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.
The exhibit said, 'These diagrams show the pure gravitational potential, which always produces an attractive force.' A disembodied hand appeared and placed a small test particle at the edge of each well, with predictable consequences: both particles fell straight in. 'Starting from rest, a collision is unavoidable. But if there's any sideways motion, that alters the dynamics completely.' The hand placed a particle on the rim of the first well, but this time gave it a flick that sent it into an elliptical orbit around the central weight.
'The best way to see what's really going on is to follow the body along its orbit.' The surface's grid pattern began to spin, tracking the particle, and as it did the shape of the well changed dramatically: the center of the funnel inverted into a tall, steep spike, raising the weight above the surrounding surface. 'In a rotating reference frame, the centrifugal force for a given amount of angular momentum acts like an inverse-cube repulsion.' Inverse-cube conquered inverse-square for small distances, so centrifugal force won out over gravity near the center; the star or planet from the bottom of the well was now high on a summit. The outer region of the funnel continued to slope down, though, so there was a circular trench around the spike where this initial fall in the surface reversed into a climb.
The patches of floor on which they were standing began to circle the table, tilting as necessary to keep them from overbalancing. Orlando groaned at the gimmick, but seemed amused in spite of himself. They caught up with the rotating reference frame, leaving the particle apparently moving only along a fixed, radial line. It rolled back and forth in the trench, cradled and confined by this hollow in the energy surface, the extremes of its elliptical orbit now revealed as nothing more than the farthest points it could reach as it tried to climb either the central spike or the gentler slope of the outer wall.
When the ride stopped, the exhibit offered them three chances to flick a particle into orbit around the second gravity well. Orlando accepted. The first two particles he launched spiraled down to a collision, and the third went skidding off the rim of the table. He muttered something about wishing he was deaf, dumb, and blind.
The exhibit transformed the surface to show the effect of centrifugal force. The inverse-fourth-power attraction of gravity was stronger than inverse-cube repulsion near the center, so even when the reference frame began to spin, the well remained a well. But further away, centrifugal force took over and turned the downward slope of the approach into an ascent. And where the ascent reversed and the surface plunged, in place of the first well's circular trench there was a circular ridge. Compared to the three-dimensional universe, the entire potential energy surface was upside-down.
The exhibit spun them around with the reference frame. Then, its disembodied hand moving with them, it placed a particle on the outer slope of the ridge; unsurprisingly, it fell directly away from the center. A second particle, placed on the inner slope, fell straight into the well.
'No stable orbits.' Orlando picked up the particle that was rolling away and tried to balance it precisely on the ridge, but he couldn't position it accurately enough. Paolo saw a flash of fear in his eyes, but he said wryly, 'At least that means no Lacertas. Everything that's going to fall together would have done it long ago.'
They walked on to the next exhibit, a model of the macrosphere's cosmological evolution. As matter clumped together under mutual gravitational attraction from the initial quantum fluctuations of the early macrosphere, rotational motion either cut in at some point and blew the condensing gas cloud apart, or the process 'crossed over the ridge' and the collapse continued unchecked. Star systems, galaxies, clusters and superclusters, all stabilized by orbital motion, were impossible here. But the fractal distribution of the primordial inhomogeneities meant that the end products of the collapse process had a wide spectrum of masses. Ninety percent of matter ended up in giant black holes, but countless smaller bodies were predicted to form, sufficiently isolated to survive for long periods, including hundreds of trillions with a stability and energy output comparable to stars.
Orlando turned to Paolo. 'Stars without planets. So where will the Transmuters be?'
'Orbiting a star, maybe. They could stabilize an orbit with light sails.'
'Built out of what? There'll be no asteroids to mine. Maybe they created a lot of raw materials with the singularity when they first crossed through, but for anything new they'd have to mine the star itself.'
'That's not impossible. Or they could live on the surface, if they chose. That's where any native life is expected to be found.'
Orlando glanced back at the model, which included something like a Hertzsprung-Russell diagram, plotting the evolving distribution of stellar temperatures and luminosities. 'I wouldn't have thought many stars would he cool enough. Except for brown dwarves, and they'd freeze completely in no time at all.'
'You can't really compare temperatures. We're used to nuclear reactions being orders of magnitude hotter than chemical ones, making them inimical to biology. But in the macrosphere they both involve similar amounts of energy.'
'Why?' Orlando's gestalt still betrayed a sense of unease, but he was clearly hooked now. Paolo gestured at an exhibit further along, beneath a rotating banner reading PARTICLE PHYSICS.
