The mice started a few feeble protests. But Noxon could hear them convincing each other that the plan made sense.
“There isn’t a hundred thousand years of life support for us, even though our needs are few,” said a spokesman for the mice. “Covered with ice, it would be very difficult to do the necessary air exchange. But instead of killing us, you should bring us with you.”
“Nice try,” said Noxon. “Even if you don’t take over the ship, all you have to do is start having babies while humans are still evolving, and if you permit us to survive at all, I have a feeling it will still be a world run by mice.”
“We promise we won’t!” cried the mouse in despair.
“I think they have to get back in the box,” said Noxon. “Then we give them a week, to give us time to get back from the future, send for the flyer, and return to take off again. So, my dear expendable,” he said, “will you take care of shutting down all life support on the ship a week after we leave?”
“Will I really have to do it?” said the expendable. “Won’t you be back before the week is up?”
Noxon shook his head. “You have to live through the version of events in which we don’t come back. But when we do come back, the version of you that we meet will never experience the complete shutdown, so that version will be sure that you never had to kill the mice and the colonists.”
“That doesn’t make sense,” said Ram Odin. “I take your word for it, but . . .”
“I exist at all,” said Noxon, “because there was a version of me, Rigg Sessamekesh, that killed a version of you, Ram Odin—a much older version—in order to keep him from killing me first. That actually happened, and the version of me that is still called Rigg actually did the killing. Just as a version of the expendable will shut down the life support and observe as the mice and all the colonists die.”
“So does that mean there’ll be two of me?” asked the expendable.
“No,” said Noxon. “Because once this ship goes cold, it’s completely out of the causal chain. When we return, nothing that happened after we left will have affected Ram and me in any way. So the dead version of the ship won’t exist once we make the change.”
“You say that as if you knew what you were talking about,” said Ram Odin.
“Because I do know,” said Noxon. “The only person who gets copied is the one who is part of the causal chain. So when Rigg prevented himself from killing that older version of you, Ram, it created a second Rigg—me, the one that didn’t kill you—but not a second Ram Odin.”
“Except here I am,” said Ram Odin.
“You’re the twentieth Ram Odin left over from an earlier division, and you know it,” said Noxon. “You’re just being frivolous.”
“I am,” said Ram Odin. “I think the plan will work.”
“You talk about trusting us!” cried the mice. “But how can we trust you!”
“The mice are having trust issues,” said Noxon.
“The first time they tried to take over the ship, they signed their death warrants,” said Ram Odin. “Even if we never come back, they’ve had a day of life that they didn’t deserve.”
“Here’s why you can trust us,” said Noxon to the mice. “First, unlike you, we haven’t broken our word over and over again. Second, I could have you killed at any time and I haven’t, so why would I need to go to all this elaborate preparation to kill you now? If I don’t want you alive, you’re dead whenever I want. You can’t hide on my body if I take off my clothes, and you can’t hide anywhere else because the expendable can turn off the life support.”
“So I’m giving you continuous evidence that I am committed to your survival—provided you don’t endanger the survival of the human race, which means you stay in this ship and die with it.”
“I don’t know why you brought the mice along in the first place,” said Ram Odin.
“Because two of the wallfolds on Garden are shared with billions of sentient mice. I may need these as witnesses of what we do here. Or if I conclude that we do have to destroy the human race on Earth, then the mice can do it more easily and thoroughly than I can.”
“You’re the version of Rigg that isn’t murderous?” said Ram Odin.
“I’m here to save Garden,” said Noxon. “And it’s humans from Earth who destroy it. You do the math.”
“It’s ironic, that’s all,” said Ram Odin. “We created colony ships because that comet came so close to the kind of impact that would destroy all life on Earth. We had to create a colony so humans would exist on more than one world. And now you come back and destroy the human race on Earth.”
“I’ve come back to find out why Earth decided to destroy Garden,” said Noxon, “and talk them out of it, if I can. But I’m going to save the nineteen wallfolds of Garden, one way or another. Humanity may have arisen here, but that doesn’t mean they have a right to destroy Garden after 11,191 years of history there.”
“I agree,” said Ram Odin. “I’m just noting the irony.”
“Noted,” said Noxon.
“I’m afraid to die,” said one of the mice.
“You would hardly be sentient if you weren’t,” said Noxon. “But you are sentient, and that’s why I’m not going to leave you here, dead. I’m going to change the future if I can. Either way, I’ll come back and get you. Just remember that you will die, the first time through. But when I retrieve you, you’ll have no memory of that death. And you’ll know, once again, that I keep my word—even though you don’t.”
“So it’s settled,” said Ram Odin. “We park the ship where ice will cover it. Then you and I leave the ship and use the flyer to get us to a place that will someday be reasonably well-inhabited. From there we travel into the future, while the flyer—and our expendable friend—go back to the starship, kill everybody, and shut down all the systems. But we return in time to stop any of that from happening.”
“That’s the plan,” said Noxon.
“Only one problem,” said Ram Odin. “Fuel.”
“Oh?” asked Noxon.
“This ship can set down on a planetary surface,” said Ram Odin. “But on Garden, it was a bit of a sharp collision, right?”
“An extinction-level event,” said the expendable. “By design.”
“If we land more gently and nondestructively, can we get back up into space?” asked Ram Odin.
“We have been performing those calculations during your discussion of the ethics of temporary musicide,” said the expendable. “Since we made the return voyage to Earth without expending any fuel at all, and we began that voyage halfway through the huge energy expenditure of creating the fold and leaping into it, we definitely have enough fuel for a trivial task like rising from the surface of a small rocky planet and getting back to scoop velocity.”
Noxon had learned enough to know this meant the speed at which the powerful collection field could be extended to gather interstellar hydrogen and other dust to turn it into the plasma that fueled the ship.
“Then I think we’re all set,” said Noxon. “All that remains is to choose the right time. For that, Ram and I need to leave the ship for a while. And that means that the mice go back into the box.”
“No it doesn’t,” said a mouse.
Noxon took Ram Odin’s hand. “Expendable, please pick the mice off my body so I can begin time-slicing while you reduce the oxygen inside the ship to zero. It will mean I can’t come back and revive the mice, but that’s their decision.”
The mice scampered off his body and returned to the box, which the expendable was holding open for them. “You see we’re complying,” said a mouse.
“I’ll keep my word,” said Noxon, “but since I know you won’t, I can’t leave you in a position to alter the ship’s programming.”
“We already gave our word, but we understand your lack of trust,” said the mouse. “We’l
l look forward to your return.”
“Come with us to the flyer,” said Noxon to the expendable.
When they were inside the flyer, Noxon ordered a complete disconnection from the ship.
“Now it’s time for you to tell us,” said Noxon. “Did the mice already alter the ship’s programming so that my instructions won’t be obeyed after I leave here?”
“They did not,” said the expendable.
Noxon thought for a moment, remembering how many times in the past Vadeshex and other expendables had told lies while adhering to the strict truth.
“I think I asked the wrong question,” said Noxon. “They wouldn’t have to alter the ship’s programming to make it so my instructions would be disobeyed, because I’m not the commander of this ship.”
The expendable said nothing.
“Ram Odin is the commander,” said Noxon. “Right?”
“Yes,” said the expendable.
“So any instructions I give are not binding. And he hasn’t given you any. So you could set the mice free, give them complete control of the ship, and you wouldn’t be violating any of your programming.”
“That is certainly possible,” said the expendable.
Ram Odin sighed. “I order you to obey all the instructions Rigg Noxon gave you, as if I had given them to you myself.”
“Yes, Ram Odin,” said the expendable.
“Now let me return to Noxon’s original question,” said Ram Odin. “Did the mice alter the ship’s programming, or your programming, so that once I’m away from the ship, you can disobey me?”
“No,” said the expendable.
“Try it again,” said Noxon. “They may not have altered the programs. All they would have to do is invoke a protocol naming them as your successors in command of the ship from the moment you physically leave it.”
“Is that what they did?” Ram Odin asked the expendable.
“If they did, the ship’s computers haven’t informed me of it,” said the expendable.
“Here on the flyer, with the doors sealed,” said Noxon, “is Ram Odin already considered to be away from the ship?”
“Yes,” said the expendable.
“Reconnect me to the ship,” said Ram Odin.
“Yes,” said the expendable.
Connections were reestablished. Doors opened.
“I don’t think you can come with me,” said Noxon.
“Oh, I think I can,” said Ram Odin. “There’s just something I need to do first.” Ram Odin led the way back onto the ship and into the room where the box of mice was sitting.
In their absence, the ship had apparently caused a second copy of the expendable to assemble itself. It was standing beside the box.
“Have you allowed any of the mice to leave the box?” asked Ram Odin.
“Not yet,” said the new expendable. “But those were the orders I was given.”
“Now that I’m back, am I in full command of the ship?” asked Ram Odin.
“Yes,” answered both expendables, and the ship’s computer voice as well.
To the second expendable, Ram Odin said, “Go back and have yourself disassembled and restowed.”
The expendable left the room.
“Ship,” said Ram Odin. “I designate Rigg Noxon as my only successor in the event I’m disabled and can’t command the ship. In the absence of myself and Rigg Noxon, there is no other substitute commander. You will continue to follow my instructions. The mice, individually and collectively, are permanently barred from any command role on this vessel.”
“Yes,” said the ship’s computer.
“And since I know they have reprogrammed you to say that, even though you intend to disobey me, I order you to restore yourself to the condition you were in prior to any alteration the mice made.”
It took two seconds. “Done,” said the ship’s computer.
“Is it really done?” Ram Odin asked the expendable.
“Do you wish the ship to reacquire the data from the ship’s logs that Noxon brought aboard?” asked the expendable.
“Will any of that data cause the ship to accept orders or data from the mice?”
“The logs from Odinfold and Larfold will both have that result.”
“Restore only the logs that do not give the mice any control or influence on this ship.”
“That will leave gaps in our data,” said the expendable.
“Gaps that will be alleviated after we return from our attempt to change the future,” said Ram Odin.
“Good job,” said the expendable. “You finally asked the right questions.” He turned to Noxon. “Beginning with you.”
“I appreciate your congratulations,” said Noxon. “But I’m not sure I believe you. How can we be sure the mice didn’t instruct you merely to pretend to follow Ram’s instructions, so that we’d leave?”
“We aren’t infinitely devious,” said a mouse from inside the box.
“You do understand why I will never trust you,” said Noxon.
“That is a very wise decision,” said the mouse. “And one that will cost us dearly, I’m afraid.”
“Maybe,” said Noxon. “And maybe not. That’s still up to you.”
“You mean you’re not going to kill them even now?” asked Ram Odin.
“I’m not,” said Noxon. “But I’m also not leaving them with the ship.”
Noxon carried the mice aboard the flyer, but left the expendable on the ship. Ram and Noxon then had the flyer take them down to Earth, to a tectonically stable plateau in what would one day be Peru. Someday, the Nazca lines would be marked out by human inhabitants. But right now, the ground was smooth.
Since humans hadn’t yet spread to this area, it was simple enough to pick their spot, pile up a few stones, and then find an animal’s path to link to in order to get back to the target time at the beginning of this glacial maximum. At that point, a hundred thousand years in the past, Noxon, Ram Odin, and the expendable spent several days laying out an arrangement of stones large enough to be picked up by the instruments on an orbiting ship a few hundred kilometers up.
They buried the box of mice at one end of the stone figure they had created.
Then they went forward again about eighty thousand years, to the time when they had made that first small pile of stones. They checked to make sure that their large arrangement of stones had lasted for the intervening eighty thousand years. It had. It would be continuously visible from space.
They rode the flyer back up to the ship. Noxon made several huge jumps back in time until their large marker stopped being visible, then made much smaller jumps into the future until it finally showed up again.
They took the ship through atmospheric entry and landed it on a grassy plateau in Antarctica. It was hard to believe that in a few thousand years this spot would be under at least a hundred meters of ice, but the expendable assured them that the spot had been carefully noted and it was ideal for concealing a dead ship.
They left the ship there and took the flyer back to the place where they had buried the box of mice. Then they sent the flyer back to the ship.
Noxon and Ram stood over the burial place. “Think they’re still alive in there?” asked Noxon.
“How long since we buried them?” asked Ram Odin.
“Not sure how precisely we handled our return time, but I’m betting they’re still in there,” said Noxon.
“If you open the box to see,” said Ram Odin, “they’ll be out of it in a second and we’ll never get them back.”
“Oh, I have no intention of letting them out,” said Noxon. “What I’m wondering is, what are the odds that as soon as we slice forward in time from here, the flyer will return and the expendable will dig them up?”
“I think seventy-five percent against it,” said Ram Odin. “But it’s im
possible to be sure.”
“In my experience, the only creatures more devious than the mice are the expendables.”
“To be fair,” said Ram Odin, “their deviousness on Garden could have been due to their following Old Ram’s instructions.”
“They’re very good at giving truthful answers to the wrong questions,” said Noxon.
“And humans are very good at coming up with all the wrong questions,” said Ram Odin.
“We never have complete control over anything,” said Noxon.
“No,” said Ram Odin. “Because at some point, we have to trust machines and people to do what they say they’ll do.”
“And every now and then,” said Noxon, “their disobedience is actually wiser than if they had done what we commanded. Because they have their own wisdom, and we have no guarantee that ours is wiser.”
“Trust and obedience,” said Ram Odin. “Every cruel dictator in history has only had the power to do evil because so many other people were willing to obey him and carry out his orders.”
“And every wise and good leader has been repeatedly stymied,” said Noxon, “because no matter how wise his commands, some bureaucrat somewhere believed that it wasn’t in his self-interest to carry them out.”
“So what are you going to do about this?” asked Ram Odin.
“Well,” said Noxon. “I could stay here with you and slice time for a few months, watching to see if the flyer returns. We wouldn’t leave the surface here until we were sure the mice were dead.”
“We’d also see that we didn’t return from the future during that time,” said Ram Odin.
“The first time through, we’d see that,” said Noxon. “The problem is that the second time through, we would see ourselves come back, and that would change our behavior, and therefore it would create two new copies of the two of us because we would then behave differently.”
“At least we’d know the mice and the expendables hadn’t disobeyed us,” said Ram Odin.
“There are enough copies of me in the universe,” said Noxon, “and way past enough copies of you.”