Finity

by John Barnes

  She drew a deep breath and said, “All right, here’s the thought. Suppose people are crossing from one history to another—all the histories are sort of tangled together like spaghetti, all right? And most of the time, when you cross over, you cross over to a strand very near your own, so only small details are different—like how you met, or how long your cat lived, or something. But every so often you accidentally take a big leap, like I did when I came here to this history. And whatever causes those crossovers, the crossovers have been getting more and more frequent in the recent past, so that people have been having more and more disagreements about the past. Well, you know, when a subject becomes controversial—especially when it becomes controversial and impossible to settle—”

  “Of course!” I said, and now my head felt like it was in a vise. “Polite people start avoiding it. Nobody wants to be the rude person who brings it up. Ways are found to pussyfoot around it... sometime in the last few years, then, or maybe the last twenty or so at most, the worlds have started to drift together—”

  She was sobbing again, and I rolled over and held her. This time I could guess. “Your mother?”

  “Oh, yes, that.” She turned and hung on to me for dear life. “That, and if we’re right, then after all these years I just found out I’m not crazy.”

  I suppose we could have talked more, but exhaustion swept over us, and though it seemed I just shut my eyes for a moment, when I looked up, it was already dawn. Helen was still in my arms, traces of tears all over her face, her lips wet and red, hanging slack. She looked impossibly young to me, and I lay there watching her till she began to move and her eyes opened.

  * * * *

  At breakfast, we tried to have a normal, trivial conversation, but we discovered that we just weren’t going to be able to talk about much else. “There is a certain kind of sense to it,” Helen said. “Figure Iphwin owns all of ConTech, and ConTech might be as much as half of one percent of the global economy. He’s so big that he has to operate internal markets and figure out trade policies between his own holdings. There isn’t much way to take him down by a frontal assault—but if you can somehow make things less predictable, disrupt the causality inside the company, then that changes things. In some ways it’s not much different from doing random damage, like twentieth-century bombing raids, or getting the company directory and sending letter bombs at random. But in other ways it’s worse, because how can anyone plan that a certain number of time reversals will happen, or that some shipments that were never ordered will turn up from companies that don’t exist, or, like that case in Mexico, where ninety tons of specialty steel get shipped and forty thousand sets of pajamas get delivered? For most of the other possible kinds of attacks, you can control risk with insurance, because you know what the range is of what might happen, and what the likelihood is. Random bombings might be terrifying but they just add one more bad thing to the list of bad things that are likely to happen, and give it a high likelihood. But when the two things being messed with are the range of what might happen and how likely it is—then there’s no bet you can take out against it.”

  “Suppose the enemy is Murphy,” I said, before I had time to analyze what I meant myself.

  “Who’s Murphy?”

  “Murphy’s Law?”

  “Still never heard of it.”

  “Oh. Well, it’s not really important. What I’m getting at is, how often do you discuss the past with your friends, in a way that matters to them? How many people have a long-running argument with their spouse about which of two perfectly plausible events happened to them a long time ago? There could be tremendous amounts of random noise in the past before anyone would notice there was any pattern of any such thing. And maybe small violations of causality account for Murphy’s Law, which is the law that ‘If anything can’t go wrong, it will.’ I mean, that’s a violation of causality right there.”

  “Who was Murphy?” she asked.

  “Funny thing,” I said, “but I’ve heard at least ten different stories about him. The inventor of the parachute but not the first successful parachute. The guy who invented a safety hatch for submarines, that was supposed to make it impossible to dive with a hatch open, but actually made all the hatches open at the bottom of the dive. A man who ran a mail-drop blackmail operation and was caught in the Tsunami of 2002, which kept him from getting to the post office but allowed the post office to stay open and send the mail. The navigator on the Titanic. All sorts of stories about the guy, actually. I always figured most of them were folklore, but maybe in all of history there was just one Murphy, and he has multiple pasts in which he always ends up coining his law, the same way that the multiple American pasts always seem to have the ‘27 Yankees and the Wright brothers.”

  “And you’re suggesting—”

  “That maybe perverse anticausality—just call it perversity— is just a physical factor in the universe, like entropy or gravity. Maybe it normally occurs at such a small level that people who encounter it don’t think enough of it to care very much; or they notice it, like Murphy, but they don’t try to do anything about it systematically. This implies that either the background level of perversity is increasing—or it might be caused by Iphwin himself. Maybe he’s got the first economic unit that’s both big enough and self-aware enough to detect perversity, so that he sees it happening, where none of the markets did.”

  “How would we test that?”

  “I don’t know,” I admitted. “I was just seeing if there was any reason to question an assumption that we were making, that there was a real enemy somewhere doing something, and not just the system itself generating the events. But though it could be the system, it could just as easily be a real enemy. And having been beaten the hell out of by Billie Beard, I find it hard to think of her as just a system artifact, or purely an expression of the law of perversity.” I looked at my watch. “Probably about time to get ourselves up to the office. I guess we should think about what sort of experiment would allow us to distinguish between a physical law and a physical enemy—but that would depend on knowing what an enemy could do, and until three days ago I wouldn’t have believed that anybody could tamper with causality.”

  When we got to the office, about five minutes early, the only instruction was to continue experiments by whatever means we wished; there was also a budget that told us that we had a ridiculous amount of money to play around with.

  “What say we go do research in Fiji for a year?” Helen said, grinning at me.

  “I’m worried about getting shot,” I said, “so how about we beat the bad guys and then honeymoon in Fiji?”

  “Oh, all right,” she said. “Has anyone ever told you you’re excessively responsible?”

  “Nearly everyone. Let’s see. One thing we could try to develop is a map of all these alternate pasts we’re finding—they seem to occur in families, like the way that Terri is from a world that includes the Reichs and Empires, like I am, or that Kelly and you both share Diego Garcia, with all of our personal histories tangled up into something you can’t unscramble when we tried to fit them together, so we seem to all be from different worlds, but not from evenly distributed different worlds—there wouldn’t be that many similarities in such a small group if the distribution were even across the infinite possibilities. It suggests that there’s some huge diversity of pasts out there, but it’s grouped into a much smaller number of ‘supergroups’ or ‘history families’ or whatever you want to call them.”

  “Have you thought of an experiment?”

  “Let’s try this one. We’ll send a small payment to anyone who answers a questionnaire, identifying as many things as they can and labeling the rest ‘never heard of it.’ Sort of like what the shrinks did with us, you know. And we’ll make it sort of a chain letter—there’s another payment for anyone who modifies the quiz according to directions, and then sends it on to another person. The modification will be adding a couple of things to be identified to the list—that way we’re n
ot just restricted to what we know about, so that if there’s some Supreme Court case called Hickenlooper versus Iowa or something, that’s important in histories that neither of us has, it stands a good chance of being added to the list. We could pay the first few thousand respondents and cut it off after three hours; the net’s a big place and that would give us a starting map, to see whether addresses correspond to histories, for example.”

  That took us the better part of the morning, devising a questionnaire, a payment system that couldn’t be cheated too easily, and a system for modifying the questionnaire that still would not let them cheat on the payment system. It was ten-thirty before we managed to fire it off; we had agreed we wouldn’t check until everything had come in, which wouldn’t be till one-thirty, so we spent two hours reviewing all the mystery cases: shipments that arrived before orders or were transformed into other objects by the time they arrived, nonexistent branches of the company that left frantic messages—and then, just as often, called in to thank ConTech’s central office for the help. Some ships and planes had vanished; one ship had been found floating without a crew, a hundred miles from its exact duplicate, which was also crewless. A few days later the whole crew turned up in jail, four thousand miles away, having been there since before the voyage started.

  “There’s definitely something peculiar about time in all of these,” Helen offered, after an hour. “Doesn’t it look as if many of them are cases of time flowing backward or going into a loop?”

  I nodded. “From the results we can’t tell if time is looping, or if it’s just caused by there being a multiple stream of pasts. Maybe the shipment that arrives before the order just has a past where the order was dated earlier. Maybe the two ships are both from pasts where the ship just vanished.”

  “But if the ship vanished in the past, how can it be here today?”

  I swallowed hard, because I had thought of something that might upset Helen. “Helen, if there are multiple pasts, and if there are going to continue to be multiple pasts—and we haven’t seen anything putting a stop to them—then there have to be multiple presents, because we’re the past of the future. And since the future is the present of the future—”

  “God, that makes my head hurt, but I see what you mean. We can’t assume we’re the only present...” She stared at me. “A few months ago you were very, very drunk and you told me about something called the Many Worlds Interpretation. What was that?”

  I shrugged. “I hadn’t thought of it, but it’s another hypothesis we could add. Down at the quantum level—we’re talking subatomic particles here, really small stuff, nothing you can observe in everyday life—there’s a little problem called the uncertainty principle.”

  “I’ve heard of that. Doesn’t it mean that the observer creates reality or something like that?”

  “That’s what it means in the humanities, where people just pin new labels on ideas they inherited from the Greeks. But what the uncertainty principle means in physics is a lot stranger and much more rigorously demonstrated. Suppose you had a car whose speedometer could only register five speeds—maybe zero, two miles per hour, ten miles per hour, twenty-six, and a hundred and ten. It would always register one of them, and the closer your actual speed was to one of those speeds, the more likely it would be to register that speed.”

  “I’d take it in and get it fixed.”

  “Damn straight. However, we can’t take the universe in and get it fixed, obvious as the need might be. Now it so happens that the only way we know what’s happening with subatomic particles is to bounce other subatomic particles off of them, and subatomic particle behavior is quantized—it can only take on certain values, like that five-speed speedometer. Therefore when we bounce one particle off another one to find out what’s going on, we don’t get a single answer—we get a distribution of probabilities. Sort of the way you’d take a guess at what your car was doing—’Well, probably ten percent chance it’s between 10 and 26, seventy percent it’s between 26 and 110, and twenty percent it’s more than 110, so I’m probably okay on the highway.’ No matter how exactly we bounce the particle or measure its behavior after the collision, we don’t get a precise picture, but a set of bets, probabilities assigned to possibilities. Still with me?”

  “This is worlds easier when I’m not drunk.”

  “I bet. Okay, now here’s the tricky part: there’s no difference between a measurement and any other interaction with the universe. Any physical process that depends on that particle will act as if all the possibilities were happening at once, with that mix of probabilities. Unless you do something for which the particle must be in exactly one state—and if you do that, then it will ‘collapse’ into that single state.”

  “Pretend I understand you and give me an example.”

  “Ever hear of Schrödinger’s cat?”

  “Why would I want to shred anybody’s cat?”

  I ignored that. “Schrödinger suggested a thought experiment, trying to get at how weird the problem is. He said, suppose you put a cat in a box so that you can’t observe the cat, and inside there’s a bottle of poison gas, which has a fifty percent chance of releasing the gas, based on some quantum event it’s going to observe. Then since the unobserved quantum state is 50 percent one way and 50 percent the other, until you open the box, the cat must be 50 percent alive and 50 percent dead.”

  “Sounds like something a German would think of doing.”

  “He didn’t do it. He just pointed it out as an example of how hard that is to understand in ordinary life. Naturally, when you open the box, since the cat has to be either alive or dead, what you find is either a live cat or a dead one, and that tells you how the quantum event came out. But up till then the box should behave as if it had a 50 percent alive cat—whatever that means— inside it.

  “Now, one of the greatest arguments in all of science, still going on after 150 years, is about what that means. The Copenhagen Interpretation, which most physicists buy, is that it’s all just a computational device, and that it’s just that we don’t know how to really understand our own equations—all we know is that they work. The Aphysical Interpretation is that somehow there’s a ‘real’ world that ours is only a shadow of, and the probability distributions somehow reflect an underlying unified reality that we can’t perceive. And the Many Worlds Interpretation says that every time a quantum event happens, the universe splits into multiple worlds, enough so that across all those worlds, each event happens all the possible ways. When a Copenhagen interpretation guy opens the box, he finds the cat alive and says, ‘The calculations showed a 50 percent chance that this would happen.’ The Aphysical guy opens it and says, ‘This live shadow cat reflects the state of the real cat.’ And the Many Worlds guy says, ‘Aha! I am in the universe that got the live cat; in some other universe at this moment someone is recognizing that he is in the universe with the dead cat.’ And the really clever trick, so far in the history of physics, is that all these are just interpretations. The experiment doesn’t go one bit differently from one interpretation to another; the only thing that changes is the meaning we read into the event. At least up till now; we might be conducting, somehow, a giant experiment that’s showing that Many Worlds has, let us say, a certain edge.”

  Her jaw dropped. “So if Many Worlds is right, then there could be an infinite number of universes with divergent pasts out there? And maybe what’s happening is that things are crossing the fence, or whatever it is, between the universes?”

  I nodded. “That’s what I mean. But there’s a lot of what is going on that doesn’t seem to fit that theory. Why should that make it impossible to phone America? Supposing that you and I are meeting different versions of each other—Lyle Prime flew you to Saigon, and Helen Prime rescued me in the shooting at the Curious Monkey—why don’t we ever run into ourselves? And why do the crossings over only seem to happen now and then, and why don’t we all just have multiple pasts until someone asks us a question?”

  “Pro
ve we don’t.”

  “All right, I’m thinking of a past event. I’m not thinking of a distribution of them. Is any part of your past a distribution of events?”

  She thought hard for a moment. “As far as I can tell, no.”

  “See? It doesn’t fit with what I’d expect. Let’s go to lunch and try to get away from all this for a while; by the time we get back we should have results from our survey.”

  Since we were trying not to talk shop, there was practically nothing to talk about; wedding plans seemed hopelessly indefinite, managing the apartment together required practically no consultation (since we were both neat minimalists), and the weather was perfect as it tended to be at this time of year. We ate, we looked out the window, and we read the paper to each other (learning mainly that the world was proceeding about as always—I can’t recall a single surprising thing). By one-thirty, when it was time to return to the office, we were looking forward to it.

  The results were about as much of a nonresult as you could get; we had a few hundred responses, and the “I don’t knows” for each item, plus the disagreements, were generally uncorrected with address, time of response, domain, or anything else. “Some of the answers correlate,” Helen said, “but that kind of figures. Hardly anyone has Mickey Mouse being a Disney character and a newspaper character named after a brand of chewing gum; nobody has Teddy Roosevelt assassinated by German agents in 1916 and being Secretary of War during World War Two. Which just tells us that most people live in a locally consistent world. Not the most informative thing I’ve ever seen, eh?”