“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.

  The short story “Expendables” appears as chapter prologues in the first fifteen chapters of the novel Pathfinder.

  Eye For Eye—Part 3

  Eye for Eye was published in 1990 as a Tor double novel, along with “Tunesmith” by Lloyd Biggle, Jr. It is currently out of print, although it is available as an audiobook.

  Part 3

  Continued from issue 18

  No, I better tell the truth here, cause I wasn’t that smart. It wasn’t till I was halfway to the house that I really wondered if he believed me, and it wasn’t till Mama had me with a nice clean pair of pajamas up in a nice clean room, and she was about to take my jeans and shirt and underwear and make them nice and clean it occurred to me that maybe I was going to wish I had more clothes on than pajamas that night. I really got kind of mad before she finally gave me back my clothes—she was scared that if she didn’t do what I said, I’d do something to her. And then I got to thinking that maybe I’d made things even worse by not giving her the clothes, because that might make them think that I was planning to skip out, and so maybe they weren’t planning to kill me before but now they would , and so I probably just made things worse. Except when it came down to it, I’d rather be wrong about the one thing and at least have my clothes, than be wrong about the other and have to gallivant all over the country in pajamas. You don’t get much mileage on country roads barefoot in pajamas, even in the summer.