Dark as Day

16

The model… a worrying new insight, burning to be tested.

A meeting with Prosper and Lena Ligon… top priority, they insist it can’t be put off even for a day.

Kate Lonaker… cold as Charon, unsympathetic to any attempt at reconciliation, refusing to talk.

Travel notification… a trip to the Saturn system, with no explanation.

Alex was going mad. He had never felt himself under such multiple pressures. Somehow he had to impose logic and a set of priorities.

Prosper Ligon and his mother first. Alex composed the shortest message he could imagine: Meet four o’clock at Ligon HQ, Notify if not acceptable.

Next he checked the travel authorization. As soon as he saw the origin: Ligon Industries, he put the worry to the back of his mind. He would find out what it was about soon enough.

Now for the tough one. He called Kate.

She answered at once, as though she had been sitting waiting by her communications terminal.

“Yes?”

“I’m going to run the model again. I have a new idea, and to test it I’m going to DP Central. I would very much appreciate your assistance and insights.”

“Very well. I will meet you there.”

Still cold, still aloof. What was wrong with the woman? Would he make a big deal of it, if Kate had gone off and screwed somebody and she didn’t even remember who?

Alex decided. Yes, he would mind. He would be totally pissed. He owed Kate a big apology, if only she would endure his company long enough to listen.

He hurried along to DP Central, where they would enjoy access to the highest computational priority and the best displays, courtesy of Magrit Knudsen. Somehow, Kate was there ahead of him.

“Kate, I just want to say—”

“I’m ready for work when you are. You tell me you have a new idea. What is it?”

So much for apologies. Hell hath no fury like a woman scorned. He hadn’t exactly scorned her, but that logic wouldn’t get him far. To work.

“I’ve reviewed the old results over and over. I’m still convinced that the model is basically correct.”

“So you mean, a hundred years from now there will be no humans left, anywhere. Right. That’s very reassuring.”

“I don’t believe that result. I think that the problem lies in the Seine.”

“Two weeks ago you told me that the Seine would solve all our problems.”

“All our computational problems. We have ample computing capacity for the first time ever, but the Seine is much more than simple computer power.”

“Like what?”

“Like a huge number of external databases, online for the first time. We were careful not to introduce what we thought of as inappropriate exogenous variables into the model, but the Seine doesn’t have that constraint. Anything that is not specifically ruled out is open for consideration. The trouble is, the Seine is so complex that we don’t know what it includes and what it excludes. I believe that we have to do something radically different. We have to introduce our own exogenous variables, things that we believe are possible logical components of the future. We have to see how this affects the computed results.”

Kate, for a change, didn’t act like an ice princess. The lines of her face softened, and she stared directly at Alex. “But there could be a million things in the possible future. How are we supposed to know what to choose?”

“We assess possible events on the basis of our own estimates of their likelihood. We change the model to reflect it, and see what difference it makes to the results.”

“I wouldn’t know where to begin.”

“Well, I think I do. The Seine doesn’t try to predict the future, or make random assumptions. It uses only facts that are present somewhere in the System right now. If the computed future suggests the extinction of humanity, that’s because those factors are already present today.”

“Such as what?”

This was one that Alex wished he could avoid. “Such as the Commensals. They are basically human, but a thousand other life forms have been spliced into them. It occurred to me that the way we have been running the model, neither the computer nor the Seine data banks makes any distinction between a human and Commensal. We don’t know if future population figures refer to humans, or Commensals, or both. If everyone in the System eventually elects to become a Commensal, then the model that we have may be predicting that the future holds no true humans. On the other hand” — Alex had to face an intolerable possibility — “maybe Commensals become the human norm, but they have a built-in flaw that causes them to die out.”

A built-in flaw like guaranteed sterility, so that no one is reproducing anymore.

Kate began to nod agreement, then stared wide-eyed at Alex. “But if that’s the case, then your mother—”

“I’ve already thought of that.”

“Oh, Alex.” She reached out as though to take his hand, then withdrew. “I’m really sorry. I hope that’s not true.”

“So do I.” Alex saw his chance, and jumped in. “And I’m really sorry, too. I don’t mean for my mother and the other Commensals, I mean for what I did. I know I screwed Lucy Mobarak, or Deirdre de Soto, or somebody. Maybe I screwed all of them. But they sabotaged me, I’m sure of it now, down in the Holy Rollers. The drinks were spiked. I had no idea what I was doing — I don’t even remember it. That doesn’t excuse what I did, but maybe it explains it. I want to say again, I’m sorry.”

“Let’s talk about all that later.” But Kate reached out, and this time she did squeeze his hand. “For the moment we have to concentrate on the model. If it’s the Commensals that are causing the trouble…”

…then we are in for a battle royal. The Commensals, and the Sylva Corporation that oversees their creation, between them have tremendous political clout. Kate didn’t need to say that to Alex. His own mother was far from unique in her willingness to do anything to restore and maintain her youth and beauty.

“We’re going to find out.” Alex set to work at the console. “I’m setting up the model to treat Commensals and unmodified humans as separate but interacting populations.” He turned to Kate. “Do you know, can someone who decides to become a Commensal change her mind, and have the process reversed to become a normal human?”

“I don’t think so. I believe it’s one-way only. If it is possible to undo it, I’ve never heard of a case where someone chose that option.”

“So we’ll assume it goes on like that.” Alex set parameters so that any member of the human population could elect to become a Commensal. The human population changed by reproduction, by transfer to Commensal form, or by death. The Commensal population could decrease only through death. An all-Commensal solar system ultimately implied an empty solar system.

He glanced at Kate. His finger hovered over a final key. She nodded. “I can’t think of anything more. Do it, Alex.”

It was the power of a god. Alex pressed. At one touch of his finger, databases all across the System came into play. Within the computer, the separate Faxes that represented more than five billion humans (and now Commensals) began to live, die, love, hate, act and interact, and move around the solar system. Days sped by too fast to follow. As the years rolled on, the full panoply of solar system activity was revealed on the displays.

Most of Alex’s attention focused on just two counts: the ratio of the number of Commensals to the total human population, and the human population itself.

The yearly aggregates came into view. By 2105, System population was a figure familiar from their previous runs: 5.6 billion. Commensals were less than one in ten thousand of humans. But the fraction was creeping up. In 2124, one percent of the human population of 7.6 billion had become Commensals. In 2134, that percentage was close to five percent.

“I think you’re right, Alex.” Kate was crowding close, no longer aloof and standoffish. “It’s the damned Commensals.”

Alex didn’t think so. He could make the extrapolation in his head. The proportion of Commensals was increasing, but nowhere near fast enough to cause problems. With ninety-five percent of the total still human, and still actively breeding, the number of people or Commensals would never start to nosedive by 2150.

But here came 2140, and trouble. The conversion to Commensals were steady at five percent. The trouble lay in the human population. Birth rates were down, along with every other index of activity. Alex and Kate sat and watched in grim silence, right to the bitter end when in 2170 the number of humans hit a flat zero. A small population of Commensals lingered on for a few years, but by 2185 that count was also down to nothing.

“That’s it.” Alex smacked his fist down on the console, ending the run. “Exactly the same results as before. Now we know it’s not the Commensals that cause the problem. Another idea bites the dust.”

“That was just one thing to try.” Kate didn’t mention that in some ways she was relieved. The idea of a solar system filled with Commensals, and only Commensals, did not appeal to her. “We can examine the effect of other important variables.”

“We could.” Alex hesitated. Did he really want to go through with this? “But there’s one other thing I’d like to do before we change variables. There is an alternate way of running the model itself, what I call Snapshot Interactive — SI — mode.”

“I’ve never heard you mention it.”

“That’s because we’ve always stressed the need for repeatable runs. You need results that you can take up the line to Mischa Glaub and Tomas de Mises, and if you have to run again you’ll always want the same answers.”

“Damn right. Alex, I don’t understand you. I know we run with a variety of possible inputs, but each run is deterministic. Except for database changes, we get the same run today as we did yesterday.”

“That’s not guaranteed in SI mode. There can be differences.”

“I think you’d better be specific. Remember, I’ll have the job of explaining all this to Mischa Glaub.”

“I’ll be as clear as I can. As you know, the big difference between my model and the ones developed in Pedersen’s group is that I include a separate piece of code for every single individual in the solar system. Each person is represented by a Fax with some level of decision-making logic of its own. The interaction of all those human-simulator components makes up the complete model. The average properties, such as transportation activity or food needs, are not regarded as independent variables. They are constructed values, built up from all those billions of separate needs.”

“I got that much from your briefing the other day. You’re saying nothing new.”

“I’m about to. When I said that individuals are represented in the model, I meant exactly that. Each person in the solar system census is in there, represented by anything from a Level One to a Level Five Fax. There’s a Mischa Glaub in the model, also a Kate Lonaker, even Cousin Hector, though I bet his Fax is smarter than he is. Most important, there’s an Alex Ligon.”

“Most important to who?”

“Most important for what I’m proposing to do next. The SI mode allows a person to take the place of his or her own Fax, inside the model. I’ve never done it before with the Seine in operation, but I’ve tried it with a reduced model in a limited environment. I know it’s feasible. I’m going to enter the model, as myself. For me it will feel like just another VR environment, same as in the media shows.” He gestured to one of the half-dozen VR helmets on the bench in front of the displays.

“Alex, you’re out of your mind. Your model runs at umpteen-million times real-time.”

“About a million, in SI mode.”

“A million, then. So the model simulates a year every thirty seconds. There’s no way your brain can possibly keep up.”

“I won’t even try. For most of the interactions, my Fax will be making decisions. Once a simulated year, I’ll have thirty seconds to review where I am, make decisions, and hand control back to my Fax. I won’t be able to change much, because my Fax isn’t powerful or influential enough for that. But with me in the program, you lose exact repeatability.”

“But why do it at all? What will you get that you can’t see right here?” Kate gestured at the displays.

“I don’t know. Immediacy? Perspective? Perhaps nothing at all. Don’t worry, I’ve done this before. It was never very enlightening, because the model was oversimplified and aggregated so much that the setting felt bogus and artificial. I’m hoping it won’t be that way now.”

“Not artificial — when you’re being jerked forward a year at a time, every half minute? Give me a break.”

“I built in a smoothing function and a neural connector designed to help with that. It ought to be that I’ll feel like I remember whatever my Fax has been experiencing.” Alex picked up one of the VR helmets. “We can talk about all this when I come out. Once I wave my hand, start the model running.”

“And then do what?”

“Watch, and wait. We’re going to run for sixty years. That’s half an hour in real-time. If I’m still in the helmet after that, drag it off me.”

“Alex!” But the helmet was going on, and Kate’s cry of protest sounded far-off and muffled. The inside of the VR helmet was totally black. The only sound was Alex’s own breath in the oxygen supply tube.

He waved his hand. Nothing at all happened. He sat for a few seconds and was on the point of removing the helmet when he realized that this was exactly what he should expect. Time was blurring along in the computer model, but his first one-year snapshot was thirty seconds in the future.

It came to him not as some form of description or image, but as memory. He remembered the whole of the past year, but with a variable degree of detail. System politics were far-off and vague, while anything that affected him personally was clear. He had persuaded the bosses that his models were the right way to approach prediction, he had been promoted, and he had moved in with Kate — over the screams and protests of his mother and the rest of the family.

Was this the program, or mere wishful thinking? He was still trying to decide that when — memories — another year sprang full-blown into his mind.

So much for his smoothing function! It didn’t seem to work at all. The merger of the Ligon and Mobarak families had taken place — but how and when? Who had married whom? Alex could not remember, although he was somehow sure that he himself was not married to Lucy-Maria.

Here was other news, confusing and muddled, coming from the farther reaches of the Jovian system. Signals had been received there, perhaps from the stars. It could mean the discovery of aliens. The message was being looked at — had been looked at — had been dismissed as bogus. Or had it? It still seemed to be there. Alex felt his own confusion beginning. The future was filled with an infinity of branch points, and the model could not pursue all of them. He had the nagging feeling that he disagreed with some of the program’s choices, but before he could analyze his reasons — memories — another snapshot came pouring in.

Was this only three years out, or were multiple years somehow being crushed together? The solar system had escaped a great disaster that would have ended all life, from Mercury to Neptune and beyond. This was not the gradual dying-off that the model runs had predicted. This one would have been quick, extreme, and total. But it had not happened. So why was it here at all? The program was responsible. The non-event must have been on a high-probability path, otherwise it could not be in Alex’s memories at all. He tried to dig for details and a better understanding, but he was too late. Memories. Something — war, natural disaster, technological failure? — on Earth. Discoveries on Triton, Neptune’s giant moon. Loss of the Oort Cloud explorers. A dozen more events crowding all at once into his mind. He ought to have known this was impossible, even the highlights of a full year could not be comprehended in half a minute. Kate had been the realist, he had not. (Did they live together now? He could not say.) Memories. The tempo was increasing, a year was shrinking to nothing. What had happened to his thirty seconds per year? A trip to Venus — for what possible reason? A death, someone in the family. He could not tell who it was. A great rain of comets, sweeping in from the Oort Cloud and endangering the whole System. Was this the source of humanity’s disaster? No, some form of deflection shield had operated. Memories. Of a meeting, with the population chart of the System spread out before him. Ten billion people — as many as had ever been predicted in the models. But the total was decreasing. Memories. His mother, face changing color and melting like hot wax. Cousin Juliana, shriveling, dying — along with all the Commensals? The data were not there. Destructive forces unleashed around the solar system, as powerful as they had been during the period of the Great War. But he saw only their shadow, an unrealized potential. Was this the warning of coming holocaust? Memories. They came not as individual images, but as a great collective tide. The Seine had collapsed, the Jovian worlds were uninhabitable, Mars did not communicate, battered outposts on the moons of Uranus clung on to diminished life. And Alex himself. Where was he? He had committed a major blunder in planning the model. He had not allowed for his own death. If his Fax “died” within the model, what would happen to the connection? Could he die too? Memories. The worlds of the solar system were dark. He sat on the outer fringes, alone, beyond the planets, beyond the Edgeworth-Kuiper Belt, looking in toward the weak spark of the distant Sun. Memories. Of solitude and silence. Had he come here hoping to be safe? He knew, through an unexamined accumulation of doomed memories, that his was the only life within light-years. How long had he been alone? How long would he remain here?

There hath he lain for ages, and will lie…

The VR helmet was ripped from his head. Light, world-filling light so bright that he was forced to squeeze his eyes tightly shut, burned around him. He heard the voice of a stranger, calling through the effulgence.

“It’s been more than half an hour, and you were mumbling to yourself. I couldn’t understand what you were saying. I had to get you out. Alex? Alex? Are you all right?”

He was not all right. He had swept far forward in time, to the death of humanity and beyond. He had hovered alone on the rim of the universe. How could anyone be all right after that?

“I knew I shouldn’t have let you do it,” the voice said. “I’m a total bloody fool. Here. Sniff this.”

An acrid vapor filled his nostrils. Alex gasped and gagged. His heart raced, he opened his eyes, and the room flickered and reeled around him.

“Alex!”

“Sa’ right. I’m — mm — a’ right.”

“You don’t sound it. Who are you? Tell me your name, where you are and who you are.”

“I am Alex — Ligon.” The room steadied. He was sitting hunched in a chair, with someone — Kate. Kate… who? — gazing down at him. “I’m — I — where am I? I’ve… been…”

“Alex! What happened to you? When I removed the VR helmet your eyes looked ready to pop and your pupils were all dilated.”

Alex shook his head, not to disagree but to try to clear it. “Dunno. Can’t think straight. Gimme a boost.”

“No. Alex, that’s a bad idea.”

“Need it. Got to have it. Mental overload, too many futures. Too much, too fast.”

“You’ll regret it. You’ll feel terrible later.”

“Give it.”

Alex closed his eyes and lay back. Hours seemed to pass before he felt the cool spray of the Neirling boost on his temple. The world inside his head steadied and came into focus.

He opened his eyes. Kate was frowning down at him.

“I’m all right, Kate. I’m fine. But it’s going to take days to sort out what I experienced. My head was spinning around like a top. It’s my own fault, I ought to have realized what would happen.”

“And I ought to have forbidden you even to try. I thought you said that you had done this kind of experiment before.”

“Not with the Seine running the show.” Alex’s pulse was beginning to slow. The Neirling boost had taken effect, and he would have at least three hours of mental clarity. He leaned back in his chair and rubbed his forehead. Everything from there to his brain stem had ached. It would ache again, when the boost lost its effect, but for the moment he felt he could understand — and explain — anything.

He said, “I’ll tell you what I think was happening, but I may be wrong. The Seine has enough computational power to consider and select from thousands of branches at a time. A Fax is too simple to be employed in more than one future, but apparently a human isn’t. I was catching glimpses of many possibilities — too many for me to handle.”

“You’ve lost me, Alex.”

“That’s not surprising. I’ve never gone into those elements of the predictive model with you. I would have, but you insisted that I work on a briefing that Macanelly would follow.”

“I did. But if you’re suggesting that I’m a dimwit like Loring Macanelly…”

“No, not at all. It’s just a question of where I put my time. I was trying to produce a simplified version for Macanelly, and that meant I had to leave some of the trickier elements out. Then we had to brief Mischa Glaub and Magrit Knudsen when we weren’t expecting it, so I went with the same approach—”

“Information, Alex. I need information. What did you feel you had to leave out?”

“All the probabilistic elements of the model.”

“Then you’re right, we have never discussed any such thing. You’ve always insisted that your model is deterministic. Unless you are in your Snapshot Interactive mode with a human in the loop, it will produce the same results every time.”

“That’s true. It will. But that doesn’t mean there are no probabilistic elements.” He felt a mild irritation at Kate’s slowness of comprehension.

“Alex, now you’ve got my head spinning like a top. Back up, take it easy, and remember who you’re talking to. I’m not Loring Macanelly, but I’m not boosted and I’m no genius when it comes to models.”

“I’ll do my best.” Alex remembered a piece of advice from the leading scientist of the last century: An explanation should be as simple as possible, but no simpler. It wouldn’t help to quote that now to Kate.

“I’m going to use an analogy. I was afraid to do that with Loring Macanelly, because from everything you’ve told me he’d not know how to distinguish an analogy from the real thing. But it’s the way I often think of the predictive model.

“Imagine that our model is playing a game of chess, and it’s the model’s move. It knows the layout of the board pretty well at the present time, but the board isn’t the usual one with just sixty-four squares and at most thirty-two pieces; our board is the whole extended solar system, with at least five billion humans and any number of computers and natural features. The model has to take into account all the actions and interactions of all the elements, and then decide how the board is likely to look one move ahead. Let’s say, one move ahead means one day from now. The opponent — in this case, humanity and Nature — makes a move. Then the model has to decide how the board will look at that point, which is two days ahead. After that the opponent moves again, and again, and again. The model has to decide in each case what the board is likely to look like. It is making a prediction.”

Kate was nodding — a little uncertain, but still a nod.

Alex went on, “The best human chess players can look ten or even twelve moves deep. They have an idea what the board might look like that far ahead, and they make their next move accordingly. How do they do it? Well, one thing we know for sure is that they don’t do it blindly. They also don’t do it by evaluating every possible move that their opponent might make, and choosing the best one for them. There isn’t enough time in the universe for a human player to adopt such an approach, even though it was the method used by the earliest and most primitive chess-playing programs. What the human player does, based on instinct and experience, is to assign a probability of success to particular sequences of moves, taking into account every reasonable move that the opponent might make. Those sequences with a low probability of success are dismissed. They don’t even make it to the level of conscious consideration. The high-probability sequences are examined and compared. Finally, the player makes a move. That move is the move that offers the best chance of winning, given all the moves that the opponent might choose to make in the future.

“The predictive program faces the same problem as the human chess player, only worse. It doesn’t know what the ‘opponent’ — the natural universe, plus the five billion or more human ‘pieces’ — will do, day after day after day. Even with all the computing power available in the Seine, a short-term prediction would run to the end of the universe. So the model, like the human chess player, is forced to work with probabilities. And like the human chess player, it rules out the low-probability futures, unless we insist, via exogenous variables, that it must consider them. If we do that, the model automatically converts that low-probability future to a high-probability one. Even then, when we go farther into the future the case that we insisted be considered may drop in probability, if the exogenous variable was introduced at only a single point in time.

“From the point of view of the model, there never is a single future. There are huge numbers of possible futures, branching off and diverging from each other the farther ahead we look in time. What we see reported as the future is simply the one to which the model assigns the highest probability.” Alex paused. “You don’t look happy.”

“I’m not happy. You are telling me that we went ahead and presented a briefing to my boss and my boss’s boss and my boss’s boss’s boss, talking as though what we had was gospel brought back from the mountain. Now you’re saying what they heard was just one of a billion trillion possibilities.”

“No. The model is much smarter than that. All possible futures will progress through time, and as they proceed they will diverge from each other. That’s inevitable. Think of the futures as being like photons of light, forming a cone that gradually widens as the light travels farther from its source. But if you sum all the probabilities for all the futures, you must get unity — some future must happen. The model considers the thousand futures for which the computed probabilities are the greatest, and makes a measure of dispersion. How much has the cone of those probable futures widened over time? If the number it calculates exceeds a pre-set value, the model will return a message that with these parameters, the future is indeterminate.”

“But that never happens. At least, is hasn’t happened in any runs that I’ve ever-seen.”

“That’s good news, not bad. It means that all likely futures are rather similar, which is a reason for having confidence in our model. Implausible futures damp out over time, unless we insist on forcing them back in via exogenous variables. What I didn’t expect, and what I had trouble handling when I was in the Interactive mode, is that I would be able to sense other futures — maybe even improbable ones — as the program was running. They hadn’t had enough time to damp out.” Alex could feel them stirring again inside his head. Comet showers, disintegrating Commensals, the discovery of aliens, mysteries on Triton…

“So the most probable futures are much the same as each other,” Kate said. “You were still interacting with the model at the end. You must have seen them. What were they like?”

She was anxious but hopeful. Alex for one moment considered giving her the answer she wanted to hear, but the run records would reveal the truth.

“Nothing to offer us comfort,” he said. “Exactly the same result as before: a century from now, no humans survive. The solar system will be empty and lifeless.”