Thrice upon a Time Read online

  The alternative was that the future selves who had sent the signals had existed on a different timeline, or timelines, entirely. That would be another possible way of explaining how those future selves had apparently done things that nobody in Murdoch's universe had later done. This picture implied some parallel branching structure of universes in which every point along a timeline became a branch-point into a possibly infinite number of other timelines, with the branches forking unidirectionally like those of a tree.

  Neither concept was especially new; people had been speculating on possibilities like that for a century or so at least. The big difference now, of course, was that previously there had never been any means available of testing such notions. Having separated the two alternatives in his mind, Murdoch turned his thoughts back to reexamming the first—that of serial universes—more closely.

  Suppose, he thought, that fixed instants in time corresponded to landmarks along the river bank. A particular tree, for example, could be noon on a particular day. Thus each of the boat universes would come to experience its own noon in turn as it passed on its way by. At the instant that a given boat was passing by the tree, some random event could take place in the "now" of that boat's universe, such as a fish jumping out of the water alongside it… or somebody onboard typing a particular string of characters into a computer touchboard panel. Given Charles's machine, the crew of that boat could inform another boat following ten minutes behind that a fish had been seen just as they were passing the noon tree. But in general, the crew of the second boat would not expect to observe the same event when they came to pass the tree, for they would be accompanied by a different body of water with different things happening in it. Therefore, in the serial-universe model, different crews would observe different things at similar times. Some changes might evolve slowly, such as a patch of bad weather that many boats might pass through before it cleared, but insignificant random things like the fish jumping out of the water would have no correlation.

  But the string of random characters that Murdoch had typed in had matched the one that had been received sixty seconds before. Thus the serial model, or at least that interpretation of it, did not appear to fit the facts. An inhabitant of the boat type of serial universe would be able to influence what happened to other boats following his by advising their occupants of things he knew but they had not encountered yet, but nothing he did could ever alter his situation, which would have resulted from events in the universe moving along with him. In other words he wouldn't be able to change his own past. But Murdoch had received the same data as he had later sent. If that data had been perhaps the sequence of a roulette wheel or the result of a horse race, he might well have changed his past very significantly indeed.

  He sat back and exhaled a long breath as he relaxed to give his mind a break.

  Lee returned from his own realms of thought and looked up. "I don't see that it can be serial."

  "No." Murdoch agreed.

  There was nothing more to be said about that.

  Mrs. Paisley took the sudden burst of conversation as a sign that normal civilities were in order again and glanced around from where she was stacking dishes in the dishwasher. "You're way past your normal time today, Murdoch," she remarked. "The two of ye were late getting to your beds, I'll be bound."

  "Well, we had a lot to talk about last night," Murdoch answered. "I guess we must have been up until… oh, I don't know what time. Anyhow, we're still on U.S. time, don't forget."

  "Every bit as bad as Sir Charles," she declared. "I'd give you another six months here, and there'd be no telling the two of you apart."

  "With my accent? You've got to be kidding."

  "It's what goes on inside o' your head I was meaning, not what comes out of it." She closed the dishwasher and began returning unused food to the refrigerator. "And did you sleep well after all the talking, Mr. Walker?"

  "Fine, thanks. I prefer just Lee."

  "I should have guessed you'd be every bit as easygoing as Murdoch," Mrs. Paisley said, nodding. She closed the refrigerator door and stood for a moment looking at the two Americans as if trying to make up her mind about something. Then she moved a step nearer the table and allowed her voice to drop to a lower, almost conspiratorial, note. "There is something I've never really felt I could ask Sir Charles about," she said. Murdoch raised his eyebrows inquiringly. "If you don't mind my being inquisitive, what is it that he's doing down there with all those machines and things?"

  "He's making a Frankenstein monster," Murdoch whispered. "What else do people do with strange machines in the basements of old castles?"

  "There's many a true word spoken in jest," she murmured, looking doubtful.

  "Well, actually he's not."

  "I'm very glad to hear it."

  "Seriously, he's just using the computers to try and prove some of his mathematical theories. All very academic. Nothing spectacular."

  "I see." Mrs. Paisley nodded and seemed satisfied. "I'd have thought that maybe he'd have seen enough o' that kind o' thing in his lifetime. Ah well, I suppose it can become an obsession just like most other things in life." She shook her head and sighed. "And yet it's a strange thing—Robert cannot trust him with the household accounts."

  Murdoch spread his arms along the edge of the table and looked across at Lee. "Feel like stretching your legs before we get back to work?"

  "That sounds like a good idea."

  "Aye, why don't the two of you be getting along," Mrs. Paisley said. "Hamish will be in from the grounds any minute for his cup o' tea."

  "Sure. We'll get out of the way," Murdoch said, standing up. "Come on, Lee. I'll show you the rest of the house."

  The large room that Murdoch led the way into looked out through the French windows over a stone-railed terrace. There was a small bar at one end, and all around chairs were upended on small tables. Most of the other furnishings were covered by white dustsheets. Lee's footsteps echoed emptily on the bare wooden floor as he followed Murdoch in and stopped to gaze around.

  "This part's normally closed down at this time of year," Murdoch said. "It'll be opened up again when the visitors start coming back."

  "Visitors?"

  "Grandpa keeps himself and the staff to the central part of the house, where we've just come from. The North Wing is practically self-contained. It's got bedrooms, its own kitchen, the lounge here, plus a few other rooms. Grandpa rents it to shooting parties later in the year… and sometimes for small business conferences and stuff like that. We call it the Guest Wing."

  "I'd imagine the company does him good," Lee said.

  "It sure does. He often gets a lot of his pals staying out here. They have some good times when the Scotch starts flowing."

  "That's the stuff you drink, right?"

  "Right." Murdoch smiled and walked across to the French windows, opened one of them, and led the way out onto the terrace. The balustrade overlooked an expanse of gardens, lawns, a tennis court, and a summerhouse, all looking neat and trim despite the covering of snow.

  "This area was laid out by Grandpa's father," Murdoch said, gesturing. "Colonel James Ross."

  "Soldiers in the family too, huh?" Lee asked.

  "That's right. He commanded a British Army regiment in France during World War I—Infantry. In World War II he was a cryptographer for Military Intelligence in London. You see, there's the mathematical streak coming out again." The air outside was cool and fresh with the breeze coming down off Ben Moroch's west ridge. The sky had cleared since the previous day, allowing the sun to take the edge from the season's chill. "We can walk back around the outside," Murdoch said. "The door will close itself." They descended from the terrace by a flight of shallow steps at one end and began crunching their way along a gravel path that followed the wall of the building.

  "There've been some alterations to this part," Lee commented, looking up as they walked.

  "Mostly in the 1960s and 1980s. The estate was managed by a trust while Grandpa was in
the States. They ran it as a private hotel and shooting resort, which is how the Guest Wing came to be the way it is. When he came back to Scotland, he more or less left it the way he found it."

  They rounded a corner of the Guest Wing and crossed the rear courtyard to reenter the house through the door by the kitchen. The kitchen was now empty except for Maxwell, who was lapping noisily over a dish on the floor and paid no attention to them. They walked on through to the front of the house and met Morna outside the sitting room, who informed them that Charles was in his study and had given the impression that he wanted to be left alone for an hour or so. That meant that they would not be able to run further tests on the machine for a while, since they were not yet familiar with the detailed operating procedures. Charles had, however, told them to feel free to browse through any of the records and notebooks lying around in the lab, and they decided to go down anyway to see what more they could learn.

  Fifteen minutes later Lee was lounging against one corner of the desk and studying a listing of one of the system's computer programs, while Murdoch was seated in the operator's chair at the console, replaying again in his mind the sequence of events that had taken place there the previous night. After a while Murdoch said suddenly, "It's not parallel."

  Lee looked up. "Huh?"

  "It can't be, when you think about it," Murdoch told him. "Grandpa asked me to key in a random character string, right?"

  "Right."

  "If the structure was parallel, then that instant in time should have formed the branch-point to as many parallel branches as there were possible sequences that I might have typed, which must have been thousands… tens of thousands. According to the idea of parallel universes, all those branches actually exist as different timelines, and we just happen to exist on one of them."

  "I think I know what you're going to say," Lee said, straightening up from the desk. "The instruction to send the sequence back would have been carried along every branch from the point they diverged at."

  "Exactly!" Murdoch said. "So every one of all the me's who existed on all the timelines would each have sent his own particular sequence back down his own branch. And all the sequences would have arrived together at the point where the divergence had taken place, that is, the point where we got the hardcopy print. Everything possible would all have come in at the same time."

  "You'd have saturated the receiver," Lee said. "It would have given a binary full-house—all ones with no information content at all."

  "Right. All the codes would have been scrambled up together. The decoders could never have made sense out of it. But it didn't happen that way. We got one code out, and it turned out to be the right one. Therefore the explanation of parallel universes doesn't hold up."

  Lee tossed the papers he had been reading down on the desk and paced slowly across the lab, rubbing his brow thoughtfully with his knuckle and frowning. Then he about-faced and returned back to where Murdoch was sitting.

  "So it isn't serial and it isn't parallel," he said. "There wasn't anything else, so what the hell is it?"

  "I don't know." Murdoch propped his elbows on the armrests of the chair and swiveled it absently from side to side, his fingers interlaced across his chest. "Let's go through the whole thing again, step by step," he said after a while. He swung back to face the console and swept his eyes over it, as if the act of seeing it again might aid his memory.

  Lee perched himself back on the edge of the desk. "It worked okay until you decided you were going to try to fool it," he said. "You were going to wait for a signal to come in and then not send it when you were supposed to. We waited for a long time, and nothing happened."

  "Right. But we did get a signal without any problem the time before that, in the demo we got from Grandpa when we first came in. We didn't think of trying to fool it that time because we didn't know what was going on. So what was the difference?"

  "You just said it," Lee replied. "'We didn't know.' Somehow that in itself was enough to change what happened afterward." Murdoch nodded. Lee thought for a moment, then went on, "Maybe that's not so strange. Present intentions affect future actions all the time. You decided you weren't going to send anything, and sure enough nothing got sent. So we never received anything. The future you was simply not doing what the earlier you had decided not to do. So far it makes sense."

  "So far," Murdoch agreed. "But then something did come in, so evidently the future me changed his mind. The message said MURDOC, so I assume it was from a 'me' somewhere, and from the look of it a me who was a few minutes ahead of that point in time. What would have changed my mind and made me decide to send something after I'd made my mind up not to?"

  A brief silence descended. Lee straightened up, walked slowly across to the storage rack by the door, and stood toying idly with a section of waveguide that was lying in a cardboard box. Then he turned to face back across the room.

  "You hadn't made your mind up not to send anything," he pointed out. "You'd only made your mind up not to send whatever came in. So let's assume that the future you who sent MURDOC had also decided the same thing. And since there's no reason not to, let's also assume that he stuck to it. That means he couldn't have received any signal that said MURDOC in his past, because if he had he wouldn't have sent it. But obviously he did send it. So the question is: What made him send that signal back on the spur of the moment, at a time when he hadn't received anything at all?"

  "I shouldn't have to ask that question because I ought to know the answer," Murdoch replied. "A few minutes after I received that signal, I should have become him. But I never was him because I never sent it." He sighed with exasperation and pivoted the chair through a full circle.

  Lee waited until they were facing one another again. "Well, let's imagine first for the sake of argument that you did become him," he suggested. "What were you thinking of a few minutes before that signal came in?"

  Murdoch sat back and covered his eyes with his hand as he tried to cast his mind back to the previous night. "Let me see now… I'd been waiting for a signal to come in. When it came, I wasn't going to send it. We waited… Nothing happened. We've been through that. What then? … " His face screwed itself into a frown as he thought. Lee watched and waited in silence. Then Murdoch went on, "After a while I was starting to get fed up with waiting. I was looking at the screen here and seeing the time-axis empty with nothing on it. I started wondering… " Murdoch's voice trailed away for a second. Then he looked up sharply. "Hey! I wondered what would happen if I decided to send a signal back to a point that was already recorded as having had no signal coming in. I thought maybe I'd try fooling it that way instead, since the other way didn't seem to be getting us anywhere."

  "And the you that sent the MURDOC signal would have existed at just about the time that you were thinking that," Lee said, an undertone of excitement creeping into his voice. "So perhaps he was thinking the same thing. Only maybe he did send something. And maybe that was what we received a few minutes earlier."

  "So what happened to him?" Murdoch objected. "Where is he right now?"

  "You could ask the same question about all the other you's who sent all the other garbage you never sent."

  "Okay, I'll ask it. What happened to all the other me's who sent all the other garbage I never sent, and where are they right now?"

  "Well, if you don't know, what am I supposed to say?" Lee said. He spread his arms wide, then folded them across his chest and rocked back on his heels until he was propped against the door.

  "Okay then, let's go back to the me that was me," Murdoch said. "I was getting fed up waiting, and I was thinking of sending a signal back anyway, but I hadn't got to the point of actually doing it. Then suddenly the signal that said MURDOC came in, which changed everything. At that point I forgot all about what I'd been thinking, and went back to what I'd made my mind up about in the first place: not to send any signal that came in, when the time came to send it. A signal had come in; I wasn't going to send it."

&
nbsp; "And sure enough, you didn't."

  "And we couldn't understand it."

  "And a little while later, others started coming in. What were you thinking then?"

  "I'm not sure," Murdoch confessed. "I think I was too confused to think of anything. Then the garbage started coming out of the sky. The next thing I remember is noticing the gaps, and wondering what would happen if I sent a signal back into one of them." An intrigued look appeared on his face. He pulled himself upright in the chair suddenly. "Say… that's the same situation that we've just been through. In another minute or less I'd have been at the point of trying it."

  "Which is precisely where all the garbage was coming from," Lee pointed out.

  Murdoch became visibly excited. "And it did look as if whoever sent all that stuff had thought exactly that. Think of some of the signals that came in—GAPFIL, FILGAP—things like that. See, they're just the sort of mnemonics you'd pick if you were trying to do what I'd started thinking of doing. Whoever sent those signals must have seen gaps just like I did, and had the same idea."

  "And they succeeded," Lee said, nodding. "But they couldn't have known they were succeeding. If they'd known, they wouldn't have kept on doing it over and over."

  "And that means none of them could ever have been me," Murdoch said. "Otherwise they'd have remembered seeing what I saw." He slumped back in the chair again and threw out his empty palms. "Which gets us back to the original question: Who were they and where are they right now?"

  Another silence ensued.

  "I don't know," Lee said at last. "But it has to have something to do with trying to set up paradox situations, which is what you were doing. When you played it straight, everything worked okay; when you, or somebody somewhere, started trying to fool the system, that was when weird things started happening. That was the only thing that could have made a difference."

  "We got results though," Murdoch said. "The problem is they don't make sense."

  Lee unfolded his arms and walked back to the console. He stared at the empty screen for a while. "Then perhaps it's our ideas of what makes sense that need revising. After all, what we call common sense is based on the obvious fact that causes always come first and effects later. But this machine says that things no longer have to be that way. Therefore they can violate what we call common sense. We've always called anything that did that crazy." He clamped his hand around the top corner of the console panel and wheeled to face Murdoch. "Which seems, Doc, to lead us to the conclusion that, whatever the explanation turns out to be when we get to the bottom of it, it's gonna have to seem pretty crazy."