a smooth curve through the neutron stars' declining angular momentum, and extrapolate it into the future. The fall grew faster, gently at first, but it ended in a steep descent. Karpal felt a cool horror wash through him: if this was the ultimate fate of every binary neutron star, it helped make sense of an ancient puzzle. But it was not good news.

For centuries, astronomers had been observing powerful gamma-ray bursts from distant galaxies. If these bursts were due to colliding neutron stars, as suspected, then just before the collision—when the neutron stars were in their closest, fastest orbits—the gravitational waves produced should have been strong enough for TERAGO to pick up over a range of billions of light years. No such waves had ever been detected.

But now it looked as though Lac G-1's meson jets would succeed in bringing the neutron stars' orbital motion to a dead halt while they were still tens of thousands of kilometers apart. The Catherine wheel's fireworks, having finally triumphed, would sputter out, and the end wouldn't be a frenzied spiral after all, but a calm, graceful dive—generating only a fraction as much gravitational radiation.

Then the two mountain-sized star-heavy nuclei would slam straight together, as if there'd never been a hint of centrifugal force to keep them apart. They'd fall right out of each other's sky—and the heat of the impact would be felt for a thousand light years. Karpal dismissed the image angrily. So far, he had nothing but a three-minute anomaly in an orbital period, and a lot of speculation. What was his judgment worth, after nine years of solitude and far too many cosmic rays? He had to get in touch with colleagues in the asteroid belt, show them the data, and talk through the possibilities calmly.

But if he was right? How long did the fleshers have before Lacerta lit up with gamma rays, six thousand times brighter than the sun?

Karpal checked and re-checked the calculations, fitted curves to different variables, tried every known method of extrapolation.

The answer was the same every time.

Four days.

5

BURSTER

Konishi polis, Earth

24 046 380 271 801 CST

5 April 2996,21:17:48.955 UT

Yatima floated in the sky above vis homescape, surveying the colossal network that sprawled across the hidden ground as far as ve could see. The structure was ten thousand delta wide and seven thousand high; winding around it was a single, elaborate curve, which looked a bit like one of the roller coaster rides ve'd seen in Carter-Zimmerman—and which ve'd ridden with Blanca and Gabriel, for the visual thrill alone. The "track" here was unsupported, just like the one in C-Z, but it weaved its way through what looked like a riot of scaffolding.

Yatima descended for a closer inspection. The network, the "scaffolding," was a piece of vis mind, based on a series of snapshots ve'd taken a few megatau before. The space around it glowed softly in a multitude of colors, imbued with an abstract mathematical field, a rule for taking a vector at any point and calculating a number from it, generated by the billions of pulses traveling along the network's pathways. The curve that wrapped the network encircled every pathway, and by summing the numbers that the field produced from the tangents to the curve along its entire length, Yatima was hoping to measure some subtle but robust properties of the way information flowed through the structure.

It was one more tiny step toward finding an invariant of consciousness: an objective measure of exactly what it was that stayed the same between successive mental states, allowing an ever-changing mind to feel like a single, cohesive entity. The general idea was old, and obvious: short-term memories had to make sense, accumulating smoothly from perceptions and thoughts, then either fading into oblivion or drifting into long-term storage. Formalizing this criterion was difficult, though. A random sequence of mental states wouldn't feel like anything at all, but neither would many kinds of highly ordered, strongly correlated patterns. Information had to flow in just the right way, each perceptual input and internal feedback gently imprinting itself on the network's previous state.

When Inoshiro called, Yatima didn't hesitate to let ver into the scape; it had been far too long since they'd last met. But ve was bemused by the icon that appeared in the air beside ver: Inoshiro's pewter surface was furrowed and pitted, discolored with corrosion and almost flaking away in places; if not for the signature, Yatima would barely have recognized ver. Ve found the affectation comical, but kept silent; Inoshiro usually viewed the fads to which ve subscribed with appropriate irony, but occasionally ve turned out to be painfully earnest. Yatima had been persona non grata for almost a gigatau after mocking the practice, briefly fashionable across the Coalition, of carrying around a framed portrait of one's icon "aging" in fast-motion.

Inoshiro said, "What do you know about neutron stars?"

"Not a lot. Why?"

"Gamma-ray bursters?"

"Even less." Inoshiro looked serious underneath all the rust, so Yatima struggled to remember the details from vis brief flirtation with astrophysics. "I know that gamma rays have been detected from millions of ordinary galaxies—one-off flashes, rarely from the same place twice. The statistics come down to something like one per galaxy per hundred thousand years… so if they weren't bright enough to be seen a few billion light years away, we probably wouldn't even know about them yet. I don't think the mechanism's been conclusively established, but I could check in the library—"

"There's no point; it's all out-of-date. Something's happening, outside."