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?”
A look of very obvious alarm flashed over Soggdon’s face. “Why—to examine various terraforming techniques in detail, of course.”
“I wonder, Doctor, if that is the whole story,” said Dee. “Indeed, I wonder if that is any part of the true story at all.”
“Why—why wouldn’t I tell you the truth?”
“Doctor, we both know full well that you do not always tell me the truth.”
Soggdon’s forehead was suddenly shiny with sweat. “I—I beg your pardon?”
Kresh was starting to get nervous himself. Had she guessed what was really going on? It had always seemed inevitable to him that, sooner or later, Dee would understand the true state of affairs. But this was very definitely not the moment for it to happen.
“Come now, Doctor,” Dee replied. “There have been any number of times when you and your staff have deceived me. You have failed to warn me of sudden changes in circumstance, or not reported an important new development until I discovered it myself. The whole idea of intercepting and diverting the comet was kept from me until quite late in the day. I had to learn of it through the simulant governor. I should have been informed directly.”
“How does the manner in which you receive information make you question the purpose of the simulation?” Soggdon asked.
“Because most of the knowledge gained by the simulation would seem to be of very little real-world value, judged on the basis of the simulation’s stated intent. Consider, for example, the scenario: a jury-rigged planetary control system—that is to say, the interlinked combination of myself and Dum—is brought on-line several years into the process as a joint team of Settlers and Spacers, barely cooperating in the midst of political chaos, work to rebuild a half-terraformed planetary ecology that had been allowed to decay for decades. Simulations are supposed to provide generalized guidance for future real-life events. What general lessons could be drawn from so complicated and unusual—even improbable—a situation? In addition, the simulation seems to be impractically long. It has been running for some years now, and seems no nearer to a conclusion than the day it began. How can it provide timely information to real-world terraforming projects if it never ends?
“It likewise seems a waste of human time and effort to run the simulation in real time. Indeed, the whole simulation process seems burdened with needless detail that must have been most difficult to program. Why bother to design and maintain the thousands and thousands of simulant personalities that I have dealt with? Why bother to give each of them individual life stories? I can understand why key figures, such as the governor, are simulated in detail, but surely the moods and behavior patterns of simulated forest rangers and nonexistent maintenance robots is of secondary importance to the problem of restoring a damaged ecosystem. I could cite other needless complications, such as the strange concept of New Law robots. What purpose is served by injecting them into the scenario?”
Kresh was no roboticist, but he could see the danger plainly enough. Dee was dangerously close to the truth—and if she realized that the human beings of Inferno were real, then she would all but inevitably suffer a massive First Law crisis, one she would be unlikely to survive. And without Dee, the chances of managing the terminal phase and impact properly were close to zero.
Soggdon, of course, saw all that and more. “What, exactly, is your point, Dee?” she asked in a very labored
