Blanca protested, half-seriously, 'Why couldn't you have positioned the Forge so the time lags were equal?' Gamma rays should have been emerging instantaneously from the wormhole's other mouth, but the far end of the accelerator was three billion kilometers further from Earth than the near end, so it would be another three hours before they'd know what had happened there, 68 hours earlier.
Gabriel defended himself almost absent-mindedly 'It was a compromise. Comets to avoid, gravitational effects to balance…' Blanca followed his gaze into the flickering gamma-ray glow, and knew at once what he was thinking. What they were witnessing here opened up some very strange possibilities. According to a hypothetical observer flying along the axis of the Forge toward the far end, these photons, transported faster than light, would be coming out of the wormhole before they went in. That peculiar ordering of events was largely academic—the traveler wouldn't even know about it until photons from both ends had had time to reach ver—but if ve also happened to be carrying a wormhole mouth of vis own, linked to one in the hands of an accomplice in a second spacecraft following behind, then as the traveler flew past the far end of the Forge ve could signal the accomplice to destroy the gamma-ray source at this end… before the photons ve'd just seen emerging had ever been sent.
Once they had a second wormhole, the Forge group would be able to make this ancient thought experiment a reality. The most likely solution to the paradox involved virtual particles—the mouths of vacuum wormholes— traveling in a loop that included both the Forge wormhole and the ship-borne one. Virtual particles were constantly streaming along every available path through space-time, and though crossing ordinary space between the mouths of the two wormholes would take them a certain amount of time, moving through the ship-borne wormhole would carry them back into the past, reducing the total time needed to go around the loop. As the two spacecraft neared the point where signaling from future to past became possible, the transit time for the loop would approach zero, and each virtual particle would find an exponentially growing army of doppelgangers hard on its heels: future versions of itself which had already made the trip. As they slipped into perfect phase with each other, their rapidly increasing energy density would make the wormhole mouths implode into tiny black holes, which would then vanish in puffs of Hawking radiation.
Apart from ruling out time travel, this would have serious practical consequences: once the galaxy was crisscrossed with wormholes, there'd be loops of virtual particles threading them all, and any careless manipulation of the mouths could see the whole network annihilated.
Gabriel said, 'It's almost time. Shall we…?'
They jumped to the far end of the Forge, where the scape was showing the most recent data available: still a few minutes before the gamma-ray bombardment had begun. The second FM sat in an observation chamber, under the scrutiny of a cylindrical array of gamma-ray detectors, nudged occasionally by UV lasers to keep it perfectly centered. The faint scatter from the lasers was the only sign that the thing was really there; with no electric charge or magnetic moment, it was a far more elusive object than a single atom.
'Don't you think we should be with the others?' Blanca had lived with the distant promises of the Forge for so long now that it was hard to be moved by this first, microscopic hint of what lay ahead. But if they really were on the threshold of a change that would shape the history of the Coalition for the next ten thousand years, it seemed like a fair excuse for public celebration.
'I thought you'd be pleased.' Gabriel laughed curtly, offended. 'At the end of eight centuries, we're together for this moment. Doesn't that mean anything to you?'
Blanca stroked his hack. 'I'm deeply touched. But don't you think you owe your colleagues—'
He disengaged from ver angrily. 'All right. Have it your way. We'll join the crowd.'
He jumped. Blanca followed. As they re-entered the scape in public mode it seemed to expand dramatically; half of Carter-Zimmerman was hovering in the space above the observation chamber, and the image had been re-scaled to fit them all in.
People recognized Gabriel at once, and flocked around to congratulate him. Blanca moved aside and listened to the excited well-wishers.
'This is it! Can you imagine the gleisners' reaction, when they arrive at the next star and find that we've beaten them to it?' The citizen's icon was an ape-shaped cage full of tiny yellow birds in constant flight.
Gabriel replied diplomatically, 'We'll be avoiding their targets. That was always the plan.'
'I don't mean we should explore the system in competition with them. Just leave an unmistakable sign.' Blanca considered interjecting that the first few thousand wormholes they widened would be most unlikely to include any of the gleisners' immediate destinations, but then thought better of it.
On jumping to the scape, they'd synched by default to the average rate of its inhabitants, a rush of about a hundred thousand. It was fluctuating, though; some people were growing impatient, while others were trying to prolong the suspense. Blanca let verself drift with the average, enjoying the sense of being jostled through time by the whims of the crowd. Ve wandered through the scape, exchanging pleasantries with strangers, finding it hard to take the vast machinery of the observation chamber seriously so soon after experiencing it all on a scale where there'd barely been room to spread vis arms. Ve spotted Yatima in the distance, deep in conversation with other members of the Forge group, and felt an amusing surge of quasi-parental pride—even if most of the skills ve'd taught the orphan would have been more use to a Konishi Miner than a C-Z physicist.
As the moment approached, people started chanting a countdown. Blanca searched for Gabriel; he was surrounded by demonstrative strangers, but when he saw ver approaching he broke away.
'Five!'
Gabriel took vis hand. 'I'm sorry.'
'Four!'
He said, 'I didn't want to be with the others. I didn't want to be with anyone but you.'
'Three!'
Fear flashed in his eyes. 'My outlook's programmed to cushion me, but I don't know how I'll take this.'
'Two!'
'One traversable wormhole, and then the rest is mass-production. I've made this my whole life. I've made this my whole purpose.'
'ONE!'
'I cap, find another goal, choose another goal, but then who will I be?'
Blanca reached up and touched his cheek, not knowing what to say. Vis own outlook was much less focused; ve'd never faced a sharp transition like this.
'ZERO!'
The crowd fell silent. Blanca waited for the uproar, the cheers, the screams of triumph. Nothing. Gabriel looked down, then Blanca did too. The femtomouth was scattering the lasers' ultraviolet, as ever, but no gamma rays were emerging.
Blanca said, 'The other mouth must have drifted out of the focus.'
Gabriel laughed nervously. 'But it didn't. We were there, and the instruments said nothing.' People around them were whispering their own theories discreetly, but their gestalt seemed more tolerantly amused than derisive. After eight centuries of setbacks, it would have been too good to be true if the Forge had delivered the definitive proof of its success at the first opportunity.
'Then there must be a calibration error. If the mouth drifted, but the instruments thought it was still at the focus, then the whole system needs to be recalibrated.'
'Yes.' Gabriel ran his hands through the fur of his face, then laughed. 'Here I am expecting to fall off the edge of the world, and one more thing goes wrong to save me.”
'One final screw-up to smooth the transition. What more could you ask for?'
'Yeah.'
'And then what?'
He shrugged, suddenly embarrassed by the whole question. 'You said it yourself: linking the Forge is only the start. We haven't wrapped the universe in wormholes yet. And at this rate, there'll he screw-ups to smooth the transition for another eight hundred years.'
Blanca spent half a gigatau exploring vis new imaginary world, fine-tuning the parameters and starting again a thousand times, but never intervening and sculpting the landscape directly. That was wicked—it made it less artful, and more mock-physical—but no one had to know. When ve opened it up to the public, people would marvel at its perfect blend of consistency and spontaneity.
