Introduction: Where do they come from?

"I have called together the greatest minds in Equestria to explore this exciting new frontier of science!" Twilight Sparkle said, rearing up and spreading her wings on 'science'.

Sunburst looked around. Other than himself, there were precisely two ponies in the room.

"Granted, most of them couldn't make it," Twilight said on seeing Sunburst's look.

"Your letter did say you wanted to, quote, 'explore the practical uses for alicorn death,'" Starlight Glimmer, the third pony in the room, said, "That may have scared ponies off."

"It's fine, we have enough to start with," Twilight said dismissively, "Sunset Shimmer said she and the other me would drop by to help after school."

"They're still in school?" Sunburst asked.

"Yes, time works a bit differently there," Twilight said.

"Fascinating! Do you think I could..."

"Sunburst, getting off-topic," Starlight said with a hint of exasperation.

"Oh, right, sorry," he said, adjusting his glasses to hide his sheepish look.

"Right, anyway," Twilight continued, "We are here today to boldly go where nopony... except maybe Luna and Celestia... has gone before!"

"I'm assuming this has something to do with the pile of bodies outside your castle?" Sunburst said. THAT had been quite a shock. Thankfully, Pinkie Pie had set up an information/cake stand nearby to keep the populace from panicing. Though her insistence on adding a new frosting tombstone on the cakes for each corpse was probably running counter to that goal.

"Yes! You see, I recently found out Alicorns 'respawn' when we die," Twilight said, "Here, let me show you..."

"Twilight!" Starlight quickly said, grabbing hold of her friend with magic before she could teleport away, "I don't think that's necessary."

"Yes, I believe you!" Sunburst said urgently.

"Oh, right, sorry, it's just so exciting!" Twilight said, "Let's move on."

She walked over to her chalkboard and flipped it over. A white line of chalk divided the board into to. On the left side was written 'practical uses'. On the other 'rules and limitations. Each side had several entries, written one above the other in clear precise writing.

Under practical uses was written: "organ donation, blood donation, consulting dead ponies, medical cadavers, food source?, teleportation, visiting dead friends, interdimensional travel?", and then an erased attempt at writing something very small in the tiny space left.

Under rules and limitations was written: "Have to die first, takes some time?, corpse decays like a normal body, can only talk to one dead pony at a time?, have to know the destination well to respawn there", and again erased markings of further ideas.

"I take it you need a bigger chalkboard," Sunburst observed.
"Always," Twilight said, "But for now... Spike! Bring in the scrolls please!"

Spike walked into the lab, carrying a large pile of scrolls. He handed one to Starlight, one to Sunburst, then looked around.

"Just put the rest behind the chalkboard," Twilight said. She smiled sheepishly. "I was expecting more ponies."

"Any idea how long this will take?" Spike asked as he carefully set down the scrolls, "I'm supposed to help Rarity hunt for gems later."

"Oh, don't let us disrupt your schedule," Twilight said, "We can manage for a few hours on our own. Just make sure you're home in time for dinner."

"Right." Spike paused, looking at the board. "Um, it's not going to be pony meat, is it?"

"Don't be silly, Spike, ponies rarely eat meat," Twilight said, "That's strictly for emergencies or for trade to other species."

"O...kay...." Spike said uncertainly. He glanced to Starlight and Sunburst for support. Sunburst pushed his glassed up with a shrug. Starlight rolled her eyes.

Sunburst looked down at the scroll he'd been handed. It was divided by a line, like the board, but had additional entries as he unrolled it.

Practical uses: "Intimidating villains, pranking friends" (that one was crossed out), "quick escapes, healing injuries."

Rules: "New body in perfect health but hunger, fatigue, etc. remain; Cannot contact living ponies while in afterlife; Celestia doesn't like the term 'respawn'."

Sunburst was uncertain what that last entry was about. Below these was a new category: Unanswered questions.

"Can I respawn in another dimension? (wait until Sunset is told to test this), How much time does it actually take? Can I talk to a group of ponies that are all dead at the same time? (I have not been able to, but is this just unfamiliarity?) What is the afterlife actually like? (I keep forgetting to ask!) Are there dead ponies that can't be contacted? Can contact environment be made something more familiar and comfortable? (Again, I can't seem to do so, but could I with practice?) What happens if I starve to death? (Not sure I want to try it!) What level of injury is actually required to trigger? (I don't think I want to lie in agony for hours!) What happens if there are no available places to respawn? What happens if the universe ends? Can I just stay dead if I want, or do I eventually HAVE to come back? (I'm not suicidal, just curious! Please don't worry!) What happened to any alicorns that predate Luna and Celestia?"

"This is... something," Sunburst said once he had read the whole thing.

"Now you know what I've been dealing with for the past two days," Starlight said in a snarky aside to Sunburst.

"Now, of course I want to get to resolving all those questions," Twilight said, ignoring Starlight's comments, "But first, is there anything I'm missing? I have a sliiight tendency to go overboard and I want to be sure I'm not overlooking something important."

"Slight?" Starlight said.

"Where does the matter come from?" Sunburst asked before Twilight could react to Starlight's sass. Twilight looked startled.

"Huh, I don't know," she said, "I mean if the corpses dissolved back in to magic we could just say it was recycled, but they don't..."

"And as everypony knows, while you can exchange mass and energy at a rate determined by E equals m-c-squared plus h-k-cubed*, you still can't create mass-energy from nothing," Sunburst added.

Twilight paced back and forth, her wings rustling restlessly.

"What's the problem, then?" Starlight asked, "It's basically free energy."

"Not if it's taking it from somewhere else," Sunburst explained, "She might be depleting some magic reserve, or the logcal magic field. She may only be able to respawn a limited number of times. Have you noticed it getting harder to come back at all?"

Twilight shook her head as she paced in a circle. Sunburst noted the slight depression in the crystalline floor at that location. Clearly this was a regular habit.

"No, not in the slightest," Twilight said, "I've even timed it a few times, and I'm actually getting back faster."

"What about the local magic field?" Sunburst asked, "Do you have a thaumometer?"

"Of course!" Twilight said with a grin, excited to show off her lab equipment. She trotted eagerly over to one wall. "Here! And the data book is next to it."

"Probably organizing daily readings by pen color," Starlight said teasingly.

"Pfff, whaat? Don't be ridiculous," Twilight replied, waving her hoof dismissively, "Aheh... Obviously they're by date."

Sunburst started flipping through the book. He glanced at the thermometer-like device resting in its stand. "No significant drop right now," he said.

"But she hasn't actually come back here," Starlight said, "Maybe it's highly location dependent?"

"Gotcha!" Twilight said with a grin, spreading her wings and teleporting away before Starlight could react.

"Twilight!" Starlight exclaimed, rather belatedly.

"Where is she...?" Sunburst started to ask. Just then he heard a 'thump' outside. Thinking quickly, he started counting.

"One Celestia... two celestia..."

"Um, what are you doing?" Starlight asked. Sunburst held up a hoof an continued counting.

"Oh, I see, you're timing how long it takes her to get back," Starlight said.

"Seven Celestia..." Sunburst continued counting.

"And now I'm distracting you... I'll just... watch the thaumometer," Starlight said.

Sunburst had gotten up to "Fifty-three Celestia" when Twilight reappeared in a teleport-like flash.

"Well?" she immediately asked.

"A tiny drop," Starlight reported, "But no more than a standard teleport."

"Write it down! Write it down!" Twilight urged. Starlight found the pen anchored to the table the book sat on and scribbled down the reading.

"And the date and time!" Twilight said, grabbing the pen in her eagerness and accidentally pushing Starlight aside.

"You took about fifty-three seconds," Sunburst said, "How long did it seem to you?"

Twilight opened her mouth, then slapped her forehead with her hoof. "I forgot to count! Be right back..."

"Wait! Where's a..." Sunburst began. But Twilight was already gone. "...Stopwatch..." he finished.

"You know, sooner or later she'll run out of places where the bodies won't break her fall" Starlight commented.

Thump!

"...But apparently not yet," she added.

Sunburst began counting again as soon as he heard the muffled sound of the impact. This time, he got to "Fifty-four Celestia" when the flash of light came.

"Fifty-four seconds," he said as Starlight started writing down the numbers, "But I started right at impact this time instead of just after."

"I got..." Twilight took a moment to give a number. She had probably started counting before the impact.

"Twenty...nine seconds?" she said after a moment, "That's from when I hit the ground to when I showed back up here."

"Exact same magic drop as before," Starlight commented, "Same as a standard teleport, and not a thaum more."

"A thaum is actually a pretty big unit**," Sunburst said, pushing up his glasses again. He really needed to get a strap or something. He then noticed Starlight's look. "...And you weren't speaking technically. Sorry."

"So I AM losing time," Twilight said, "That's worrying."

"It's probably just the time it takes between when you break your neck and when your heart registers as stopping," Sunburst said, "The odd thing is it takes longer for the brain to die."

"Right, a few minutes," Starlight said with a nod, "Before that you can use magic to restart a pony's heart and they'll be fine. Unless you're distracted and leave them under for too long, giving them brain damage..."

The other two look at Starlight.

"Not speaking from experience!" Starlight protested, "I know I used to be evil, but I was never THAT evil."

"Hmmm, but maybe breaking my neck does something specific?" Twilight said, "So we'd need a way to stop my heart without damaging anything else..."

"Oh that one's easy, you just need some electrodes and a strong current," Starlight said. Again, those looks.

"Also not something I've done personally! I mean it's basic lightning safety, right?"

"There's a more pressing matter," Sunburst said, holding up a hoof, "We've confirmed it's not taking magic energy from the uhh... respawn point... so is the matter created from nothing, or is it taken from somewhere else?"

"Where would it be taken from?" Twilight asked. Sunburst shook his head.

"I don't have any way of knowing. Another dimension maybe?"

Twilight pondered this. She knew about dimensional travel, and there was one dimensions that she knew had very little magic.

"You don't suppose a magic-free dimension could result, do you?" Twilight asked, her voicing now having a hint of worry.

"I don't think so," Sunburst said, stroking his beard with his hoof, "You'd have to die an absurd number of times for that. But maybe it's taking a body from some other universe?"

"What?!" Twilight interrobanged, "Are you saying I'm killing some other Twilight every time?"

The others were appropriately horrified at the idea, but Starlight soon took on a thoughtful look.

"Wait, if that were the case, and there were infinite universes, wouldn't all Twilights but one ultimately die?" she asked, "I mean infinite Twilights killing infinite OTHER Twilights..."

Twilight (this Twilight) shook her head. "Not necessarily. Infinities are tricky. Even if the set of respawning Twilights has the same cardinality of the set of all Twilights, the respawn funciton itself can be injective without being surjective."***

"Fascinating," Sunburst said.

"Forget about that! Did Twilight kill... however many other versions of herself?" Starlight said.

"Forty-one at last count," Twilight said with a grimace.

"I don't think so," Sunburst said, still absentmindedly stroking his beard, "While I can't be sure of course, it's likely that if that were happening the other Twilight's friends would come looking for her, which would eventually lead them here."

"Unless they can't find us, or her friends are different there," Starlight said. She imagined a world where she had never met Twilight and also all of her friends had eyepatches. Eyepatches were a good way of distinguishing versions. That or goatees but those would probably only apply to Stallions.

"They couldn't be THAT different," Sunburst said, "Her body comes back exactly the same, remember? Too much difference in her history would lead to noticeable physical differences."

"This still means I can't kill myself anymore!" Twilight wailed, mourning the loss to science, "Since we can't even assign a probability it would be totally irresponsible!"

"Hold on," Starlight said, frowning. "I seem to remember Sunset saying something about the other you having a way to detect Equestrian magic."

"When were you talking to Sunset?" Twilight asked.

Starlight grinned sheepishly. "We may have exchanged linked books," she said.
"Starlight that's great!" Twilight said, "You're really taking the initiative at making new friends!"

Starlight blushed. "Thanks."

Sunburst looked back and forth between the two mares in confusion.

"You lost me," he said, "But from what I gather, you two know someone who can detect dimensional anomalies?"

"Right!" Twilight said, her enthusiasm renewed, "So we can find it and see if I'm giving off extra-dimensional vibes!"

"We juuust have to wait until school is over," Starlight said. Twilight's mood dropped a peg.

"Oh, right," Twilight said, "Well... I guess we wait."

*In the presence of a strong magical field, the traditional Einstein relationship that prevails on Earth ceases to apply. While the full equation is more complicated, that given here is generally a 'close enough' approximation. The 'h' here is the magical 'weight' of an object (typically given in milli-thaums), while 'k' is a natural constant much like the speed of light. Working out k's units is left as an exercise to the reader.

**Historically, a thaum was defined as the amount of magic which is needed to create a white pigeon or three billiard balls, depending on whether the author used Starswirl the Bearded's standard (former), or Rex the Magnificant's standard (latter). Rex the Magnificant, of course, being the semi-legendary mage of the Centaur kingdom. However as these definitions fail to specify the breed of pigeon or what number is on the billiard balls, it is now considered antiquated. The unit itself remains due to the inertia of tradition, but is now defined based on the constants 'k' and 'c', which are measured directly. For everyday usage, milli-thaums are typically used, despite efforts to redefine magic in terms of the amount of magic in the solarino.

***I'm not completely sure that that's correct. It's been a while since I dealt with trans-finite mathematics in any sort of comprehensive way.

Author's Notes:

And you'll have to wait too because this has spiraled larger than I expected!

This is hardly my best work, but it's silly and fun to write.

Hypothesis I: Where do they go? Only that's not really the question addressed but I needed that title to make the joke work for the next chapter.

It was a few hours and one meal later before Sunset Shimmer and the other Twilight Sparkle appeared. Twilight had quickly realized this and the trio had resorted to brainstorming other hypotheses to test. Without the critical data, however, they simple could not risk testing them. Spike had by this point returned, and was somewhat relieved to see the pile of dead Twilights had not significantly grown in his absence.

******************************************************

After a modest dinner of carrot-and-hay sandwiches, Twilight sent Spike to gather a few things before the shops closed. Twilight, Sunburst, and Starlight then went to the portal room to await their extradimensional colleagues.

It was not long before an orange unicorn with a red and yellow mane emerged from the portal, standing on her hind hooves. After a moment, she plopped down on all fours and checked her saddle bags.

"Hi Twilight! Hi Starlight! Twilight should be right behind me," Sunset said.

Indeed, very shortly thereafter, a purple (or possibly lavender) unicorn wearing glasses emerged, also standing on her hind hooves. This arrival, however, took several unsteady steps on two hooves. Sunset reached out and steadied her friend, helping support her weight as she lowered her front hooves to the ground.

"Now THAT is something tha takes some getting used to," Twilight who's not from Equestria said. Don't worry, they will get easier names in a moment.

"Hello! I think this is the first time we've met," said Sunburst, pushing up his glasses, "I'm Sunburst." He held out his hoof.

Twilight-from-Canterlot-High looked unsure what to do, so Sunset took the initiative and bumped his hoof.

"Hey," she said with a smile, "I'm Sunset Shimmer. I've heard about you from Starlight."

"Twilight Sparkle," Twilight Sparkle who wasn't a princess said, repeating the gesture the other two had shared, "Starlight was right... you two really do look alike. Are you sure you aren't related?"

"I don't think so," Sunburst said, pushing up his perpetually-falling glasses onc more, "But then I don't know all my cousins on my Father's side of the family, so maybe?"

Twilight Sparkle's own glasses had gotten a bit out of place in transition, so she awkwardly attempted to mimic Sunburst's movements to push them back into place.

"Hi umm... Twilight," Princess Twilight Sparkle said, "Did you bring the thing?"

"Oh right!" she said, nearly standing up before she remembered. She glanced back at her saddlebags, which a few minutes earlier had been a backpack.

"Oh right," Sunset said, "Hold on..."

"No wait, I've got this," Twilight said, "It's like the telekinesis stone magic, right?"

"I don't know... Probably?" Sunset said.

"Stone magic?" Sunburst asked.

"I'll explain later," Starlight told him.

It took three tries, but Canterlot High Twilight managed to use magic TK to open one of her bags. She began pulling items out and placing them on the floor.

"Thermometer... no... Air pressure gauge... no... Hall probe... no..."

"Where were you planning to plug that in, anyway?" Sunset asked.

"I've got a miniature generator in here somewhere," student Twilight said, "Multimeter... no..."

"Wow you two really ARE alike," Starlight said.

"We are not!" both Twilights said simultaneously. They blushed and student Twilight went back to her examinations.

"Say it might be kind of confusing to call you both Twilight," Sunburst said, "Maybe we can find something else to call you?"

"How about Twilight 1 and Twilight 2?" Sunset suggested.

"No way!" Twilight 2 said, "Then I'd be 2!"

"Not necessarily..." Sunset began. But Twilight had her number. Which was 2.

"You met me second, it's only logical," Twilight 2 said.

"I agree with Twilight," Twilight 1 said, "We need a way that's fair. Calling one of us Twilight and the other Twilight 1 wouldn't work, either. Hmmm... How about I be Twilight 1 and she can be Twilight A?"

"For Alternate?" Twilight A asked, "I don't know that I'm thrilled about that, either."

"Actually I was just thinking A is the first letter of the alphabet," Twilight 1 said. ¹

Twilight A thought about that for a moment, ceasing her rummaging.

"I can accept that," she said. She went back to it, switching to her other bag.

"And all that's in here is the mini-generator. Now I KNOW we packed that magic detector!" Twilight A said, "Sunset, is it in your bag?" ²

"Uh, let's see..." Sunset said, removing her saddle bags. She was about to turn it over and dump it out, but seeing the look Twilight gave her in stereo, she decided against it. Instead she set them gently on the ground and opened them up.

"I think this is it," she said, "But isn't this different from the one you used at the Friendship Games?" It was a somewhat bulky hand-held device with two anntenae and a screen.

"Yes, it's a lot easier to modify than the compact version," Twilight A said.

"Let me see!" Twilight 1 said excitedly. She took hold of the device with her magic and held it in front of her.

"So the needle showed the direction of magic and the screen shows concentration?" she asked.

"More or less, but it's calibrated for our world so..." Twilight A began.

"Hey, let's see which of us has higher magic!" Starlight said, taking hold of the device and flipping the obvious switch. The needle flipped back and forth rapidly lazily, not actually pointing anywhere. The readout on the screen showed a flat line. Starlight shook it a bit, before Sunset used her magic to grab it and return it to the table.

"As I was trying to say, it's currently calibrated to detect Equestrian magic. But there is so much Equestrian magic around here that it wouldn't know what to do. I've got to tweak it to detect dimensional frequencies first," Twilight A said. She then added under her breath, "Assuming Starlight didn't damage it..."

"Right, let's get to the lab," Twilight 1 said. She closed her eyes and her horns glowed. With a 'pop' sound, they were all in her lab, along with Twilight A's equipment and Sunset's saddlebags.

"Wow, you've gotten good at that," Sunset said admiringly.

"Oh that's nothing!" Twilight 1 said, "You should see... well that's why I asked for your help, actually."

"Yeah I wasn't clear on that. You said you die an respawn?" Sunset asked.

"Oh right well... Oh wait I can't do that until we test this. Ok, let's try this..." Twilight 1 said.

***********************

Twilight A had set the detector on the lab bench (which is a type of stabilized table) and was sorting through the tools in Sunset's bags, when suddenly she found herself outside. Staring at a pile of her own pony-form's corpses.

"AAAAAAHHH!" she yelled. Sunset was a bit more prepared, but was still clearly startled.

"Oh, hey Twilight, hey other Twilight," Pinkie Pie said happily, "Here for the 'Twilight's dead but not really so let's all eat cake' party?"³

Sunset blinked. That phrase was, in fact, written on a sign above a stand that Pinkie now sat behind. It said "Cake, 5 bits. The baker is IN" on a paper sign taped to the front. Behind Pinkie was a table of cakes frosted in black with little tombstones sticking up out of them.

"This is a party?" she said, looking around, "I don't see anyone... err anypony else here."

"Yeah, the pile of corpses scared them away," Pinkie said non-chalantly, "Oh well, more for me!" Pinkie opened her mouth wide and stuffed a piece of cake into it.

"Also we should probably figure out what we're going to do with these before they start to smell," Starlight said.⁴

"These are all RECENT?" Twilight A exclaimed.

"Uhh, let's go back to the laboratory for now," Starlight said, igniting her horn. With another 'pop' they were back in the lab.

*******************

"So yeah," Starlight said once they were back," Turns out Alicorn immortality works by forming a new body when their old one dies. And apparently it can be done repeatedly."

"Huh..." Sunset said, unsure what else to say. "So umm... what did you want us to test?"

"Well we're a bit worried that Twilight might be taking those bodies from other Twilights in other dimensions," Sunburst said, pushing his glasses up yet again. Teleporting with Starlight always managed to shift them juuust far enough down his nose to need correction, for some reason.⁵

Twilight A shook herself out of her shock on hearing this. "Hmmm, that is a possibility," she said, putting a hoof to her chin and accidentally hitting it. How DID they manage without fingers? ⁶ "Hence the need for a dimensional detector," she continued, "Well, I can't gaurantee it will detect any dimension, since they all might act differently, but we can at least test those like the ones we know. I'll need some sort of dimensionally sensitive object. I'll also need some way to boost the output so it's still readable over the electronic background. We'll just have to hope the physical friction doesn't damp it too much."

"Oh! Were you using the electric-magic resonance for that detector?" Sunburst asked.

"That's a thing?" Twilight A said, surprised, "That would have made things a lot easier."

"Well, yes," Sunburst said, "I didn't go into electro-magic engineering, but I know it's used in Unicorn communities when there isn't a river available to dam."

"So your civilization uses entirely green power?" Twilight A asked, "Fascinating."

"Green? I don't know that it's green," Sunburst said, "The water is mostly blue and the magic is..."

"No green as in..." Twilight A began. She stopped on seeing Starlight's uncomfortable look. "You know what? Never mind," Twilight A said, "We have more pressing issues to deal with. Anyway, no that's now how this works. After I found a stray bit of magic-infused grass, I discovered it would vibrate just a little in certain areas." Twilight A at this point stopped fiddling with the device and slipped into lecture mode, standing (as much as she was able) up straight, facing the general direction of those she was talking to, and projecting to the back of the room. I hypothesized it was reacting to the presence of other magic. Hook that to a piezoelectric circuit and you've got a signal. Put two of them at angles and you have direction.* Of course around here, everything is magic, so I'd hypothesize that the effects cancel out, much like how Newton's law shows that the gravity inside concentric spherical shells depends only on the mass inside the shell youre on.**"

"You have Fig Newton in your world, too?" Sunburst said, interrupting.

"Ours is called Isaac, but he's basically the same," Sunset supplied.

Twilight A looked irritated at having her lecture interrupted. Sunburst looked abashed and waved with his hoof, motioning for her to continue.

"Now, Since we know the mirror portal reacts with the magic detector, and the portal is dimensional, Equestrian magic must relate somehow to dimensional variance," Twilight A continued, "We just need something with more dimensional than magic to test it with."

"What about the mirror?" Starlight asked, "It's dimensional. Could we break off a little piece of it without breaking it?"

"I don't know about the mirror itself," Twilight 1 said, "But the crystal frame isn't just for show.*** They've been resonating with the dimensional magic whenever the mirror is used, so we could remove one of them. We'd just need a replacement first. Starlight, think you could ask Maud?"

"Sure thing," Starlight said. She eyed Twilight A warily before teleporting away.

"And there were other mirrors, according to Celestia," Twilight 1 said, "I can probably have Spike send a scroll. It wouldn't be as fast as dying but..."

"Right, don't want to accidentally kill your parallel self," Sunset said. On seeing Twilight 1's look she added, "Probably shouldn't have mentioned that."

"The point is we'll then have more than one data point! Oooh, this is so exciting!" Twilight 1 said. She stopped her squeeing abruptly. "Um, assuming I'm not killing other Twilights of course."

"The rest of us can help you out," Sunburst said to Twilight A.

"Not sure how well that will work," Twilight A said, "Too many people on something this small tends to result in getting in each other's way." She turned her attention to the detector as she spoke. She flipped it over with her magic and picked up a screwdriver with the same. She stuck out her tongue as she concentrated on maneuvering it to undo the screws. Sunset gently took control of it and turned it effortlessly. Twilight A smiled sheepishly.

"Ok, maybe I could use a little help," Twilight A said.

"Then let's get this dimensional detecting whatever built!" Sunset said with some enthusiasm, albeit less than either Twilight.

*Piezoelectric systems are those that emit charge in response to mechanical stress. Some microphones use piezoelectric materials as their pickup, as do some electric guitar pickups. With the right material and a lot of experimentation, it is in princple possible to use a piezoelectric set-up to detect anything that produces movement in the receiver. The notion here is that Sci-Twi found something infused with magic (I can't find where Friendship Games actually showed what) and through a combination of math and trial and error rigged up such a system to detect magic. The directionality is obtained by setting up 2 such systems, each corresponding to one of the antennae on her original device. This is similar to how stereo audio is recorded: 2 mics are used (either literally or with some clever use of a single mic) to get not only pitch and volume, but also the relative direction. The best part is that while the components are not necessarily cheap, neither are they absurdly expensive, and they are easy enough to find via cannibalizing what are more commonly called 'crystal' microphones. A student who can afford Crystal Prep probably has the resources necessary to procure these.

**It's true! To first order at least. In this case we have to suppose that because magic is permeating their world but with little appreciable effect on most applications, SciTwi's instrument, being intended to pick up single large spikes sticking up from zero, reacts to random blips that occur rather than a single identifiable source. It's a signal-to-noise ratio (SNR) thing, similar to trying to discern what song is on a radio station that is almost-but-not-suite coming in. Actually without doing the math I'm not sure the SNR works as it would need to, but it's at least plausible that it could. The effect here could, interestingly, manifest as a high magical creature like Twilight having objects 'stick' to her. This will lead to comedic potential at some point, I'm sure.

***The most commonly used piezoelectric materials are crystals, so this is doubly convenient. Sometimes the universe gives you one for free.

1 She also felt that numbers trumped letters in the heirarchy of labels, but she didn't want this debate to drag on forever.

2 This is the most common use for research assistants: Moving heavy things between labs and field locations.

3 This had replaced her previous idea for that day's party, the "Anniverary of 5 days after the Cake twins first burped in a way that kind of sounded like language" party. It was a slow day for parties.

4 The pile only represented about half of the corpses. Twilight 1 had donated the first 20 to the local hospital for organ transplants, but had to stop when she was informed that they had neither the immediate need for the organs nor any way of storing that many. It was clear that a better distribution network would be needed. There were also further difficulties that would arise, but Twilight 1 wouldn't find out about those until the next day.

5 It was because Starlight thought the gesture was cute, but she wasn't going to tell him that.

6 The answer was 'surprisingly well, all things considered'.

Author's Notes:

AN: Numbered footnotes are story or character related. * footnotes are science-related. I know that's backwards but there are more of the former than the latter. At this point what I originally anticipated as a 2000 word story is going to run at least 10,000 (roughly 5 chapters), as I keep realizing there are more steps needed to actually get to the point I wanted to get to. Science is like that sometimes.

Was able to get this one out pretty fast as I already knw where I was going with it. Should be able to get the next one out in a few days. 4 and 5 might take a bit longer. In the meantime, "Rainbooms 101" and the the 'analysis' portions of "Bedtime stories for the Mare in the Moon" (at the end of each chapter) have more sciencey goodness, though not the same level of insanity.

Hypothesis II: Where do they come from Pony Donut Joe? But actually he doesn't show up until the next chapter

After a bit of fussing, Spike's return with assorted screws and different lengths of wire, some scroll sending, and a return by dragon mail of some crystal fragments wrapped in a scroll, Twilight A was ready with her device. The Twilights, Sunset, Sunburst, and Starlight were gathered back in the portal room. Spike had started yawning and been dismissed by Twilight. It was not clear whether he was tired or bored, but it was getting croweded in the laboratory anyway.

"The mirror is working just fine, see?" she said, demonstrating how the signal changed when pointing the device towards or away from the mirror.
"And me?" Twilight 1 asked anxiously.

Twilight A waved the device around in the vicinity of Twlight 1. "Nothing," she said.

"Woohoo!" Twilight A said, jumping into the air and flapping her wings, "I didn't kill myself!"

Sunset raised an eyebrow at that.

"Errr... sorry, it's just a relief," she said.

"Now wait a moment," Sunburst said, holding up a hoof, "What if the mirror is overwhelming your own signal? We should go somewhere far away from any dimensional nonsense just to be sure."

Twilight 1 dropped to the ground, crestfallen, her wings sagging.

"Oh we should stay away from the Everfree portal too," Sunset said, "So maybe on the opposite side of town?"

"Right, in that case..." Twilight 1 said, lighting up her horn. With a soft 'pop' they were outside of town on the road towards Canterlot.

"Woah," Twilight A said, a little disoriented, "That takes some getting used to..."

"It doesn't take too long," Twilight 1 said, "What does it say? What does it say?"

Twilight A waved the device around.

"Ok, so I'm getting nothing here... let me adjust the sensitivity..." she said, turning a knob she had added to the side. "Alright, so there's your castle... Were the other mirrors in that city built into the mountain?"

"That's Canterlot," Starlight supplied, "I'm pretty sure Celestia has them hidden in the catacombs somewhere."

Twilight A nodded. "Ok and... nothing from uhh... Twilight," she said, "Twilight 1 I mean."

"Once again, woohoo!" Twilight 1 said, forgoing the leap this time.

"And again, would it show up now or only right after?" Sunburst said.

"Hmmm, yes I suppose we would need to test it right when she died and respawned..." Twilight A said.

"But what if that kills another her?" Sunset asked.

"When you think about it, that was never very likely," Starlight said, "Her mind would have to push out another alicorn's. This whole test was on the basis of 'better safe than sorry'. Same principle as time travel."

Twilight 1 glanced upward. There was clear sky above them.

"Ok, so very low probability of hurting anyone," she said, "And I can't be sure when I might be forced to respawn. I think we have to try it."

"Ok, but how are you..." Starlight began. Twilight's teleport cut her off.

"Where did she...." Sunset also started a sentence before hearing a faint sound and stopping.

"Uh, maybe we should step back," Sunburst said, looking up, "Just in case.

Everypony glanced up, then took several steps backwards in a circle. Twilight A kept her device trained on the plummeting alicorn as the faint sound became more distinct.

"Hooooooooooooooo!" came the sound as she neared the ground, head-first. There was a rather disturbing 'crack' and 'squelch' sound as the rather unforgiving ground met flesh not designed to take that much force. Starlight quickly threw up a shield around herself and Sunburst. The other unicorns, despite their distance, found themselves covered in rather more bodily fluids than they wanted. Which is to say, more than zero.¹

"Huh," Starlight said, lowering the shield, "That sounded... eager."

"Injuries do trigger a release of endorphins and adrenalyn," Twilight A said as she stared at her sensor, trying very hard to ignore what was uncomfortably close to her own fresh corpse on the ground in front of her, "Ordinarily that's to counter the pain. Maybe with the pain gone she's coming back with a runner high."

"A what?" Sunburst asked.

"Trotter's high," Sunset translated.

"Oooh," Starlight said, "That would explain a lot."

After a bit of awkward silence, another question occured to Starlight.

"Huh, I wonder what would happen if we revived this corpse?" Starlight asked, "I mean I don't think we could do it with a broken neck, but what if she died from an electric shock or something?"

"Maybe we should address that next," Twilight A said, "Might pose some ethical questions of its own."

Starlight lit up her horn and a glow surrounded Twilight 1's body.

"Well I'm not picking up any magic emission," she said, "And... hmm..." Her aura shifted to a lighter shade of purple and focused around Twilight 1's head. "No brain activity either, as far as I can detect, but then I'm no medical unicorn."

"Hold on everypony, she should be back just about..." Sunburst began, "Now." He pointed a hoof towards a spot behind the corpse. When nothing appeared, he pushed up his glasses to cover his embarassment. "That would have been a good time to get that right," he said.

Just then, Twilight 1 appeared with a 'pop' directly in front of Twilight A, leaning over her device and into her face.

"Gaaah!" Twilight A started back.

"Well? What's it say?!" Twilight asked eagerly.

"Uhh..." Twilight A said as her heart beat a mile a minute. She glanced down at her device, which was poking into Twilight 1's... chest, she guessed would still be the term? The detector still showed the baseline.

"Nothing," Twilight A said, "I think we can reasonably safely assume you aren't getting bodies from another dimension."

"Again, woohoo!" Twilight 1 said, more subdued this time. "Now that that's out of the way, I think we have time for one more test today."

"Hmmm, well the fastest would be to see if you can respawn across dimensions," Sunburst said, remembering the previous list.

"First I think we should bury this," Starlight said, gesturing with her hoof at the Twilight corpse just in front of them.

"Oh, right... we need to come up with a more efficient disposal method," Twilight 1 said.

"You could just dump them in a volcano," Starlight said, "There's one in the dragon lands that would work."

"I'm not really familiar enough with it to teleport there," Twilight 1 said, "I suppose I'll need to make a trip there first. We still need to deal with this one."

"Hold on I got this," Starlight said. In seconds she had popped out a perfectly shaped grave with magic, thrown Twilight's body in there with the same, then dropped the dirt back on top. The other ponies present boggled at her.

"Uhhh... should we be concerned?" Sunset asked.

Starlight blushed. "Buried alive was one of the... ideas I toyed with when I was looking for revenge against Twilight," she said, then hastily added, "Not that I would have actually done it! I realized pretty quickly it was going too far." She then added under her breath, "Besides, she could have just teleported out."

***************************************

Ignoring that, it was not too long before they were back in front of the mirror portal. Sunset and Twilight A were wearing the saddlebags again.

"You two need to be home soon anyway, right?" Starlight asked Sunset and Twilight A.

"Sort of, but it's actually the weekend over there," Sunset said, "So it's not as big a deal."

"Oh right, then you'll be able to help for the next two days!" Twilight 1 said excitedly.

Twilight A looked around a little nervously. Seeing this, Sunset spoke up.

"We do have homework to do, plus plans with the girls," Sunset said, "So I think..."

Twilight A held up a hand... er, hoof, and took a deep breath.

"No, I can do my homework in an hour, and we don't have plans with the girls until the evening," she said, "I was a little disturbed seeing that body, but I can endure. If I'm going to do medical research some day, I'll have to get used to that sort of thing."

"Oh, you want to be a Doctor?" Twilight 1 asked.

Twilight A shook her head. "Medical researcher, not quite the same thing," she said, "And that's only one of my options. I'm thinking of going to a liberal arts school so I can delay that choice for a little longer."

"Huh, your educational system sounds complicated, "Starlight said.

"It has its moment," Sunset said.

Twilight 1 clapped her forehooves together eagerly.

"Alright, you too! Let's get going!" she said, "I'm really curious to see how this works!"

"Is it alright if I leave my equipment here?" Twilight A said, "That'll give me room to bring some more instruments tomorrow."

Twilight 1 positively beamed. "Of course!"

"Well, see you on the other side," Sunset said, then to Sunburst and Starlight, "And I guess I'll see you two tomorrow?"

"Actually we have to deal with some parent-teacher conferences," Sunburst said.

"I'm guessing we'll have some concerns about students seeing our former headmare throwing herself off the top of the castle... repeatedly," Starlight said, "Not looking forward to that one..."

"Oh, once they see that I'm fine, it'll all work out," Twilight 1 said.

"Right, later then," Sunset said, gesturing Twilight A through the portal and then following her.

*************************************

On the other side, Twilight A stepped out of the portal, her backpack back to being just that. She only had to wait a moment for Sunset to join her.

"So... Want to bet on how big that pile will be by tomorrow?" Sunset asked. Twilight A blanched. Sunset winced in response.

"Ok, so it's a bit morbid," Sunset said, "But it's not like anyone's really getting hurt."

"I suppose..." Twilight A said, glancing down at her watch², "It's still disturbing."

"Eh, think about it like a video game," Sunset said with a shrug, "One of those ones where the bodies don't instantly vanish."

"Right... so do you think this will work?" Twilight A asked.

"I guess we'll find out," Sunset said, looking around, "She said she would try to pop up right here by the statue."

Twilight A focused on her watch as the second hand went around.

"So that's a minute," she said, "Do you think the time we spend in transition counts?"

"Huh, good question," Sunset said, putting her hand to her chin. "It always seems to take time, but apparently the Sirens were outside of time before they came here, so maybe we are too when we're in-between?"

"Hmmm, might make a good research topic later," Twilight A said, "How long do we wait?"

"Fifteen minutes?" Sunset said, "Isn't that how long you're supposed to wait for the professor?"

Twilight A giggled. "That's mostly a myth," she said, "Although I've heard some colleges have adopted it."

At that moment, a flash came from the portal. Sunset and Twilight A focused on it rapidly. Out stepped another Twilight, this one without glasses.

"Still weird to see that," Twilight A said.

"Huh, that's odd," Twilight 1 said, "I meant to come in right behind you two..."

"What happened?" Sunset asked.

"Oh! Well I threw myself off the tower as usual," she began. Twilight A winced again. "Right, not that part," Twilight 1 said, "Anyway, I went to the misty place like usual, but when I thought of where I wanted to go, I didn't immediately go there. I tried to focus more on the place, picturing it as best as I could, when a mirror appeared in front of me. I stepped through it and, well, here I am."

"Huh," Sunset said, blinking, "That's interesting. I always through the portals changed our bodies, but do they make entirely new ones?"

The Twilights thought about this for a moment, but Twilight A shook her head first. "I don't think so. Remember the portal on that island? If it were making a new body, our old one would have to stay in that in-between place, meaning the portals would all have to be connected. And then why would each one always lead to the same place?"

"Plus when I first came here, I tried putting just part of my body through," Twilight 1 said, "And I had a hoof on the end of an arm for a moment."

"That sounds strange," Twilight A said.

"Moreso than being an upright nearly-hairless simian?" Twilight 1 said, gesturing with her hands with a grin.

"Or than being a tiny, talking, equine with magic?" Twilight A responded with a laugh, "I guess you're right."

"So then why could you only come through the portal?"

"I don't know," Twilight 1 said with a shake of her head, "I was going to try going the other direction, but if I can't respawn normally here, I'd rather not die here, just in case."

"Yeah, and we don't have the pull to keep people from asking about the body," Sunset said, pacing a bit with her hands gathered behind her back. She stopped and looked over her shoulder.

"Maybe it's the Equestrian magic?" she suggested, "It's strong here."

"Oh, so maybe she could pop up near where we found the stones?" Twilight A said.

"Geodes," Sunset said.

"Technically only 2 of them are geodes," Twilight A said, "A geode has to have a..."

"Separate type of rock inside the first," Twilight 1 joined in, so that they both said that at the same time. Twilight A looked a bit startled.

"Oh right, I guess you would know. have you also talked about rocks with Pinkie's sister?" Twilight A asked.

"Oh, yes!" Twilight 1 said, "Maude's research is a bit dry to some, but it really is quite fascinating! Is your Boulder also extrusive igneous?"*

"Yes! And have you heard how they met?" Twilight A said.

"Right right, we all know the dramatic and heartwarming story of how Maud met Boulder," Sunset set, cutting them off before they nerded out too much. Not that she'd have used that phrasing. "So tomorrow I guess we can take you out to Camp Everfree to try there." Sunset got a mischevous grin on her face. "And Twilight... errr, Twilight A... here can see Timber Spruce."

Twilight A blushed, and Twilight 1's ears perked up.

"Timber Spruce?" Twilight 1 asked.

"He's..." Twilight A began.

"They've been seeing each other," Sunset said.

"Huh, I don't think I know a Timber Spruce... is the Maud here seeing Mudbriar?"

"Huh? Maud is seeing someone?" Sunset asked.

"Pinkie hasn't said anything, so probably not," Twilight A said, shaking her head, "Of course, people here seem to be a little younger than ponies there. Are you seeing someone?"

"Somepony," Sunset corrected.

"No... my duties keep me pretty busy," Twilight 1 said. Sunset rolled her eyes.

"I mean I guess the dead bodies would put most boys...stallions... off. You know I tried to find Equestria's Timber Spruce when I was there," Sunset set.

"You did?" Twilight A asked, "What was he like?"

Sunset shrugged. "I don't think he exists. At least there weren't any records in Ponyville or Canterlot."

"Why were you looking for him in the first place?" Twilight 1 asked.

"You seemed like you could use the help," Sunset said flatly.

"Do not!" Twilight 1 said, bristling a bit at Sunset's line of thought.

"Well, it was a dead end anyway," Sunset said with a shrug, "Odd how similar our worlds are when they're also so different. Like here, Maud found Boulder on a family trip to an island in the sea, but I don't remember any such islands near Equestria.

Twilight 1 shook her head. "No, she was doing research in the Dragon Lands."

"Hmmm... Well nothing to be done about it today," Sunset said with a shrug, "Maybe you can try with another dimension, too. One with more magic. Might get some data on dimensional similarities there, too.
"Oooh, like the mirror dimension that used to have the evil Celestia and Luna!"³ Twilight 1 said. Sunset raised an eyebrow.

"Huh, that does sound interesting," she said, "but tomorrow. Sleep time now. And that means you too, Twilight.... Errr, Twilight 1."

***********************

That evening, as Celestia was going to bed and Luna was waking up, a scroll popped onto their dinner/breakfast table.

"Oh, that must be Twilight," Celestia said, "I wonder how she's coping with her newfound powers?"

Dear Princesses Celestia and Luna

The first day of the First Annual Alicorn Respawn Research Conference has been a qualified success. (Sorry for the name, Princess Celestia, but it's short and memorable!)

Luna giggled at Celestia's mild annoyance.

Today, after some initial concern, we determined that the new alicorn bodies are not extra-dimensional copies whose bodies we have usurped. This concern caused quite a detour, and we had to request help from Canterlot High.

"Hmmm, I suspect Principal Celestia does not have to deal with QUITE this sort of issue," Celestia said as she glanced back at Luna. Luna shrugged.

"Letters between my counterpart and I mostly discuss current events and how to deal with irritatingly composed elder sisters," Luna said. It was Celestia's turn to giggle at her sister.

We have also made the unusual discovery that I cannot simply 'spawn in' at Canterlot High, but rather enter through their portal when I try. With your kind permissions, we intend to see if this persists across other dimensions tomorrow. Do you two, with your lengthy experience, have any knowledge of this?

Luna sighed. "I suppose we shall have to find a dimension we have not been to in awhile," she said, "We do not want there to be another incident like that with Lord Sombra."

On seeing her sister's downturned expression, Luna added, "Apologies, sister. I did not mean to stir bad memories."

"It's fine," Celestia said, waving her hoof, "He is alive, and some day we shall find a way to restore him."

Yours, Twilight Sparkle

PS: I'm starting to worry respawning might be a bit addictive. Do you have any advice on this?

Luna giggled again. "Ah, it seems she takes after her teacher in yet another way!" Luna said.

"To her credit, she is approaching it methodically and with good intentions," Celestia said, a note of pride in her voice, "I was merely having fun."

"So what shall we do?" Luna asked.

"I'll have to make time to visit her conference," Celestia said with a touch of resignation, "I suppose I will have to make a statement about all the corpses, too. It has been a few hundred years."

Luna started. "Sister? What were you up to in my absence?"

Celestia shrugged. "There was a particuarly boring chancellor a few centuries back," she said, "The first time I leaned back and fell out of the window was mostly an accident while I was asleep but, well... I found it created enough of a scene to liven things up a bit. Of course HE figured it out after the second time, but he had a hard time explaining it to passersby... or visiting dignitaries... or the Council."

Luna chuckled. "An amusing prank, but perhaps a touch cruel."

Celestia sighed. "You weren't there. It was a very boring century all around."

**************************************

1 To their later dismay, Sunset and Twilight A discovered that blood-stained fur translated into blood stained clothing when they went back through the portal. Why Starswirl would have set it up that way was a mystery that Sunset resolved to address on her next visit to Equestria.

2 Twilight A would later wonder where the watch had gone when she went through the portal, or if it had been there and she just had not noticed it. Seeing a dead body of the person... or rather pony... standing next to you had a way of making one forget about functional accessories.

3 As this happened in the comics, it exists in a state of having both happened and not happened simultaneously. Appropriate, really, given the subject matter.

*From Rock Solid Friendship, Boulder is magnesium-rich basalt that's about 200 years old. Basalt is an extrusive igneous rock, meaning it's formed by the cooling of magma that reaches the surface. Magnesium-rich basalt cools solidifies more rapidly than the iron-rich version due to the lower higher melting temperature (which means it solidifies more easily). It is most commonly found around volcanoes. Maud's statement that a stripe on Boulder gives his age could only be known if she found him in situ (meaning in the place where he formed, without intervention from humans or ponies). The rate of volcanic activity can be predictable over thousand-ish year time scales, so seeing the layers of flows around him could give an estimate of age. Alternately, basalts are sometimes magnetic, and field can be 'frozen in' to them, giving the iron compounds in them an orientation. If Equestria's magnetic field changes at regular intervals, that could also give an estimate of age. Either way, the age estimate would require information we aren't privy to.
Please note: I am not a geologist by trade, so the above is based on what I could gather from research for both this and a review I did on Rock Solid Friendship (https://www.youtube.com/watch?v=d8CjxFpLODg) Any geologists in the audience, feel free to let me know what I've got wrong.
And yes this footnote primarily exists to give this chapter an educational component.

Thanks to Magnum Hocus for pointing out the rather elementary mistake I made in the last note. Corrections are indicated by a strike-through of the old phrasing.

Author's Notes:

Ah, comics cannon. Or deuterocannon as I prefer to think of it. Guess the Season 10 comics will be a chance to cannonize some of that.

Anyway, this takes me to and past what I had planned out already, partly why this took a bit longer. Going forward we'll be looking at about once a week. 2 more chapters and a brief epilogue, if all goes to plan.

Results I: Worlds Enough (Part 1)

Owing to an unfortunate incident involving Celestia and tea, Twilight Sparkle's original notes on the mechanics of respawning away from the mirror portal were lost. The following is her attempt to reproduce the results from memory.⁰

It was just before noon when Twilight A, Sunset Shimmer, and Timber Spruce arrived at the magic cave at Camp Everfree. Twilight had been reluctant to allow Timber Spruce along, though he was unclear on why.

"So this is where those magic geodes came from?" Timber Spruce asked.

"Nodules," Twilight A corrected, "Geodes have crystals growing inside a cavity. So at most two of them are geodes."*

Timber Spruce considered this. "What about those two?"

Twilight A shrugged. "Those we can't see through," she said, "So they could be geodes, we just can't tell."

"Twilight... Twilight 1 I mean... says she's ready," Sunset said, looking at her Instant Messaging Notebook (tm).

"So why is she Twilight 1?" Timber Spruce asked.

"Well, we needed something different to call us," Twilight A said, "And we didn't want it to be something like 1 and 2, so we went with 1 and A."

Timber grinned. "Was that a reference to that cartoon with all the math?"

Twilight smiled back. "Probably not, but I did consider calling our universe the Mongooses."¹

Sunset looked over at them. "I have no idea what you're talking about, so I doubt the other Twilight will either. Maybe give those references a rest while she's here?"

"So what are we waiting for exactly" Timber Spruce asked. he walked over to the pedestal to examing it more closely.

"Twilight 1 is going to try to appear here instead of at the mirror," Twilight A said.

"I just hope a picture is enough for her to go on," Sunset said, "Thank goodness for Pinkie Pie's compulsive picture-taking."

"Yeah I've seen that," Timber Spruce said, "Does her room just have like, piles of hard drives stacked up?'

Sunset chuckled. "No. So I guess she deletes most of them."

"Yes she always has the one you want," Twilight A said.

Right around then, a breeze started blowing. Timber Spruce took a step back, and the other two looked at the pedestal. There was a small, silverly circle hovering over it. The circle was about the size of a low-denomination coin of some sort. As they watched, the circle expanded and the wind increased. When it was just large enough to accomodate a pair of hands, such a pair appeared. The purple hands gripped the side and began to pull the hole wider.

"Should we do something?" Twilight A said.
"I've got it!" Twilight's voice came from within the hole, "Just give me a moment!"

She gradually pulled what was clearly a portal open, and started to pull herself through. When she had just gotten her shoulders through, she lost her grip and her hands popped out, causing the portal to try to close on her torso. Sunset reacted quickly and grabbed her left hand. Timber grabbed her right just a touch later. Twilight A held up her hands and used her telekinesis to pull the portal open just a hair. With a slight 'pop', Twilight 1 came free. Twilight 1, Timber Spruce, and Sunset tumbled to the ground. The portal winked closed.

"So what happened?" Twilight A said, taking out her notebook. She began jotting down her own observations right away.

"Uggh... Well, I was in the bright cloudy place as usual"Twilight 1 said as she rubbed her head. Timber Spruce got up and offered her a hand. Twilight started to bump fists, then remembered that was not the custom here and grabbed his hand to shake it. Instead he pulled her to her feet, where she rocked a bit unsteadily. Twilight 1 stared at him curiously.
"Ahem," Twilight A said after a moment. Twilight 1 realized she was still holding Timber Spruce's hand and quickly let go. Timber Spruce blushed.

"Sorry, force of habit," he said, "You two really do look alike."

"Curious, isn't it?" Twilight 1 said, "Yet some ponies... people... only exist in one dimension or the other."

"Yeah. Still haven't found another of me," Sunset said, now on her feet. "Lucky thing, too. But weren't you about to explain what happened?"

"Oh! Right!" Twilight 1 said, "So when I thought of this place, a little portal opened. I tried to picture it larger, but I guess because I didn't know what it could come out of here, I had to pull it open wider."

"We saw that," Twilight A said, nodding, "And there was a wind blowing out of it. So that place has air?"

"I guess it must," Twilight 1 said, putting her fist to her chin thoughtfully. "So that means the body is being formed there?"

"Wait, body?" Timber Spruce said, picking up on the odd wording.

"Uhhh, you know what?" Sunset cut in, "Maybe we should go get lunch. You should probably be sitting down when you hear this.

"Oh good, more guinee pigs for my camp recipes!" Timber Spruce said, "It's hard to get Twilight here to give me an honest opinion."

Twilight A blushed slightly at this.

"I think we can handle that," Sunset said with a grin.

The quartet tried out Timber Spruce's latest concoction² while they explained the general situation to him. He nearly choked on his food when they got to the part where Twilight 1 killed herself to test the 'respawning'.

"So I guess you can't get back the way you came?" Sunset said as Timber calmed down. She hesitated a moment. "Not that I would want you to."

"Even if it worked, it might be a bit awkward," Twilight 1 said with a nod, "I guess we have to get back to Canterlot High and use the mirror portal. I left the notebook with Spike. Send him a message and let him know I'll be awhile."

When they were done eating and heading back to Twilight A's car³, the notebook buzzed. Sunset took a look.

"Spike says you have a message from Princess Celestia," Sunset said.

"What? What does it say?" Twilight 1 asked excitedly.

"He didn't say yet. Hold on..." Sunset said. She wrote back asking for clarification.

"It says she'll be stopping by to check on our progress later today," Sunset said, becoming a bit nervous.

"I thought you two made up?" Twilight A asked.

"Yeah, but it's still awkward," Sunset said.

"So I guess she's the counterpat of Principal Celestia?" Timber Spruce asked.

"Yes," Twilight 1 confirmed. Her face brighted. "I guess we'd better get moving then! Got to have results to present!"

"Huh, I'm impressed," Sunset said, "I thought you'd be freaking out."

"Pssh, whaaat? Me? Freak out?" Twilight 1 said. Sunset, Twilight A , and Timber Spruce all gave her a look. "Ok, maybe once," Twilight 1 said, "But I'm good now. Really."

Timber Spruce stayed behind at Camp Everfree, while the others made the drive back to Canterlot High. Along the way they brainstormed on things to test.

"Based on this list, I'm not sure there's much else we can test," Sunset said, "I mean, I'm not going to sit there and stab you or whatever."

"Yes, and we'd need some way of quantifying injury anyway," Twilight 1 said, "I am wondering if a body could be resucitated, but I'm kind of afraid to try."

"Right, two Twilights? Can you imagine?" Sunset said wryly. All three of them chuckled.

"So we should look into the practical applications more," Twilight 1 said.

"Alicorn steaks sound like they might be good," Twilight A said, with only a slight shudder.

"Ponies don't usually eat meat," Twilight 1 said, "But I did put out some feelers to the Griffons and Dragons. They might be interested."

"Blood transfusions and organ donations are the next, "Sunset said, checking the list Twilight 1 had given them all, "What blood type are you?"

"O-positive," Twilight 1 said immediately, "So I should be a good donor."

"That's my blood type!" Twilight A said. After a pause she added "Which makes sense I suppose."

Twilight 1 nodded, though Twilight A could not really see that while driving.

"I asked Nurse Redheart to examine a specimin," she said, "To see if alicorn organs are the right size and shape."

"Huh, I guess Celestia would be too large for that to work," Sunset said.

"Probably," Twilight 1 said with a nod, "And since she's AB positive, blood donation opportunities would be limited."

"You know Celestia's blood type?" Sunset asked wryly. Twilight 1 blushed.

"It's in one of her biographies," she said, "I found it a serious deficiency that more of them didn't include that information."

"So do we take a bit of a tour when we get there?" Twilight A asked.

"I'd like that, but we'll be a bit short on time," Twilight 1 said, "We should probably split up."

"I guess Twilight A here can stick with me," Sunset said, "Between the glasses and lack of wings, people... ponies... shouldn't get too confused."

* Thanks to Vaguely Demented for correcting me on this point.
0 Rather, the author's computer ate a good bit of what he wrote, but this sounds funnier.
1 I apologize for nothing!
2 Lake fish, filleted, seasoned with salt and herbs from the camp garden, over bulk purchased rice. Celery from the local garden served as a side. It was palatable, but the limited available herbs led to a slightly bitter flavor.
3 Actually her parents' car as she was still in high school.

Author's Notes:

This was only supposed to be half of the chapter, hence the 'part 1.' I wanted to go ahead and get something up.

Also I forgot the footnotes when I first posted this.

Results I: World Enough (Part 2)

Sunset plus Twilight squared¹ arrived in Ponyville a bit later in the day. Twilight was all prepared to make a death-induced trip to the dragon lands, but Spike stopped her and said they should check outside first.

Outside the castle was Pinkie Pie's stand, formerly of funeral cakes, but it had changed. Whereas before it had read 'Twilight's dead but not really so let's all eat cake', to that had been appended in increasingly small and scrawled letters "Also information on all the Twilight corpses lying around", and then the entire thing had been crossed out in read. On top of it had been placed a new, carboard sign reading 'Alicorn Enterprises, LLC'. Though they couldn't see it until they got closer, in small print below it was written'"A division of Barnyard Bargains, inc.' Maning (pony-ing? creature-ing?) the booth was one Gabby Griffon.

"Oh hi guys!" Gabby said brightly,² "Hi Spike! Are you here to try some before they're shipped out? Wait, do ponies eat meat? I think someone told me they did, but I don't spend that much time around ponies, you know?"

"Um, hi," Twilight 1 said, approaching first as the one most concerned with this. "What is this?"

"Oh you didn't know?" Gabby said, "Filthy Rich heard from Grandpa Gruff, and said we had to move fast before your bodies rotted too much to be used! Good thing Griffons can eat carrion, huh?"*

"I guess it is. Is Filthy Rich making money off of the deal?" Twilight 1 asked.

"I dunno," Gabby said with a shrug, "He's paying me so I guess he must! I'd have helped for free, but Grandpa Gruff said it was part of the deal!"³

Seeing her counterpart's disturbed look, Twilight A cut in. "Do you want to go deal with that? It sounds like he's dealing fair but you should really have a say in it," she said.

"Oh, hey, I didn't know you had a twin sister, Twilight!" Gabby said.

"Alternate dimensional counterpart," Sunset said by way of explanation.

Gabby tapped the bottom of her beak with her claw. "Oh yeah, I remember Spike telling me about how he was a dog in another dimension," she said, "Does this mean I have a counterpart-sister, too?! And if I do, can I meet her?"

This caught the trio slightly off guard. Sunset, who had spent the most time on this sort of thing, spoke up first. "I'm not sure. Not everyone has a counterpart, and most that do seem to be ponies over here."

"Aww," Gabby said, crestfallen. But she quickly recovered. "Oh well, I guess that makes me even more special! Ooh, but if you do find another me, you'll let me know, right?"

"Of course!" Spike said.

"Ok ponies... people... and dragon... Sunset and I will to talk to Filthy Rich. You two check in with Nurse Redheart," Twilight 1 said, gesturing in the appropriate directions, "Spike, show the other Twilight where Nurse Redheart is. And make sure to explain that she's not me. We'll meet at Donut Joe's in an hour."

"Got it," Spike said, standing up straight and saluting. He waved at Gabby. "Later, Gabby!"

"Later Spike!" Gabby said brightly, waving back.

*********************************************************

Spike and Twilight A (for Alternate, though that was not how she thought of it) went to the Ponyville Clinic, held up by occasional explanations to confused passerby. And again by explanations to Nurse Redheart that Twilight 1 had neglected.

"A renewable source of organ transplants is certainly a boon," Nurse Redheart said one she understood, "But there's a problem..."

"Alicorn organs incompatible?" Twilight A guessed.

"Not exactly,"Nurse Redheart said, consulting a clipboard⁴, "It's that Twilight's blood type is AB positive. Most patients will reject her organs."

"What? But she was Type O positive, same as me," Twilight A said, "Unless... her changing species changed her blood type?"

"That's what we think," Nurse Redheart said with a nod, "We have her records from Canterlot, and she was definitely O positive before, but she definitely isn't now."

Twilight A sighed. "So it's not ideal, but surely with her resources she can figure out how to distribute spare organs to those who can use them."

"I'm sure Princess Celestia can figure out something," Nurse Redheart said. Which Twilight and Spike both thought was a bit of a jab. "But organ transplants aren't all that common," she continued."

"Hmmm, because of magic?" Twilight A said thoughtfully.

Nurse Redheart seemed surprised. "Oh, right, you don't have magic in your world," she said, "Well yes, to elaborate, we can often call in a unicorn or a potions expert to heal minor organ damage or restore function from certain types of failure."

"So doubly reduced," Twilight A said with a sigh, "Alright, thank you for your hard work. I suppose we'd better meet with the other Twilight."

"Wait, there was one more thing," Nurse Redheart said, flipping to another page, "Is Princess Twilight brainless?"

Twilight A was shocked. "What?"

"Oh, sorry, I don't mean that as an insult. I mean, does she physically lack a brain?"

"Ummm... I don't think so but I can't say for sure," Twilight A said, "Spike?"

"Not as far as I know," Spike said, "Why do you ask?"

"Well, the... sample... she sent us has no brain," Redheart said, flipping the clipboard around for the others to see. On the picture was a carefully-cropped display of a pony head with the top of the skull missing. It was, in fact, empty.

"Hmmm," Twilight A said as she stared at the picture intently. "I suppose she'd need an MRI or whatever the magical equivalence is to be sure, but maybe her brain turns to magic when she respawns? Or maybe it already is magic and so it's a physical organ?"

"Ask her to come by and we'll sort it out," Redheart said, flipping the clipboard back to the first page.
"Alright, we'll be going then," Twilight A said.

***********************************************************

On the walk over to Donut Joe's, Spike and Twilight A started talking.

"You know it's kind of weird you not being a dog," Twilight A said.

"Oh so there's one of me over there?" Spike said, "I guess it makes sense that he'd be a dog."

"I should bring him over next time, see if he becomes a dog here," Twilight A said, "Come to think of it, I wonder what would happen to a Griffon in the portal? Or a changeling?"

"Huh... I hadn't thought about it," Spike said, "Oh, by the way, you called my Twilight 'Other Twilight' back there. I thought you had settled on 'Twilight 1'?"

"Y-es, but it occured to me that might be confusing in a paper," Twilight A said, "And Dr. Turner says confusing your reader is a good way to get a journal to reject your paper."

"Huh, so what should we use?"

"Maybe Twilight H and Twilight P? H for Human and P for Pony?" Twilight A or possibly H said.

"What about A for alicorn?" Spike said.

"Yes but that would get us confused since we already tried A," Twilight A said, "We'll talk about it when we meet them."

*************************************************

At donut Joe's, the quartet each got a donut and updated each other on their efforts. Twilight 1 or possibly P was not thrilled at the news about her changing blood type.

"Awww, I hoped this woudl solve the organ shortage," she said when told, "I mean there were negative blood types but that's recessive so there aren't as many."

Spike and Twilight H also discussed her possible empty skull.

"I guess that solves the resucitation question," had been Sunset's comment.

And the naming issue.

"I'd say Twilight and Princess Twilight," Sunset said.

"I don't know, I don't want my title to be why we're published," Twilight 1/P said, "Let's go with the H and P idea."**

Twilight P and Sunset, meanwhile, informed the others of their relatively boring negotiation with Filthy Rich. He was a natural opportunist, but he was also the sort to go out of his way to retain a customer. He had explained that time had been of the essence, but that he would be glad to re-organize Alicorn Enterprises as either a non-profit or a governmental organization. Twilight P planned to talk to Mayor Mare and Nurse Redheart later to help figure out which would be better for those involved, and had in the meantime gotten him to agree to sell to the Griffons and Hippogriffs at cost. Twilight jerky was apparently going to be on menu.

"I suppose the next set of questions to answer are afterlife related," Twilight said, "But since none of you can go with me on that, I'll need to start solo until one of the other Princesses can get time off."

About this time they had finished off their donuts, and Donut Joe came by to see if they needed anything else. Something was off, though.

"Will there be anything else?" Pony Joe said in an unfamiliar voice. The accent sounded British or possibly French⁵. Stranger, when he finished speaking, cheers and applause came out from nowhere.

"Hey, Joe?" Spike said, "What's with your voice?"

"What about my voice? Oh I hear it now," Joe said. He became visibly exasperated. "I'll never get used to this... Discord!"

In a flash of light, the draconequus appeared in a flash of light, arms raised wide and a showman's (showpony's?) pose.

"Discord! What are you up to?" Donut Joe said, "Wait why did I say that? I'm usually fine with your antics."

"Why thank you," Discord said, "I do so enjoy your sense of humor, Nut Joe."

"Nut Joe?" Joe asked.

"The reference works better with 2 syllables," Discord said, "And really, if we aren't going to pander to the fans, why bother with this bit?"

"Discord! Change him back!" Twilight P said angrily, "I know for a fact Fluttershy's told you why it's wrong to change ponies against their will!"

"Oh relax, it was just his voice," Discord said. He snapped his claws anyway. "Try now."

"Ahem. Testing testing. Ah, much better," Joe said, "Now, do you folks want anything else?"

"Just the check please," Discord answered for them, "They have some pressing business with me."

"What are you...?" Twilight P began.

"Well hello my little ponies!" a familiar voice said from behind him. Discord twisted his body out of the way, revealing Celestia. "Oh, I see Discord has already noticed!"

The ponies and other creatures in the donut shop bowed, some of them getting up. Twilight H was confused, but imitated the others as best she could.

"Go about your business everycreature," Celestia said, "Oh, and you must be the other Twilight. How is your principal doing?"

"Uhh... fine.. your highness," Twilight H said once she was out of her bow.

"Oh no need for formalities. Think of me as your principal's sister," Celestia said.

"Oh, uh, thank you," Twilight H said.

"How did you know where to find us?" Twight P asked, "We were planning to meet you at the castle after this."

"Gabby told me where you were meeting," Celestia said, "And since Discord is here, that simplifies things."

"Simplifies what?" Twilight P said.

Discord vanished in a snap and reappeared just slightly to the left (so as not to block Celestia), now in judge's robes, complete with a wig and gavel.

"You, Twilight Sparkle, have desecrated my home!"

Discord then appeared behind her and gasped.

"I've done what now?" Twilight P asked.

*Eagles and lions, which are the two halves of Griffons, are opportunistic predators. While they can and do hunt for themselves, they will eat carrion left by other predators as well. They'll also steal smaller predators' kills if it's easier than hunting, which might be the source of their selfish society in the show. And now you know!

**Thanks to Caffeinated Pinkie for the suggestion on a clearer naming scheme.

1 Equals Friendship!

2 Gabby said everything brightly. Twilight 1 had not had an opportunity to test it, but she hypothesized that if you put Gabby in a dark cave and set her talking, the resulting illumination would be enough to find the exit.

3 Gabby also used a lot of exclamation marks. A remarkable feat considering she was talking, but if you asked anycreature who spoke to her regularly what punctuation most of her sentences ended with, a majority of those who understood the question and bothered answering would have said exclamation marks.

4 Clipboards were a necessity in medical settings, even in a species whose anatomy rendered opening the clip somewhere between difficult and unpleasant. Dimensionalists argue whether clipboard inter-universality is due to some multiversal resonance, or because they look cool. Some Cool-ologists claim it is both, and that 'cool' is a universal concept across dimensions, but Dimensionalists deemed them 'uncool' and banished them to the metaphorical table way in the back in the metaphorical metaphor lunchroom.

5 Patrick Stewart. It's Patrick Stewart.

Author's Notes:

Alright finally finished this chapter! One more to go plus an epilogue... but the next chapter will likely also be split in two.