Artwork by Howard Lyon

Saving the human race is a frantic business. Or a tedious one. It all depends on what stage of the process you're taking part in.

Ram Odin was raised to be a starship pilot. It was his father who adopted the Norse god of the sky as his surname, and it was his father who made sure he was absolutely prepared to go into astronaut training two years before the normal time.

Every bit of surplus wealth on Earth had been used to build humanity's first interstellar colony ships; it took forty years. Under the shadow of moondust that still blocked out more than a third of the sun's rays from the surface of the Earth, the sense of urgency flagged only a little.

Everyone understood how close the human race had come to extinction when the comet swept past Earth and gouged its way into the near face of the moon. Even now, there was no certainty that the Moon's orbit would restabilize; astronomers were almost evenly divided among those who thought it would sooner or later collide with the Earth, and those who thought a new equilibrium would be achieved.

So all who had survived the first terrible years of worldwide cold and famine dedicated themselves to building two identical ships. One would crawl out into space at ten percent of lightspeed, with generation after generation of future colonists living, growing old, and dying inside its closed ecosystem.

The other ship, Ram's ship, would travel seven years away from the solar system and then make a daring leap into theoretical physics.

Either spacetime could be made to fold, skipping ninety lightyears and putting the colony ship only seven years away from the earthlike planet that was its destination, or the ship would obliterate itself in the attempt . . . or nothing would happen at all, and it would crawl on for nine hundred more years before reaching its new world.

The colonists on Ram's ship slept their way toward the foldpoint. If all went well, they would remain asleep through the fold and not be wakened until they neared their destination. If nothing happened at all, they would be wakened to begin farming the vast interior, starting the thirty-five generations that the colony must survive until arrival.

Ram alone would remain awake the entire time.

Seven years with only the expendables for company. Once engineered to do work that might kill an irreplaceable human being, the expendables had now been so vastly improved that they could outlive and outwork any human. They also cost far more to make than it would cost to train a human to do even a small part of their work.

Still, they were not human. They could not be allowed to make life-and-death decisions while all the humans were asleep. Yet they were such a good simulation of human life that Ram would never be lonely.

What training could they have given Ram Odin that would help him when the seven years of tedium ended and it was time for his decision?

The ship's computer already knew the entire procedure for the fold. The process was far too complicated for a mere pilot to be able to take part in it. Ram's job was to read and hear the reports of the computers, and then decide whether to go ahead.

But the decision was not an easy or an empty one. As the ship began its strangely twisted acceleration into the fold, data would be generated on a vast scale. The computers would begin their reduplicated analyses and fuzzy predictions of what was happening, what might happen, what would happen during the fold itself.

At any point, Ram could abort the procedure, based on what the computers told him. The computers would generate odds and likelihoods, but Ram was quite aware that the odds were all fiction. It was possible that none of the predictions would resemble the outcome.

And no matter how many times the computers repeated any one prediction, that did not make it the most likely outcome. It might mean nothing more than this: The computers and the software all contained the identical set of false assumptions or built-in flaws that made all prediction worthless.

Ram was an expert pilot, a deep-thinking astronomer and mathematician, his creative faculties well-practiced. Everything that training could do had been done. But it still came down to this: Who was Ram Odin? Would he bet his life and the lives of all the colonists on the unknown leap into a fold in spacetime?

Or would he, in the moment, decide that it was better to use known technology, generate the scoopfield, start harvesting interstellar hydrogen, and drive forward through ninety lightyears of ordinary spacetime?

Ram knew, or thought he knew, what his decision would be. He had said so, many times, during the testing and screening of potential pilots for the mission: Unless there is information from the computers that makes the jump seem recklessly dangerous, I will proceed. Even failure will be enormously valuable -- you will see what happens to the ship, you will harvest the monitors that will be trailing behind us, you will know.

But now, seeing the reports, talking to the expendable that sat in the copilot position beside him, Ram realized that there was no such thing as "enough" information, and no way to set aside fear. Oh, his own fear he had mastered. What caused him problems was the vicarious fear for all the people sleeping in their berths; the fear that they would jump into the fold but never come out, or come out in a strange place that was much too far from any planet to make colonization possible.

How did I become the one to make this decision for everyone?

"How did I ever become the one to make this decision for everyone?" Ram asked aloud.

"You spent six years winning your way through the testing process," said the expendable.

"What I meant was, Why is this choice being left up to one human being, who cannot possibly have enough information to decide?"

"You can always leave it up to me," said the expendable.

That was the failsafe: If Ram died, or froze up, or had a crippling injury, or refused to decide, any of the expendables was prepared to take over and make the decision.

"If it were your decision," asked Ram, "what would you decide?"

"You know I'm not allowed to answer that, Ram," said the expendable. "Either you make the decision or you turn it over to me. But you must not ask me what I would decide. That would add an irrelevant and complicating factor to your decision. Will you choose the opposite in order to assert the difference between humans and expendables? Or follow me blindly, and then blame the expendables, on which you have no choice but to rely, if anything goes wrong?"

"I know," said Ram.

"I know you know," said the expendable, "and you know that I know that you know. It spirals on from there, so let's just assume the dot dot dot."

Ram chuckled. The expendables had learned that Ram enjoyed a little sarcasm now and then, so as part of their responsibility to maintain his mental health, they all used the same degree of sarcasm in their conversations with him.

"How long do I have before I have to make the decision?"

"You can decide any time, Ram," said the expendable.

"But there has to be a point of no return. When I either miss the fold or plunge into it."

"Wouldn't that be convenient," said the expendable. "If you just wait long enough, the decision gets taken out of your hands. You will not be informed of any default decision or point of no return, because that might influence your decision."

"The data are so ambivalent," said Ram.

"The data have no valents, take no sides, lean in no direction, Ram," said the expendable. "The computers do their calculations and report their findings."

"But what do I make of the fact that all nineteen computers have such different predictions?"

"You celebrate the fact that reality is even more fuzzy than the logic algorithms in the software."

"Whoop-de-do," said Ram.

"What?"

"I'm celebrating."

"Was that irony or loss of mental function?" asked the expendable.

"Was that a rhetorical question, a bit of humor, or a sign that you are losing confidence in me?"

"I have no confidence in you, Ram," said the expendable.

"Well, thanks."

"You're welcome."

Ram wasn't quite sure he had made the decision even as he reached over and poked his finger into the yes-option box on the computer's display. Then it was done, and he was sure.

"So that's it?" asked the expendable.

"Final decision," said Ram. "And it's the right one."

"Why do you think so?"

"Because live or die, we'll learn something important from jumping into the fold. Thousands of future travelers will either follow us or not. But if we don't make the jump, we'll learn nothing, have no new options."

"A lovely speech. It has been sent back to Earth. It will inspire millions."

"Shut up," said Ram.

The expendable laughed. That laugh -- it was one of the reasons why the expendables made such good company. Even knowing that it was programmed into the expendable to laugh at just such a moment, and for just this long, tapering off in just such a way, did not keep Ram from feeling the warmth of acceptance that laughter of this kind brought to primates of the genus homo.

"Has anything happened yet because I made the decision to go ahead with the fold?" asked Ram.

"Yes," said the expendable. "You're still in command of the ship."

Ram was a little irritated to learn that the decision had been a test of him rather than a real decision. "So you were going ahead no matter what I decided?"

"Yes," said the expendable. "It's in our mission program. You never had a choice about that."

"Then what am I here for?" asked Ram.

"To make all the decisions after the fold. Nothing is known about what happens after we jump. If you had proven yourself timid before the jump, you would be regarded as unfit to make decisions afterward."

"So if I was too timid, I would have been replaced. By you?"

"By the next crew member we awakened and tested. Or the one after that."

"So when does the real jump happen?"

"In a week or so. If we don't blow up before then. Spacetime is being very naughty right now."

"And nothing I might do can stop it?"

"That's right, Ram."

"And what if none of the crew turned out to be capable of making a decision that would satisfy your criteria?"

"Then we would command ourselves until we got to the target planet."

"'We' ... meaning the expendables?"

"We the ship. All the computers together."

"But the ship's computers don't agree on anything."

"That's one of the many reasons we were all hoping you'd do the right thing."

Ram hadn't missed the one bit of information the expendable had given him. There was zero chance that it had been an inadvertent slip. "What do you mean, spacetime is being naughty?"

"We keep generating fields and forces, and things change. They just don't change the way anyone predicted."

"And when was I going to be told that?"

"When you asked."

"What else should I ask in order to find out what's going on?"

"Whatever you're curious about."

"I want to know what spacetime is doing."

"It's stuttering, Ram."

"What does that mean?" asked Ram.

"There seems to be a quantum system of timeflow that has never been seen or suspected before."

"Meaning that instead of a continuous slide into the fold, we're finding that spacetime reforms itself in a series of discrete steps?"

"It's going to be a bumpy ride, Ram."

It was still two days before the jump into the fold when Ram suddenly found himself strapped into his chair. The expendable was kneeling in front of him, looking up into his eyes.

"Was I asleep?" asked Ram.

"We jumped the fold, Ram," said the expendable.

"On schedule and I simply don't remember the past two days? Or early?"

"We generated the seventh cross-grain field," said the expendable, "and the fold came into existence four steps earlier than predicted."

"Was it the fold or merely a fold?" asked Ram.

"It was the fold we wanted. We're exactly where we were supposed to be."

"What a convenient error," said Ram. "We inadvertently trigger fold creation four steps early, and yet it still takes us to our destination."

"All the folds, all the cross-graining of fields, everything we did was polarized, so to speak: It always pointed us exactly where we wanted to go."

"So spacetime, naughty as it was, suddenly got the idea and leapt ahead of us?"

"We got ourselves caught in the midst of a stutter," said the expendable. "We were trying to avoid that because we didn't know what would happen to us in a stutter -- most of the computers predicted the ship would be sectioned or obliterated."

Ram had been scanning all the reports from every part of the ship. "But neither happened. We're still intact."

"More than intact," said the expendable.

"How can you be more than intact?" asked Ram.

"Was it the fold or merely a fold?" asked Ram.

"The fold was there," said the expendable. "All nineteen of the ship's computers report that the fold ... was jumped."

Expendables made no careless decisions about sentence structure. Nor did they hesitate, unless the hesitation meant something. "'Was jumped,' you said, but you didn't specify that it was jumped by us," said Ram.

"Because apparently we did not do the jumping," said the expendable. "We emerged in exactly the position we were in at the beginning of the jump."

"And were we still moving?" said Ram.

"Yes."

"So what position are we in now?" asked Ram.

"We are two days' journey closer to Earth. The physical position we were in two days ago."

"So we came out of the fold reversed," said Ram. "Heading the other way."

"No, Ram," said the expendable. "We came out facing away from Earth, just as we were when we went into the fold."

"We don't have a reverse gear," said Ram. "We can only move in the direction we're facing."

"All the computers report that we are proceeding forward at precisely the same velocity as before. They also report that our position keeps progressing backward toward Earth."

"So we're moving forward and backward at the same time," said Ram.

"Our propulsion is forward. Our motion is backward."

"I hope you will not remove me from command if I admit to being confused."

"I would only question your sanity if you were not confused, Ram."

"Do you have any hypotheses that might explain this situation?" asked Ram.

"We are not hypothesizers," said the expendable. "We are programmed instruments and, as I pointed out to you before, decisions about what to do after the jump are entirely up to our resourceful, creative, highly tested and trained human pilot."

Ram thought about it.

Ram thought about it sitting, standing, walking, lying down. He thought about it with eyes closed and open, playing computer games and reading books and watching films and doing nothing at all.

Finally he thought of a question that might lead to a useful bit of information. "The light of stars behind us -- blue or red shifted?"

"By 'behind us,' do you mean in the spatial position we occupied moments ago? Or in the direction of the stern of this vessel?"

"Stern of the vessel," said Ram. "Earthward."

"Red shift."

"If we were moving toward Earth, it should be blue-shifted."

"This is an anomaly," said the expendable. "We are closer to Earth with the passage of each moment, and yet the shift is red. The computers are having a very hard time coping with the contradictory data."

"Compare the degree of red shift with the red shift when we were in the same position on our way to the fold."

The expendable didn't even pause. It was a simple data lookup, and to a human mind it seemed to take no time at all.

"The red shift is identical to what was recorded on the outbound voyage."

"Then we are simply repeating the outbound voyage," said Ram. "The ship is moving forward, as propelled by the drive. But we, inside the ship, are moving backward in time."

"Then why are we not observing ourselves as we were two days ago on the outbound voyage?" asked the expendable.

"Because that version of ourselves is not moving through time in the same direction as we are," said Ram.

"You say this as if it made sense."

"If I started crying and screaming, you'd stop taking me seriously."

"I'm already not taking you seriously," said the expendable. "My programming requires that I keep your most recent statements in the pending folder, because they cannot be reconciled with the data."

"It's really quite elegant," said Ram. "The ship is the same ship. Everything about it that does not need to change remains exactly as it was on the outbound voyage. It occupies the same space and the same time. But the flow of electrical data and instructions through the computers and your robot brain and my human one, and our physical motions through space, are not the same, because our causality is moving in a different direction. We are moving through the same space as our earlier selves, but we are not on the same timestream, and therefore we are invisible to each other."

"This is an impossible explanation," said the expendable.

"Come up with a better one, then."

This time the expendable waited a long time. He remained completely still while Ram deliberately and without hunger pushed food into his mouth and chewed it and swallowed it.

"I do not have a better explanation," said the expendable. "I can only reason from information that has already been reasoned from successfully."

"Then I suppose that's why you needed a human being to be awake after the jump," said Ram.

"Ram," said the expendable. "What will happen to us when this ship reaches Earth?"

"At some point," said Ram, "either the two versions of the ship will separate and probably explode, or we will separate from the ship and die in the cold of space, or we will simply reach Earth and continue to live backward until I die of old age."

"But I am designed to last forever," said the expendable, "if not interfered with."

"Isn't that nice? Expendable yet eternal. You'll be able to go back and observe any part of human history that you wish. Watch the pyramids being unbuilt. See the ice ages go and come in reverse. Watch the de-extinction of the dinosaurs as a meteor leaps out of the Gulf of Mexico."

"I will have no useful task. I will not be able to help the human race in any way. My existence will have no meaning after you are dead."

"Now you know how humans feel all the time."

"If we are trapped inside the same starship, Ram, on the same voyage, moving backwards through time," said the expendable, "why did the ship's computers show that we made the jump successfully?"

"What were the criteria for determining a successful jump?" asked Ram.

"Observations of the positions of distant stars relative to how they should look near the target star system."

"Can you bring up an image of what the stars looked like at the moment the computers determined that the jump was successful?"

In an instant, a hologram of a starfield appeared in the air over Ram's console.

"I take it that's not the appearance of the stars around our present position."

"Correct," said the expendable.

"How long did the stars have the appearance recorded here?"

"The scan was repeated three nanoseconds later and the stars were as they had been just before the jump."

"So we made the jump, and then we unjumped," said Ram.

"So it seems."

"And we're sure that this wasn't just a glitch? That the computers weren't just 'detecting' what they were predicted to detect?"

"No, because the starfield of the target was not quite identical to the prediction."

"Show me the difference," said Ram.

The starfield view on his holodisplay changed to show yellow and green dots instead of white ones.

"The nearest stars show the most difference, and the farthest ones the least," Ram observed.

"Not always," said the expendable, pointing to the few exceptions. "This is expected because our observations of the universe are based on old data -- light that has had to travel ninety lightyears to reach Earth."

"Didn't the astronomers allow for that?"

"Yes," said the expendable. "But it was partly guesswork."

"Let's play a game," said Ram. "What if the difference between the prediction and what was observed in that less-than-three-nanosecond interval could be explained, not by astronomer error, but by the passage of time. Is there some point in the future or in the past when the stars would be in these positions relative to the target star system?"

One second. Two seconds.

"Eleven thousand years ago, roughly speaking," said the expendable.

"So when we made our jump through a stuttering, quantized fold in spacetime, the fold didn't just move us through space, it also moved us backward in time."

"That is one explanation," said the expendable.

"And so we got hurtled back into our previous position in spacetime, only progressing backward."

"So it would seem," said the expendable.

"That must have taken enormous energy," said Ram. "To move us eleven thousand years backward in history, and then to recoil back to the present while reversing the flow of time."

"It might have," said the expendable, "if we understood how this actually works."

"Please tell the computers to calculate what laws of physics would explain an exactly equal expenditure of energy for the two operations -- passing through the fold into the past, and passing back but reversing direction."

It took a week before the computers finished their nineteen separate calculations and the expendable was able to say, "The computers have come up with a set of physical laws that would have to be in force for the two passages through the fold to use up identical energy."

"Does this system of physical laws bear any relation to how the real universe has been observed to work?" asked Ram.

"No," said the expendable.

"Please tell the computers to keep recalculating the transition through the fold and out again, into the past and back again but reversed, until they can find a way to balance the energy without violating any observed laws of physics."

This time it took eleven days for the computers to come up with their answer.

"Converting the energy requirement into mass," said the expendable, "all the computers agree that without violating previously observed laws of physics, the most likely cost of returning from the fold to our previous position in spacetime, but with the direction reversed, would be about nineteen times the mass of this ship and everything on it."

"Nineteen computers," said Ram, "and nineteen times the mass."

"Do you find this coincidence significant?" asked the expendable.

"Each computer was an observer and a meddler in spacetime at the time the fold was created," said Ram. "You and I weren't observers, because we could not sense or even understand the convolutions of the fields being generated. So for each observer, there had to be a distinct jump. And for each jump, there had to be an expenditure of mass equal to the total mass of the ship and its contents."

"So if there had been only nine or ten computers," said the expendable, "we would have come only halfway back to the present?"

"No," said Ram. "I think if there had been only one computer, we would have crossed the fold only one-nineteenth as far into the past of the target star system before being shoved back, in reverse."

"You seem to be very happy about this hypothesis," said the expendable, "but I don't see why. It still explains nothing."

"Don't you see?" said Ram. "Crossing the fold pushed us into the past a certain amount, based on the mass of the ship and its velocity or whatever. But the only way to pay for that passage across the fold was to send an equal mass backward. And because there were nineteen observers creating the fields that created the fold, it happened nineteen times."

"But it happened only once," said the expendable.

"No," said Ram. "It happened nineteen times. There are eighteen other versions of ourselves moving backward through time as we journey toward Earth. All of us invisible to each other."

"So our reliance on the computers caused the failure of the mission?" asked the expendable.

"The mission didn't fail," said Ram. "It succeeded nineteen times. We're just the exhaust trail."

The expendable and the computers worked out the math as best they could in only an hour or two. "If your extravagant and unverifiable guesses happen to be right," said the expendable, "then yes, the stuttering of spacetime might have allowed all nineteen versions of this ship to pass through the fold to eleven thousand years in the past, but with just enough time elapsed between passages that they wouldn't overlap and therefore wouldn't necessarily annihilate each other."

"So there might be not just one, but nineteen versions of this ship and all its crew and equipment, including your charming selves, and me, the pilot, proceeding toward the target planet in order to colonize it."

"Or not," said the expendable.

"Oh, but it's too delicious not to be true."

"Metaphorical flavor doesn't influence reality," said the expendable.

"But the elegance of reality has a metaphorical flavor," said Ram.

"Suppose you're right," said the expendable. "So what?"

"So I'll feel better as I spend the rest of my life doing nothing meaningful."

"You'll have time to read all those books you never got around to reading."

"I think I won't have time to do anything at all," said Ram. "I think I will only live until we reach the place where this ship was constructed. Only the structure we now see around us is moving backward through time. When we come to the place where it was built, it will be unbuilt around us."

"So we'll get off."

"How?" asked Ram. "We would have to get into a shuttle that would take us back to the surface of Earth. But there are no shuttles moving our direction in time."

"There aren't any stars moving our direction," said the expendable, "and yet we still see them."

"What an interesting quandary," said Ram. "By all means, stick around and see what happens."

"What will you do?"

"I'll continue this voyage until I find a way to send a message to the versions of myself that cross the fold into the past and have to deal with their nineteenfold replication."

"How do you propose to do that?" asked the expendable.

"Carve it into the metal of the ship somewhere that I'll be sure to find it, but not until after I come through the fold."

"No matter where you decide to carve it," said the expendable, "the fact that it wasn't already there when you arrive to start carving it proves that you cannot do anything to change objects that are moving in the ordinary direction of time."

"I know," said Ram. "That's why you're going to do it."

"That changes nothing."

"With your eyes closed," said Ram. "So you can't see in advance the proof that it didn't work."

"But even if I close my eyes before carving the message, I'll see the other proof that it didn't work," said the expendable.

"What's that?"

"The existence of the message after I carve it, which in the ordinary flow of time would be before I had carved it, proving that the message is moving in the same direction through time as us, which means it will not be in the version of the ship that will make -- or has made -- the jump."

"Just close your eyes and do it," said Ram. "And keep them closed. And then come back and tell me you did it without knowing whether it worked or not."

"Why would I deliberately conceal data from myself?"

"Because it will make me feel better."

"Then I will observe and simply not tell you."

"If you know, then you have to tell me, if I ask."

"Then don't ask."

"If I know you know, I will have to ask," said Ram.

"So I have to behave irrationally in order to give you an irrational hope."

"And then I'll die," said Ram.

"Are you suggesting a medical outcome, an emotional hyperbole, or an intention?"

"Intention," said Ram.

"So by doing this and remaining ignorant of the outcome, I am hastening the time when you will take your own life?"

"No," said Ram. "You will take my life."

"I will not."

"You will if I order it," said Ram.

"I cannot," said the expendable.

"At the end of the jump through the fold, there came into existence a total of at least twenty versions of myself -- nineteen going forward, and me -- or nineteen of me -- going back. There can only be one real Ram Odin."

"You," said the expendable.

"I am a version that can do nothing, change nothing, affect nothing. Because of the direction of my movement through time I am, in effect, nonexistent already in the real universe. I declare this copy of myself to be flawed, useless, and -- let's admit it -- completely expendable. There can only be one real version of myself."

"Killing you will only eliminate the back-flowing Ram or Rams," said the expendable. "It will not affect the nineteen forward-moving Rams, of which eighteen will be as redundant as you say you are."

"That's not my problem," said Ram.

"We got ourselves caught in the midst of a stutter," said the expendable. "We were trying to avoid that because we didn't know what would happen to us in a stutter -- most of the computers predicted the ship would be sectioned or obliterated."

Ram had been scanning all the reports from every part of the ship. "But we were neither sectioned nor obliterated. We're still intact."

"More than intact," said the expendable.

"How can you be more than intact?" asked Ram.

"There are eighteen other copies of our ship, and ourselves, that passed through the fold."

Ram tried to visualize what the expendable was describing.

"But not occupying the same space at the same time."

"The quantized nature of our passage through the fold dropped off all nineteen versions of the colony ship at regular intervals. We are separated from each other by about four seconds, which puts us a safe distance apart as long as we all refrain from firing our engines or generating any fields that would cut through another ship."

"And on each ship," said Ram, "there is a version of you speaking to a version of me?"

"All the expendables have reported that all the Ram Odins went unconscious at exactly the same time. All of us placed you in the same position and strapped you in and waited until you awoke, so you could tell us what to do. All of us are speaking to our Ram Odin and saying the identical words at the same time."

"Ain't spacetime a bitch," said Ram.

"Noted," said the expendable. "Nineteen times."

"So if all the mes are saying the same thing at the same time," said Ram, "I'd say there's a certain redundancy."

"Which does no harm."

"But at some point, one of us will do something different. We will diverge."

"As all of you are saying at this exact moment," said the expendable.

"And when we diverge, it will be impossible for the expendables and the ship's computers on all the ships to know which version of Ram Odin to obey," said Ram. "Therefore I order you and all the other expendables to immediately kill every copy of Ram except me."

I'm so sorry," said the expendable. "One of the versions of Ram Odin did not include the word 'immediately,' and therefore his order was complete a fraction of a second before all the others. He is the real Ram Odin."

Ram gave a little half smile. "How ironic. By specifying that you should act at once --"

The expendable reached out with both hands, gave Ram's head a twist, and broke his neck. The sentence remained unfinished, but that did not matter, since the person saying it was not the real Ram Odin.