By the time Spike and Pinkie came into the room to (presumably) confront and-slash-or comfort her, Twilight was already cutting a much more sedate path around the room. Of course she was also maintaining seven levitation matrices, an object blinker to flip the hourglass, an acceleration spell and her usual dictation spell (for when Spike was unavailable). That brought the aforementioned dragon to a slow and shocked stop, and she really had to work to suppress her giggle. Even for her notoriously absurd magic this was over the top, and some explanations were owed... On all sides.
"H-hey Twilight, we... wanted to check in on you, after-"
"You bolted outta the blue like Rainbow Dash dodging a super-literal bolt!"
The comparison almost caught her off guard, but she'd been preparing to shut down the Superb Stenographic Spell anyways. The note-paper and quill sent themselves back to their respective drawers and she turned to her friend and (word-not-found) with a sheepish grin.
"Sorry Pinkie, sorry Spike. I really didn't mean to get so worked up, but... This is a big deal."
Spike gestured to all the floating objects nearby, and the thick corona of magic around her horn.
"Like emergency big, or just the usual freakout?"
"Oh it's not an emergency!"
"Goo-"
"Not yet anyways. Assuming neither of you two, or me I guess, ever inform any other pony about what happened with dessert today. We might have an emergency on our hooves then, but not any sooner!"
"...uh?"
"I second that uh. Doubleuh!"
Twilight rolled her eyes at that, wishing she could rush over there and hug them both: They were clearly unnerved by things and she wasn't exactly helping with her dialogic nature. It just made more sense to explain this kind of thing slowly rather than blurt it all out and then sort the aftermath, you know?
"There won't be an emergency, I trust you both. At the very least we will be able to tell other ponies about this... Once we find a way to mass-produce it!"
Pinkie's eyes narrowed and Twilight quickly realized how bad her phrasing was.
"Twitwi, you know how I feel about ponies asking me to do factory scale desserts! Especially if it's something like this that was supposed to be special."
"Of course! I misspoke, that wasn’t my intention at all. I'm... Still sorry. More sorry? Sorrier. Although I'm feeling quite good at the moment, which is rather surprising given the workload I'm maintaining. But what I meant was the buff, not the food. Your trifle was incredible Pinkie, and I'd never ask you to do something like that. But I mean... Spike and you working together made something that can actually increase a pony's reservoir of magic!"
Of her audience? Pinkie Pie clearly didn't understand the significance at all, while Spike only recognized it as a topic she had harped on in the past. Either she'd never been explicit on the details or his Eidetic Memory skill wasn't retroactive... She was fairly sure it was the second one, but yesterday was still kind of a blur.
"Spike, I assume you did get the benefits of those foods added to your menu? The way our experiments at breakfast did?"
He made a few passes of his claws through thin air, and yet again she wished it was possible to see his Menus with her own eyes... Although they were supposed to test his Party system after this, so maybe she could! Oh the data, the sweet sweet science...
"Yeah, one of them."
She tried to keep the sudden horror off her face. If it was lost, so soon after she found it...
"J-just one?"
"Yeah, the stir fry said it had an error because it 'couldn't reach its full potential', so I think I must be missing some kind of subskill or specific supporting ingredient."
The relief flooded her from hoof to horn and she physically sagged back, putting her flanks against the nearby dresser. Above her, the hourglass flipped again and a small cone of incense ignited in an automagical spark to keep track of the overall passage of time.
"That's fine, then: I'm sure you'll figure that part out someday. But I'd really like to ask you, speaking as your... Me. Speaking as Twilight Sparkle with whatever that means, I'd be grateful if you don't use that effect on any pony except for myself or Pinkie. Or yourself, I suppose."
"...Why?"
As expected, he didn't take that without questioning, and she was incredibly proud. Not despite the fact that he was questioning her, but precisely because of it. It had taken Celestia much longer to get her to grasp the same lesson, sad to say.
Of course, it helped that she actively wanted to be questioned under these circumstances! Because to be brutally honest? If she didn't get to go on an expository blitz about this right now she would surely go mad. The cursed life of a researcher, forever doomed to want to talk about things no other pony in their right mind would understand, much less care about.
That meant it would be best to make her presentation as interesting as possible, and for bonus points her prior display would even double as a demonstration! Sweet marefriend, Twilight really loved efficiency.
Her other spells quieted and inverted in places: Incense snuffed out, hourglass set into a balanced position that sent no sand. Quills and paper away, books marked and replaced. Windows closed, curtains drawn, candles lit... It was time for a dramatic reveal.
- - - -
Twilight arranged the details in her head, which wasn't difficult. She'd been thinking about all of this quite recently anyways, and it was a subject near and dear to her. Pinkie would have little prior information about the topic however, and Spike's knowledge wasn't going to be much deeper. So she got to explain it all from the start, which she'd always found useful when constructing a new thesis or way of thinking. Summary and review, rephrasing and explanation: Critical tools!
"Unicorns, ponies in general, don't... There's no concept of a 'Magic Point' outside of games, at least not an established one. There's no standardized unit of measuring magic as-it-is-spent and as-it-is-kept. We can measure magical radiation, the remains and offgassing so to speak, but the actual inputs? It's all relative!"
Neither of them interrupted her or asked questions yet, which Twilight was very grateful for. It was harder to verbalize the concepts than you would think, but she had been practicing! Questions could come later.
"For unicorns it's taught as a matter of what is comfortable, and what is safe. Think of them as different thresholds. Or bands! First is the absolute maximum, all the magic in your body. Then how much of that you can spend without permanently hurting yourself, that's the safe amount. And then there's the normal 'limit' for a unicorn: How much can you spend without pain or major discomfort."
She'd relearned those limits over and over again growing up, between one study binge or another. Outside sources like the Rainboom-induced overload that hatched Spike? Those were special. But even on her riskiest binge she never dipped into unsafe territory... Barring national emergencies, of course.
As she continued to speak, she took a moment to look over her audience. Spike was clearly running the ideas down in his head, while Pinkie hadn't shifted her expression at all... Which was very Pinkie, all things considered.
"So, there's no quantification except for relative values! It might be 'Oh, levitating this box would take about half of my comfortable limit' or however a given pony would phrase it. It could even be a hard number like 'My safe limit is 20 and this spell is a 10', but those numbers wouldn't translate to any other pony's use of magic: They're just a relative measure that specific unicorn came up with."
Now she finally got an interjection, right in the pause she left for it: If it weren't for the interpersonal aspects? She'd probably be an OK teacher. Then again, she was always improving there as well...
Pinkie poked her head up, having come to a conclusion rather quickly.
"So just by raising the big total, you raise all those other smaller ones too!"
"Exactly! More magic means a higher safe limit and a higher comfortable limit. But it's an even bigger deal than that, because-"
"...Because you didn't freak out like this at breakfast. I made a dish that boosted efficiency, but I'm going to guess that doesn't have the same impact."
She couldn't hold back the pride in her heart, reaching over to ruffle Spike's spines... It was a lot easier now that he was tall enough to look her in the eye.
"No, I didn't. And yes, it doesn't. Efficiency is a concept we already have an understanding of, scientifically-speaking. And it’s more... A unicorn putting magic into a spell gets most of that magic back afterwards, returned through the spell's circuit. It's like if you went to the store and the clerk required you to pay with 20 bits, even if your item only costs 15. You do get the remaining 5 back in change after but for whatever reason he can't accept a smaller coin to begin with."
"Oh, oh! So efficiency would be like you were still paying 20 up front, but getting back more change! A rebate instead of a discount, like with the cereal box flap thingies!"
At this point Twilight was prancing on her hooftips with joy: It was so easy to talk with smart ponies! Well, a smart dragon and a smart pony. Whatever. It was a wonder she hadn't done research with Pinkie in the past, if she was this quick on the uptake! Although maybe that had been an instinctive dodge of all her other quirks.
"Yes! Which is very useful for sustained casting, but it's not going to give you a bigger budget for one purchase... So to speak. Um, this is where that analogy breaks down unfortunately. I tried to figure out a good way to bridge the comparison into my next point, but the last time I really tried? There was some Hearth's Warming cider lying around, one thing led to another, and I might have blacked out and rewritten a quarter of the Equestrian postal code instead."
The joke (and only Spike's exasperated expression showed that he remembered it was no joke) helped lighten the mood, and got her mind back in position. The last part was... hard to talk about.
"If anypony is doing magic, whether that's a pegasus working with the weather or a unicorn casting a spell, an earth pony tending their trees or Fluttershy... doing her things. When that happens, there's three main factors that make it possible: How much power they can put in, how complex the working actually is, and their affinity for what they're doing."
She let that pin drop, but neither of the audience members interrupted: Either they hadn't reached the natural conclusion, or they were waiting for her to say it. This was really so much better than the Canterlot symposiums.
"...Complexity and difficulty, you can overcome that with practice and understanding. You could even figure out a better, more efficient version of the spell! Affinity, you can improve through learning and immersion, or changing the angle of approach. But power? There's no easy way to change that apart from long-term growth, and that has limits. As for other methods of increasing power... We all remember what Trixie did when she came back to town."
Pinkie raised a hoof to her muzzle, as if making sure it was still attached. Twilight cursed herself in her head, wishing she hadn't picked that specific incident, but... It was equally serious business.
"What Spike discovered here today changes everything. This ‘buff’ raised what is essentially the density of my magic. The same volume in the body, if we were talking about a material substance, but with a greater weight in that volumetric space! More value for every coin, in the previous analogy. That’s a direct increase of power and potential across the board, even if I don’t change the perceived ‘input’ at all.”
Twilight took one more deep breath and finally arrived at the conclusion.
“If this is even a little replicable, especially if we can find a way to reproduce it without leaning on Spike as the source? We could be talking about a complete upheaval of everything the scientific world knows about magic! That is why I want you to be hush-hush about it, and why I don't want anypony but us three to find out until we know more."
Spike laughed, and for a moment she thought it was a nervous thing... But then he kept going. When he finally leaned back he was waving his claws through the air, looking at menus again.
"And the best part is, none of this applies to me! All my skills either have variable costs or they have a maximum within my limits: I don't know if I even could learn something I don't have the MP capacity for, instant wards aside. So it's a buff that means everything to other ponies, and... It still helps me. But it's so much less important for me, to the point where I hadn't even thought about the difference it could make for you."
Twilight nodded solemnly, even as Pinkie went through the visible motions of a Pinkie Promise. Spike did the same thing, and Twilight followed: They were all going to hide this information until it could be properly researched... At which point, even Celestia might not know what would change.
"You two... Today you accidentally, in one moment, helped me achieve a lifelong goal. Even beyond that! This is an advancement that ponies have been seeking since before my lifetime. I-"
Spike held up a claw to stop her, looking as if he had seen some kind of ectoplasmic apparition.
"...Say that again but slower."