Diaspora

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 or six rotations at most—or if the neutrons were sadly normal, just two. A few segments would have been enough to prove the point, but maybe the Transmuters had had no control over the total length.

Orlando said, "Is this equipment failure, or wild success?"

"Wild success, I hope."

Yatima sent the screen gestalt instructions to rewind. The start of the data showed the neutron slipping in and out of phase with repeated rotations:

-++-+-+++-+-++++-+-+-+-+++++…

Directly below was the interpretation: FbFFbbFFFbbbFFFFbbbb…

Orlando read aloud, "Fermion, boson, fermion, fermion, boson, boson…"

Yatima said, "It's not a hoax, I swear."