“It may be even narrower because they have such a strong incentive to get into space,” said the expendable.
“What incentive is that?” asked Ram.
“Their binary,” said the expendable. “It is also inhabited.” The expendable seemed about to say more, but it froze for a moment. “A twentieth ship has appeared.”
“He did it,” said Noxon.
“Who did what?” asked Wheaton.
“Well, I did it,” said Noxon. “I was watching carefully during the jump through the fold. If we divided, I was going to try to snag the backward-moving ship and bring it back into the forward timeflow.”
“The ship reports that you failed,” said the expendable. “The backward-moving ship in fact moved backward, not making the jump through the fold. But the mice on that ship were able to reprogram the computers to avoid the twenty-fold duplication and then jumped the fold going backward, in order to separate the backward-moving ship from the outbound ship that was us just before our jump.”
“My head hurts,” said Wheaton.
“It does not,” said the expendable. “But your lie is apparently intended to express humorously exaggerated confusion which you do not, in fact, feel.”
“Exactly,” said Wheaton. “It’s nice to have someone get my jokes, even though you have to explain them aloud.”
“I wanted to confirm that I had understood,” said the expendable.
“If they jumped the fold backward,” said Ram, “how are they here?”
“Noxon was able to reverse timeflow and rejoin our spacetime,” said the expendable. “Very good work.”
“Thanks,” said Noxon. “But it wasn’t me.”
“It was you-ish,” said the expendable. “It’s within your capabilities.”
“And then what?” asked Noxon. “He jumped forward to our time?”
“The backward-moving ship had not made the 11,191-year pastward leap that these nineteen ships made. So it arrived in this space in the future, relative to our current timeplace.”
“What did they see there?” asked Ram.
“Not very much,” said the expendable. “The aliens immediately attempted to seize control of the ship’s computers, remotely. The mice were able to resist their reprogramming, which was feeble and unsophisticated compared to the one they will use near Earth several hundred thousand years from now. Then the Noxon of that ship attached to our paths and jumped back to our time, when the aliens are not able to project their computing prowess this far into space.”
“Narrow escape,” said Wheaton.
“It was a very good thing that we had the mice with us,” said Noxon.
“Thank you,” said the alpha mouse. “We’re glad to reward you for refraining from crushing my head.”
“I never wanted to do it,” said Noxon to the mouse.
“Talking to the mice?” asked Wheaton.
“I wonder,” said Ram, “if our presence here, now, accelerated the aliens’ development of the ability to make remote assaults on human computing systems. Having seen us enter their space . . .”
Wheaton agreed. “Why, it might be that our presence is what led them to attack Earth!”
“No,” said Noxon. “They attacked long before we ever showed up here.”
“We’re here now, and that’s hundreds of millennia before the attack,” said Wheaton.
“Prepare for your head to hurt again,” said the expendable.
“Let me guess,” said Wheaton. “‘Before’ doesn’t always mean ‘before.’”
“The calendar and the clock keep a single line of time,” said Noxon. “But with us, causality jumps all over the place. We’re here before the invasion, by the calendar, but we’re here after the invasion, by the causal chain. Their invasion is what caused us to come, so by cause-and-effect, the invasion was first.”
“I can’t even make my little joke,” said Wheaton, “because the expendable already said it.”
“I anticipated your humor?” asked the expendable.
“You stepped on my joke,” said Wheaton. “Clever, but not polite.”
“You’d already said the joke,” said Ram, “so it wasn’t going to be funny this time. Whereas the expendable stepping on it, that was funny.”
“Amusing, anyway,” said the alpha mouse.
“The mice don’t think any of this is all that funny,” Noxon reported.
“Oh, the women are laughing uproariously,” said the alpha. “I’m the one who isn’t hysterical about it.”
Noxon could see that the female mice were busy at various tasks throughout the ship, and not one of them showed any sign of paying much attention to what they were doing.
“What are you doing to the ship?” asked Noxon.
Noxon could see Ram stiffen a little—he must know Noxon was talking to the mice, and so he feared that the mice might be doing something dangerous and irrevocable.
“We’re making the same alterations to this ship that our counterparts made to the backward-moving ship,” said the alpha. “So we can jump the fold without making nineteen forward copies and one backward one.”
“Are we planning to jump again?” asked Noxon.
“I believe that when the expendable finishes explaining about the civilization on the binary planet, you’ll decide that ten of these twenty ships should jump to a spot much nearer the binary.”
“Will they still skip eleven millennia back in time?” asked Noxon.
“No. Curing the replications also cures the time skip.”
“Are you ready for me to explain about the binary planet?” asked the expendable.
“I am,” said Ram. “Unless the mice now command the ship.”
“They’ve fixed it so we don’t split into nineteen pieces every time we jump,” said Noxon.
“You asked them if we’re planning to jump again,” said Ram. “Why would we do that?”
“Let’s hear the expendable and find out,” said Noxon. “The mice apparently already know what he’s going to tell us.”
The expendable took a breath before proceeding. Such theatricality from a machine that doesn’t need to breathe, thought Noxon. “Earth’s Moon was important to the evolution of life, by causing tides and controlling other cycles,” said the expendable. “But this world is really two planets, nearly equal, as close as they can be without tearing each other apart with tidal forces.”
“So both have atmospheres,” said Ram.
“Both have life?” asked Noxon.
“Both have widespread electricity and radio communications,” said the expendable. “They each monitor the other’s radio broadcasts, and I believe the ability to interfere with and eventually control remote computer systems was developed by the nearer planet in order to use it against the farther one.”
“They have a million kilometers between them,” said Ram, “and they’re attacking each other?”
“That suggests reciprocality,” said the expendable. “The nearer planet is attacking the farther one. The farther one seems to be working only to protect their own systems against attack.”
“Let me guess,” said Ram. “The one that attacked us is this aggressive one.”
“I don’t know,” said the expendable. “Whichever world emerges victorious, it will be convinced that the only way to deal with aliens is to destroy them utterly.”
“So even if it’s the nice guys on the far planet,” said Noxon, “they might still be the enemy that attacks Earth.”
The alpha mouse spoke to Noxon. “We don’t know which one is our enemy. Both must be brought under control.”
“It seems wrong to punish one world for what the other world did,” said Noxon.
“We’re not punishing anyone,” said Ram. “We’re saving the human race against a threat, and we don’t know which of these worl
ds poses that threat.”
“We know that both of them pose a threat,” said the alpha.
“It’s possible that both pose a threat,” said Noxon. “But to take preemptive action against both seems unfair. Stifling a civilization, a species that might be completely innocent—”
“Hold on,” said Wheaton. “Garden has already tried dozens of ways to forestall the destruction of humanity, so there are lots of timestreams in which one of these species wipes out all rivals and rules this bit of the galaxy. The other one was probably destroyed before the victor ever came near us, so we’re not the ones who snuffed them out. All we’re doing now is creating one slim timestream in which the human race survives. It is not so very much to take for ourselves, compared with what they’ve taken already.”
“So you’re arguing in favor of xenocide?” asked Ram.
“Not at all,” said Wheaton, looking horrified. “Nothing of the kind! Garden has endured for eleven millennia with tight restrictions on their ability to develop high technology, right?”
“Yes,” said Noxon.
“And that was a lid placed on the planet by other humans, right?”
“By computers,” said the expendable, “but obeying human orders.”
“So if we go into the past and put such a lid on both these species,” said Wheaton, “we’re doing to them nothing that we haven’t already done to ourselves.”
“To one portion of our species,” said Noxon. “Earth didn’t put any such lid on themselves.”
“We don’t have to destroy their whole biota in order to set up colonies here, do we?” asked Wheaton.
“It depends on what proteins they produce, and whether we can digest enough of them,” said Ram.
“I don’t suppose now would be a good era in which to make our investigations,” said Wheaton.
“You want to go into the past and see them early in their evolution,” said Noxon.
“I am what I am,” said Wheaton. “But I’m also right.”
“Put us back a few hundred thousand years ago,” said the alpha mouse, “and we’ll be their lid.”
“The mice have already suggested,” said Noxon, “that ten of our ships go to the other world, and ten stay here.”
“I wonder if versions of you are saying exactly the same thing on all nineteen of the other ships,” said Ram.
The expendable answered. “The exact wording is quite different, but yes, on every ship you have reached approximately the same point in your discussion.”
“What have the others decided?” asked Ram.
“They’re all asking their expendables what the others decided.”
“We haven’t decided anything,” said Wheaton. “But the only sensible thing is to go back in time, split the fleet in half, and explore both worlds to see what damage we might have to do in order to use them.”
“But we don’t even know what the sentient species look like on either world,” said Noxon. “How will we know which life forms in the past are going to evolve into them?”
“We have images of both species,” said the expendable. “Both worlds are regularly broadcasting visuals using primitive raster scans.” Holograms appeared in the middle of the cockpit. One species was low to the ground, with many limbs, all of them capable of grasping, and many of them with sharp claws or blades at their fingertips. The other species was tripedal, tall, and gracile, with a head crowned with vicious-looking horns. All three feet were prehensile, and one of them had two thumblike projections.
“Let me guess,” said Ram. “The low, scuttling one is the aggressive species that’s trying to take over the other side’s computers.”
“Wrong,” said the expendable.
“You wanted the roachlike one to be evil,” said Wheaton, delighted. “Easier to hate them!”
“Oh, I could easily hate them both,” said Ram. “For all we know, they teamed up to attack us. We never saw who was piloting those aircraft.”
“It’s too dangerous to go into the future to see what happens,” said the alpha mouse. “Our counterparts on the twentieth ship are still searching to make sure they’ve cleaned out all the intrusions.”
“The mice don’t want to go into the future to learn any more,” said Noxon. “If they’re scared of the aliens’ capabilities, we’d be crazy to make the attempt.”
“So we just go blindly backward,” said Ram.
“To find out if we can leave the flora and fauna on either world intact,” said Wheaton.
“We can,” said Noxon. “We can always decide not to establish colonies on either world.”
“That’s not an option,” said Ram. “We’re here to neutralize the threat. We have no way of monitoring whether we’ve succeeded without establishing a permanent, technologically powerful presence.”
“That’s not really true,” said Noxon. “For instance, we could drop off the mice a million years ago and then pop back to this time to see where we stand.”
Ram laughed. “We’d find that the mice were completely prepared to destroy us, take over our ship, fly back to Earth, and take over everything.”
“We would never,” said the alpha mouse.
“I was just pointing out that if we establish human colonies, it’s because we want to, not because there’s no other way,” said Noxon.
“Well,” said Ram, “whatever we do, I don’t propose to leave it all up to the mice.”
“The other ships have all decided to go back and test the proteins on both worlds,” said the expendable.
“How do we divide the fleet?” asked Ram.
“The computers have already divided the ships randomly into two groups of ten. We’re in the group that stays at this near world, while the others jump the fold to the far one.”
“The one with the tripods,” said Wheaton. “That’s a shame—I was most interested in studying them.”
“That’s how all the Wheatons felt,” said the expendable. “But then they all decided that both species need to be studied, so half the Wheatons have to take the second choice.”
Wheaton sighed. “I suppose for every Professor Wheaton who lost, there’s a Professor Wheaton that won.”
“Depending on how you define ‘won’ and ‘lost,’” said the expendable. “You could say that they all win, with an entirely new sentient species to study.”
“I feel much happier already,” said Wheaton.
“Ironic or sincere?” asked the expendable.
“Pissed off but compliant,” answered Wheaton.
Noxon sliced them through the time it took for the ship to fly into stationary orbit around the near planet. At Noxon’s insistence, the mice stayed on the ship with him and Ram, as Wheaton and the expendable flew down to the surface. “The scientist and the robot can do the job perfectly,” said Noxon. “The time traveler and the pilot have to stay here, in case we have to undo something horrible the mice have done.”
“So untrusting,” said the alpha mouse.
Noxon regarded this comment as not worth answering.
Wheaton and the expendable made frequent reports during their days of data collection. Ancestors of the scuttling aliens were easy enough to spot—they were already as close to sentience as, say, Homo habilis. Using tools, but not yet making fire. “It is difficult for Professor Wheaton to stay focused on the project at hand,” said the voice of the ship. “He keeps wanting to go backward and forward and the expendable has to keep reminding him that only Noxon can do that.”
During one of the lulls between reports, while Ram was exercising, Noxon said, more to himself than to Ram, “I miss Deborah.”
Ram didn’t answer, but the alpha mouse did. “Why didn’t you simply copy her and bring her along? There’d be twenty of her now. Plenty to go around.”
“She wanted eyes,” said Noxon. “The twenty who came with us
would be disappointed for the rest of their lives.”
“What?” asked Ram. Now he heard.
“Just talking with the mice,” said Noxon.
“Whatever you say to them, they’re going to use against you later,” said Ram.
“Unless we use it for you,” said the alpha mouse.
“He can’t hear you,” murmured Noxon.
“I wasn’t talking to him,” said the alpha.
“I’ll eventually find someone among the colonists,” said Noxon. “I’m not worried.”
“You’re really strange-looking,” said the alpha. “Most of the colonists will be completely repulsed by you.”
“Is that why all the females were pregnant five times over before they came on this voyage?” asked Noxon. “So they wouldn’t have to do something as repulsive as mate with a small-testicled male like you? Or was I right that you were castrated?”
“I don’t have body-image issues the way humans do,” said the alpha.
“No, you don’t have any kind of shame at all,” said Noxon.
“Someday you’ll understand us,” said the alpha.
After three days, thousands of samples had been brought aboard and stored in the gene banks. The conclusion was clear. Most of the proteins that humans needed could be found readily among the native flora and fauna on both worlds. And a simple array of fast-spreading, highly edible plants would make up the deficiencies. “We can release any Earth fauna we choose,” said Wheaton, “and thus we’ll have meat to eat and enough plants for a varied and pleasing diet.”
“That’s what they’ve found on the other world,” said the expendable, “except that they need to spread a different array of Earth plants.”
“So, no destruction?” asked Noxon.
“Are you disappointed?” asked Ram.
“I still think that walls are a good idea,” said Noxon.
“Because you grew up in a wallfold,” said Ram.
“We can give the mice one wallfold,” said Noxon. “And reserve one on each world for the aliens alone.”
“And give us one to combine with them,” said the alpha mouse.