Yatima performed an elated backflip through the layered ocean, and found verself upside down. "Let me kiss your feet. You're a genius."

Blanca laughed, a remote sound from a hidden part of vis body. "It was a trivial problem. If you weren't rushing like a flesher, you would have solved it yourself long ago.

Yatima shook vis head. "I doubt it." Ve hesitated. "So do you think the Transmuters could have—?"

"Migrated? Upward! Why not? It's a closer escape route than heading for Andromeda."

Yatima tried to imagine it: a Diaspora into the macrosphere. "Wait. If our whole universe, our whole space-time, is the standard fiber for macrosphere physics, then our entire history only corresponds to an instant of macrosphere time. Their equivalent of a Planck moment. So how could the Transmuters create a sequence of particles, spread out in time?"

Blanca gestured at a portion of the catalyst. "Look more closely at this domain. Macrosphere space-time is woven out of vacuum wormholes, just like ours. It's the same kind of Kozuch-Penrose network, only five-plus-one dimensions instead of three-plus-one." Yatima righted verself for a better view, and peered at the multi-lobed knot Blanca was pointing to; it seemed to hook into the ghostly structures of the vacuum like a grapple. "They've pinned our time to macrosphere time. What would have been a fleeting Planck moment endures as a kind of singularity. And that singularity can emit and absorb particles in macrosphere time."

Yatima's mind was reeling. The Transmuters hadn't indulged in any of the spectacular acts of astrophysical monument-building that a bored and powerful civilization might have gone in for: no planet-sculpting, no Dyson spheres, no black-hole juggling. But by tailoring a few neutrons on this obscure planet, they'd hitched the entire universe into synch with the time stream of an unimaginably larger structure.

"Wait. You said emit… and absorb? What happens if the singularity absorbs a macrosphere particle?"

"A small proportion of the catalysts change state. Which causes a small proportion of the long neutrons here to undergo beta decay, even if they're in supposedly stable nuclei. If you monitored a ton of Swift's atmosphere, you could detect absorption events with an efficiency of about one in ten billion." Yatima had positioned vis viewpoint in the same layer as Blanca's head, and ve caught a characteristic tilt of amusement. "So it might be worth trying. The Transmuters' macrosphere clones could be blasting messages at the singularity even as we speak."

"After a billion years? I doubt it. But they might still be nearby; the originals would have fled the galaxy, but the clones would have had no special reason to travel far from the singularity. So if we went into the macrosphere ourselves, we might still have a good chance of finding them."

If they could make contact with the Transmuters, they'd have a chance to learn the reasons for both Lacerta and the core burst, helping to convince the skeptics to protect themselves. And if there was no other choice, anyone who was willing could hide in the macrosphere to escape the burst.

Yatima was beginning to feel a kind of vertigo. The Fomalhaut Blanca's remote, hypothetical, six-dimensional universe of universes had suddenly become as real as the space of the Diaspora itself. As real, and perhaps accessible. For a space-faring civilization to step into the macrosphere was like a bacterium in a rain drop finding a way to stride across continents—and there was a vestigial ancestral temptation to respond to the scale and strangeness of this revelation with paralytic awe. Yatima struggled to concentrate on the practicalities.

"If we could work out macrosphere physics in enough detail, do you think we could cause the singularity to emit a stream of particles that coalesced into a functioning C-Z clone? Or maybe we could start with a cloud of raw materials, then create nanomachines to fabricate the polis?"

Blanca said, "You're going to need something more like femtomachines, I think. Femtomachines larger than the universe. Do you want the laws of macrosphere physics?" Ve moved down through the scape a few layers, then reached into the blue colloid. As Yatima approached, Blanca opened vis dark palm to expose a single blue speck, which was radiating a gestalt tag.

"What is this?"

"Five spatial dimensions, one time. A 4-sphere as the standard fiber. Physics, chemistry, cosmology, the bulk properties of matter, interactions with radiation, some possible biologies… everything."

"When did you do this?"

"I've had a lot of time, Orphan. I've explored a lot of worlds." Ve spread vis arms to encompass the whole scape. "Every point you see is a different set of rules." Ve ran a hand below the blue sheer from which ve'd plucked the macrosphere rules, "These are six-dimensional space-times. Below is five. Notice how its thinner. But seven is thinner too. Even numbers of dimensions have richer possibilities."

The speck had escaped from Blanca's hand and was drifting hack toward its place in the indexscape, but Yatima had memorized the tag.

"Will you come with me, Blanca? Into the macrosphere?"

Blanca laughed, swimming in worlds, drowning in possibilities.

"I don't think so, Orphan. What would be the use? I've already seen it."

Part Six

Yatima said, "Blanca should he with us. Orlando should be with us."

Paolo laughed. "Orlando would be miserable here."

"Why? Traveling in any kind of scape he liked, with all the comforts of home…"

"You don't know Orlando as well as you think."

"No? Enlighten me."

15

5+1

Carter-Zimmerman polis. Swift orbit

85 803 052 808 071 CST

3 April 4953, 4:33:25.225 UT

A megatau before the cloning, Paolo finally managed to drag Orlando along to the Great Macrosphere Exhibition. A group of physicists had set up the scape, a long hall with an arched roof of leaded glass ribbed with wrought iron, packed with demonstrations of those features of the macrosphere that could be predicted with reasonable confidence. Although Orlando was determined to be part of the expedition, he seemed daunted by the prospect of confronting the exotic reality that the new C-Z clone would inhabit.

Paolo surveyed the hall. Less than a hundred citizens had decided to be cloned, but half the polis had been through the Exhibition. It was almost deserted now, though, and the angle of the light, cued to the number of visitors, gave an impression of late afternoon.

They approached the first exhibit, a comparison of gravity wells in three and five dimensions. The gridded surfaces of two circular tables had been made magically elastic in such a way that placing small spherical weights on them produced funnel-shaped indentations, with the effects of the gradient in each case mimicking the gravitational force around a star or planet in the different universes. The force diminished with distance as if it was being spread out over, respectively, an ever larger two-dimensional surface, producing an inverse-square law, or a four-dimensional hypersurface, yielding a visibly steeper inverse-fourth-power effect. It was a simplified pseudo-Newtonian model, but Paolo wasn't about to scoff; he'd found Blanca's rigorous six-dimensional space-time curvature treatment heavy going, and he'd skimmed over the hard parts where the Einstein tensor equation was derived by approximating the interactions between massive particles and virtual gravitons.