Distinguishable:

By Charles Swanson

There exist on this planet many rooms. There also exist many academic professors. Indeed, at any given time many of these professors are located in rooms. At any given time it is also possible to distinguish any professor from any other professor, and any room from any room. Times are distinguishable, rooms are distinguishable, and professors are distinguishable. It is therefore permissible to say "On a particular day, a specific professor was in a certain room".

On a particular Friday, a specific professor of physics was in his office. This professor was the most dedicated physics professor in the University (a distinguishing characteristic, certainly), possibly the City, maybe the world. Every day, he awoke and a shiver of excitement at the prospect of teaching went through him. The idea of imparting his knowledge to the future generation so enthralled him that, by the time his lecture started, he was warmed to the very roots of his stupid neck-beard. When speaking, he could barely contain his exuberance, exhibiting variable volume and tone levels as he tried to control the enthusiasm that racked him. This same enthusiasm led him to schedule his office hours for the entirety of every working day.

No student had ever come to his office hours. Never before had any student shown appreciation for his efforts. Never a "thanks professor", or even a "have a nice weekend, professor". He'd never gotten an apple as a gift, never received a score above "1: Falls Significantly Below Expectation" on any field of the student survey. But never in his head, clad in a ten-to-the-one-hair comb-over, did the thought arise that this was anything but the single best pursuit that any man can hope to follow. He was utterly hated, yet spent every day in his office, moved to his core that at any moment a student might require help and seek it there.

His clock ticked. "This time," he quietly said to himself. "This time a student will come. They need my guidance! There's so much I know, so much I can tell them! I'll be here when a student arrives; I'll be here to sort out that student's problem in no time!" His clock ticked again. This second, just like last, he maintained a forward, eager stance in his chair. This second, just like last, his eyes darted back and forth between objects on his desk to make sure all was in readiness for the eventual visitor. There was note paper underneath his helpfully placed collections of pens, pencils, and a chalk-extrusion device that helped minimize the number of exuberance-related breakages. There was a four-function calculator helpfully placed central to the student's seat. There was a bowl of M&Ms to the hypothetical student's left, the better to put them at ease. There was a box of Kleenex to the empty chair's right, in case its occupant should at any time become overcome by emotion.

The clock ticked again. This happened tens of thousands of times. Then he went home, went to sleep, came back, and did it again.

As previously mentioned, times are distinguishable. Because of this we can identify two times and claim that a third lies between, if we also assume times are ordered. Let the first two times mentioned be two sequential ticks of the professor's clock, and the third time be when a student, a girl, walks into his office.

The professor looked up. His eyes widened. Here was his culmination, his reason to exist. If ever he had difficulty justifying his life to himself, this moment would assuage that thought. He began to bob up and down just a bit before opening his mouth to speak... and was beaten to it.

The girl said "Hello professor. Can I borrow some tissues?"

He froze. It was difficult to fully comprehend what was happening. After all these years, countless hours of waiting, a student finally came into his office and... didn't need academic help? For a moment, despair was on the verge of gripping him before his supernaturally-goodhearted attitude took his mind and buoyed it. So what if she didn't need academic help? He was still able to help in some small way. In fact, she needed those tissues, probably for some crucial task like dealing with an imminent mother-of-all-sneezes! He was her savior right now! She was coming to him in her time of need, and he was able to completely resolve the situation to her satisfaction. He felt good inside. He was doing exactly what needed to be done to aid this poor soul.

"Absolutely!" he said, his face reddening from the thrill, "Take as many as you need. And remember my office is always open for absolutely anything you ever might require, ever, be it tissues or, for example, academic help. Ever."

She gave a quick but sincere smile, said "thanks!", pried a wad of thirty to forty tissues out of the Kleenex box, and left. The only proof he had that she'd ever been here was a significantly lighter box on his desk and a pounding heart. But that was all he needed, because he knew that somewhere, someone was slightly happier because of an action that he was able to perform. He leaned a little back. Then the small moment he'd allowed himself for relaxation passed, and he leaned forward again, anxiously scanning his desk to ready it for the next student. The clock ticked again.

In the hallway, the girl took her wad of tissues under her arm and walked toward one of the machine shops on campus. The University was small when it came to traveling time and number of rooms, so one would not imagine that it would be possible for the administration to lose track of a whole machine shop, or not discover on their records that exactly one person, a student by the name of Rex Riptide, had access to one of the rooms. The girl had a name, too, but she was much more comfortable being called the Atomic Girl. When she rounded the last corner into the shop, she was greeted by Rex, the equally sillily named NASA Lass, the curiously aptly named Dr. Polski, another assistant to whom Rex had grown quite attached, and a very bewildered journalist by the name of Gil Eggars.

In the shop there was a huge, many-meter-wide metal dodecahedron. It was steel, brushed shiny by the metal-loving assistant. Between the twenty individual flat steel plates that composed it, there was a thin rubber seal to keep the inside at high vacuum. There were thick glass portholes inlaid at intervals, but the only thing visible inside was darkness. The entire thing looked more like an experimental test apparatus, like those that were strewn discarded around the lower floors of the building, than an artifact of superscience.

Rex was speaking. "...so essentially teleportation is possible, but it takes seven years."

His audience was the confused but honored Gil, who looked as if he'd taken in none of what the Atomic Girl missed on her tissue-run. "Uh... ok," he said uncertainly, "Got it. Now what are the tissues for?"

"Electrostatic detection. They're light and charge easily. When we get some eka-coulombic forces going, those tissues, spread around the floor of the shop, will be the first to exhibit motion when the two universes are close enough to interact."

The discerning hard-science-fiction fan or science enthusiast is asked not to take that last paragraph personally, and is preemptively requested to forgive what is to come.

"Right. Got it" Gil replied. Rex looked at him in a concerned manner, apparently picking up on the fact that Gil had no idea what was going on.

"Ok Gil, one more time: the big thing is just a vacuum-container. It's this little thing that's the issue. When two universes get close enough, coulombic interaction on one is coulombic interaction on the other. Everything we do to objects in our surroundings is coulombic interaction. This means that if I were to bring another universe close enough to this spot, I could pick up, throw, crush an object from that universe. Got it?"

"I'll take your word for it. Now why the vacuum?"

"Because if I can touch it, I can breathe it. If I take otherworldly oxygen into myself, I irrevocably assimilate it into my workings in mere seconds. Then when the universes are brought out of contact, or I simply walk away from this spot, the bonds between the oxygen and whatever I've bonded it to break, and the oxygen is pulled back to its own universe. That's bad. It's exactly like a gamma-ray or any other ionizing radiation came and cleaved that molecule."

NASA Lass chimed in: "Actually, here's where !N had some issues with Rex's work. Since all of the oxygen atoms in Rex's body wouldn't be indistinguishable, he thought you'd get some weird quantum wavefunction summing effects that could... um... I've lost you, haven't I?" This last was in response to Eggars's even more bewildered look.

"Let's save that for later," said Rex, visibly shaken by the mention of his old comrade. "For now all you need to know is that the same thing happens if I eat. As long as there are only small concentrations of otherworldly particles in me, the symptoms will be exactly like radiation poisoning when I leave. The problem is that even a chicken nugget corresponds to a lethal dose. Even one breath of air. As soon as I interact in any meaningful way with the other universe, I'm toast."

"Right. But now onto teleportation?"

"Smart chap you are, Eggars. Now let's say I stay so long in the area that's effectively in both universes that I cycle every one of my particles through me, and am composed completely of the otherworldly ones."

Gil's eyes widened. He was being forced to take into account the relative non-importance of the actual physical stuff of the body. "So... you're saying that I'm not an object... I'm how objects cycle through me?"

"Oh, you mean you hadn't assimilated that memeplex yet? Then no wonder this wasn't getting through! In order to teleport myself to somewhere else, I simply have to be as an acoustic wave, slowly propagating through a different physical medium. More and more of my elemental units will be those of the other side, fewer and fewer will be those originating here. The particles that composed me will be here, but I will be there. Brilliant, isn't it?"

If Gil's eyes were wide before, they were doubly so now. "But how... How can you only eat and breathe on the other world? And it must take an eternity to filter every last particle out."

"That's where the vacuum comes in. I completely isolate myself from physical parts of this world. I only eat, only breathe stuff from the other world. But as you pointed out, I can never get every particle out of my system. The proportion of me that is otherworldly will grow sharply at first, and I get to 50% in just a few weeks, but it approaches 100% asymptotically." Rex's face became hard. "It will be seven years until I'm complete enough to survive without this world, until I can leave the area corresponding to this dodecahedron in another universe. And even then it takes all sorts of medical considerations to keep me alive after the effective dose of ionizing radiation I'll have the symptoms of having taken."

"This only opens up new questions, Rex! How do you know there'll be oxygen on the other world? Why do you call it 'teleportation' if it's more like traveling between dimensions? How did you get medical supplies on the other side? How did you get food on the other side? But more importantly, good God man, how can you stay in the same little box, a prisoner between the very planes of reality, for seven years?!"

"It only opens up new questions? Hah, now you're thinking like a scientist, Gil" Rex said cryptically.

Rex's assistant opened her mouth for the first time so far. "Oh, wipe that smug look off of your face Rex. Mystery doesn't become you. Gil: We picked the world for oxygen, we seeded it with the Atomic Girl's biosystems for food with the vacuum chamber, we seeded it with Dr. Polski's nanotech for medical supplies, we call it 'teleportation' because it's not entirely clear whether it's in our universe or not, but if it is it's unimaginably far away and outside our Hubble-Bubble. And Rex is doing it because he's a madman. If the vacuum fails or we lose anchor on the other universe, Dr. Polski has an experimental solution, but odds are he's done for." These last two sentences prompted a catch in her throat that the others looked likely to mirror.

With that she turned around and started tightening the bolts holding the vacuum chamber together. Her face wasn't visible to the rest of the group.

Gil shrugged. "I guess there's no arguing with you, Rex. I suppose this lot has already tried to talk you out of it. When do you start?"

"Now", said Rex.

Gil's arm hairs stood on end. He sensed the familiar smell that comes from taking a baseball bat to a cathode ray monitor, or exploding a capacitor. The tissues that were strewn about the left side of the room began to lift in a uniform way, the wave of lifting slowly encompassing those farther and farther from the wall, closer and closer to the point-group vacuum chamber. When those that the Atomic Girl placed around the chamber lifted, NASA Lass, who had been operating some soft-looking apparatus, began to furiously actuate controls. The circle of electrostatically lifted tissues contracted around the dodecahedron, and finally even those closest to it dropped to the ground and clung. She nodded at Rex.

He stepped into an EVA suit, presumably NASA surplus. Before putting on the helmet he spoke to his assistant: "You keep tightening those bolts, dear. Air gets in, I'm done-for." Then something inside him shifted. He broke eye contact. "I'm happy with how far you've come. Keep at it while I'm away." Then he looked up, gave a big, toothy white smile, and donned his helmet. He did not exude trustworthiness while doing this. He did not exude enthusiasm. He simply did it.

The white, pressurized figure that Gil had to remind himself was actually his amazing friend then got inside the dodecahedron. Pumps whined and removed what little air got in when he entered. The group crowded around the portholes. The balloon figure inside gave a thumbs-up. NASA Lass threw a lever. All of a sudden light streamed out of the dodecahedron. Gil was momentarily stunned by the brilliance. When his eyes adjusted to the light, he saw that the pressure-suited figure was standing not in darkness but in a rolling, grassy field. He saw light from beyond where the other side of the vacuum chamber must be. It seemed impossible.

Dr. Polski spoke first. "You know, it's not actually that bright. Photon's aren't localized to specific universes, but since they're still electromagnetic in nature they're shared between worlds. When one leaves the merged area, it has a 50/50 chance of exiting into either one. We only see it as more than 50% as bright because the logarithmic-scale our eyes follow..."

"Please, Doctor. Stop talking". It was the Atomic Girl who said this. She looked into one of the circular portholes. Gil followed her gaze.

This was the true point-of-no-return. At any point up until this one, Rex could have turned around and left, the air could have rushed into the vacuum, the universes could have followed their separate eka-trajectories, and he could have spent the next seven years battling clone-Hitlers and bragging to his friends about the scale of his achievements. Rex did not do this. Instead, he cracked the seal on his suit. The helmet came off. Rex stood, looked around, took in the sunlight on his bare head, and drew a deep, long breath.

"Can he see us?" his assistant choked to Dr. Polski.

No," he answered, "the light from his sun is completely drowning out what light comes through these portholes"

"Good," she got out before becoming silent for a long time.

***

When Gil Eggars got back to his room, the room Rex vacated when he'd begun the slow process of leaving this world behind, he tried to write some of this up. He kept a journal, and knew that a newspaper would some day pay a fortune for his account. For some reason, he couldn't make the words on the page truly tell what he felt. "Today, I saw someone willingly die. At least, that's what the effect on his friends was. Rex willingly forgoes all physical contact with everyone he's ever met, communicating only through a text-feed to a screen on this side, and though he was quick to point out that he could be back in as little as fourteen years, he's uncharacteristically transparent in his lack of intention to return. This is not the Rex I met during the events of the Summit. I saw Rex put together a detailed plan to bring down a Steel Land Leviathan in less than ten minutes. I saw his resolve when he prevented muggers from beating down his friend. I caught a glimpse of the compassion that motivated him to dispatch dozens of Steel's laser-bearing dronebots. But today, all of that was gone. He just felt... defeated."

It was worse than that, Gil conceded to himself. He'd acted just like a normal person, motivated by normal insecurities and problems. It almost seemed like he was running away from something.

He put his pen down. He'd come back to it later. This was a fun little house. On his way downstairs he ran into Rex's assistant, who'd been living in another vacant room. Gil got just a bit of a feeling that something was amiss... Wasn't the house full before Rex left? Had another one of the roommates gone on some voyage?

He got the feeling he shouldn't ask. "How are you holding up?" he asked the assistant. She made a halfhearted attempt at answering, then looked down and left.

A few weeks passed. The roommates all went to classes and worked in their lab-basement at intervals. The assistant disappeared to somewhere on the campus for long stretches of time, apparently to the disquiet of the roommates. Gil wasn't re-assigned to another story yet. They all spent the days at their respective endeavors, but they all spent the evenings around Rex's tank, watching him program his nanites to make himself new clothing, build shelters from the nano-extruded ceramics, stare off into the as-yet forbidden distance. Sometimes it was day, sometimes it was night where he was. Then, the light streaming into his universe from the portholes illuminated him, forming a glowing ring around him. He'd talk to them over his texting terminal, but most of the time he was planning new research, putting schematic after schematic into the terminal's memory. Gil saw that his roommates considered this a good sign.

One day, alarms started sounding. Gil came back to himself after a long muse to see Rex frantically typing to the light of his terminal screen, softly lit also from the ring of alien portholes around him, so close yet so far. Gil found, to his surprise and shame, that he was the only one with his face pressed against the glass. The rest were gathered around the little piece of soft technology, NASA Lass at the controls. They were talking very quickly over the whine of the alarm.

"What's going on?" Gil said, trying to keep his voice level. He didn't get an immediate response. Dr. Polski and the Atomic Girl were just getting heated (literally, in the Girl's case) over one point or another, and Rex's assistant looked like she was ready to do something very rash. "What the Hell is going on?" he repeated, louder.

NASA Lass at the controls was the one to answer. "We are losing anchor. We're not likely to be able to hold onto this specific position in Rex's universe." Then she murmured, "Damn. !N was supposed to do the preliminaries on this one. Never had a chance..."

Gil was still lost. But the Lass was back at her control panel, causing mad patterns of light to appear on her readout. He looked at the only person who wasn't discussing strategy for averting this odd disaster: Rex's assistant. "Please tell me you can explain what's going on." The assistant's tense face turned toward him. It seemed that every muscle was bunched into a ball of readiness. She was obviously ready to spring into any kind of action that was required, but knew that there was none.

"Didn't you wonder how Rex always stayed in one place relative to both frames? We had to get the right spot in that universe, even when both our and their trajectories were being pulled around, twisted by the gravitational influence of our respective galaxies. The relative velocity has no meaning, after all they could be in completely different universes, but the difference in accelerations is huge, and we need a way to deal with that."

"And that way has failed? Then what can we do? Can we pull him out? Can we re-establish anchor?"

"Pull him out? As far as we can tell he's as close to 0.5 otherworldly as he's going to get! He'd be reduced by half, and the tattered half would burst into reactive flames!" She shuddered to her very core. Gil could see that the thought was wrecking her. If minds could shake to pieces, that's what hers was doing.

"So get anchor back. Come on, let's help them! What caused us to lose it? What can we do to help?"

Dr. Polski stopped shouting at the Atomic Girl and madly pushing buttons to shout "Thirty seconds!"

A tear made its way out of the assistant's clenched face. "We can't. Do you know what my job was on this thing? It was to tighten bolts. I tightened them to the optimal level for every purpose." A stifled sob was forced from her chest. "Two months ago I couldn't even do that. I couldn't touch a wrench. And they all wanted to keep me that way! When I was finally free, they all said I should stay away from machines! There was only one man who believed in me, one man who smiled at each step I took. That man!" She pointed an accusatory finger toward the center of the giant dodecahedron in which toiled one-half of Rex Riptide. "Now what can I do? I can tighten bolts! No air got in, Rex! No air got in!" She ran to a porthole. She put her hands against the glass.

"Ten seconds!" shouted Dr. Polski.

Rex stood up. He kicked over the terminal and strode as far as he could toward the porthole. "Oh, God" Gil breathed. Rex reached his arms toward the glass, toward his assistant. A big, white smile emerged from underneath eyes that could not hide their sorrow, and for a moment such comfort emanated from him, such trustworthiness, such friendship. Then the feeling abruptly ended as the scene inside turned from dark to black, and Rex turned from Rex into flash-paper.

Half of the atoms composing him were stripped away, and the remaining reactive shreds of stable molecules recombined to lower their potential energy. In short, he burned. Though he was in a high vacuum, he burned. Instantly and brightly, he burned.

After the sudden flash of her immolated friend washed over her, his assistant fell to her knees.

***

Rex awoke, his eyes opening on an alien sky.

No wait, that's not right...

Rex awoke, his eyes opening to the view of his friends, looking down at him.

No, that's not quite it, either.

Let's back up a bit. "So this is your experimental solution? A back-up?"

That's right," said Dr. Polski, "If anything fails during your transfer between worlds, I at least want a chance of getting you back." He looked at Rex. "You're not stupid. We need as many people like that as we can get."

"Ok. I've gone over the design of this device, and as long as you keep the data received in the manner I specified in my memo, I'm happy to undergo the procedure."

"I still don't know why you want the data so carefully held. It's not like copies of you, or slightly tweaked – no, improved – versions, would be a bad thing. You're being uncharacteristically squeamish about this."

"I've been kind of busy with the vacuum chamber recently, and haven't had a chance to work through the implications of this sort of procedure. Plus, this is one of the things !N was working on, as you'll recall. I don't want to take any chances."

The Doctor sighed. "Ok. If that's how you want it done, that's how I'll do it. Lie down on the bench, and I'll position my scanner."

Rex lay down on Polski's lab bench as the latter wheeled a large, hollow, half-cylindrical metal scanning device over him. "Here goes", said the Doctor. There was a flash of light, and suddenly Rex was lying instead in the Atomic Girl's intensive care bed. His roommates, plus the journalist from the Summit – Gil Eggars, was that his name? – were standing above him, peering down in a nervous manner.

"Don't be frightened, Rex. I imagine you're pretty surprised right now. I have some explaining to do..." said Dr. Polski in as calming a tone as he could muster.

"I'm not frightened. Obviously something went wrong with the transfer and you restored me from backup. I'm impressed that it worked, Doctor. What have I missed?"

Rex took the next 0.5 seconds to assimilate the new memeplex: Some time ago, he had gotten up from the bench, alive and well, and in the course of his life he had died. His friends had then turned to Dr. Polski's backup to get him back. Now his main concern was the following: had enough time passed for him to be considered a different person, a Rex 2.0? It seemed obvious that the shorter the interval between backup and restoration, the more similar the backup would be to the "recent" model. Indeed, if the events were simultaneous they would be identical. But the longer the time separating the events, the less the backup of Rex would resemble the Rex that died. His job was now to ascertain exactly how much had changed in the outside world while he'd been dead, and in so doing to approximate how much he had changed before dying.

But there was more: presumably Rex was the only person to have ever been restored from backup. This meant that he was setting an important precedent. How he acted now would affect the identity of not only backups of anyone in the future, but also copies and alterations. Were they the same person, entitled to the same interpersonal relations and property as their originals? Or were they different people, whose contracts and possessions were no longer connected to them?

Before actually experiencing the dilemma, Rex would have not thought the issue a difficult one. The answer, like so many undergraduate-philosophy-level questions, was simple: "Identity" didn't mean anything concrete because it was the sum of how others related to a person. Presumably there are interpersonal connections for a reason, and those reasons would be identically applicable to the backup/copy/alteration. Furthermore, if someone remembers an event, the person has the effect that the event would have on that person if he/she had actually attended it. Therefore the backup/copy's history is identical to the original for all intents and purposes. It just didn't make sense to ask the question "is he the same person?" when they wouldn't treat him any differently either way.

But now Rex was seeing the holes in this view. 0.4 seconds into his 0.5 second break, he began to notice that the way that one of his friends in particular, his assistant, related to him was much different than he remembered. They were all relieved and somewhat solemn, and had no idea that they were leaking their concern for him like a sieve, but that didn't account for what his assistant was unconsciously broadcasting to him. This spoke of a wide divide in the sides of their relationship, and re-opened the question that he thought he'd answered. Had it been he who had spent time with her (probably seduced her, by the way she looked at him)? Or was it another Rex, a Rex 1.0 for whose actions he shouldn't be held accountable? If he did want to maintain his former view, should he go along with her view of their relationship, or should he insist on reverting to the old version? Wasn't the latter admitting that he was a different person?

Rex now had 0.05 seconds budgeted before he was going to interact. In that time he crunched the numbers and implemented his new schema. To say that it combined weighted portions of all of the views above would be a drastic oversimplification. The reader will be able to construct models of the result by analyzing Rex's actions.

Dr. Polski spoke: "We lost anchor at approx 0.5 otherworldly. You didn't make it."

"Lost anchor? Then !N, he didn't...?" Rex queried. Polski shook his head. In some ways, Rex was relieved. Much more profoundly, though, he felt one outstanding hope torn from him. It was a net loss. "What date is it? I'm not getting exocortical readings yet; how long was I out?"

This went on for some time, the Atomic Girl, NASA Lass, and Dr. Polski filling in Rex on the time since his backup. He'd missed a lot, and was excited by their descriptions of his own research. So much he'd be able to re-discover! But there was an elephant in the room. None of them made eye contact with his assistant. This was more than a romantic involvement would justify. Something was different about her.

He confronted it. To his assistant he said, "They're uncomfortable around you. It's been a while since... Is your conditioning wearing off? Are you working in the machine shop now?" He was careful not to put emotion into the words. He neither condoned nor condemned it, hedging his bets.

She'd been standing, tense, a step back from the intensive care bed. She'd been intent on his face for most of the conversation. Now her manner softened. She took a step forward and collapsed onto him, her arms enveloping him. "It's really you," she whispered, "you're really back!" Then louder, "Yes, I work in the machine shop. I tightened the bolts on the vacuum chamber. I polished it and brushed it until it shined. And I worked on many of the experimental apparatus that you designed, after the backup." Now she took on an accusatory tone. "And these three have been against it. They all remember things that I'm supposed to have done years ago, they blame me for destruction I don't even know about. They'd rather I just help with the filing, answer the phones, feel empty inside! Only you could look past the misery I didn't cause, only you approved of putting the regained talent to good use!" She collapsed one more time, apparently overcome with emotion. Rex wished he had some tissues to give to her. Using the mental model he'd built up of her to comfort her wouldn't work, as she'd obviously changed so much, and the general-purpose 'comfort' stimulus seemed cheap in a situation like this.

He said "there, there" and touched her shoulder tentatively. It seemed to help.

The only thing that needed to be resolved now was why the reporter, Gil Eggars, was there. Rex looked at him quizzically, but he didn't pick up on it. It didn't seem likely that he'd worked through the implications of this being a back-up Rex, and at the first opportunity would try to relate to Rex in a way that wouldn't be reciprocated. This had to be dealt with now, with a minimum of feelings hurt.

"So why are you here, Gil? Don't you have a story to chase down?"

"I haven't been reassigned from the Summit case. I guess Head Office is still reeling from the unofficial version I put on the Internet. Doubt I'll be fired, though. That was sensational news." Gil added an afterthought, as if he was still having trouble understanding Rex's situation: "I've been living in your house, in your vacated room." He looked uncomfortable after that.

That got Rex up-to-speed on all time-sensitive matters, and so he immediately began to query the Atomic Girl as to when he could get up and start experimentation. The next morning found him in his basement lab, taking the dust-jackets off of pieces of equipment that he had no memories of making, yet which obviously came from his hands.

He got to work. He went to classes after a long absence. He fought crime downtown. He ducked classified federal interest in himself, renewed after Gil's version of the Summit got out. He took down a couple of monsters. He shook off a couple of ninja assaults.

***

One night he and his roommates fought off a particularly nasty attempt to take over the City by ex-Soviet warriors who had gussied up their tech to impersonate alien invaders. They'd gone with the classic: Rex and Dr. Polski dealt with the delicate matters, NASA Lass ran support, and the Atomic Girl burned the hell out of everything that wasn't necessary. The assistant and Gil watched from the sidelines, aiding the Lass when they got the chance.

When they'd all gone back to the house, they had a quick dinner and went to bed as soon as possible. They needed all of the sleep they could get for a test tomorrow. Rex and his assistant parted last.

"Well, good night. I'll see you tomorrow."

"Good night, Rex."

Rex went into his room and closed the door. He heard his assistant do likewise. Rex didn't have much of a subconscious, but something was definitely bothering him. He just couldn't put his finger on it. It was like those few seconds before you realize that this is what a thousand ninjas looks like.

Suddenly a very fast attack came out of nowhere. It was much like a ninja assault, a black-clothed figure taking a rectilinear trajectory that intersected with his own in order to expend its kinetic energy into his vital organs. Rex didn't have time to feel annoyed or bored by the assault; it was all he could do to slow his perceptions enough to counter the attack. He grabbed the leg that his assailant had outstretched for a kick, and twisted the black figure around it, putting its torso, and presumably most of its destructive potential, out of harm's way.

Huh. That was odd. The blow got him anyway. The new direction of his momentum was toward the street-facing wall, and there was a real danger of crashing into a wall, which would cause him severe physiological damage. Instead, he pushed on the window-frame to guide himself through the glass. The pane shattered instantly to any outside observer, but to Rex it bowed and flexed before finally cracking and shattering. The time-slowed night air gripped at his clothes and slowed him as he took stock.

No ninja could have moved as this being did, back there. Sure, they had become faster recently, as much as "stronger" translated to "faster", but his attacker had reacted faster than he'd ever seen a ninja do. If he was honest with himself, and he always was, it had reacted faster than himself. Rex was concerned. He didn't know enough of this thing to work up a battle plan or assess its probability of success. He needed to know more, to fight it more.

When he fell to the street below, there was a significant portion of his velocity that was parallel to the ground. This necessitated frictional slowing, which took time. As the rubber of his shoes scraped against the asphalt of the street, the shadowy black figure leapt from the vacated window frame and alighted on a brilliant street lamp. "Alighted" was a subjective term, as the impact was enough to bend the lamp post 30 degrees from its original configuration. The sound of wrenching metal eventually reached Rex's ears when he came to a stop.

He'd let it come to him. He wasn't in a hurry. Apparently it was, however, and it's jump downward toward him tore the street light from the ground. The metal pole that housed the light flew in a long, graceful arc before falling in two units onto someone's expensive car. Long before it did so, however, Rex was engaged in a mode of combat that he never allowed ninjas to get close enough to do: grappling. The being had been fast enough to grab his hand before it was upon him. Fortunately Rex could sidestep (side and up, as motion purely parallel to one's frictional surface is impossible in a time-slowed fight) in time, but he wasn't fast enough to dodge a punch coming from the being's human-like fist. He had to deflect it. But before he could recover from the block, his enemy had circled his fist around once more to attack. Moving at that speed, even something as relatively massless as a human fist could have serious destructive power.

Rex knew that this day could come his whole life. Reaction time is a spectrum, and just because he had never before faced an opponent faster than he was, he wasn't necessarily the logical fastest one could be. This fight exemplified that. This was why Rex carried his defensive tools with him.

The IR laser came out. It didn't need to come far, just out of it's belt-holster and pointed toward the enemy. There was obviously nothing it could do... Rex thought the latter too soon. His enemy was... prepared for this? No, that's can't be right. But improbable as it seemed, the fist that was going to be a punch was instantly converted into a down-slap that caused Rex to drop his device. The feather-light laser cracked the asphalt beneath them when it struck. But even though it didn't turn out to be the trump-card he needed, Rex was able to use this opportunity to attack. The hand that was still on it's super-fast course after Rex blocked the first punch suddenly slowed to the extent that the elbow, which was pointed toward the assailant, could jut out suddenly. This by itself was not enough to make contact, but at the same time Rex began to pull his other hand, the hand held by his enemy, toward him. No being on Earth had the reaction time to let go in time to avoid an elbow to the face.

No being, apparently, except this one. It dropped Rex's hand before he'd moved it even 0.10 meters. The frictional moment Rex had exerted on the ground in order to push one arm forward and one arm back now worked against him. Without the added load of his attacker, his feet came off the ground as he twisted, removing the retreat option of a Newtonian fight, pushing directly against one's surface to flee perpendicular to it. This was, in a word, bad.

The opposition's arm was now freed of holding Rex's. It formed a point of fingers and savagely streaked toward his soft-tissue. Rex had no time to work through even half of the maneuvers he wanted to compute. He simply wasn't fast enough at simulating the effects of his actions. He had to go with the one that had the highest projected success rate even when he expected to find another, had he only milliseconds more to think. His hand grabbed for another of his weapons. Instantly, the attacker's fingers again went for it rather than his vulnerable kidneys, and slapped it down, away from Rex. This time, though, Rex was able to push off of a surface in the time granted to him: the assailant's chest.

They flew away from each other, the adversary hitting the ground first. Rex came to a stop far away, panting to reduce the heat-rejection stress on his system. Interestingly, the adversary seemed to do the same, or perhaps more so. Now Rex had time to calculate more paths. He'd seen the thing in action and come to an estimate on its effective reaction times and strength. The situation wasn't hopeless, it just produced unacceptably high probability of defeat. He now had time to muse upon the identity of this rival.

It moved much like a ninja, yet didn't fight like one. Ninjas weighted their combat options in a different manner than this one. It also wasn't wearing black from head to toe, just black pants and short-sleeved shirt. The night was too dark to say anything about the face except that it was either human or a good facsimile. That took it beyond his experience. Nothing but a ninja fought with even comparable speed to Rex, so there were no other contenders. But something about the way it moved was familiar. He'd seen it before. Sadly, memory retrieval was a relatively time-intensive task during a fight, and since it wasn't in a short-term storage in Rex's head, he couldn't realistically expect to get the answer within a usable time-frame.

Then, just as the adversary destructively launched itself from the surface where it perched, it hit Rex: the other universe had a backup unit, didn't it? He definitely remembered seeing preliminary plans for a nanotech-derived unit based on Dr. Polski's plans here. Had it gone into effect when his non-backed-up copy had made his attempt to hop universes?

Well, this explained a lot. It explained the adversary's appearance, style of fighting, speed... hell, it even explained its choice of dress. Rex looked down at himself. He was wearing black pants and a black short-sleeved shirt. The adversary was another backup, taken from the time when Rex was actually in the vacuum chamber. He'd been restored from backup on the other side. But how had he come back at such short notice? He didn't wait seven years. And how had he solved the anchoring problem? And why was he so fast?

This was truly Rex 2.0, the later model. Rex 1.0 was momentarily taken aback. How could he be expected to fight himself? He hadn't even totally assimilated his view of himself yet, let alone the existence of another version.

In milliseconds, the question was rendered unimportant by the drive for self-preservation. But that was odd. The trajectory Rex 2.0 was on wouldn't intersect with our original hero's. It was off by several degrees. Then, when the adversary had gotten to his closest point to Rex, he changed direction. Rex 1.0 was dumbfounded. This was not something for which he could have planned, nor would he if he'd had the time. The very idea was ridiculous. Absurd. Rex 2.0 hadn't pushed off of anything, he'd just... pushed. Empty air was his surface. It wasn't possible.

The real issue was what Rex 1.0 would do about it. He was rapidly running out of defensive apparatus, and they didn't even confer much of an advantage as his opponent knew enough not to let him use them. Plus, he didn't really want to fight, anyway. He wanted to communicate.

This combat iteration pushed the thought from his head. He was wide-open. He watched Rex 2.0 arc toward him. He willed his arms, which had been in his ready-position but not ready for this, together in a block. It was going to be a close race. His arms had to start from rest, and the adversary was already moving toward him at high velocity. But his arms were smaller in mass and therefore quicker to respond, and had a shorter distance to go. In an interaction that had to have taken thousandths of a second, that would have been imperceptible to any other being on the planet, Rex finally got a block ready in time to transfer the destructive kinetic energy from his otherworldly counterpart using his skeleton, rather than his vital fleshy parts. In exactly the maneuver he'd inflicted on so many of the single-combat-optimized recent ninjas, Rex was crushed, squeezed between the brittle street and his slowly compressing adversary. Clever applications of skeletal muscle pressure kept his bones from snapping like twigs. They still bowed and flexed to an alarming degree for something so rigid.

Rex was glad alter-Rex had to alter his course a full 90 degrees to come at him, even though it was impossible to do so. Though he had nothing off of which to bounce, bounce is what he did, and in doing so he wasted much of his kinetic energy. Had he tried this crushing technique at-speed, our original Rex would have been pulverized.

Without assessing his own damage, which must have been extensive at this point, Rex shot out from under alter-Rex as soon as the pressure let up. He thought hard. This was not working. What could he do that Rex 2.0 couldn't? He still didn't even fully understand how Rex 2.0 could stand before him, much less outperform him or change direction in midair. There was something very wrong about Rex's basic assumptions, here. What was he missing?

Start with the first impossibility: He had changed trajectory by exerting a force that had no equal and opposite reaction. This is impossible, therefore it didn't happen. But sadly, no help there. Now the second impossibility: A being identical to Rex outperformed Rex. This was an impossibility because Rex has already taken his ability to fight to its logical limit. Therefore it did not happen. But how could this be the case? Was the being not identical to Rex in some way? Rex couldn't immediately see an advantage in this thought. Last impossibility: That this Rex 2.0 was in our universe. It was impossible, therefore it wasn't happening.

Rex let in a rush of air. Therein lay the answer. Rex 2.0 wasn't here, he was there. Rex had awoken to the view of an alien sky, discovered that he was free on an alien planet a full seven years ahead of schedule, realized his goal of exploring his new domain completely cut off from the world that spawned him, failed to create the little paradise he'd envisioned, spent weeks working on the anchor problem, apparently improved the anchor solution to the extent that his effective range on Planet Earth was at least several hundred meters (the range of the fight so far), took precautions to keep from getting "infected" with Earth-particles, and made his return, only to find that another Rex was in his place.

Now Rex was the most sane, stable individual anyone could know, but the last few months had not been kind to him, and on top of this he'd spent several weeks more isolated than any human had ever been before. Rex 2.0 had not reached the conclusion about backups and copies that Rex 1.0 had. To him, it was justified to kill Rex 1.0 and assume/resume his life.

This explained the sudden ferocity with which he attacked, the foreshortened return to our universe, and the other impossible aspects. The equal and opposite reaction to the change in direction was on an object in the other universe. Rex would have to watch out for that. Rex 2.0 could use scenery to move around not only from this world, but from his also. But the extra speed? Rex recalled a slight issue with the transfer. He only remembered the preliminary phase of planning, but the conversation had to do with that the temperature would seem too high when he first entered, then seem to cool down over time. The cause was going to be the lower gravitational potential of the planet on the other world. Its general-relativistic effect would make time seem to go by slower there. As more of Rex's particles were to be transferred to the new universe, more of him would interact at the faster rate, and the particles of the surrounding air would seem slower and therefore cooler. Obviously this is what happened, with the added bonus of a speed boost. It was a great advantage! Rex couldn't believe that wasn't in his list of motivations behind the trip.

Now, how could he use this information to his advantage? What vulnerabilities did this expose? Rex had to think quickly as the adversary again leapt toward him, either from the ground or just above it, from his eka-ground. He couldn't do anything interesting gravitationally, as gravity did not transfer planes of space when close as electrostatic interactions did. Could he do anything with the anchor? No, that process wasn't understood well by any current members of his group, and alter-Rex had obviously made modifications in order to have such a free range here on Earth.

Suddenly the optimal use of his processing time became determining what the adversary could do to him, rather than what he could do to the adversary. Rex 2.0 was mid-leap again, and coming right for Rex 1.0. Rex decided to use another one of his valuable and dwindling supply of defensive devices. Not for its intended purpose, as he knew from experience that Rex 2.0 had the motives and means to stop this from happening, but as a game piece. When the other Rex took the time to remove the technological threat, our original Rex had extra time to implement his own plans.

Out came the weapon, a cutting tool this time. Down came the otherworldly hand of the adversary, to impact and remove the device from Rex's own hand. But the process had made alter-Rex use up the opportunity he had for turning the jump into a win. Rex had time to make his escape once more.

But Rex knew that escaping was not going to win this fight. He needed the upper hand for either his optimal scenario (getting Rex 2.0 to talk) or his failure mode (eviscerating Rex 2.0). That meant he needed some advantage. An advantage, in Rex's experience, could only be conferred by observation and calculation.

Briefly, both Rexes stood once again on the pavement, surrounded by the various craters and cracks in the rigid material that their battle had created. Briefly, they were both stationary except for the panting that racked them. Oxygen was not the issue, and the adversary would certainly not be breathing this world's oxygen, anyway. The issue was heat. They had both expended a tremendous amount of energy in the course of their fight, and the large portion of that energy that eventually found its way to being waste heat in one or the other's body had not had time to be bled off into the surrounding air. Waste heat retention was the bane of Rex's existence. It was his kryptonite. During the summer months, when convective heat loss was at its minimum, Rex felt sluggish. He couldn't fight as hard. Repelling ninjas was that much more of an effort.

Which, now that he thought of it, was "it". His "eureka" moment after the two realizations that 1) his enemy was himself and 2) his enemy was himself in another dimension. The realization was that Rex 2.0 had just as much heat to dissipate as Rex 1.0, but – drum roll – was under two atmospheres, Earth's and his own world's. Normally if there existed someone under two atmospheres (a phrase that is never likely to be repeated outside of the word's SI meaning), the average heat transferred to him from the gas would be simply double, from double the number of particle collisions, which would effectively sum the absolute temperatures of the atmospheres. Normally the rate of heat transfer from himself to the air would also double, canceling the effect, but Rex 2.0's precautions against contamination apparently lessened this transfer. That would put Rex 2.0 in a gas that was effectively at 600K.

This was obviously not the case, as Rex 2.0 was alive. Rex 1.0 already knew that his alter-ego had some means of dealing with Earth-universe-gas-particle contamination so as to not breathe in any of our oxygen, but apparently this was insufficient to prevent our atmosphere from heating him. The adversary was panting harder than Rex, but still not removing all the heat that was necessary. Now Rex thought back, his enemy had indeed fought to minimize waste heat. There were any number of things the enemy could have done to turn the tides by now, but his fighting style was handicapped by this limitation. Now all Rex had to do was fight in a manner that forced Rex 2.0 to produce more waste heat than he could reject.

Rex could do this. It was one of the scenarios for which he'd prepared template combat calculations. It did not take long to implement them. In the ensuing combat iterations, it was clear that Rex was turning the tide. Rex 2.0 was getting closer and closer to Rex 1.0, exactly as the latter intended, but had to expend more and more effort, and therefore create more and more heat, to do so. Soon alter-Rex broke off the combat briefly. Twelve seconds from crashing out of his bedroom window, Rex found himself face-to-face with himself.

"I know what you're doing." Said this unearthly facsimile.

"Then you should know it's non-lethal. Now I've proven that I can best you, we should talk. I'm not the enemy. I'm you. That's as far on the 'ally' end of the spectrum as it's possible to get."

"You're not an ally. You're not even human. You have no value in any objective value system."

Rex 1.0 was afraid of this. It seemed his later version had chosen the exact most dangerous philosophy to implement. Rex himself had accounted for the bias that necessarily arose from being a copy himself, but the Rex that spent weeks on end as far removed from the rest of humanity that any human being is ever likely to get did not. He assigned a falsely high utility to his old life, his old possessions, his interpersonal relations he'd left behind. And the memeplex that allowed him to justifiably take them back was the one he'd implemented.

"You know as well as I do that we're both exceptionally smart people. The optimal route is to discuss this. Communication is the key."

A smile sidled onto the extra-dimensional copy's face. "You're right. I have at my disposal a very valuable resource: another viewpoint, untouched by my own bias. This is a valuable opportunity. There's so much we can learn from each other." His face and voice conveyed his sincerity. He radiated trustworthiness.

"I'm sorry, Rex" said Rex, "but I know that trick. In fact, I know you're humoring me for the sole purpose of expelling all the heat you can, then coming at me again." Rex shook his head. "Well, you've seen what I can do, I've seen what you can do. And presumably you've also come to the conclusion that 6.0 seconds from now you'll have rejected enough heat that your probability of success is 50%. I'm sorry, but I can't wait that long." 3.0 seconds after his time-mark, Rex 1.0 flew at Rex 2.0, but not too late to hear one more remark:

"You're underestimating my time dilation factor, you abomination of a copy. This is my 50% mark."

***

There came a knocking on Rex's door. He opened it.

"What is it?"

His assistant stood outside. "What is going on in there? I heard a crash, and I've been pounding on your door for a whole 30 seconds! And yes, I timed it."

Rex poked his head out. "Nothing's wrong. I'm fine. I just slipped." He gathered himself. "But now that I have your attention, I think we need to resolve an issue that eventually killed me. We all need to sit down and talk about !N." Before calling everyone down to the living room for a meeting, he smiled and spoke once more to his assistant. "I wrote a poem for you. Would you like to hear it?"