“Maybe the robots won’t survive that long,” said Chad. “We’re talking about more than sixty million years. A lot can happen in that amount of time.”
“Even at the atomic level?” Jane asked.
“Well, the robot’s atoms could wind up almost anywhere. Think about it. Right now, the land mass that will become North America is attached to Europe. South America is completely detached from any other continent. The western hemisphere doesn’t even exist yet. Neither do mammals or birds as we know them-we’ve talked about this before. Five microscopic robots will have to deal with uncounted generations of hostile microbes. They might not outlast the dinosaurs, or the woolly mammoths, or even early human years, once they reach the time of humans.”
“They will not have to survive in robot form to be a threat,” said Hunter. “If their unstable atoms still exist in any form, the danger of nuclear explosion remains in effect.”
“The microscopic robots will have a pretty good chance to survive for most of that time,” said Jane. “They won’t be operating simply by random chance. Their intelligence and stored data will help them make deliberate choices, driven by the Third Law to keep themselves from harm.”
“The other danger, of course, is still to be found when their miniaturization ends,” said Hunter. “Especially if some of them return to full size in the human era, when the Second Law will force them to obey any instructions they receive that do not violate the First Law.”
“But they didn’t explode,” said Steve. “We were still in Mojave Center for a while after MC Governor disappeared from his position. Right?”
“That’s true,” said Jane. “What about that, Hunter?”
“My calculations have a degree of uncertainty,” said Hunter. “The explosions may take place a little later than I calculated, and, I suspect, not all at once. This makes the First Law weigh on me even more heavily than before.”
“The robots could be anywhere in our own time,” said Chad. “Under the ocean, deep under the earth. Anywhere. Nuclear explosions that occur a substantial distance underground may not affect any form of life at all.”
“If the robots are still functioning, they’ll be on the surface,” said Jane. “They would arrange that deliberately as part of their survival under the Third Law.”
“We should return now,” said Hunter. “We can continue these deliberations later.”
“All right,” said Jane. “MC 1, you will continue to cooperate with us in every way. You won’t make any attempt to escape our custody or to avoid further examinations. The First Law requires that you be studied. If Wayne makes contact with you again, you will remember to interpret my instructions under the Second Law in the knowledge that a First Law imperative is behind them.”
“Acknowledged,” said MC 1.
“I’ll start packing up the camp,” said Steve.
The team returned to the Bohung Institute less than a minute after they had left. As soon as Hunter saw that the particle shower had ended and the process was turned off, he immediately rushed out of the unit. Hunter was hoping to catch Wayne in the room, but he was not there.
No one else was either.
Steve climbed out next and helped Jane. MC 1 aided Chad. Meanwhile, apparently at Hunter’s radioed signal, R. Ishihara entered the room. Ishihara had been waiting outside the room for half a minute, as Hunter had instructed before they had left.
“Has anyone left this room?” Hunter asked.
“No,” said Ishihara. “Have you completed your mission?”
“Our trip is over but only partly successful,” said Hunter, with quiet formality. “A new security problem has arisen. Dr. Wayne Nystrom may come into F -12 or attempt to leave. I understand now that you cooperated with him under the Second Law earlier. If at all possible, you must apprehend him and hold him for me under a First Law concern.”
“Acknowledged.” Ishihara walked into the room and waited patiently. “I heard the equipment in use for several seconds twice between the time of your departure and your return. Perhaps that was he, arriving and leaving again.”
Hunter nodded impassively.
Steve started lifting gear out of the big sphere. MC 1 got out and stood motionless. While Steve unpacked the equipment, Hunter accessed the records of the unit’s use that were stored in the control panel.
“Are you finding anything important?” Chad asked Hunter.
“Yes,” said Hunter stiffly. “Wayne has come and gone, as Ishihara suggested. Let me explain. I did not dare time our return any closer to when we left. The First Law prevented me from taking a risk as serious as meeting ourselves. Wayne, as a human, was able to take a greater risk with his own life.”
“You think he got back here ahead of us?” Jane asked. “Are you sure?”
“Yes.” Hunter’s voice had a monotone that he had never used before. “The standard records in the control panel say nothing about additional trips into the past. That is why I did not see them before. MC 1, can you, explain this?”
“Yes. I was the last of the components to travel. I erased all the records of the previous trips but could not erase the record of my own. Consequently you were able to track me.”
At the odd sound of his voice, everyone turned to listen to Hunter.
“This time, instead of just reading the control panel, I analyzed power usage and the extent and intensity of the particle showers recorded by the internal monitors of the system. That process has given me enough information to re-create the erased records, using the trips on record to the Late Cretaceous for calibrations.”
“What have you found?” Jane asked softly.
“Nine time trips into the past have been taken. That accounts for the six component robots fleeing, Wayne’s trip back to the Late Cretaceous, and ours…plus one more.”
“So he’s been here and gone,” said Steve. “But you can calculate where each of the component robots went?”
“Yes,” said Hunter. “The last trip into the past matches one of the other five trips. It clearly represents Wayne’s pursuit of another component robot.”
“What do we do next?” Steve asked. “We have to make sure that MC 1 is secure,” said Hunter. “Right now, we will all go to MC Governor’s office. I will arrange for a Security escort to meet us on the way.”
“You sound worried,” said Jane. “What is it?”
“No matter how long Wayne remains in the past, he may come back at any time of his choosing. This time I will leave Ishihara here in the room to apprehend Wayne in the expectation that he will come back soon.”
“That sounds good to me,” said Steve.
“Ishihara may catch Wayne,” said Hunter. “However, Wayne may anticipate this plan. He could come back far enough in the future that unpredictable factors will obtain here. I do not dare interfere with the equipment in any way; the First Law will not let me take any risk with his ability to return. At the moment I want to get MC 1 away from this room.”
Ishihara remained on guard in the room. Hunter walked out with MC 1, followed by the three humans. He explained to them that he was radioing the city computer for a Security detail and vehicle. When the vehicle arrived, the detail transported everyone to MC Governor’s office.
Steve saw that a Security robot was on duty there. Hunter greeted him briefly out loud, apparently so that the humans could hear what he was saying. “Horatio, please be on the alert for Dr. Wayne Nystrom. Apprehend him and hold him if you can.”
“Agreed,” said Horatio.
Hunter took his own party inside the office and closed the door.
“Well?” Steve said. “Now what? You’re acting a little strange, Hunter.”
“Maybe you have forgotten the question of whether or not we would change history by even small actions that we took in the past,” said Hunter.
“I did,” Steve admitted. “But I don’t see anything different so far.”
“I don’t, either,” said Jane. “We have come back safely, haven’t we?”
“So far,” Hunter said carefully, “I believe that we have returned to the world just as we left it. That means that none of the changes we caused have brought about noticeable changes.”