Carter-Zimmerman polis, Swift orbit
85 801 737 882 747 CST
18 March 4953, 23:17:59.901 UT
Yatima had arranged to meet Orlando in a scape of Lilliput Base, a twenty-meter dome full of scientific instruments located on an equatorial plateau, far from the temperate lowlands where the oases formed. The dome and everything in it had been built by conventional nanomachines, but the raw materials would have been impossible to obtain in situ without far more sophisticated technology. A former Star Puppy called Enif, who'd switched outlooks upon reaching 51 Pegasus and taken up nuclear physics with a vengeance, had succeeded in constructing the first femtomachines about a century before C-Z Voltaire's arrival. Using the loosely-bound neutrons of halo nuclei in a manner analogous to the electron clouds of a normal atom, he'd managed to build 'molecules' five orders of magnitude smaller than those with electron bonds, and then worked his way up to femtomachines able to ferry neutrons and protons to and from individual nuclei, holding the necessary increments of binding energy as deformations in their own structure. The invention had turned out to be priceless on Swift; not only were the normal, light isotopes of the five transmuted elements essential for some experiments, many other elements were rare on the planet's surface in any form.
They'd had to wait two days for a bay to become free. Yatima entered the scape just as the previous apparatus, designed to search for traces of oxygen-16 in ancient mineral grains, was dissolving back into reservoirs of its constituent elements. Scaled at one centimeter to a delta, the meter-square hay looked big enough for any conceivable experiment, but in fact it was going to be a tight fit. Yatima had found plans for a neutron phase-shift analyzer in the library, designed by Michael Sinclair no less, a former student of Renata Kozuch. When Blanca's proposed extensions to Kozuch Theory had reached Earth, most physicists had simply dismissed the new model as metaphysical nonsense, but Sinclair had scrutinized it carefully, hoping to devise an experimental test that would go beyond its success in explaining, after the fact, the length of the Forge's traversable wormholes.
Orlando appeared. The scape software didn't seem to know quite what to do with his exhalations; the Lilliput dome was maintained at high vacuum, and at first a faint cloud of ice crystals materialized and fell in front of him as his breath expanded and cooled, but after a moment some subsystem changed its mind and starred magicking the apparent contamination out of existence as soon as it left his mouth.
After raising a lattice of scaffolding, the bay's nanomachines began work on the analyzer, drawing threads of barium, copper, and ytterbium from the reservoirs and spinning them into delicate gray coils of superconducting wire for the magnetic beam splitter—an odd name for the component, when the 'beans' in this case would consist of a single neutron. Orlando regarded their handiwork dubiously. 'You really think the Transmuters were relying on someone doing an experiment as subtle as this?'
Yatima shrugged. 'What's subtle? The shift between the spectrum of deuterium and hydrogen is a few parts in ten thousand, but we can't imagine anyone missing it.'
Orlando said dryly, 'Deuterium at six thousand times the normal abundance isn't subtle. Water vapor weighing twenty percent extra isn't subtle. But particles that behave exactly like neutrons until you split them into two quantum states, rotate one by more than 720 degrees, then recombine them to check their relative phase? Somehow I think that might qualify.'
'Maybe. But the Transmuters didn't have much choice; you can't make neutrons twenty percent heavier. All they could do was wrap them in other layers that would draw attention to them. What makes Swift special? The heavy isotopes in the atmosphere. What makes those isotopes special? The extra neutrons they contain. What makes those neutrons special? There's only one thing you can change about a neutron, without turning it into something else entirely. The length of the wormhole.'
Orlando seemed about to object, but then he raised his hands in a gesture of resignation. There was no point arguing; they'd soon have an answer, one way or the other.
In Blanca's extension of Kozuch Theory, as in the traditional version, most elementary particle wormholes were as short as they were narrow; the two mouths, the two particles, shared the same microscopic 6-sphere. That was the most probable state for a wormhole created out of the vacuum, and unlike traversable wormholes they weren't free to adjust their length once they were formed. But there was no theoretical reason why longer ones couldn't exist: chains of short ones joined end-to-end, a string of linked microspheres looping out into the extra six macroscopic dimensions. Once created, they'd be stable; it was just a matter of knowing how to make them in the first place. Ordinary splicing methods—brute-force collisions—simply merged the two microspheres into one.
Sinclair had tested a few trillion electrons, protons, and neutrons, and found no long ones at all, but that didn't prove that they were physically impossible, it merely confirmed that they were naturally rare. And if the Transmuters had wished to leave behind a single, enduring scientific legacy, Yatima could think of no better choice. Long neutrons had the potential to illuminate a fundamental question that might otherwise take an infant civilization millennia to resolve. Locked up in stable isotopes on a planet orbiting a slow-burning sun, they'd remain accessible for thirty or forty billion years. It was even possible that they'd shed some light on the diametrically opposite problem to their own creation: keeping traversable wormholes short, the secret to bridging the galaxy.
The nanomachines moved on from the beam splitter to a second set of coils, designed to rotate one quantum state of the neutron when it traveled simultaneously down two alternative paths. At first glance, there was no obvious way to tell a long particle from a short one; neither possessed a traversable wormhole, so you couldn't send a signal through and time it. But Sinclair had realized that the usual classification of particles into fermions and bosons became slightly more complex when long particles were allowed. The classical properties of a fermion were having a spin of half a unit, obeying the Pauli exclusion principle (which kept all the electrons in an atom, and neutrons and protons in a nucleus, from falling together into the same, lowest-energy state), and responding to a 360-degree rotation by slipping 180 degrees out of phase with its unrotated version. A fermion needed two full rotations, 720 degrees, to come back into phase. Bosons needed only one rotation to end up exactly as they began.
Any long particle made up of an odd number of individual fermions would retain the first two fermionic properties, but if it also included any bosons, their presence would show up in the pattern of phase changes when the particle was rotated. A long particle with a wormhole sequence of 'fermion-boson-fermion-fermion' would go out of phase and back like a simple fermion after one and two rotations, but a third rotation would bring it back into phase again immediately. Successive rotations could probe the wormhole's structure at ever greater depths: for each individual fermion in the chain it would take two rotations to restore the particle's phase, while for each boson it would take just one. As Orlando had put it—groping for a three-dimensional analogy when Yatima had started spouting group theory and topology—it was like sliding down into the particle's wormhole on the banister of a spiral staircase. Sometimes after going full circle, a twist in the banister left you upside down, so you had to go round once more before the staircase appeared right—way up again. Other times, a single turn left everything looking normal.
As the nanomachines put the finishing touched the apparatus, wiring the neutron source and detectors to the bays data link, Yatima thought of contacting Blanca. But the one time they'd met, the Voltaire clone had shown no interest whatsoever in vis dead Fomalhaut-self's ideas. Blanca had declined, everywhere, to rush the flesher equivalent—the de facto post-arrival standard adopted throughout the Diaspora—and as a consequence ve'd become rather isolated. Sinclair might have liked to witness the experiment, but he'd have to wait 82 years; he hadn't taken part in the Diaspora at all.
Yatima gestured at a switch on the side of the neutron source; it was just a scape object grafted onto their view of the machine, but throwing it would transmit the signal down to Lilliput to cycle the first neutron through. 'Do you want to do the honors?'
Orlando hesitated. 'I'm still not sure what I'm hoping for. Exotic physics from the Transmuters… or the entertainment value of seeing you try to squirm out of this if you're wrong.'
Yatima smiled serenely. 'The wonderful thing about hope is that it has absolutely no effect on anything. Just throw the switch.'
Orlando stepped forward and did it. The display screen beside it—another scape object—was instantly filled with symbols scrolling past in an unreadable blur. Yatima had been expecting a short pattern, recurring after five
