//------------------------------// // 11. Constructive Interference // Story: Imperatives // by Sharp Quill //------------------------------// Celestia had just raised the sun; she still insisted on doing that every now and then. The palace gardens were not yet open to the public. Meg followed the paths, devoid of ponies and humans, heading toward an aging statue of a pegasus in flight. Once it was in her sights, its purplish color caught her off guard. A pair of eyes formed and gazed back at her. “Hey, Smooze. Scrubbing it clean?” It had been too long since Fluttershy had had a talk with the local pigeons. His mouth appeared, though of course it remained frozen in a vague smile. “Susie’s statue doesn’t get the attention it deserves from the staff.” “Can’t fault them too much, you know. She’s before their time.” Meg had little doubt it’d look as good as new once Smooze was done. The standard statue preservation spell guaranteed that. “Just got back from the past, back around the time I created that first speech synthesizer for you.” She threw him a mischievous smile. “Remember that?” “I’d rather not.” She couldn’t blame him. “Well, Discord had his reasons.” “I know; it’s why I forgave him. But seeing your reaction when you finally found out who that mysterious ancient alicorn was almost made it worthwhile.” “Hah! At least you could see my reaction. You were just as shocked. We all were.” “With one exception: Discord.” Yes, Discord. “He got a sneak peek, you could say.” As did I. But the draconequus possessed senses Meg did not. And speaking of Discord… It was long past time for an intervention. She would discuss it with Twilight when she saw her that afternoon. Meg endlessly walked around in circles, perfectly matching the course her thoughts took. Chaos as a concept was easy to throw around, but as the basis for concrete action? Not so much, not if the point was to achieve specific goals—at least if one was not a draconequus. There was only one goal: take down Routledge. So what chaotic action could she take during her televised appearance in front of the Senate Judiciary Committee hearing? She wasn’t a Spirit of Chaos; her only tools were words. Well, sure, maybe she could try using weather magic—no, that was just stupid. Even if she could make it rain or something—questionable given that she’d be on a leash, so no flying—it would only play into his hands, boosting him not tearing him down. Words it would have to be, but what words? Mere utterance of facts and reason would get her nowhere, she already understood that, and anyway that was by definition the opposite of chaos. But lies and nonsense were also non-starters. Perhaps they were a form of chaos, but chaos of a primitive and unsophisticated form. Discord could not have meant that. Right? Didn’t matter; lies and nonsense would not be more effective than facts and reason, not once the talking heads on the news channels were through with her. There was a knock at the front door. She was getting nowhere anyway; going in circles tended to do that. Answering the door would be a welcome distraction. So answer it she did. Opening the door revealed Twilight, who was carrying a large box in her magic. “Can I come in?” the alicorn asked. “I’ve got your dress—and there’s something I’d like to talk about.” Meg eyed the box, then returned her gaze to Twilight. It seemed to be important, whatever it was. “Sure.” She stepped aside. “What’s on your mind?” Twilight entered and set the box down out of the way. “It’s about what your future self told you concerning the Element Bearers going human. That we could prove it would be safe for the Elements, by creating a time loop that’d be paradoxical if it wasn’t safe.” Meg realized they’d let that slip through the cracks. “Why now?” Twilight summarized what had happened at the anomaly. “So I figured this was a good time to explore the option of going human.” “Creating a paradox,” Meg said. Just the distraction she needed. She resumed her circular path. “A paradox that would only occur if the Elements were harmed.” The pegasus trudged around the circle. “Nothing’s coming to me. I mean, we know it has to involve a time loop, and in this loop you have to go human, and… I dunno. Go back to being a pony, I suppose, and check on your Element, and if it was harmed… then what?” “Go back in time and tell myself not to transform? But then I won’t, so I wouldn’t know my Element was harmed, so I wouldn’t go back in time, but the past is immutable, so I did, which meant the Element was harmed. Maybe the answer is that the time travel spell fails; that eliminates the paradox, but the Element is still harmed, so that’s no good.” Meg completed another circle. “We need a time loop where your transformation takes place only if the time travel spell succeeds, and it succeeds only if your Element is okay after the transformation.” Twilight tilted her head. “But how do we do that?” Meg ran through the conversation she’d had with her future self. It was all about reality itself being a quantum supercomputer. They just needed to run the correct “program,” a program that would answer the question, Does a bearer transforming into a human harm the bearer’s Element? How do they come up with such a program? She froze. Maybe they were looking at it from the wrong angle. “We don’t have to. Our future selves will tell us how.” “I don’t get it.” Meg approached her. “A time loop serves as a program running on the quantum supercomputer that is reality itself. Have the time loop compute not only whether the transformation is safe for the Elements, have it also compute how to figure out whether it is safe! If the time loop can be created, then it is safe.” Twilight tilted her head in the other direction. “I still don’t get it. We still have to figure out how; we will become our future selves.” Meg smiled. “No, we won’t, because our future selves will tell us how to do it.” “So… you mean we will go back in time to tell our past selves what we were told by our future selves.” Twilight closed her eyes in thought. “Then where does the knowledge come from?” “Well, technically, from the wave function collapse. The wave function, over time, forms a superposition of every possible outcome, some more probable than others. The time loop causes any paradoxical outcome, through destructive interference of the wave function with itself, to have zero probability of occurrence. If there is a way to figure out whether you going human is safe for your Element, that outcome has a non-zero probability and will be selected. If there isn’t, the time loop is paradoxical by design and the time travel spell fails. “There could be multiple ways of figuring it out, each with a non-zero probability. Which one is selected by the wave function collapse is unknowable and random, but we don’t really care which one is selected, just that there is one.” Now it was Twilight’s turn to walk in circles. While the alicorn was lost in thought doing that, Meg wondered whether this could be used to solve her “chaos” problem. But she quickly decided no; there was no apparent way to create a paradoxical situation from the lack of a chaotic solution—or the lack of a way of figuring out a chaotic solution. What even constituted a “solution?” The problem lacked proper definition. Twilight stopped and looked at Meg. “I’ve got it. First, we specify a time and place for our future selves to visit us. If they are a no-show, we can assume my going human will harm my Element. But say they show up. They somehow convince us it is safe, tell us what to do to prove it, and we shall do it. The key is—and we have no idea how they’ll do it—the key is that they’ll have to convince us, that there is no possibility of our future selves, I dunno, actually being changelings in disguise on a mission to trick us into destroying the Elements.” Meg spent a moment trying to poke a hole in that plan. “Sounds reasonable, I guess, but a no-show only means we don’t know it’s safe, not that we know it’s not safe. A time travel spell could fail for any number of reasons.” “In that case we try again, with a new place and time. If we keep getting no-shows, the odds build that it truly is not safe.” “Fair enough. So how much of a hurry are you in? I mean, we could do it right here, right now, but, to be honest, I’m not really in the mood for it.” Meg turned away. “I’ve got too many other things on my mind right now.” “Do you have to be present?” That… was a good question. “I suppose I don’t have to, strictly speaking. I’m not an Element Bearer.” “Do you want to?” “I…” Meg exhaled. “Let me sleep on it, but don’t let me hold you up beyond that.” Luna had just raised the moon, and Sugarcube Corner glowed in the moonlight. Twilight went inside and found Mrs. Cake behind the counter. “Is Pinkie around?” The place was busy, she noticed; perhaps it was best she didn’t talk to her here. “She’s in the kitchen, Twilight.” After studying her face, she added, “Is everything all right?” “What? No. I mean, yes: everything’s fine!” A few heads were turned their way. “Kitchen’s that way, Dearie.” Yeah, I know. She took the hint and got moving. Once she got there, she found Pinkie was busy cleaning pots and pans and other stuff. She did not pause her work upon noticing her. “Oh, hi, Twilight! What’s up?” It was best to just get it out of the way. “Pinkie, uh, by any chance has your Pinkie Sense been going off recently?” The pink pony put a stack of clean dishes away, then she put a hoof to muzzle. “Weeelll, now that you mention it, I did have a right ear twitch followed by an itch on my back-left frog.” Not what she was expecting. “What does that mean?” Pinkie perked up. “That somepony would ask if my Pinkie Sense has been going off recently! And somepony did. You!” Now she was starting to feel foolish. “And that’s it?” After all, she knew nothing bad would happen—yet did she know Meg’s future self was being completely honest? But what was the point in being dishonest about her ability to prove that the transformation would be harmless to her Element? Either she could prove it or she couldn’t. “Were you expecting a left ear twitch followed by an itch on my back-right frog?” Twilight’s face went blank. “Should I?” “I dunno; I can’t read your mind, silly.” “Well, what does a left ear twitch followed by an itch on your back-right frog mean?” “That we’ll be visited by our future selves.” Her face scrunched. “Or is it the other way around? I always get those two mixed up.” Mixed up? “How often do those two occur?” “More often than you’d think.” Yeah, not touching that. “Well, I’m expecting to be visited by my future self in the not too distant future. Does that count?” “Sure does! So it must be that a right ear twitch followed by an itch on my back-left frog means that we’ll be visited by a future self.” “But I did ask whether your Pinkie Sense had been going off recently.” Pinkie shrugged. “Coincidence.” Twilight sighed. “Right. Coincidence.” Pinkie Sense is what it is. She had to accept that. “Thanks, Pinkie.” “Your welcome!” As Twilight departed Sugarcube Corner, she wondered if this confirmation by Pinkie Sense was sufficient. If she was to be visited by her future self, then the time travel spell worked, and if that worked, then it proves the transformation was safe. But if she skipped the visitation as a result, then what was causing Pinkie Sense to fire? Sounded like a paradox. Or would the possibility—no, she wasn’t going down that road again. Pinkie Sense is what it is. That’s final. She would just have to go through with it and avoid any possible paradox. The moon had barely moved while she’d been inside; she had the whole night ahead of her. Being on Greek time was becoming inconvenient. She should take Yearling up on her offer and visit Knossos; afterwards she could go back on Equestrian time. But that was tomorrow. Maybe she should just get the visitation by her future self out of the way now. No, not an option. She had to let Meg sleep on it first. Twilight looked up at the moon again. Perhaps she could keep company with Luna tonight, take advantage of the situation. Meg knocked on the door to the cavern, finally able to catch her breath. Momentarily, the door opened revealing a Royal Guard. “I’ll take you to the intruders,” the guard said. Entering the cavern, she spotted her three human coworkers. “Their word isn’t good enough?” she asked, pointing at them. “With all due respect, ma’am, they have no authority here.” Dianna shrugged. “We just work here, I guess.” Meg sighed; it was too late for this. She first went over to her workstation to drop off her mining helmet, then said, “Take me to them.” The guard started walking and Meg followed. Shortly they arrived at a secure room that had been constructed near the portal for just this purpose. Inside were two humans. “I can confirm the man is my husband and the woman is Sunset Shimmer,” she told the guard. The guard turned to the humans. “Sorry for the inconvenience.” “That’s quite alright,” Sunset said. “You were only doing your job.” “Mind if we borrow your pendant?” Steve asked. “Go ahead.” Meg dipped her head as he removed the pendant from around her neck. “Should I ask why?” Steve squeezed the pendant and resumed his equine form. He levitated it over to Sunset. “Nothing too shocking. They offered us a ride back, it was a chance to discuss what we found out, and we figured that you’d probably be here anyway.” “Yeah, well, on top of my own issues, Twilight paid me a visit and gave me an issue of her own to think about—no, don’t ask. That’s for Twilight to share.” Sunset levitated the pendant back to Meg, returning it to its proper place around her neck. “We, uh, should’ve known better than to assume.” “Well, since I’m here now, you might as well fill me in on what you discovered.” “Let’s join the others first,” Steve said. Meg led the way. “By all means.” Once they had entered the main cavern, Steve began to fill everyone in. “We have some numbers to plug into your simulation, enough to narrow down the search space. It wasn’t easy; that lidar unit was never intended to measure astronomical distances.” A grim smile. “It didn’t like it, kept reporting internal errors, but with a few phone calls we figured out how to get around that.” Astronomical. “So… just how bad is it?” “It takes one point one six three seconds for light to cross the anomaly, or about three hundred and fifty thousand kilometers. It’s increasing by about nineteen kilometers every second—our seconds, don’t forget. The apparent diameter, from the outside, is nearly tripling every twenty-four hours—two point nine three to be exact.” Meg collapsed to her haunches. That was enough to suck out all the air on the planet, no question about it. It was only a matter of when. The amount of air being sucked in would increase by an order of magnitude each and every day. Yay for time dilation. It was the only reason air wasn’t being sucked in even faster. All Equestrian air too? Maybe they’d have to close the portal, to prevent that. Or did they? She had never felt a breeze from the portal; there’s no way the air pressure could be identical on both sides, not every hour of every day. Yet no one has ever mentioned having to pop any ears either. Magic? Focus. “Can you measure the time dilation? That’s an important number for the simulation.” Steve frowned. “Not yet. I’m hoping spectroscopy would give us that answer. The absorption bands are affected by time dilation. But we need a suitable white light source for that. Or maybe stimulate the atoms—somehow, probably with a laser—and observe their emission bands. That might work better. Either way, we need equipment we don’t have—yet.” “What about geodesics?” “We’re working on that too. I’m not sure we can do better than observing where a laser beam comes out correlates to where it went in. Unfortunately, that doesn’t tell us the actual curved path it took inside, only the cumulative effect of all the curvature the beam went through. Maybe we can deduce that if we had enough going-in/coming-out pairings? Sort of like a CAT scan?” “Maybe? I suppose I could see if such an algorithm exists, but aren’t we forgetting something?” Everyone looked at each other. “Like what?” Martin asked. Meg sighed. “Look, getting a good simulation going is nice and all, but how can it help us fix this thing? We know we have to replace the energy extracted via time dilation, and given the amount of mass flowing in every second, it’d make the energy output of an H-bomb look like a firecracker.” Steve laid a hoof on her withers. “Meg, we have to start somewhere. Besides, we don’t know where that energy is going. Maybe only a tiny amount, relatively speaking, is being converted into magic or expansion. Maybe the rest is being stored, somehow, like a compressed spring. We just don’t know. That’s what we need to model.” We just don’t know. That was the problem. Eventually, they would know—right? Not if the world was doomed; then there would be no future. But if there was a future. Well, she had met her future self, right? But for all she knew, all that meant was she had escaped the destruction of the Earth by remaining in Equestria. Her future self had not volunteered any information on this topic. Meg headed to the door. “I’m going to find Twilight.” If Twilight was to have a visitation from her future self, they might as well have her future self delay that trip to the past until she knew the answer. Twilight stood in front of The Mirror. She was tempted to “expect” it as a place in which she’d retain her alicorn form, so that she may probe the magic underlying this realm of pure magic. The problem with that, however, was that query on historical portals. It’s been a few days since anypony had last checked on it. Surely it had finished by now. But if she changed the rules by which that realm operated, it would reset the simulated computer. That had already happened several times. Probing the magic would have to wait a little longer. She went through the mirror, expecting it to remain exactly as it was. And so it was. There was the console where the query had been entered, and Twilight walked over to it on two legs. The monitor was dark; she understood that to mean the screen saver had kicked in—it seemed silly that a simulated screen would need saving, but that was part of the simulation. She gave the mouse a shove, and the screen dutifully came to life. “Great,” she muttered. Instead of a list of past portal openings, there was a dialog box complaining “operation timed out.” “If I didn’t know better,” Twilight said to the empty room, “I’d say somepony didn’t want us to know.” But did she know better? She wasn’t an expert on computers; that was Meg’s area of expertise. Yet she had had plenty of experience using real computers, and she had never encountered such problems with what ought to be a simple query. Why should it take so long? Archivists at the Royal Library were faster than this at retrieving data! On the other hoof, there was that portal Discord had created at the Parthenon. Meg had tried to close it, but couldn’t; she lacked the authority to do so. Could Discord be behind this too? Granted, they had the authority to do the query. Maybe this time he was being subtle about it? One cannot expect consistency from Discord. Which, of course, raised the question as to why he would want to keep them ignorant of the details, when they already knew he had done it. Twilight sighed. She would bring it to Meg’s attention the next time she saw her. Returning through the mirror back into Equestria, she set out for the throne room, that being the most likely place to find Princess Luna in the early evening. The stroll through the palace was placid enough; not many were around this late to bow to her as she passed. It was kind of refreshing, actually. Could she even get away without her regalia? Best not; her mentor would not approve. How would Luna feel about it? She didn’t know. But then, Luna was no less likely to be seen in public without her regalia than her elder sister. Soon enough the foyer to the throne room came into view. The doors were closed, and Luna’s staff were on the wrong side of it. That probably meant a private audience was taking place. Technically, it was within her rights to intrude, but what was the hurry? A unicorn approached her and bowed. “Princess,” she began. “Your presence would be welcome.” She held a hoof out to the throne room doors. That was unexpected. Luna couldn’t have known she was coming; were there ponies out searching for her? She nodded in response and continued on. As she approached the throne room, a pair of Royal Guards opened the doors with their magic—but only enough to let her through. Luna was sitting on her throne, and she smiled as she noted Twilight’s entrance. Only as the doors were closing behind her did Twilight discover who had been granted the private audience. In a raised voice, to cross the distance, Twilight said, “I just came back from the mirror realm, Meg. The query ‘timed out.’” “Timed out? I’m beginning to think something fishy is going on.” “Thoughts of Discord had crossed my mind too.” Meg stood up. “Well… yeah, maybe. But let’s put that aside for now. About your upcoming visit from your future self. I have a suggestion to make, to take advantage of that.” Twilight reached the throne by which Meg was standing, as Luna observed in silence. She briefly wondered what they had been discussing, not that that was any of her business. “What sort of suggestion?” she asked in reply. “We don’t know how to deal with the anomaly—today. But we will in the future, or at least I certainly hope so. So why not have your future self tell us how it was dealt with? Have the ‘program’ solve two problems at once?” Solve two problems at once? Was that feasible? What if the anomaly couldn’t be dealt with? Well, her future self could inform them of that too. But where was the potential paradox? If the time loop occurred regardless of whether it could or could not be dealt with… What if could not became self-fulfilling? Because they were told it could not, they didn’t even try, so it wasn’t. No paradox in that! Twilight shook her head. “I don’t think that’s a good idea. There’s no potential paradox, none that I can see, so we may get an answer we don’t like instead of no answer at all, even if an answer we would like was also possible.” Meg grimaced. “Because it’s random. You’re right. Too dangerous. No way to constrain the set of outcomes to those desired. Forget I mentioned it.” Luna tilted her head. “Could somepony explain it to me?” “If you really want to know,” Twilight said, “I can explain it later. I was planning on keeping you company tonight anyway.” “Truly?” “Side effect of being on Greek time.” “I’d love to hear an explanation of that too.” Meg took a step towards Twilight. “I’ve decided to be present when your future self visits.” She looked around the empty throne room. “I guess we could take care of it right now, if you want.” All six Element Bearers appeared in front of the closed doors to the throne room. “The past looks aaawfully similar to the present,” Pinkie Pie proclaimed. “Except for the extra Twilight Sparkle by the throne,” Rarity said. The new Twilight stamped a hoof. “Girls, please!” She cleared her throat. “Ahem. My past self does wish to take care of it right now.” The first Twilight scowled. “Was it asking too much to let me say it out loud first?” Applejack adjusted her Stetson. “Told ya we ought’ve arrived a minute later.” “That’s not how I remembered it!” complained Future Twilight. Present Twilight stamped her hoof. “Can we just get on with this?”