Thrice upon a Time (24 page)

"It's absurd," she said slowly at last. Murdoch nodded in satisfaction. She went on, "You'd keep going round the same loop forever. There wouldn't be any way out of it." Her eyes narrowed thoughtfully as she remembered what Murdoch had said a few moments previously. "It's obvious, isn't it… the first thing that you'd imagine anyone would think of. So what are you saying—that you never thought of trying it?" She paused as a new light of understanding flowed into her eyes. "Or should I say that if you did try it, you've no recollection that you did?"

"You've hit it right on the head," Murdoch told her. "We're nearly at the end of April now, and we've been running the machine since January. And in all that time something that should have been first on the list of things to try never occurred to us. But if we had tried it, the machine would have gone into an infinite loop. What does that say to you?"

"There must have been timelines on which you did try it."

"Yes," Murdoch agreed, nodding. "That loop would have sustained itself permanently,
unless
some quantum fluctuation got us out of it. For example, somebody who existed on the timeline inside the loop might have made a decision for no particular reason to discontinue the experiment, or maybe somebody ahead of the loop decided not to commence it in the first place… or, maybe…
never thought of it in the first place!
It would have to be something with billions-to-one odds against, but it would happen sooner or later if the loop iterated indefinitely. When it did happen, the loop would disappear, and on the final timeline we'd end up right where we are now in April, with no record preserved that any experiment like that was ever performed."

"And having acted very much out of character," Anne remarked.

"Which is just what you'd expect from those odds," Murdoch said.

"So how did you test it?" Anne asked again. "Or did you have to infer that indirectly?"

"No, we found a way," Murdoch replied. "We set up a program just like I said, but in such a way that it incremented a count every time it went around the loop. When the count reached a preset number, the program discontinued the test. So there was a mechanism to break out of the loop built in. The loop couldn't become infinite. Tests like that gave us enough data to figure out how the loops are structured. Later on we included random factors, which was how we managed to measure the stability. That was the part that was really unexpected. You have to run tens of millions of numbers to get a handful that don't match."

Anne subsided into silence for a while, and then picked up the communicator pad again. "Would you like a coffee?" she asked.

"Good idea."

She tapped a brief code into the pad, and in the kitchen the percolator began filling itself. "So where do you go next?" she asked. "Has your grandfather lifted the ban on ad hoc dialogues with the future yet? I'm dying to find out what happens then. Just think how we could clean up at the races."

Murdoch shook his head. "Not yet. There are still a few more things that he wants to find out about first. The model seems to imply some dimension of 'supertime' that the patterns can reconfigure in. He wants to know what the relationship is between time and supertime. There are reasons for believing that causal influences can only propagate along the threads at a finite rate in supertime. What's the rate? What's the rate at which tau waves propagate? He wants to know a lot more about things like that."

"It certainly sounds as if there's still a lot more to do," Anne said. She sighed. "Oh, I do wish you'd clear up this business about my knowing what you're doing down there. I'm sure your grandfather wouldn't mind as much as you think. I'd love to be able to help in some way, even if it was only by debugging a few programs or something. Are you going to talk to him about it?"

"Okay," Murdoch said. "I'll talk to him tomorrow. Maybe you're right."

"Do… please."

"I will. I already said I would."

"Oh, dear, aren't I getting to be an old nag. Okay." Anne smiled, got up from the sofa, and disappeared into the kitchen. She came back a minute or so later, carrying two steaming mugs and some mints on a tray.

"There was something else I remembered while you were gone," Murdoch said as she set the tray down. "Grandpa has figured out another interesting thing: The quantum-level vibrations of basic particles can absorb energy from tau waves."

Anne's brow knitted as she handed him one of the mugs. "I'm so glad you told me that. It was just what I was wondering. Now tell me what it means."

"It means that normally, without anybody sending any tau waves through time, the timeline is highly stable; alterations at the macroscopic level due to avalanching quantum effects are rare. But an incoming tau wave raises the energy-level of some quantum processes, and makes them far more likely to alter large-scale events on the timeline. So every time we use the machine, we destabilize the system to a degree at the moment in time that receives the signal."

"You mean that it interferes with the outcome of chance events in the universe that the signal arrives in… and therefore all the universes after that as well?"

"Yes," Murdoch replied simply.

Anne looked slightly uncertain. "Chance events where… at Storbannon? In the lab?… "

"No, everywhere," Murdoch said. "You're forgetting that the wave rematerializes in a volume that expands at light-speed as it gets farther away in time from the instant of transmission. The range of the machine is one day. In that time the Earth moves about twenty-one million miles. So everywhere inside a sphere of that radius, the signal is at least as strong as it needs to be for the machine to detect it. In other words if it can affect chance events in the lab when it rematerializes, it sure-as-hell can do the same thing here in Nairn, or come to that anyplace else on Earth too."

Anne remained very quiet for a moment. "I hadn't realized that," she said, for the first time sounding genuinely awed. "You mean that whenever you use the machine to send a signal, you could be changing the outcome of chance events all over the world in the universe that you inject the signal into?"

"Exactly that," Murdoch said slowly. His tone had become very serious. "Imagine a guy somewhere in New York who made a million last night on the spin of a roulette wheel. The overwhelming probability is that the part of the timeline that includes him in it has remained stable since then, and tonight he's out somewhere whooping it up. But now suppose we decide to run a test on the machine at Storbannon right now. Suppose that in the course of that test we happen to send a signal back to the exact moment in time at which the ball on the wheel was balanced between falling into red or black last night. The tau-pulse field materializing at that instant, here, in New York, and everywhere else inside twenty-one million miles of where the Earth is right now could be enough to make the ball go the other way, and reconfigure that part of the timeline from that moment on. So tonight, instead, the guy's on a bridge, about to jump into the East River.

"It makes you think, doesn't it."

When Murdoch returned to Storbannon in the early hours of the following morning, he was surprised to see Elizabeth Muir's car parked outside the main entrance. He hurried inside and found the team and Elizabeth gathered in Charles's study. Charles was at his desk with his tie loosened and his waistcoat unbuttoned, and Cartland was propped wearily against the blackboard to one side, his arms folded across his chest. Elizabeth was sitting in another chair, and Lee was standing by the window. The room was littered with papers and empty cups, and evidently the scene of much hard work for many hours. There was an atmosphere of tension about the place.

"What's happened?" Murdoch asked.

Charles looked up and passed a hand across his brow. "If it's what we think it is, it's bad, Murdoch," he said. "Elizabeth called earlier today about some thoughts she'd been having on the wee wormholes that are appearing all over the place. She came down later to go through some of our formulas. We think we know what they are."

"The bugophants?" Murdoch stared at Elizabeth. A smile flickered briefly on her mouth to acknowledge his arrival, but she was evidently too tired to volunteer a lengthy explanation. Murdoch shifted his gaze to Lee. He couldn't imagine what the mysterious objects could have to do either with anybody at Storbannon or with Elizabeth.

"When is a fusion pellet like a supernova?" Lee asked simply. There was no humor in his voice.

Murdoch blinked back his bewilderment at the question. "What the hell is that supposed to mean?" he asked them.

"Think about it, old boy," Cartland said quietly. Murdoch stared helplessly around the circle of somber faces. Nobody was offering any clues. So he thought about it.

A supernova: a catastrophic explosion of an abnormally large star. Throughout its stable life, the star maintained an equilibrium between the gravitation of its mass, which tried to make it collapse, and the radiation-pressure resulting from the fusion reactions going on inside it, which tried to blow it apart. The radiation was conveyed to the surface by photons, which moved extremely slowly because of their repeated absorption and reemission by matter along the way. The inside of the star generated energy faster than the surface could radiate it away, so the core got hotter… and hotter. Eventually it reached a temperature of sixty billion degrees—at that number, who cared on what scale?

At that critical temperature, the rate of production of neutrinos suddenly increased abruptly to an enormous figure. Neutrinos hardly reacted with matter at all; they went straight out through the body of the star, carrying away with them lots of the energy that up until then had gone into producing photons. So, all of a sudden, there were far fewer photons being produced, and consequently far less radiation-pressure to hold the force of self-gravitation in check.

At that point the star started to collapse, suddenly and violently.

In the process it released gravitational energy at a phenomenal rate—far faster than the material of the star's outer layers could absorb it. So they exploded away into space, producing a supernova. The opposite reaction of that explosion drove the already collapsing core harder and faster inward toward the star's center.

A fusion pellet was imploded in the same way… almost. The difference was that, because the pellet possessed negligible self-gravitation, the energy to implode it had to be supplied externally, such as by lasers or particle beams. But apart from that, the mechanics were similar. An inertial-confinement fusion reactor was, in effect, a supernova in a test tube. And a supernova produced…

Murdoch gasped in disbelief as the answer to the riddle at last became clear. "Oh, Jesus Christ!" he murmured, sinking weakly down onto the nearest chair, the color draining from his cheeks.

A supernova compressed its core all the way down to a black hole!

Ralph Courtney, Chairman and Managing Director of the local Board at the Burghead Heavy-Ion Fusion Facility, and Associate Director of the European Fusion Consortium, studied the faces of the dozen or so people sitting around the polished oak table that formed the centerpiece of the main conference room. Some of the faces were wearing worried frowns, some were still looking bemused, and others were just deep in thought.

Elizabeth Muir was still standing where she had finished speaking a minute or so before, in front of a large map of the world pinned to a board halfway along one side of the room, opposite the middle of the table. The meeting had been specially convened at her request. In the half hour that it had been in session, she had already said all there was to say. In fact she had said that in the first ten minutes; it had taken the rest of the time for the turmoil that followed to die down, and more than a few of those present were still only beginning to recover their capacity for coherent thinking.

She had begun by announcing her conviction that a serious flaw existed in the body of theory upon which the design of the Burghead reactor system had been based. Despite the decades of research that had gone before, and despite the carefully verified formulas and figures, she claimed, something completely unexpected, and at that stage inexplicable, had occurred during the full-power tests that had been conducted in January: The target pellets had been crushed down into miniature, probably nuclear-sized, black holes. The black holes had fallen through the floors of the reactor vessels toward the Earth's center, and that was what had caused the erosion that nobody had yet been able to explain.