There was no way to prove causality, no way to he certain that any of the orphan's mutant shapers really were to blame. But the conceptory was programmed to err on the side of caution. It marked the old, unmutated values for the orphan's altered fields as the only valid codes, discarding all alternatives as dangerous and wasteful, never to be tried again.

PART THREE

Paolo said decisively, "What comes next is the Forge. You helped design it, didn't you?"

"I wouldn't go that far. I played a minor role."

Paolo grinned. "Success has a thousand parents, but failure is an orphan."

Yatima rolled vis eyes. "The Forge was not a failure. But the Transmuters won't want to hear about my towering contribution to analytic methods in relativistic electron plasma modeling."

"No? Well, I was never an insider at all, so whatever we tell them will have to come from you."

Yatima thought it over. "I knew the two people who really mattered." Ve smiled. "You could say it's a love story."

"Blanca and Gabriel?"

"Maybe I should have said 'triangle.'"

Paolo was baffled. "Who else was involved?"

"I never met her myself. But I think you can guess who I mean."

7

KOZUCH'S LEGACY

Carter-Zimmerman polis, Earth

24 667 274 153 236 CST

10 December 3015, 3:49:10.390 UT

Gabriel asked the Carter-Zimmerman library to show him every scheme on record for building a traversable wormhole. The problem had been studied long before the necessary technology was remotely within reach, both as an exercise in theoretical physics and as an attempt to map out the possibilities for future civilizations. It had seemed like an act of ingratitude, as well as a waste of resources, to discard the fruits of all this ancient labor and start again from scratch, so Gabriel had volunteered to sort through all the methods and machines advocated in the past and select the ten most promising candidates for detailed feasibility studies.

The library promptly constructed an indexscape with 3,017 different blueprints, laid out in a conceptual evolutionary tree which stretched across the scape's imaginary vacuum for hundreds of kilodelta. Gabriel was taken aback for a moment; he'd been aware of the numbers, but the visible history of the subject was still an intimidating sight. People had been contemplating wormhole travel for almost a millennium; longer, counting the early designs based on classical General Relativity, but it was with the advent of Kozuch Theory that the field had truly flourished.

In Kozuch Theory, wormholes were everything. Even the vacuum was a froth of short-lived wormholes when examined at the Planck-Wheeler length of ten-to-the-minus-thirty-five meters. As early as 1955, John Wheeler had suggested that the apparently smooth space-time of General Relativity would turn out to be a tangled maze of quantum wormholes at this scale, but it was another idea of Wheeler's—finally made to work, with spectacular success, by Renata Kozuch a hundred years later—that had transformed these wormholes from arcane curiosities far beyond the limits of detection into the most important structures in physics. The elementary particles themselves were the mouths of wormholes. Electrons, quarks, neutrinos, photons, W-Z bosons, gravitons, and gluons were all just the mouths of longer-lived versions of the fleeting wormholes of the vacuum.

Kozuch had labored for more than twenty years to refine this hypothesis, drawing together tantalizing but partial results from dozens of other specialties, cannibalizing everything from Penrose spin networks to the compactified extra dimensions of string theory. By including six sub-microscopic dimensions along with the usual four of space-time, she had shown how wormholes with different topologies could account for the properties of all the known particles. No one had directly observed a Kozuch-Wheeler wormhole, but after surviving a millennium of experimental tests the model was widely accepted, not as the best tool for most practical calculations, but as the definitive expression of the underlying order of the physical world.

Gabriel had learned Kozuch Theory in the womb, and it had always seemed to him to be the deepest, clearest picture of reality available. The mass of a particle was a consequence of the disruption it caused to a certain class of vacuum wormholes: those with virtual gravitons at both ends. Disturbing the usual pattern of connections between these wormholes made space-time effectively curved, much as a change in the weave of a basket could force the surface to bend by bringing parallel threads together. It also created a few loose threads: other wormholes squeezed out of the vacuum by the "tighter weave" wherever space-time was curved, giving rise to both Hawking radiation from black holes and the even fainter Unruh radiation of ordinary objects.

Charge, color, and flavor arose from similar effects, but with virtual photons, gluons, and W-Z bosons as the mouths of the vacuum wormholes involved, and the six rolled-up dimensions, to which gravitons were impervious, now playing a crucial role. Spin measured the presence of a certain kind of extra-dimensional twist in the wormhole mouth; each half-twist contributed half a unit of spin. Fermions, particles such as electrons with an odd number of half-twists, had wormholes which could themselves become twisted like ribbons; if an electron was rotated 360 degrees, its wormhole would gain or lose a definite twist, with measurable consequences. Bosons, such as photons, had full twists in their wormhole mouths, but a 360-degree rotation left them unchanged because the kinks in their wormholes canceled themselves out. A single boson could be "self-linked," the only opening into a wormhole which looped back on itself, or any number of identical bosons could share a wormhole. Fermions were always joined in even numbers; the simplest case was a particle at one end of the wormhole, with its antiparticle at the other.

Under the extreme space-rime curvature of the early universe, countless vacuum wormholes had been "squeezed from the weave" to take on a more tangible existence. Most had formed particle-antiparticle pairs like electrons and positrons, but more rarely they'd created less symmetric combinations, such as an electron at one end of the wormhole with a three-pronged branching into a triplet of quarks, making up a proton, at the other.

This was the origin of all matter. By sheer chance, the vacuum had shed slightly more electron-proton wormholes than their antimatter equivalent, positrons linked to antiprotons, before expanding and cooling to the point where particle production ceased. Without that tiny random excess, every last electron and proton would have been annihilated by a matching antiparticle, and there would have been nothing in the universe but the microwave background, reverberating through empty space.

Kozuch herself had pointed out in 2059 that if this version of Big Bang cosmology was correct, it meant that every surviving electron was linked to a proton, somewhere. Brand new wormholes with known endpoints could be manufactured at will, simply by creating pairs of electrons and positrons, but existing wormholes already crisscrossed interstellar space. After twenty billion years drifting through an evolving and expanding universe, many particles torn from the vacuum side-by-side would have ended up thousands of light years apart. Chances were, every grain of sand, every drop of water on Earth, contained gateways to each of the hundreds of billions of stars in the galaxy, and some that reached far beyond.