The pattern continued in the tenth macrosphere, the eleventh, the twelfth. The artifacts changed shape, slightly. Ten or twenty percent of the bits in all the exabytes they sampled at corresponding positions were different.
Paolo said, "They're like rows of tiles from the Orphean carpets. Only we don't know the dynamics, we don't know the rules to get from frame to frame."
Yatima contemplated the prospect of trying to work it all out by inspection. "This is hopeless. We should stop poring over every artifact, trying to deduce the nature of the Transmuters from their technology."
Paolo nodded soberly. "I agree. The quickest way to understand what these things are for will be to ask their makers."
They automated the process, and had their exoselves rush, freeze, and clone them as necessary. They granted themselves eight-dimensional senses, and sat on the girders of an 8-scaped Satellite Pinatubo, watching perpendicular pairs of slender three- and five- dimensional artifacts rotate in and out of view. It was like whirling around a spiral staircase running from macrosphere to macrosphere, dimension to dimension.
As they reached the ninety-third level, contact was lost between the polis and the singularity on the twelfth.
On the two-hundred-and-seventh level, the twenty-sixth singularity slipped ten thousand years.
Yatima felt a surge of panic. "We're fools. This will go on forever. They're one step ahead of us, making these things as fast as we can jump.
"You don't believe that. Didn't you tell me, back at Swift, that you were sure they weren't malicious?"
"I've changed my mind."
They agreed to silence the software that reported breaks in the chain; if they had no intention of turning hack, there was no point being distracted by had news.
The artifacts mutated, slowly.
Then, past the trillionth level, there were suddenly two in every universe. Locked rigid in relative position, despite being separated by hundreds of kilometers of vacuum.
Yatima asked Paolo, "Do you want to stop and find out how that's done?"
"No."
They couldn't change the real time it took to complete each link, but they rushed ever faster, until they were perceiving only every tenth, every hundredth, every thousandth level.
A third artifact appeared, then a fourth.
Then they all drifted together, level by level, and merged.
One by one, three new artifacts appeared, all drawing closer to the large central one. Just as they began to fuse with it, a fourth budded off. The large artifact changed shape, becoming more spheroidal. It shrank, grew, shrank, vanished. The fourth of the second set of smaller artifacts—roughly the size of the very first, back in the sixth macrosphere was all that remained.
It persisted for ten trillion more levels, changing only slightly, then abruptly shrank to a tenth, a hundredth its original size.
Then it vanished.
Their ascent halted.
The last singularity—267,904,176,383,054 levels from the home universe—was in empty interstellar space.
They converted the scape and themselves back to three-dimensional versions, and looked around. They were in the plane of a spiral galaxy, and a band of stars wrapped the sky like the lost Milky Way. Paolo swayed on a girder, laughing.
Yatima checked with the observatory. There were no new Swifts in sight, no new long-neutron gateways leading upward. If the Transmuters were anywhere, they were here.
"What now? Where do we look for them?"
Paolo swung around the girder he was holding, then launched himself into space. He tumbled drunkenly away from the satellite, then violated the physics and came spinning back.
He said, "We look right in front of us."
"There's nothing in front of us."
"Not now. Because it's over. We've seen it all."
"I don't understand."
Paolo closed his eyes and forced out the words. The artifacts were polises. What else could they have been? But instead of changing the data in one fixed polis… they kept building new ones, level after level."
Yatima absorbed this. "Then why did they stop?"
"Because there was nothing more to do." Paolo's gestalt seemed to hover between comic agony over the failure of their search, and sheer exaltation at its completion. "They'd seen everything they wanted to see in the outside world—they'd risen through at least six universes—and then they'd spent two hundred trillion clock ticks thinking about it. Building abstract scapes, making art, reviewing their history. I don't know. We'll never decipher it; we'll never know for sure what event on. But we don't need to. Do you want to ransack the data, hunting for secrets? Do you want to rob their graves?
Yatima shook vis head.
Paolo said, "I don't understand the shapes, though. The changes in size, and number."
"I think I do."
Taken together, the artifacts comprised a giant sculpture, spanning more than a quadrillion dimensions. The Transmuters had built a structure that dwarfed universes, but touched each one only lightly. They hadn't turned whole worlds to rubble, they hadn't reshaped galaxies in their image. Having evolved on some distant, finite world, they'd inherited the most valuable survival trait of all.
Restraint.
Yatima played with a model of the sculpture until ve found the right way to assemble it. He converted the scape to five dimensions, then held the figure out to Paolo.
It was a four-legged, four-armed creature, with one arm stretched high above its head. No fingers; perhaps this was a stylized, post-Introdus version of the ancestral form. The tip of one foot was in the sixth macrosphere. The highest point of the Transmuter's raised arm was in the level just beneath them, reaching up.
To the infinite number of levels above. To all the worlds it would never see, never touch, never understand.
They examined the record of communications failures. There'd been more than seven million broken links, and over ninety billion years of identified slippage in total. Statistically, by now it was beyond belief that at least one of the hundreds of trillions of singularities in the chain hadn't been lost by the machinery. And even if they could return to the second macrosphere—or some level above, if that universe had been deserted as its stars ran out of fuel—there'd be nothing for them. The Earth culture they'd known would either have merged with others from the second macrosphere, or simply evolved beyond recognition.
Yatima shut off the flow of gestalt from the log book and looked around the star-filled scape. "What now?"
Paolo said, "The other versions of me would have done everything I'm capable of doing. And lived better lives than any I could make for myself, here."
"We could keep traveling. Search for local civilizations."
"That could he a long, lonely voyage."
"If you want more company, we can always make some."
Paolo laughed. "You do have a beautiful icon, Yatima, but I can't see us making psychoblasts together,
"No." After a while Yatima said, "I'm not ready to stop. Not yet. Are you afraid to die alone?"
"It won't be death." Paolo seemed calm now, perfectly resolved. "The Transmuters didn't die; they played out every possibility within themselves. And I believe I've done the same, back in U-double-star… or maybe I'm still doing it, somewhere. But I've found what I came to find, here. There's nothing more for me. That's not death. It's completion."
"I understand."
Paolo took ancestral form, and immediately started trembling and perspiring. "Ah. Flesher instincts. Bad idea." He changed back, then laughed with relief. "That's better." He hesitated. "What will you do?"