by Isaac Asimov
But, somehow, he no longer saw it that way. Others here, mostly the Settlers, were far more skilled at handling the detailed mathematics of moving a small world through space. He saw his position as a penance, and a fitting one. How brilliant and noble could his vision have been if his closest associate was willing to die in order to stop it? Davlo found himself embarrassed and ashamed whenever someone recognized him and congratulated him on his grand plan. Most of the crew had learned to avoid the subject, and, indeed, had learned to avoid Davlo.
But he had been sent here to do work, and he had agreed to do it. So he accepted the tasks he was given, and did them as best he could. Besides, work got his mind off things. He could worry about solving the equation, determining the proper thrust and orientation. Off-shift was the worst, nights spent staring into the darkness, thinking of all the ways things could go wrong. No, he wanted no congratulations.
Something inside him had changed. Or was it merely that something had been burned out, destroyed, when he watched Kaelor destroy himself! Surely the last of the old Davlo had died with Kaelor? Had anything, anyone, taken the old Davlo’s place, or was he just an empty shell of a man, going through the motions?
No. Never mind. Think about other things. Think about the plan to move the comet.
Davlo’s initial plan had been to use a fairly standard high-yield nuclear bomb, but the Settler-designed detonation thrusters were a vast improvement on that idea. In essence, a d-thruster was a nuclear bomb set off inside a powerful force field formed in the shape of a huge rocket nozzle. The force field directed the force of the explosion into the proper direction, in effect producing a shaped charge that was far more efficient and far more controllable.
Other explosive charges were being rigged as well, of course. Once the comet had been redirected into its intercept course with Inferno, it would still be quite some distance away from the planet. It would take it just over thirty-two days to move from the point in space where the initial course change was made to its intercept with Inferno.
Just before arrival at the planet, the comet would be broken up into smaller pieces by explosive cutting charges, each piece to be directed toward a different point on the surface. Each fragment would have its own smaller, non-nuclear propulsion system and attitude control system.
And that was the part that worried Davlo. That was the greatest danger in the plan. In theory, at least, it might be possible for human operators and standard computer systems to manage the complexities of the operation. But the current plan called for Grieg to be broken up into twelve fragments, and it was far from certain that all the cutting charges would shear the massive body into pieces of precisely the intended size. Besides which, there were bound to be thousands of smaller fragments produced by the blasts of the cutting charges. Most would be too small to do any damage.
But all it would take was a fragment smashing into a thruster at the wrong moment, or for a fragment to end up being larger or smaller than expected, and then the whole careful sequence of events could go out of control. There were enough spare thrusters to serve as backups, so that if some of the thrusters on a given fragment were destroyed, the rest would be able to do the job. Indeed, there were no ifs in the question. Some part of the established plan was going to go wrong – it was just that no one could be sure which part. It would require immediate, real-time management of the operation to deal with the inevitable problems.
Managing the terminal phase of the operation would mean dealing with thousands of operations simultaneously. It would require juggling the twelve fragments at once, keeping them out of each other’s way while guiding them down to their intended impact sites, while dealing with the cloud of debris produced by the cutting charges.
No matter what theory said, in practice, the job was beyond humans, beyond any combination of human and computers. The only entity able to deal with it all would have to have the decision-making ability of a human combined with the computational speed and accuracy of a computer – in short, a robot.
Nor would just any robot do. The task was too complex for any standard robot to contend with. Even just handling the hundreds of sensory input channels would overwhelm a normal positronic brain.
The one, the only, possible way to control the terminal phase was to hand the job over to Units Dee and Dum.
And that, of course, meant putting a Three-Law robot, and her computerized counterpart, in charge.
And if Kaelor had killed himself rather than cooperate with the comet intercept, how the devil was Dee actually going to run the operation without losing her mind – or point-blank refusing to do the job?
The same sort of question was very much on Alvar Kresh’s mind as he and Fredda settled into their aircar for the brief flight from the Winter Residence to the Terraforming Center. Their days had settled into a routine with startling speed. Get up, go to the center, spend the day sorting out the details of the planet’s fate, then go home to the Residence for dinner and a good night’s sleep, or at least an attempt at sleep, before getting up to do it all again the next day.
Somehow, he hadn’t expected there to be so many decisions for him to make, so much hands-on work for him to do. For all the power and capacity and sophistication of the Terraforming Center and the twin Control Units, there were some decisions that no robot or other human could make, disputes that only the governor had the authority to settle. And besides, there were a lot of humans out there who were not going to take orders, however sensible, from a robot. And there were things that Kresh knew that Dee and Dum did not – how best to handle this local leader, which prices for emergency supplies he could expect to bargain down and which he could not, where he could ask a favor, where he could call one in, how far people could be pushed if need be, and when to give up.
But everything was routed through the Terraforming Center. It had soon become clear to Kresh that he would have had to relocate his command operations at the Center if it hadn’t started there to begin with.
Fredda followed him into the aircar and sat down in the seat next to him. Donald took his place at the controls, did a safety check, lifted off, and headed for the center.
So far, the preparations for the comet diversion were going quite well. But he could not stop worrying. It was never far from his mind that Dee believed all Inferno to be a simulation. Whether or that was likely to be help or hindrance he still could not decide. “So what do you think?” he asked his wife.
Fredda looked at him with an amused smile. “About what? It’s a little hard to offer my opinion unless I get a few more clues than that.”
“Sorry. I’m a little preoccupied. Do you think Dee and Dum are going to be able to control this operation?”
“I don’t know,” said Fredda. “I spend every day monitoring Dee, watching her behavior, trying to understand her. But there’s a very basic barrier I can’t get around. She doesn’t think any of this is real. I can understand the logic behind telling her the world is imaginary, but I must admit I question the wisdom of the decision. So much depends on her getting things exactly right – and yet, to her, it is all a game. She’s so casual about it all, as if the whole situation had been set up solely for her amusement.”
“From her point of view, it was all set up for her amusement,” said Kresh. “As far as she is concerned, the world of Inferno is just a puzzle for her to solve – or declare insoluble.” He was silent for a moment before he spoke again. “I’d have to agree with you about her attitude,” he said, “but at the same time, I’d have to say the quality of her work has been impeccable. She may not take it seriously, but she does it seriously. Maybe that’s all that counts.”
“I hope so,” said Fredda, “because I don’t know what the devil we do if we decide we don’t trust her. In theory, we could pull the plug and let Unit Dum take up the slack. But I don’t think that’s really possible anymore. The two of them are too interlinked, too interconnected. They rely on each other too much for us to pull one of them abruptly off
-line.”
“And Dee is in charge,” Kresh suggested. “It seems to me she just uses Dum as a sort of auxiliary calculating device.”
“No,” said Fredda, quite sharply. “That assumption is an easy trap to fall into. She does run the show when it comes to human interaction – that much is obvious. But that is the smallest fraction of their work. In everything else, they are coequal. There are some areas where Dum very definitely takes the lead – such as computational speed. Yes, he’s just a dumb machine, a mindless computer system with a crude personality simulator to serve as an interface. But he’s carrying a lot of the load. We not only need both of them – we can’t have one without the other.”
“There are times,” said Kresh, “when I could do without either of them, or any of this.”
Neither of them spoke as Donald brought the aircar into a smooth landing in front of the Terraforming Center.
Kresh, Fredda, and Donald walked into Room 103 at the Terraforming Center and took their accustomed places at the console nearest to Dee. Their division of labor was straightforward. Kresh worked through the endless sequence of decisions large and small presented to him by Unit Dee.
Fredda monitored Unit Dee’s performance and behavior, and consulted with Soggdon and the other experts on the subject. Thus far, Dee’s level of First Law stress was remarkably low – indeed, alarmingly low.
Fredda had another job as well. In order to preserve the fiction that Inferno was a simulation, and Governor Kresh merely a simulant, he could not have any direct communication with any of the Terraforming Center staff whenever it was possible that Dee could overhear. Fredda served as an anonymous intermediary, passing information back and forth, mostly via scribbled notes and whispers.
Donald, meantime, was in constant hyperwave contact with Kresh’s office back in Hades. He used preexisting and standing orders to handle most of the queries and requests, and bucked whatever decisions he had to up to Kresh when he needed to do so.
Kresh sat down at the console with something very close to dread. All would be in readiness soon, and the clock was running out. They were getting close, very close, to the moment when he would be forced to make the final, irrevocable decision. He glanced at the wall chronometer. It was set in countdown mode, showing the time left until the comet diversion maneuver. Ninety-four hours left. Before that clock reached zero, he would have to decide whether to send the comet toward Utopia – or to turn his back on all of it, walk away from all the madness and chaos that had led them to this place. He had thought he was sure, that he was ready, that he was ready to step forward. But by now all the pressures were pushing him forward, urging him onward. Suppose, just suppose, that he now concluded the comet diversion would be a dreadful mistake? Would he have the courage to say no, to stop, to let it go past?
“Good morning, Governor Kresh,” said Unit Dee the moment Kresh put on the headset.
“Good morning, Dee,” he replied, his voice gruff and not at all at ease. “What have you and Dum got for us this morning?”
“Quite a number of things, sir, as you might imagine. However, there is one point in particular that I thought we might discuss at once.”
Kresh leaned back in his chair and rubbed the bridge of his nose. It was not going to be an easy day. “And what might that be?” he asked.
“A plan that, if you forgive the expression, I have named ‘Last Ditch. ‘It provides you with an abort option for the comet impact long after its diversion. Dum performed most of the calculations, and only finished a very few minutes ago.”
“How the devil can we abort after the diversion?” Kresh demanded.
“As you know, the whole body of the comet has been rigged with explosive charges, intended to break the comet up into the desired number of fragments just before impact.”
“What of it?”
“Virtually all of those explosive charges have been damped down, or directionalized in one way or another, mostly by means of shaped forcefields. The plan is for these controlled charges to be set off one at a time in a very carefully planned sequence, so as to limit undesired fragmentation and lateral spread. By shutting down all the damping and directionalization, and by detonating all of the explosives in a different order, and much more rapidly, it should be possible to disintegrate the entire comet, reducing it to a cloud of rubble.”
“But the whole cloud of rubble will still be headed right for the planet,” Kresh objected. “It will all hit the planet, in a whole series of uncontrolled impacts.”
“That is not quite correct, Governor. If the blasts are done in the right way, and far enough before the impact, the explosion will give the vast majority of the material a large enough lateral velocity that it will miss the planet completely. Our model shows that, even in a worst case scenario, over ninety percent of the comet debris will miss the planet and continue on in its orbit about the sun. Of the ten percent or so of the debris that does strike the planet, ninety percent will strike in areas already slated for evacuation, or in the open waters of the Southern Ocean.
“That still leaves something like one percent of the comet coming down in uncontrolled impacts,” Kresh said.
“And some areas will experience a brief period of increased danger,” Dee replied. “Small pieces of debris will fall all over the planet, for about 32 hours after detonation – however, the impact danger for most inhabited regions will be on the order of one strike per hundred square kilometers. Persons in most areas would be in more danger of being struck by lightning in a storm than by being hit a piece of comet debris.”
“But some areas will be more trouble,” Kresh suggested.
“Yes, sir. The closer one gets to the initial target area, the higher the concentration of impacts. However, all the persons in such areas are to have taken shelter as a precaution in any event. If those plans are followed, I would estimate something on the order of one impact per square kilometer in the populated areas of maximum danger – and most of those strikes corning from objects massing under one kilogram.”
Kresh thought for a moment. “How late?” he asked. “What’s the last possible moment you could detonate the comet?”
“In order to stay within the parameters I have described, I would have to perform the explosion no later than ninety-two minutes, fifteen seconds before the scheduled impact.”
“Not bad, Dee,” said Kresh. “Not at all bad.”
Fredda and Soggdon were both listening in on their own headphones, alarmed looks on their faces. Fredda signaled him to cut the mike with an urgent throat-cutting gesture. Soggdon nodded and made the same gesture.
“Just a moment, Dee,” Kresh said. “I want to think about this for a minute. I’ll be right back.”
“Very good, sir,” Dee said.
Kresh cut his mike and took his headset off. “What’s the problem?” he asked. “Why does that idea worry you two so much? I have to admit it sounds pretty damned tempting to me. It gives us a lot more room to maneuver.”
“That’s not the point,” Fredda said. “That’s a robot talking. A robot casually talking about dropping thousands meteorites on the planet at random!”
“But even with fifty thousand – a hundred thousand meteorites – the odds against significant danger to a human being are –”
“Tremendous,” said Donald. Only a First Law imperative could have made him dare to interrupt the planetary governor. “They are unacceptably high. And I would venture to add that any sane Three-Law robot would endeavor to protect a human in danger of being struck by lightning. That level of danger is not negligible.”
“Not to a robot it isn’t,” Fredda agreed. “Or at least it shouldn’t be. To a human, yes, but not a robot.”
“Hold it,” said Kresh. “You’re upset because Dee isn’t overreacting to danger?”
“No,” said Fredda. “I’m upset because this makes me question Dee’s sanity. A robot would have to be on the verge of becoming completely unbalanced to even suggest something that might
cause widespread, uncontrolled danger to humans.”
Kresh looked toward Soggdon. “Your opinion, Doctor?”
“I’m afraid I’d have to agree with Dr. Leving,” she said. “But what I find troubling is that all our reading and indicators show Dee’s level of First Law stress has been well within normal range right along. She ought to be flirting with the maximum tolerance levels, given the operations she’s dealing with. And yet, if anything, her readings are a little in the low range.”
“Maybe you ought to have a little talk with her about it,” Kresh suggested.
Soggdon switched her mike back on and spoke. “Unit Dee, this is Dr. Soggdon. I’ve been monitoring your conversation with the simulant governor. I must say I’m a little surprised by this Last Ditch idea of yours.”
Kresh and Fredda put their own headset back on and listened in.
“What is it that you find surprising, Doctor?”
“Well, it would seem to expose a great number of humans to potential danger. I grant that the danger to any single human is reasonably low, but surely, on a statistical basis, the plan represents an unacceptable danger to humans, does it not?”
“But, Doctor, they are only simulants,” said Dee. “Surely a statistically remote risk to a hypothetical being is not something that should be given too much weight.”
“On the contrary, Dee, you are to give danger to the simulants an extremely high weighting, as you know perfectly well.”
There was a brief but perceptible pause before Dee replied – and that was in and of itself something to wonder at, given the speed at which robots thought. “I would like to ask a question, Doctor. What is the purpose of this simulation?”
