Author's Notes:

Many many thanks to alfamaniac for his theories on Physics of Magic in Equestria.

Without him... there would be no fic.

It'd been a long day. Tomorrow promised to be even longer. With a sigh, Big Mac shrugged out of his work collar and nosed it onto the hook in the wall. Everything was sore, from his haunches to his ears. Still, he was happy the farm was producing so much, and Applejack was going to have one heck of a cider turnout this season.

Wearily, he sauntered over to his bed. He'd made it neatly that morning when he woke, before the sun rose. He always felt better coming back at the end of the day to a clean, crisp bed - white sheets tucked neatly beneath the simple blue quilt, pillow centered on the mattress at the headboard. He nodded silently to himself in approval. Simple things.

"Big Mac!" He heard his sister call from downstairs.

"Eeyup!" He called back. Hooves came up the stairs rapidly, and Applejack edged in the door, balancing a cardboard box on her head.

"I was cleanin' out the barn an' found a box of yer old stuff. Thought ya might want to go through it before I tossed anythin'," she smiled, popping the box into the air, bouncing it off her rump, and bucking it gently to the floor. Big Mac smiled at his sister's display of athleticism. "Well, ya look beat. Get some rest," Applejack instructed, nodding once. "Early day tomorrow. Those apples ain't gonna buck themselves."

"Eeyup."

She pulled the door closed behind her.

He crossed the room to the box, nosing the lid off, sneezing at the dust... and stared at the contents in silence.

They were his college things.

The acceptance letter his parents had framed from Horse U. in Fillydelphia. The ridiculous identification card photo he'd taken freshman year. The first formula he'd ever drafted on his own. He rummaged through the box with a hoof, and uncovered a stack of papers.

My thesis...

He leaned down and carefully extracted the yellowing papers with his teeth, carrying them over to the small table at his bedside. He examined the hoofmanship - he'd been so young then, so confident in his theory. It was evident in his pen strokes. The bravado of a colt not yet marred by the reality of life. The first Apple to ever attend college, much less attempt a doctorate.

"Physics of Magic in Equestria" it read. "A Dissertation by M. Apple."

That day came roaring back like a dragon...

He paced the hallway. Butterflies with a wing power of 10 formed a tornado in his stomach. Mac was certain he was going to expel the oats he'd eaten earlier that morning, soon and violently. For the nineteenth time, he checked his mane in the reflective surface of the wall.

It was still there.

Be cool... Just be cool... He told himself.

The door creaked open. Mac nearly jumped out of his skin. Professor Hardhorn smiled gently.

"We're ready for you, Macintosh," she said.

Taking a deep, steadying breath, the big red stallion slowly entered the room. It was not set up as intimidatingly as he'd imagined: the three professors sat at a table across from a presentation area with a podium, and he nodded in greeting to each of them in turn.

First was Professor Tuft, as cranky as he was ancient, head of the Physics of Flight and Dynamics department. The old griffin nodded gruffly in return, ruffling his feathers.

Next was Professor Saand, head of the Earth and Science department. Originally from Saddle Arabia, Macintosh was most concerned with convincing her of his theory on earth ponies.

Finally was Professor Hardhorn, head of Magic and Sorceries. The kindly unicorn gave him an encouraging nod as she took her seat. Mac cleared his throat.

"Ahem. Well... ah..."

"Speak up, boy," Professor Tuft cackled.

Mac took a deep breath and stood straight.

"My name is Macintosh Apple, and I am here today to defend my thesis, which you should all have a copy of before you, entitled 'Physics of Magic in Equestria.' In it, I explain how magic is not inherent to unicorns, but evident and expressed in all ponykind." Here, he took another deep breath as three pairs of eyes met his with interest. "It is my belief that magic, as we call it, is not so unique, and everypony is born manifesting some talent or another by the very nature of being Equestrian."

"I will begin with unicorns. As dictated by common sense and modern knowledge, unicorns channel magic via an organic enhancement known as a horn. These ponies have an advantage, as the horn is a kind of magical antennae. Regardless of the talent indicated by the unicorn's flank marking, their magic is used to alter, or otherwise change, the world and reality around them. The way in which this alteration of reality occurs, however, varies greatly, resulting in spells that span a wide range of difficulty and complexity. At the basic level, we have levitation of matter and telekinesis. At a more advanced stage, the caster becomes able to teleport matter, or advance the age of another living being. This manipulation of matter, both organic and not, is unique to the caster and the way they interact with their magic via their horn. A spell is a basic blueprint, but a unicorn must channel that through their own body's magic before they are able to wield mastery over the concept."

He paused, taking a sip of water from the glass at the podium. Professor Saand waved her hoof, indicating he continued.

"Pegasi, in contrast to unicorns, internalize magic and incorporate it into the extra appendages they have come to grow for the purpose of flight: wings. It has been proven that pegasi who suffer from a magic deficiency are no longer able to fly. When modern aerodynamics is applied, as done by a recent study at Cloudsdale College of Modern Engineering, it is shown that the wingspan of a pegasi does not generate enough lift to keep a pony afloat, much less break free of Equestria's gravity. It is then theorized that pegasi magic does one of two things: increases the surface area of the wing without increasing the mass, or magnifies the amount of lift generated by the wing. This magic is channeled by the wings the same way a unicorn channels magic through a horn. There are outliers at first glance that disprove this - not all pegasi are adept at flight. While this can be looked at as a lack of natural ability, closer inspection reveals specification of a different talent, unique to the mare or stallion, while still being able to generate and maintain enough lift to float after continued practice. These pegasi often choose to live closer to the ground. One noted subject works as a reporter, and has an adrenal gland that functions in an advanced way, granting a rapid reaction time that allows them to take a picture at the perfect moment."

Mac paused here again for another sip of water. He was less nervous now. The three professors were enthralled. Even Professor Tuft, the crotchety old bird, was leaning forward to catch his every word. Mac took a couple slow breaths and launched into the finish.

"Earth ponies have completely internalized their magic. It has resulted in seemingly endless unique abilities. It has enhanced their bodies, the magic a direct influence on their musculature and constitution, making them stronger and more energetic as a general rule than the other two pony types. However, this internalization of magic has limited how earth ponies may use their talents. Their magic may only affect the pony in question, as it is confined to their body. Earth ponies have no direct tie between their brains and their magic, unlike a unicorn and its horn, so they cannot visualize or see the effects of their magic. They also have no physical link to their magic, like a pegasus does with its wings, so they have no way to control the effects of their magic. This is why earth ponies manifest their magical abilities with techniques and skills."

He stopped, placing both forelegs together, letting the room fall quiet. Professor Hardhorn moved to speak, but there was a loud, sudden knock at the door. She frowned.

"We are in a dissertation defense!" She shouted tersely, giving Mac a look of apology.

The door cracked open and a very timid pegasus edged in the room holding out an envelope in a trembling hoof.

"I-I'm sorry, but the mailmare s-said this was urgent. Came Pony Express from P-ponyville for Mr. A-Apple."

Mac took the proffered envelope.

"Thank you," he said softly, tearing it open. He read it slowly. The room remained silent. His eyes went to the top of the letter and read it again. When they reached the bottom, he had also reached a decision, and in that moment, he was no longer a colt.

He'd become a stallion.

"Professors," he said solemnly, folding the letter. "I thank you for your time today, and apologize for wasting it. I have to go."

"Go?" Professor Saand exclaimed. "We are about to question your thesis!"

"You must defend it, boy!" Professor Tuft squawked. Mac shook his head.

"Macintosh..." Professor Hardhorn said urgently, "If you leave now..."

He met her eyes, and she saw the change in them. Mac smiled. It was not a smile of resignation, or of defeat, but of acceptance. He'd left Ponyville to find his place in the world, and now he'd found it.

"My sisters need me."

Big Mac nosed the last page of his thesis on top of the others. It was still sound... and he was still convinced he was right. So much had happened since then, so much to support his theories...

With a determined set of his brow, Big Mac picked up the papers and took them to his desk. Pulling open a drawer, he removed a fresh ream of paper, an inkwell, and a pen.

Better late than never.

The big red stallion went down the stairs as quietly as he could, an envelope clutched in his mouth, avoiding the third from the bottom. He kept meaning to fix the squeak. Someday. He looked around when he reached the bottom. No one was awake yet. Good. Quietly, quietly, he made his way to the door.

"Yer up early!"

He winced. Applejack trotted up and nudged him.

"Ooooooh, whatcha got there?" she asked. Big Mac shrugged. "A letter? What're ya doin' sneakin' around with a letter?" she pressed. Her eyes twinkled. "Is it a love letter? Are ya writin' naughty notes to Princess Luna?!"

She jumped up and snatched the sealed envelope from him. Big Mac made a noise of protest as Applejack danced away with it. She stopped suddenly.

"Hey... this..." She held the envelope out. "This is going to the offices of Scientific Equestria," she said softly.

"Eeyup," he replied. Applejack looked up at him, her eyes shimmering with tears.

"Is this...? Are you finally...?"

"Eeyup."

She ran forward and hugged her brother tightly.

"Let me walk to the mailbox with ya. I want to be part of this moment."

Big Mac nuzzled his sister's mane.

And I'd do it all over again, AJ.