Even before the first contact with Ganymeans, when the Shapieron from ancient Minerva returned from its strange exile out of normal spacetime, the majority of Earth's physicists had come to favor the explanation of quantum weirdness known as the Many Worlds Interpretation, or MWI. Its claims were so bizarre and counterintuitive that many maintained it couldn't have been conceived by unaided human imagination or unwitting self-deception. Therefore, it had to be true. The discovery that a race of advanced, starfaring aliens had reached the same conclusion seemed as strong an endorsement as anyone could wish for and pretty much won over the last of the doubters.
The "quantum paradoxes" that textbooks and popular writers of years gone by had reveled in arose when a system of quantum entities such as photons or electrons existing in some particular state changed to some different state when a number of new states were possible. Examples might be an energetically excited atom that could relax back to its minimum-energy "ground" state via any of several alternative sequences of intermediate energy levels, or a photon hitting a half-silvered mirror, which gave it a fifty-fifty chance of being reflected or transmitted. How did Nature "choose" from the various possibilities the one that actually took place?
On the face of it, the situation seemed no different from that of, say, a gambler's die, which from the rolling state could assume any of six discrete final states, each showing a different number. The mechanics of moving objects was well understood, and only inability to specify precisely the die's shape, mass, and motion prevented the outcome to be predicted reliably every time. In other words there was no mystery. The outcome was determined, but imperfect knowledge made it unpredictable. However, this was only another way of saying that the situations were not the same to begin with. At the quantum level, this was not so. The systems being investigated were identical in every way that could be established. Why, then, should they behave differently?
Quantum objects acted as if they were everything at once while they were not interacting with their environment, but the instant they encountered another entity capable of pinning them down—for instance, a detector in a measuring instrument designed to find out something about them—they abruptly took on one from the available selection of possible states. Hardly surprisingly, such oddness did not sit lightly with beings accustomed to a world in which things knew what they were and continued to be that while nothing was looking at them. The scientific debate about the perplexing accumulation of quantum paradoxes raged through the first two decades of the twentieth century—beginning, ironically, immediately following a series of confident assurances that everything of substance was known and science was effectively a closed book. But there could be no getting away from what the results of countless experiments seemed to indicate. The challenge was to account for them in a way that described what was "really" going on.
Some refused to get embroiled in the issue at all, and instead took the view of science as being simply a pragmatic process for generating numbers to be compared with experimental results, beyond which nothing more could be said. For a long time the predominant view was that nothing really existed in any objective sense at all until an act of observation caused it to assume one of its possible sets of attributes ("states") randomly. Exactly what constituted an "observation" was a further source of contention, opinions covering the range of steps from any interaction with another quantum object, to the final registering of an impression upon a human consciousness. Others avoided the disturbingly mystical implications of this kind of approach by maintaining that the allegedly identical objects weren't really identical but differed in some subtle ways that eluded detection at the present time. The problem with this, however was that it required everything in the universe to be capable, just as subtly, of instantly influencing everything else, a notion which many considered to be every bit as mystical as anything else that was being said, if not more so.
By the end of the twentieth century, the scientific world had come to terms with accepting that whatever answer they settled on was going to be bizarre by normal standards anyway, so they might as well get used to throwing away all preconceptions and focus purely on what the facts seemed to be trying to say. And what the facts said, when the formalism was taken at face value without imposing some arbitrary wave-function "collapse" that the mathematics said nothing about, was that the world showed evidence of being everything at once because it was everything at once; the reason it didn't appear that way was that everyday awareness only apprehends a small part of it.
By the picture that finally emerged, neither an energized atom nor an impinging photon "chooses" one state from an ensemble of possible states—thus provoking endless debates about how, when, and why it gets to make that choice; every possibility is actualized—but each in its own separate reality, which then continues to evolve the various consequences of the particular alternative that led to it. The various realities all contain versions of their inhabitants that are consistent with the unfolding of events making up that reality, remaining unaware of all the rest. The dice thrower in one reality rolls a boxcar, double six, breaks the bank, and retires rich; his counterpart in another of the thirty-six possible two-die variants rolls zilch, loses his shirt, and jumps off a bridge. This formed the essence of the Many Worlds Interpretation of quantum mechanics.
Many popular accounts talked about the universe "splitting" into alternative forms, with notions of what constituted a branch point varying from "every quantum interaction" to any event deemed sufficiently significant by humans—the realities continuing thereafter to exist adjacently but separate and discrete, somewhat like the pages of a book. Hence the term "parallel universe." But while perhaps more easy to visualize, this did not accurately capture the strange state of affairs that the formulators of the MWI were proposing. New universes didn't spring into existence out of nothing every time some kind of decision was called for, anymore than New York or Boston suddenly materializes in response to a driver's going right or left at a junction in the highway. They were there already and always had been, just like all the other possible destinations on the road map.
In a similar kind of way, not only all the futures that could possibly arise from a given "now," but all the different "nows" that could have come about, existed as parts of an immense, branching totality, all of it equally real. Within it, every quantum alternative led to a unique consequent reality which in that detail at least differed from all the rest. Rather than resembling a stack of pages, its nature was more that of a continuum of change existing in as many directions as change was possible. The kind of change depended on the direction taken, occurring sometimes gradually, sometimes abruptly. Every conceivable way in which one world could differ from another therefore corresponded to an axis of change within the continuum, endowing it with an as good as infinite number of dimensions. The totality itself was unchanging and timeless. The phenomenon of time measured by physics arose as a construct of the event sequence that arose from tracing a particular path through the tree of branching alternatives. Every such path defined its own discrete reality, or "universe." The perception of time emerged from a consciousness following such a path through the alternatives that it encountered. Exactly how was something that the physicists left to philosophers, theologians, and mystics to explain.
The normal "forward" flow of experience within a universe ran up the tree of branching time lines. Direct knowledge of the other realities existing to the "sides" seemed to be precluded—except for the interference paradoxes that resulted from information leaking across at the tiniest level, from which the necessary existence of the entire stupefying whole had been inferred. Of course, this didn't prevent speculation on whether some kind of communication "horizontally"—between branches—might be possible. Even if it were, nobody had the remotest idea how such a thing would be achieved. It remained just an intriguing hypothesis, good for philosophical Ph.D. dissertations, becoming known in obscure journals, and getting a discussion going at cocktail parties. Nothing in the whole of history suggested any precedent for taking the subject seriously. . . .
And then, the last pictures came back from the probe that had pursued the fleeing Jevlenese spacecraft, showing that they had been hurled across light-years of space and back tens of thousands of years in time to reappear near the planet Minerva in the era of its habitation by the Lunarians, long after the Ganymeans had departed. The proof was there, indisputably, that it had happened. The demonstration that put an abrupt end to any further speculation as to whether such a happening was possible came to be known as the "Minerva event."
After the years he had spent as Hunt's boss in some capacity or other, Gregg Caldwell had thought he was past being capable of surprise anymore. Four years previously, in 2028, when the first evidence of the Lunarians was discovered on the Moon in the form of a fifty-thousand-year-old spacesuited corpse, Caldwell, as chief of UNSA's former Navigation and Communications Division, had set the ebullient Englishman the task of unraveling the mystery of where "Charlie" had come from. Exactly what reconstructing pictures of vanished civilizations had to do with the business of navigating UNSA's spacecraft and maintaining its communications around the Solar System was a good question, but Caldwell had always been a compulsive empire builder. His way of going about things had always been to stake out a claim on getting something done while others debated the demarcation lines, and possession being nine-tenths of the law, like some of the ideas of quantum physics that he had been hearing lately, he created what became reality. Hunt, along with his biologist partner-in-crime, Christian Danchekker, who now directed the Alien Life Sciences Division, had responded by causing the story of human origins to be rewritten from its beginnings. When Caldwell sent the pair of them to Jupiter to look into some relics of long-vanished aliens that came to light shortly afterward on Ganymede, they came back with a starship full of live ones. Despatched to Jevelen to help pinpoint the source of mass mental derangement among the natives, they turned up an entire functioning universe evolved out of data structures inside a planet-size computer. But this latest was straining Caldwell's credulity, even yet.
He sat at the desk, flanked on one side by a wall of display screens, in his office on the top floor of the Advanced Sciences building, drumming his fingers on the armrests of his chair while Hunt paced in front of the picture window overlooking the Goddard complex. Caldwell was stockily built, with steely gray hair cropped short and the kind of solidly carved, heavy-jowled face that suggested granite slabs and lunar crags. His expression remained impassive despite the excitement that Hunt was still unable to contain. Just what kind of reaction should be expected from someone who had talked to another version of himself, calling on the phone from another universe, Caldwell wasn't exactly sure. If the story had come from anyone other than Vic Hunt, he would simply have refused to believe it. Hunt had also kicked his lifetime smoking habit not long ago, which probably added to the theatrics.
"Gregg, it means that somewhere in another part of the Multiverse they've figured it out," Hunt said, not for the first time. "Somewhere corresponding to a future ahead of where we are right now." As a rule, he kept his thought processes orderly enough to avoid such repetition. Caldwell granted that these were somewhat unusual circumstances. "It must have been some kind of test to establish a channel across time lines. They were going to send us a file containing what they knew, but the link went down too soon. My God, Gregg! Can you imagine what it would mean if this ever became routine? Suppose you could get a copy of a new Shakespeare play that he never wrote in our history! Or an authentic account of how the pyramids were really built! What do you think that kind of cross-cultural fertilization might be worth?"
"Let's not get too carried away by that for now, and just stick to the basics," Caldwell suggested. "We figure it had to be some kind of communications relay that appeared out there in orbit." The message routing log into Goddard had shown the signal to have come in via a channel that didn't exist. The signal turnaround delay indicated that it couldn't have been much farther away than the synchsat belt, twenty-two thousand miles out. Hunt had reasoned that it had to have been a relay device rather than a manned vessel of some kind on the grounds that the premature termination pointed to an experimental program still in its early days. Hunt, sure as hell, would never have climbed into a conjuror's box like that, to be shot off into another universe at that stage of the game. It seemed a fairly safe bet that no other version of what was, after all, Hunt's same self would have, either. Caldwell couldn't argue with that.
"Interfacing into the Terran comnet in the same way the Thurien relay satellites that we've got now do," Hunt affirmed. That would have made the device massive, though not necessarily huge in size. Information transfer into and out of the realm used by the Thurien interstellar communications system, referred to as h-space, was effected via spinning microscopic black-hole toroids generated artificially. Putting them in orbit avoided the weight problems that would have resulted from locating the equipment on the Earth's surface. The various Terran outposts across the Solar System were being equipped with Thurien relays as well. When the network was completed, it would mean that a link from a UNSA base at Jupiter to Goddard, for example, could be routed via the Thurien system, making communications turnaround delays of hours or more a thing of the past.
"And the gist of what you . . . he, this other Hunt, whatever, had to say was that Eesyan and his guys are going about it the wrong way," Caldwell went on. "It needs a different kind of physics. The Multiverse is more like the JEVEX computing matrix?"
The Minerva event involving the fleeing Jevlenese had demonstrated cross-Multiverse transfer to be possible. Ever since it happened, Thurien scientists had been trying to unravel exactly what had taken place in the hope of being able to reproduce the effect. Porthik Eesyan was one of the Thuriens' principal scientific figures, attached to their culture's highest administrative body at their Government Center in the principal city of Thurios. Hunt moved back from the window and across in front of Caldwell's desk, frowning while he collected his thoughts.
VISAR, the computing entity that managed the technicalities of the Thurien civilization, was a distributed system scattered across all the star systems that they had spread to. The Jevelenese, by contrast, had built their counterpart to VISAR as a centralized system physically located in one planet, where the workload was handled in a gigantic, contiguous, three-dimensional matrix of cells, each combining the functions of computing, storage, and communication. Changes of state propagating through the matrix from one adjoining cell to another in the course of computation behaved in a way comparable to that of elementary particles moving in physical space, which was interesting but amounted to no more than an unremarkable analogy. But things hadn't stopped there. The rules adopted by the Jevlenese system designers to govern the interactions between cells resulted in the emergence of behavior that uncannily mimicked such properties as mass, charge, energy, and momentum. These in turn gave rise to extended structures formed in the manner of molecules by the balance of opposing forces, out of which emerged a universe of worlds orbiting data-radiating "suns," and eventually harboring its own form of peculiar, squabblesome, sentient beings. It sounded as if Hunt was saying that the underlying nature of the Multiverse was something similar.
"It seems as if it could be the key to the whole thing," Hunt said. "Forget all the physics you've heard before, that talks about mass and energy moving through space. That's the physics that happens within a Multiverse reality that you happen to be a part of."
"You mean on some particular time line—like the one we're in here, right now?"
"Exactly. Where serial ordering gives rise to the perception of change, unfolding in ways that differential equations describe. Ordinary physics—and that includes all the Thurien h-space business as well—is expressed in the language of change. But the Multiverse itself is changeless. So crossing it would have to involve something other than physical movement. In the JEVEX matrix nothing actually moves. Cells just flip between states."
Caldwell stared while he digested that. It seemed almost obvious once it was spelled out. "Wouldn't the same underlying cell structure apply everywhere, here included?" he queried. "It's all part of the same MV."
"Yes," Hunt agreed. "In fact, Dirac proposed something very like it: a universe filled with a 'sea' of particles in negative energy states. They become observable when they're kicked up to positive states. Antiparticles are the holes left behind. They can move around too, as if they were particles—like holes in semiconductors."
"Go on," Caldwell said.
Hunt arrived back at the window, stared out for a second, then wheeled around and spread his arms sideways along the sill. "The matrix supports two kinds of physics. One, we just mentioned: the familiar kind that describes change, which applies to the event sequences ordered along time lines. The other involves a different form of cross-propagating cell states."
"What kind of propagation speed might we talking about, do you think?" Caldwell inquired.
Hunt shook his head. "I don't know."
"Have you talked to Sonnerbrandt yet?" Josef Sonnebrandt was a quantum theoretician at the Max Planck Institute in Berlin, who probably knew more about Entoverse physics than anyone else at the Earth end of the Jevlen link.
Hunt nodded. "He thinks we're probably talking about basic elements of the dimensions of Planck length switching in Planck time or something like that, but how any of it would translate into the dimensions that we measure things on is impossible to say right now. The Thuriens might be in a better position to guess. They've been doing the experiments. We and they need to get our acts together."
Caldwell sucked at his teeth while he contemplated the desktop. Silence ensued for perhaps half a minute. Hunt turned and stared out at the dark marble-and-glass bulk of the Biosciences building, looming above trees on the far side of one of the airmobile parking areas.
"Then let's do that," Caldwell said.
Hunt turned back to face him again. Caldwell got the feeling that this was what he had been angling for. "Are we talking about a Thurien trip? That's what it would need, Gregg. Would that be on?"
Caldwell gave him a long, pensive look, then nodded. "Okay."
"Seriously?"
"If I say it's on, it's on." Caldwell studied him for a moment longer. "You know, Vic, you don't seems as surprised as you would have been in days gone by. What's happening? Does it come with getting older?"
"No, it comes from getting to know you. Nothing could surprise me anymore."
"Well, that works both ways." Caldwell turned to one side and touched a key on the desk unit. The face of his secretary, Mitzi, in the outer office, appeared. "Did you talk to Farrell?" he inquired.
"Yes, I did. He says how about ten tomorrow? You're clear then."
"That's fine. And another thing, Mitzi. Could you get on the h-net and see if VISAR can raise Porthik Eesyan at Thurien? Also, I'd like the schedule of the Thurien ships that will be here and when, over, say, the next month."
"Going on vacation?"
"I think we've maybe found another job for Vic."
"I should have guessed. Will do."
Caldwell cleared down and looked back at Hunt. "I think I'm pretty much past surprises, too. The last time I sent you anywhere, you came back with a Universe. This time it's the entire Multiverse. That's it, the ultimate. It has to be. You can't get any bigger than that. Am I right?"
They stared at each other for a second. Then Hunt's face split into a grin. They were in business once again. He obviously liked the feeling. Caldwell allowed his craggy features to soften into the hint of a smile and snorted. "What about Josef in Berlin?" he asked, getting back on track. "Do you figure you could use him along, too?''
"Sure—if he's up to it. Want me to sound him out?"
"Yes, do that. And I guess it goes without saying that Chris Danchekker's going to want to be in on it, too. We can put it to him at the dinner for Owen tonight, after you make the big announcement."
"Sounds good," Hunt agreed.
So far, the story of Hunt's contact with another version of himself had not gone beyond a select few among UNSA's senior management and scientific staff. A dinner was being held that evening in honor of one of the original UNSA founders, who was retiring, at which Hunt was due to say some words of appreciation on behalf of the physical sciences side of the operation. Someone had suggested that this might be a good opportunity to make the news of Hunt's strange experience public. Caldwell's initial reaction had been negative on the grounds that such a bombshell would risk eclipsing Owen on what was supposed to be his night, after all. Hunt had felt that it could just as well work the other way: having one's retirement dinner cited as the occasion when the world had been was told could be the best memorial to a lifetime's work that anyone could wish for. In the end they had decided to put it to Owen and let him decide. Owen's answer was that he could think of no greater honor than to have his name linked with what could qualify as one of the most exciting scientific revelations of all time.
"I take it we're still going ahead," Caldwell said. People did have second thoughts about things like this.
"I was planning to double-check with Owen before I get up to speak," Hunt answered. "I can always switch to a fallback routine of Irish jokes or something if he changes his mind." Caldwell nodded that they were both thinking the same way.
The screen by his elbow came to life again to show an elongated Ganymean head, dark gray in color, with a protruding chin and vertical gothic lines framing large, ovoid eyes. The shoulders were covered by the top of a light orange tunic, with a yellow collar enclosing the neck. The countenance compressed in the way Caldwell had learned to recognize as an alien grin.
"Porthik Eesyan," Mitzi's voice announced. "I told him Vic is with you. He says it sounds like a sure sign of trouble ahead."