I was still in the chair when I woke up. The sky was starting to lighten. Princess Celestia was raising the sun. I could see it now. I'd watched her standing in my hospital room raising the sun before, but now I could see the actual process itself. I couldn't see the sun's disc; it was a single overwhelming vector made of pure willpower, laying out in no uncertain terms exactly where and how fast the sun was moving. The colors of the sunrise around it were touched by shimmering twirls of potential, as though that single burst of will was radiating out the rest. It sounded like diamonds.
Maybe that was exactly the case. Physics in Equestria is much more subjective. Regardless, whether or not I could enjoy it, I could recognize that with my new perceptions, it was the most beautiful thing I had ever seen. I watched it until the colors settled and there was just the sun again, moving steadily upward. If I ever did get myself fixed, I suspected I would want to remember that.
A pencil moved. I looked away from the window. Pinkie Pie was sitting in another chair. Her mane was drooping, but not limp. She had her clipboard in her hooves.
"Not the sunrise either," I told her.
"I asked Princess Celestia to make it a really good one just for you," she said, and slumped. "I came in through the door, promise. I just held real still so you wouldn't notice me until after."
"That was just for me?" I said, and looked out the window again.
"Uh huh," Pinkie responded, and yawned. "Princess Luna helped. She said you should get to have it and she looked sad."
"I never had a sunrise before," I said. "It wasn't possible, on my world."
"I never heard of Princess Celestia making a sunrise just for one pony before either," Pinkie agreed. "But I'm gonna pull out all the stops. I'm going to see you smile, Gus. I Pinkie Promised."
She wasn't that bouncy, energetic pony who pounced me outside the hospital. Her jaw was set and she was holding that clipboard tightly.
"Can you smile, Pinkie?"
She lifted her head and put a small, watery smile on.
I shook my head and patting my knee. She tucked the clipboard back into her mane and walked over. Not bounced. She climbed up over my lap, and I set my hands on her back.
"Can you smile for me, Pinkie? A real smile. From inside, like you said. Not smiling at me. Smiling for me, smiling because I can't." I didn't want her to, I didn't care, but I couldn't. Just because you don't care doesn't mean it doesn't matter.
"I don't know," she said in a small voice. "Smiling because you can't smile doesn't make me want to smile."
"Don't smile over me not being able to smile," I told her. "Smile the smile I should have because I got to meet you. Smile the way I should have smiled when I met your friends. Laugh for me at the idea of having my own sunrise."
"Those are your smiles," she said. "It's sad you don't get to have them."
"Then smile with the smiles I should have," I told her. "Smile because it's all going to be okay."
She sniffled and looked up to me. "Pinkie Promise?"
I ran my fingers through her mane. "I Gus Promise. Cross two worlds and all the rest, this'll turn out for the best."
I don't know where that came from.
She turned and sat up in my lap and hugged around my neck very hard. "Nopony ever got that," she breathed, and then she started to laugh and cry at the same time. I hugged her back until she fell asleep holding me.
***
The first thing Twilight Sparkle wanted to do in the morning was run another brain scan. She put it up next to the first one.
She dropped onto her rear, looking up at it. There was a clear visual difference.
"Gus," she said in a very uneven voice. "That's grown by almost five percent overnight. At that rate of progression..." She trailed off. I'm certain she had the math down to well beyond the last significant digit.
"All the more reason to get to work while I can," I said. I could do the math too. About fifty days, more or less, if my eyeballed estimates on volume and growth were right. Assuming that I'd stay conscious and functional right up until the last brain cell was overtaken by the magical graft, which was probably not a reasonable assumption.
"No!" she said, and she dissolved into possibilities. Most of the rest of the lab did, too. The pain came. Everything else became numbers again.
Then it all came back. Twilight was holding onto me with her hooves and gasping out something at high speed, her eyes shut. I reached up to pat her side. Her mane was frizzy.
"GUS!" she all but screamed, and then collapsed on top of me. She was definitely hyperventilating. The question of what to do about that resolved itself a few seconds later when she fainted. Her breathing quickly returned to normal at that point.
I worked myself out from under her and sat up. I took stock of the situation. Unconscious unicorn who just had consecutive panic attacks and dropped me as a side-effect of the first one. Brain-damaged human. Lab that doesn't look like anything exploded in that first magical thing she did. First order of business, decide what to do about Twilight. Hyperventilating is just breathing too fast, so she should wake up shortly, I guessed. I didn't know if there might be anything else to do; I was studying to be an engineer, not a doctor or a veterinarian.
Between trying to wake her up and letting her sleep, I choose to let her sleep. If she woke up in the same emotional state, nothing productive would get done. She seemed to be much calmer, unconscious. The next question was to stay or to go try to get medical help, in case she was in some danger. If she needed help and I stayed, she could be in trouble. If she did not need help and I left, she would wake up without me there and might have another emotional reaction. She made it this far in life without self-destructing, so I should go get help to avert the worst-case scenario.
I fell over trying to stand up. I felt fine, for my recent definition of fine. I just couldn't execute. I got onto my knees without incident, but I could only get on my feet by supporting myself on a table. The moment I tried to take a step away, I toppled.
It didn't take too many experiments to confirm a new hypothesis: I'd lost my sense of balance. Much more of a problem than losing my sense of smell. That made walking across town to the hospital to get help for Twilight a much more significant challenge. I recalled an alternative.
Pinkie was still asleep where I'd left her, laid atop a couch with a blanket pulled over her. The couch was in the house when I moved in, and human-sized. She fit on it easily. I didn't have any trouble crawling in from the lab to the house. I sat down at the side of the couch and put a hand on her side, trying to wake her without startling her. My head has enough problems without being bashed with a hard hoof like a cartoon alarm clock.
Her eyes snapped open and she beamed a smile into my face. "Good morning, Gus! I feel a lot better now! You're right! Everything's gonna be oooooo-kay!"
I should have thought ahead to exactly how to tell her. She caught my hesitation. Numbers and pain slammed into me, but a hoof grabbed around my shoulders and kept me upright, and the moment passed as fast as it came.
"I'm sorry I'm sorry I'm sorry," she said, but she looked me right in the eyes. "You and Twilight were taking a brain scan and it showed something really really bad and she started to panic and you fell down and she snapped out of it realizing she hurt you and then she hyperventilated but now you can't walk and she's fainted and you need me to go to the hospital and get an ambulance but everything's going to be okay just a hunch be right back!" She let go of me and galloped for the door. She didn't bother with the handle and it swung inward. She just lowered her shoulder and charged right through.
She looked like she was trailing red lightning. The jagged bolt kind.
***
Doctor Vital Signs ran me through a series of tests, checking my legs. They seemed to be working fine. I could lift well more than my own weight with them, I could move my foot and wiggle my toes, and I passed the bucking test with flying colors. The last was a target set up with a weight attached, with marks set for eath pony, pegasus, and unicorn adults and juveniles. My results, according to the doctor, were in line with Lero's. Precision high-end for an adult earth pony's buck, strength at the low end for a unicorn juvenile. I mentioned Applejack and he informed me that the Apple family has a separate scale entirely.
I simply couldn't balance on two feet. I didn't feel any vertigo, nor did I feel drunk. My ears were fine, or as fine as Doctor Signs could tell. Given supports for balance, I could walk perfectly well. As for neurological examinations, he checked me for a concussion and then told me frankly that Twilight Sparkle's equipment was better than anything the hospital had that didn't require active spellwork, and that she was by far the pre-eminent expert in Equestria on human mental functions. Anything else he could do would be redundant. He did, however, send word to Princess Celestia, and she sent a scroll back via Twilight's dragon to say she would come in the evening, before sunset. I'd somehow managed to miss finding out that Twilight Sparkle kept a dragon in her library. That must be a fire hazard. I'd been busy.
Twilight was fine; she woke up before the ambulance arrived, but the pony paramedics insisted she come along and be checked out anyhow. She, Lero, and Lyra escorted me out of the hospital again. Rainbow Dash was at work. Nurse Redheart told me on the way out that they'd have crutches for me and in the meantime to stay in the wheelchair. It was too small, still, but I could manage.
I noticed that Twilight Sparkle had a horn inhibitor on again, but she wasn't wincing the same way. I asked her about it.
"Princess Celestia's orders," she said, and the hangdog expression on her face gave me an urge to hug her. "She said not to cast any spells around you at all, and do whatever I have to to make sure I don't. So... inhibitor. I'm so sorry, Gus, I lost control and I should know better than that by now. Maybe I should just wear one all the time until I learn to stop overreacting."
"No," said Lyra firmly. "That's not learning control, that's training yourself to stop using your magic. For a unicorn like you to stop using her magic would be a tragedy of historic proportions."
"It'd be better than getting Gus hurt!" Twilight said. "Or anypony else. I could hurt somepony. It'd be better to just shut myself down until I'm not a danger to Ponyville anymore!" Her mane was getting frizzy again.
Lero stepped forward, putting himself between Twilight and Lyra. They both froze in place, and then their heads ducked down. Lero looked between them and waited. Twilight mumbled, "I'm sorry, Lyra. I'm overreacting, aren't I?"
Lyra nodded her head. "Yes," she agreed.
Lero rubbed them both on the cheek. "Better now?" he asked.
"Better now," Twilight said. She sighed. "So... what do we do now? Something without magic."
"There's always science," I said.
"What? But? Even after this morning? I mean when I?" Twilight sputtered. "I almost killed you, Gus! And now you want to go back?"
The numbers were swirling around me.
This was a triumph.
I'm making a note here.
HUGE SUCCESS.
Then they went away. My stomach hurt, but only moderately.
Lyra pulled her hoof back. "No songs," she said sternly. "No magic, no songs."
"Lyra!" exclaimed Twilight. "Couldn't you have interrupted him some other way?"
"I don't have a bucket of water handy, I didn't want to hit his head, and I don't have your variety of options, so no, a poke to the barrel was the best I had," Lyra said. "I didn't hit you too hard?"
"I'm still alive," I told her.
***
We went to the library first. Twilight had some books on Equestrian physics that she thought I might be interested in. I asked for information on light and anything she had on chemical theory. She knew she had lots of the first, but the second was unfamiliar. Given that she hadn't known the composition of water, that wasn't too surprising.
"Anything about the theory of what things are made of at very, very, very small levels," I said instead.
"I'll see what we have," she promised, but I believe she was dubious.
I met Spike. I revised my earlier statement from 'Twilight kept a dragon' to 'Twilight adopted a dragon.' I had been using a mental image of one of Anne McCaffrey's firelizards, which was a grossly inaccurate model for Spike. Once I learned his name, Sweetie Bell's comment about fire becoming a habit made a lot more sense.
Spike was a friendly little dragon, and Twilight's personal assistant along with being her de facto son. He was running the library while Twilight was with me, in fact, and knew better than she did where everything was located. He also had a great deal more restraint than she did.
"Okay, Gus, here's Practical Optics by Cut Glass, and the best I could do on that very-very-very-small stuff was this one," he told me. The second book was Light Within Dew by one 'Princess Celestia.' "It's all about what's inside a single drop of water," Spike apologized. "There's some books about microscopic life and genetics and things, but they don't get as small as this one."
"Thank you, Spike," I told him. "This should be a good starting point."
Twilight started writing, but quickly discovered that her mouth-penmanship was tremendously rusty, and the inhibitor prevented her usual form. She recruited Spike to take her dictation instead, writing up an initial monograph on our discoveries regarding gravity's subjective nature. The cadence of her voice was steady and calm; she was very clearly in her element.
The book on optics was, in a word, illuminating. Equestrian light does not straddle the boundary between particle and wave; it straddles the boundary between physical and magical. White light is a type all its own and apparently pegasi can condense light into a liquid form. There was no mention of prisms or of refraction separating light into different frequencies, nor did I find any concept of chromatic aberration. Refraction and lenses were the primary focus of the book, and a variety of familiar formulae were waiting there for me in that regard.
Different colors of light, instead of being different frequencies, apparently feature different weights, creating a superficially similar pattern to the red-orange-yellow-green-blue-indigo-violet of my world's rainbows. The colors of light can be blended, but tend to remain separated unless something forces them together. There was a photograph of liquid light running from a pegasus weather factory built of clouds, streams of color remaining separated even as the fluid flowed freely.
Light is also distinct from heat, though the book noted the difficulty in separating the two; the only known process involved what it indicated was a tricky bit of spellcasting for little practical benefit. There was a section on X-rays, and then a chart that made the matter very clear. Equestrian light is quantized at a much more macroscopic level. Infrared light, heat, separates out from visible light and requires much higher energy inputs to force into a different state. Visible light occupies a bucket of its own, with internal segments. X-rays are a completely different area of the spectrum. Large parts of the spectrum were blank and annotated with 'No process has been found to interact with or generate light in this range.'
Magic had a large mention as well. It could be summarized like this: Light is the easiest thing for magic to influence, and even a relatively unskilled caster can make most of the other rules about light go out the window. The book also noted that it was difficult to explore the non-visible spectrum magically, as most unicorns need to visualize what they want to do and have great difficulty trying to visualize non-visible light. Some pegasi innately exude light-altering magic, and when I mentioned that Lyra confirmed that their alpha mare, Rainbow Dash, frequently leaves an extended rainbow trail behind herself.
All in all, Practical Optics moved radio and related technologies far to the back shelf. There was nothing that could detect radio waves, and absent electrochemical reactions I couldn't think of a way to make a semiconductor to use in an antenna.
The other book, Light Within Dew was much more of a philosophical piece. Princess Celestia wrote in a fluid, inviting style, though it was wasted on me. A large portion of the book involved relating the drop of dew to various factors in pony life, though it did also give some indications of the level of talent and power the princess had relative to her subjects. The final chapter was the only one that had anything useful to me.
As we peer deeper into the heart of our droplet, what do we find? We find water. A single ray of light searches as delicately and tightly as it can, and even at that deepest level, so small the sharpest-eyed pegasus who ever lived could not see it through a microscope, we find... water. There is something comforting in that, in knowing that the small and the large are one and the same.
Can we look deeper yet? We can, but there is little use to it. Magic and light ultimately both come upon their limitations, and the most perfect ray of light the sun can produce cannot shine itself any tighter. There is simply a point at which nothing can be distinguished any longer. At a certain point, even water becomes indistinct.
I had another hunch. I couldn't think of a way to test it and be sure, but the idea had a blue balloon with glasses and a mortarboard attached.
I do remind myself periodically that there is an excellent chance I am completely insane and sitting in a hospital somewhere, unaware of the world.
In any case, I had my hunch. "I don't know how to blow up a city, Twilight," I announced to her.
Lyra and Spike both gave me very intense looks. That probably was an excessively dramatic way to make that declaration.
"Oh, good!" was her response. "What made you figure that out?"
I tapped Light Within Dew. "My world operates on an atomic, particulate structure that devolves into probability fields below a certain threshold, around the level of electrons, more or less. Your world, based on my interpretation of this, goes into probability fields at a much higher level. You remember how I told you that water is made of two gases?"
"Of course," she said. "So that's related to your... two cities?"
I nodded. "In the very short form, our world is made of tiny particles called atoms. Like I told you, quintillions of them in one grain of sand. Atoms make up the fundamental elements - gold, for example, is a pure element, one that can't be changed into something else, because a single particle of gold is still gold."
She asked the natural question. "So what happens if you cut a single particle of gold in half?"
"Then you start to lose cities." I set the book down, since I didn't need it any more. "There are components inside each atom that make them different from each other. At the center of each atom is a nucleus made of even smaller particles called proton and neutrons. Protons have a kind of charge, neutrons do not. Electrons make up a probability cloud around the nucleus, and they have the opposite kind of charge from a proton. Two forces in our universe, the strong nuclear force and the weak nuclear force, govern how atoms hang together. They have very short range, but immense amounts of energy. When you break atoms apart, you release that energy."
Twilight bobbed her head for a minute, and I was fully aware she was taking my very basic and imprecise description of the atomic model and internalizing it. "Since you were able to put together a civilization, I assume it takes more than hitting an atom with a hammer to break one apart?" she said.
"Much more. I can go into that later, if you want to. The contrast is with your world. I'm not entirely sure what sort of experiment could prove this, but I believe that the strong nuclear force and weak nuclear force are fundamentally undetectable here, because the atomic structures themselves are below the level of uncertainty here. You can't identify a single atom, only an area where an atomic structure probably exists, but every point inside that area is functionally indistinguishable from any other. At that level, there's only probabilities that something exists."
Twilight's eyes did that sparkling thing again. "And since we've determined that magic influences probabilities based on the user, that's why magic can transmute substances from one thing to another! Because you're redefining the local probability structure!" She began bouncing around again. She got very excited about scientific discovery. "It all makes sense! And so when you and Lero came here, your atomic structures 'blurred' into probability forms, while your consciousnesses acted as observers with the innate expectation that you'd continue to exist just like you had been, so you did! And if I went to your world..."
She stopped bouncing, and her eyes went wide. "... If I went to your world, you don't have any magic there, so even if my waveform structure successfully resolved itself into discrete atoms, my magichemical-based brain wouldn't work, and you don't have anything that could substitute the way Equestrian chemical and electrical reactions could adapt..." She swallowed hard. "... So Project Technology Transfer would end up with a brain-dead pony."
"Project Technology Transfer?" asked Lero.
"I may have been doing an eensy little tiny bit of thinking on theoretical things that might possibly be able to visit your world, but so far all of them involve the step 'assume Twilight conveniently discovers an impossible new form of matter,'" she confessed guiltily. "Also assuming that I could find a way to get to your world instead of some other one."
"This is my world now," Lero said firmly.
Twilight sighed. "Yes, Lero. And I couldn't go to your old world without breaking my brain anyhow, so I have to come up with a new project." She brightened again. "Like expanding on Gus' theory! It doesn't change magical theory or existing physics very much but it's so very fundamental and hard to experimentally prove without an atomic-structured basis for comparison, there's going to be years and years and years of debates about just how to define the very basic terminology of the field!" And she was back to clapping her hooves together.
I noticed I couldn't feel the book under my hand. I could feel a pink star, though.