Diaspora

Elena said, "No, but if they'd collapsed that set of histories at random, the most likely result would have been a singularity out in intergalactic space. So either they were very lucky, or they were able to bias the collapse."

"I say they biased the collapse. Using the shape of the wormhole. Making it bind preferentially to a certain level of gravitational curvature."

"Perhaps." Elena laughed, frustrated. "One more question to ask, if we ever catch up with them."

Paolo glanced at their destination, Noether, a hot, ultraviolet-tinged star with two waterless terrestrial planets. The Transmuters might well have chosen to settle in this four-dimensional universe in preference to the first macrosphere, but Paolo didn't have high hopes that they would have picked the Noether system as their new home; when they'd arrived, it wouldn't even have been the closest star, let alone the most hospitable. If these planets were deserted, it would only take one more singularity slip to eliminate any possibility of finding the Transmuters in time. He'd suggested to Orlando that many citizens would probably be willing to take refuge in the macrosphere, regardless; after all, if the neutron map had been misinterpreted and it was all a false alarm, there'd be nothing to stop them returning. Orlando had not been impressed. "A handful of people isn't enough. We have to convince everyone."

A segmented worm with six flesher legs appeared in the scape, winding its way around the girder. Paolo startled; the icon was exactly like Herma

Paolo turned to Elena. "Is this some kind of juke"'

She looked at Karpal; he shook his head. "Not unless the joke's on all of us."

The worm drew nearer, eye-stalks quivering. Elena called out, "Who are you?" Anyone was welcome in Satellite Pinatubo, but appearing without a signature was very poor etiquette.

The worm replied, in Herma

Karpal asked coolly, "Are you Herma

"No."

"Then we'd rather not call you Herma

The worm tipped its head from side to side, in a very Herma

Elena said, "We'd rather not call you that either. Who are you?"

The worm looked dejected. "I don't know what kind of answer you require."

Paolo examined the icon carefully, but there was no clue to its true nature. Some very odd programs ran in crevices of the polis, all of them supposedly well-understood and constrained, but over the mille

"I'm a Contingency Handler."

Paolo had never heard of such a thing. "You're not sentient?"

"No."

"Why are you using our friend's icon?"

"Because you know I can't be him, so that should cause the least confusion." The worm almost succeeded in making this sound reasonable.

Karpal asked, "Why are you talking to us at all?"

"One of my functions is to greet new arrivals."

Paolo laughed. "Elena and I are home-born, and if you're Karpal's automatic welcoming party, you're fifteen hundred years too late."

Elena took Paolo's hand and spoke to him privately. "I don't think it means new arrivals to C-Z."

Paolo stared at the worm. It waved its eye-stalks endearingly. "Where did you originate? What part of the polis?"

It seemed to have trouble parsing the question. It replied tentatively, "The outside part?"

"I don't believe you." He turned to Elena. "Come on! This is a hoax! How could anyone break into the hardware in interstellar space, enter a scape, and imitate Herma

The worm said, "Your data protocols were easy to determine from inspection. The appearance of Herma

Paolo felt his certainty wavering. The Transmuters might be able to do it: read and decode the whole polis in mid-flight, laying bare their nature, their language, their secrets. Their Orphean selves had done as much with the carpets, short of actively entering the squid's world and making contact with them.

Elena asked the worm, "Who created you?"

"Another Contingency Handler."

"And who created that?"

"Another Contingency Handler."

"How many Contingency Handlers are there in this chain?"

"Nine thousand and seventeen."

"And then what?"

The worm pondered the question. "You're not interested in any level of non-sentient software, are you!!!"

Elena replied patiently, "We're interested in everything, but first we'd like to know about the sentient beings who created the system that spawned you."

The worm waved one leg at the sky. "They evolved on a planet, but they're more diffuse now, each individual spread out across the space between a million stars. That makes them much slower to act than you, which is why they can't greet you in person."

Karpal asked, "A planet in this universe?"

"No. They came here in the same ma

Paolo was growing skeptical again. Maybe this was Herma

He said sarcastically, "Seven levels? Why so few?"

"That was the length of their journey. They chose to stop here."

"But there are more levels? They could have gone further?"

"Yes."

"How can you know that?"

The worm replaced the diagram with another, showing two neutron stars in orbit. "The fate of such a system puzzles you?" It gazed at Paolo earnestly; he nodded, unable to reply. Not even Herma

The neutron stars circled each other slowly, confined to a translucent plane representing their universe. The worm added two more planes, above and below, with stars drifting across them at random: adjacent universes, separated by one quantum of distance in the macrospherean dimensions. "The interaction between these universes is very weak, but there are critical values of angular momentum where it reaches a maximum."

Karpal interjected angrily, "We know that! But it's too weak to explain Lac G- 1! The effect is orders of magnitude less than gravitational radiation. And there's no chance of a runaway spiral; once the system loses angular momentum and falls below the critical value, the coupling strength plummets and the whole process becomes even slower!"

The worm said, "With one or two levels, or six or seven, that would be true. A tiny amount of angular momentum would be lost due to random interactions with bodies in adjacent universes, and the effect would be insignificant. But each four-dimensional universe is not surrounded merely in six dimensions by adjacent universes in the same macrosphere. Nor is it surrounded only in ten dimensions, by universes in other macrospheres. There are an infinite number of levels, an infinite number of extra dimensions. So every four-dimensional universe interacts with an infinite number of adjacent universes."

The two extra planes in the diagram doubled into four, then eight, boxing the orbiting neutron stars in a cube. Then the cube mutated into a series of polyhedrons with an ever-increasing number of faces, each face representing part of an adjacent universe. The polyhedrons blurred into a sphere, swarming with stars passing "nearby" in a continuum of neighboring universes—all of them weakly tugging on the neutron-star binary.