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andkisses · 1 year ago

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♡ roman holiday | sunghoon ♡

will this bucket list trip be the thing that finally forces you to face your feelings? or will it be the thing that tears the two of you apart for good?

♡ sunghoon x gn!reader | wc. 9.4k ♡ genres/tropes: childhood friends to lovers and the fluff and angst that comes with it, college!au (not obvious but implied), road trips ♡ mentions of/warnings: arguments, references to a toxic family environment, allusions to drowning, i think that’s all but lmk if there’s smth else that needs added! ♡ a/n: this has been a wip for SOO long we’re talking YEARS and has changed muses several times but i finally sat down to finish this and im so proud of what i managed <3 truly some of my favorite things ive ever written ! inspired by roman holiday by halsey! this is also the longest thing i think i have ever written <3

♡ masterlist ♡

The coffee ring on the counter stares back at you, warm brown against a stark egg white. You can’t tell if it’s old or new, and part of you doesn’t care. Another part wants to know, though, when the coffee stain was made and why it was never cleaned. The motel is practically empty, the older lady behind the front desk and a tired-looking family in the corner of the dining room are the only other inhabitants.

Through the windows, dressed quaintly with homesewn drapes, you see the tall mountain trees, dark green and prickly, stretching up to the crystal blue sky. The television across the room is set to the weather station, and the anchor talks about how a cold front could potentially lead to an early snow.

A tray with various breakfast items clunks against the table, and the boy you’ve been traveling with settles in across from you, faux leather chair seat squeaking beneath in subtle “I’m hardly ever used” protest. His dark hair falls into his eyes messily, as if he only just now got up and rolled out of bed. The red flannel and vest he wears matches the surroundings, but looks absurd on your best friend.

“Sunghoon,” you start, interlacing your fingers and resting your chin on the bridge they form. Your eyes scan the tray, accounting each and every tiny portion of food. Eggs, both scrambled and hard boiled, some toast with an assortment of little jam containers, a little bowl of butter, two pancakes, half a waffle, and a few strips of bacon. “Thank you for getting everything,” you continue, leveling a stare over the top of your nose, “but you forgot the syrup.”

The boy in front of you blinks, bites his lips, and nods his head. A soft yeah, I forgot the syrup escapes his lips as he slides out of his chair, the pleather squeaking once again. “Give me like two minutes,” he says, “the breakfast bar is crazy to navigate. Do you see the things I do for you?” His smile is teasing.

“It’s no problem, Hoon—” Your voice trails off as he jogs off into the distance. You shake your head, feeling lethargic and sleepy beneath the slow-turning ceiling fan. Your gaze follows its metallic clink, and the fan seems as if it’s never been replaced in the 50-something years this establishment has operated.

You’re brought back down by a small tug on your sleeve, and when you look, it’s the little girl from the tired family across the room. She blinks up at you, not much unlike Sunghoon, innocent and full of curiosity. You nod your head, encouraging her to talk. The little girl takes a big gulp of air, dual pigtails bobbing, before, “I think your boyfriend is very nice and I like how he gets you your breakfast.”

The laugh that leaves you is easy, the statement hardly shocking at all. You’re used to it, strangers and acquaintances alike assuming the relationship status between the two of you. It’s nothing new. The little girl’s face is confused, her head listing to one side. You nod again, swallowing any additional laughter. “He’s not my boyfriend,” you reply, and you see a little bit of the light in her eyes diminish. “We’re just really good friends. He’s my best friend, actually.”

The girl’s brows furrowed together, a small pout forming on her lips. Obviously not the answer she was expecting. Then she nods, lips pursed. “Yeah, okay,” she mutters, seeming confused. Before she turns to walk back to her family, she looks back up and adds, “He’s a good friend. I would keep him as my friend for a long time.”

“That’s what I intend on doing, kiddo.” Your voice is quiet as the little girl skips back across the old, faded carpet towards her family. You see Sunghoon emerge from the breakfast bar, where everyone else at this motel must be. He waves small packets of syrup in the air. The smile that flits across your face is fleeting. You try to ignore, again, this feeling in your chest. Your voice is small, talking to yourself. “For as long as possible.”

***

The candy-colored Valentine stared back at you, practically mocking you. Third grade and only one Valentine. You tried to fight back the tears, attempted to sniff them back inside, but nothing worked. They fell, one by one, onto the homemade card, soaking through the pink construction paper and leaving roundly-shaped wet splotches across your only card.

You read the simple message, “Happy Valentine’s! – Sunghoon”, over and over and over again. You racked your brain, trying to figure out why, why, why no one else gave you a card. You were nice, you offered to help them when they needed it. It seemed like everyone liked you. They even let you sit by them at lunch.

So why?

The hand on your shoulder startled you, your head whipping up to face the figure standing beside the desk. It was Sunghoon, the boy who gave you the only Valentine in your possession. The edges of his dark hair curled around his eyebrows and the corners of his eyes. His brow scrunched with worry, and he ducked down to see your face.

“Are you okay?”

You shook your head, a bitter pout filling out your lips. “Does it look like I’m okay?”

Sunghoon shrugged, removing his hand to pull out the seat beside you. “I guess not.” He pursed his lips, hands clasped in his lap, before looking back at you. “What’s the matter?”

You flung the single Valentine—his own Valentine—back at him. The construction paper flew through the air before catching, floating down to land on the table by Sunghoon, who deftly picked it up and turned it over in his hands.

“It’s the only one you got?”

You nodded, crossing your arms on your desk and sinking into them. A heavy sigh left your chest and you sniffled, trying to keep the angry tears from falling again. You wished the day would end; that the bell would ring and release you so you could go home and cry somewhere comfier instead.

There was silence, then, “Does it matter if you only got one?”

You scoffed, still hidden in your arms. “Uh, duh? It means no one in this class likes me.”

“Then… why does it matter if everyone else doesn’t like you? Shouldn’t one person liking you be okay?”

You bit your lip. You can’t tell if you like his thinking or not. You decided not to respond.

You heard the chair scrape against the wood floor beside you, and you figured it was Sunghoon leaving to return to the other students. That was fine, you figured. It’s what you should expect, anyway. Even if he was the only one who gave you a Valentine, it was probably only because he gave the whole class Valentine’s. What a guy.

Then the chair was drug against the floor again, much closer this time. You popped your head up, a scowl still on your face, to see what was happening. Sunghoon had scooted it closer, and in his hands was another Valentine. You watched as he flipped the card over to the decorated side and skillfully pulled off the foam heart-shaped sticker, as if he’d had to do this thousands of times before.

His question is one you didn’t expect. “Where do you want to go?”

You look up at him, incredulous. “What do you mean?”

“Well, if you don’t have many friends here, you must want to be somewhere else?” Sunghoon shrugged, as if the thought made perfect sense to him. “Right?”

You pursed your lips, mimicking his shrug. “I guess you’re right...”

“Then,” Sunghoon began again, “where do you want to go?”

“Uhm, my house?” you answered. Crying on your fluffy bed would be much more comfortable than crying on this hard desk. Your arms were sore from resting on the edge and your back was stiff from the awkward angle.

Sunghoon shook his head. “No, think bigger. Like, vacation places and stuff.”

“Hmm... then, maybe, the big cities? The ones you always see in TV shows. And... the beach, because the ocean is really nice.”

Sunghoon nodded, diligently taking note of every place you suggested. His handwriting is a little crooked, but it fit on the now vacant front of a Valentine’s card. He looked up at you, eyes wide with question. “Anywhere else?”

You frowned, deep in thought. Then, as if someone tapped you on the shoulder and whispered it in your ear, an idea sprung to mind. “A really tall mountain, where it’s snowy all the time. No matter the season”

The pencil lead pulled across the paper, leaving information behind. Sunghoon returned to the top of the page, tapping the pencil’s eraser on the side of his cheek before scribbling a final note down. “There! It’s finished!” He slid it over in front of you.

You read the title of the list aloud: “The Wanderlist? But that isn’t even a word.”

Sunghoon shook his head. “It is now.” He leaned over, pointing at all the places you had stated. “And that’s everywhere we’re gonna go, because I’m your best friend now. We won’t be lonely, because we have each other. And we’re gonna travel all over.”

You sat up, leveling him a stare. “Well, this is gonna be expensive, you know. Trips aren’t free. They cost a lot.”

Sunghoon smiled, the kind that, even for a tin moment, makes everything seem like it’s possible. “Then we better start saving now!”

***

The pink paper stares up at you from its place on the dashboard, stuck with a random sticker right next to the air vent. The edges had aged, curling and warping, and your tear stains from 3rd grade are still faintly visible. You read over the list—your wanderlist, as Sunghoon had named it all those years ago.

1. Big cities (because TV) x2!!

2. The beach (because cool ocean)

3. Tall mountain (because always snow)

The big city had been marked off in 6th grade, when the class had a trip to the modern art museum, and again in 8th grade for a series of school-wide competitions, from writing and art to band to mathematics and science. Sunghoon had excelled at creative writing while you swept the math category for your region.

The beach was crossed off the day before the two of you left for college. How bitter it was that you had to be separated, together for ten years only to be settled in two different places. Yes, you weren’t that far away. A half day’s drive. But you both knew, deep down, how likely seeing each other was.

So you did something about it. The day before, you woke up before the sun. You loaded his car up with everything you would need for a daytrip, and you took off for the coast. You spent the whole day, afternoon, and evening parked at a spot on the beach. If you think about it now, you can still smell the seabreeze, imagine it in your hair. You can hear Sunghoon’s laugh, about what, you can’t remember. You do remember how happy you both were.

You remember sitting side by side, sharing a blanket over your shoulders as the seabreeze grew colder, watching the sun disappear on the horizon. You remember the thoughts you had–the ones you normally stamped down and annoyed. You should tell him. You’d been so close before. You wouldn’t even say the word to yourself, but you knew.

You didn’t say anything

“Can you believe these clouds?” Sunghoon says, slipping into the driver's seat and shutting the door. He places his keys into the ignition and turns like he always had. You watch the keychain you got him freshman year of high school swing from momentum. When you look back up, Sunghoon is watching you, leaning one elbow on the center console, hair in his eyes. “I suppose even the weather believes my sunny disposition is more than enough.”

“Oh, please,” you scoff, smacking his shoulder. You turn to look out the window, biting your lip. You’ve got to get it together. You blame that little girl from breakfast. You’d been doing just fine not thinking about Sunghoon in That Way. Now here you were, all these stupid feelings drummed up.

It doesn’t help that Sunghoon pulls out a cassette–MT-PSH-5–and pops it into the player. His smile grows wide as he turns out of the parking lot and onto the road, heading further up the mountain. “Nothing like some classic tunes.”

It was dumb. It didn’t mean anything.

It’s all you can think about.

Sneaking out late, hot summer heat still sticky and oppressing. You could feel the waves rise up from the concrete as it finally felt relief in the moonlight. You’d felt like dressing up, sneaking into your mother’s room and applying her fancy department store perfume to the nape of your neck. Your fingers gracefully found her pearls in the glass bowl on the dresser as you left, and you pulled them over your head, letting them rest against your collar bone. They’re still cool against your hot skin.

You escaped through the back patio, walking past the fist-sized hole in the drywall you wished you could forget about. The dusty edges kept raining down debris if someone walked too close to it. You let yourself out the gate in the fence, pulling it shut behind you. You felt for the keys to the front door in your pocket, and they jingled in response. You clasped your hand around the cool metal, the cuts sharp and edgy beneath your palm.

He met you at the corner of his street and yours, his dark hair swallowing up the soft moonlight. It made his features seem younger, softer. It felt like you were kids again.

You fell in line beside each other, walking the empty streets without fear. Who was to stop some teenagers walking the street at midnight? Random cars passed by, people finally returning home from the late shift but paying no mind to you two. And that was fine; you didn’t want them to care.

The black gates around the community pool glinted in the yellow streetlights, reaching out to you like a beacon. The closer you drew, the more the overwhelming scent of chlorine filled the air. You walked forward, hands in your jacket pockets, one wrapped tightly around your house keys. You took a deep, steadying breath. This was fine. You had this.

“Hey, [Y/N], do we really have to do this?”

You rolled your eyes, pulling your hands from your pockets and grabbing the top of the fence. You’d have to pull yourself up, and be extra careful of the metal pickets at the top. It’d be tough, but you could make it. “What?” you snapped back lightly, voice echoing amongst the night. “Scared of hopping the fence?”

“No, that’d be ridiculous,” Sunghoon replied, crossing his arms and shifting his weight to rest on one foot. “Jumping fences is nothing for me. Jumping fences into property that—” he pointed to a white and red sign just beside your knees. “—considers jumping fences into property after hours as illegal and trespassing? That sets me on edge.”

You sighed, rolling your eyes again. “It’s not like they’ve got police roaming around or anything, and the owner’s too cheap for security cameras. I’m sure if we tried hard enough, we could just pull the fence down instead of having to jump it.” For emphasis, you grabbed hold of the rods and shook. A loud metallic echo escaped into the night, and before you could pull back and shake a third time, Sunghoon had dashed to your side, placing his hands on yours to stop you.

His brown eyes caught the light as he shook his head back and forth and hissed, “If you’re going to do something illegal, do it quietly! Especially when I’m here.”

You leaned forward, head inching towards his, with a scowl on your face. “Then shut up and hop the fence.” You drew back, replacing your hands at the top and pulled yourself up and over with ease. Maybe mandatory PE did have benefits.. Your sneakers landed on the pavement, and when you stood upright from the landing, you stared at Sunghoon through the bars. “You can either join me,” you began, a smirk on your face, chin tilted up, “or you could just wait while I go and find my car keys.”

You turned on your heels, walking towards the lifeguard’s shack. You could have sworn the sigh you heard was strong enough to blow the fence down altogether

Your shoes scuffed against the concrete, and you felt the humid air of the pool spill over and try to reach out to you. Its arms clung and bit at your ankles as the water inside sloshed around with the teasing wind. You shook them off, changing course from the pool’s edge to the guard’s shack. The padlock on the door seemed old—really old—and you crossed your fingers before giving a giant tug and having it pop open in your hands.

The wooden door swung open and you stepped inside the dingy shack. Various lost pool toys littered the floor, and a box of deflated tricolor beach balls appeared to have seen better days. But you weren’t interested in any of that: you needed your car keys. Above you, nestled nearly at the top of the peaked roof was a loft filled with white plastic bins. One of them, you noted, was closer to the edge than the others, as if someone had lazily swung it up there.

You crossed your fingers again, reaching up to pull the basket down to you. “Please be there, please be there, please be there,” you chanted under your breath. You peered into the basket. On top, someone’s embroidered handkerchief. You pinched the soft material between your finger and thumb before tossing it aside in the basket. Someone’s crazy straw, two Rubik’s Cubes, a school ID lanyard, and—yes!

You fished your car keys out with one hand and swung the basket back up into the loft with the other. You turned to leave, ready to find Sunghoon, reunite with your car, and drive home, but before you can even take a single step back out you’ve run into something.

Or someone.

Your scream’s instantly shushed by your best friend, a single finger coming up against your lips. Sunghoon was so close, and you felt the pool humidity roll off his shoulders as he looked at you with confusion. “Are you done?” he asked. “And why are you screaming?”

You shook your head, holding up your keys. “Yes. Also, you scared me. How did you get in here? I didn’t think you’d hop the fence.”

“Didn’t have to.” Sunghoon held up a matching padlock to the one you’d pulled off outside. “Looks like the owner’s too cheap to buy actual locks for his gates. I simply walked in.”

You left the lifeguard’s shack, replacing the lock and headed for the entrance, where Sunghoon easily swung open the wrought iron gate. You walked towards your car as Sunghoon redid the lock, simply looping it through and clicking it shut.

You kissed your car keys and unlocked the doors, swinging down into the driver’s seat. Sunghoon slid into the passenger seat beside you, and as soon as his door shut, the engine was starting and you were pulling out of the parking spot.

“Let a guy put on his seatbelt first?” Sunghoon joked as he clicked his into place. “I don’t see you wearing yours, [Y/N].”

“Then you’re not looking close enough,” you replied, taking one hand off the wheel to pull at your own seatbelt. “Seems as if someone isn’t paying attention.”

“Forgive me, I was busy making sure no one saw our illegal activity. I would like to graduate high school next year with a clean record.”

You laughed something similar to a scoff as you flicked on your turn signal and made your way down his street. “You say that as if we robbed a bank. Is it really trespassing if the locks don’t even work? The wind could have undone them.” You turned to catch a glance at your friend, and what you caught was a judgmental glare in the green glow of the dashboard.

With a simple curve of the steering wheel, you pulled in front of his house. You shifted the car in park and rotated towards the passenger seat. “Thanks for breaking the law with me, Sunghoon. It means a lot. I’m touched.”

“Yeah, yeah, sure,” he muttered, running a hand through his hair. He leaned towards the door, making as if to pull the handle and open it, when he reached inside his pocket. His eyes lit up and he turned back towards you. “Oh, yeah!”

You shook your head, confused. You hold a single hand up. “Oh, yeah, what?”

“Here’s that mixtape you wanted,” Sunghoon answers, placing a cassette tape in your unintentionally outstretched hand. You scowled. You didn’t know how he had the technology to make a cassette in this day and age, but then again, you were the one with a car so old it still had a cassette player. You two were a pair, you supposed.

“When did you finish it?” you asked, spinning it around in your hands. The clear, Sharpie handwriting read MT-PSH-5 on the short white label.

“This morning,” he replied, fiddling with the hem of his shirt.

“Why didn’t you give it to me earlier, then?” You turn to look at him. The yellow glow of the streetlights blend in with the green of the dashboard lights. His eyes remained that entrancing brown color, though. Romantic and homey all at once, untouchable by any other shade.

Sunghoon shrugged. “Perhaps it was because you didn’t have a car to play it in when I finished it? It was unavailable to you, shall we say.”

“Ha, ha, very funny.” You kept turning the cassette in your hands, as if you’d find something new and exciting on each turn.

“Oh, and—” Sunghoon leaned across the center console, reaching to take the tape from your hands, like he had something to say or show you. But he stopped. His brows furrowed together, and he turned to you, face mere inches from your own. “Are you wearing perfume?”

You nodded. “Yeah. My mom’s, and I got mad at her since she got mad at me about the car so I...”

An eyebrow quirked up. “You’re showing your mom up by stealing some of her perfume?”

“It’s expensive,” you muttered, sliding down into your seat. “She’ll have to pay for it later. Literally.”

And with that, he laughed. Nice and hearty and his eyes turned into tiny crescent moons and you felt your heart flutter—something that had happened a lot as of late, and you’re not entirely sure why. Yes, Sunghoon was a good friend. A best friend. But that’s all he was. He—

“Hey.” Your attention snapped from a distance spot on the road over to him, and he felt even closer now for some reason. Your heart registered how soft he’d spoken and proceeded to beat faster because of it. His eyes searched yours, but for what you don’t know. When he spoke again, his voice was quiet. “Make sure you get home safe, okay? Wouldn’t want anything happening to the city’s greatest delinquent.”

“Yeah,” you laughed, but it was short and stilted. You barely heard what he said over the thumping of your own blood in your ears. You felt the red flush creep up your neck, dusting your cheeks and turning your ears a cherry color. When you swallowed, your mouth suddenly dry, all you could think about was how loud it seemed. Your grip on the mixtape tightened, it seemingly the only thing tethering you to the real world.

You couldn’t tell if the radio was one or not or whether you’d turned car off and left the keys in the ignition. All you could tell was Sunghoon, so close and so real he almost seemed unreal. And then it happened. He leaned in, eyes fluttering shut before placing a soft kiss on the side of your cheek, right next to your lips. It happened too fast and it was the slowest moment of your life all at once. Your heart was practically screaming now, hands rattling around the mixtape.

When he pulled back, he kept going, opening the car door and stepping out. Before closing it, he leaned in and nodded. “I meant what I said about getting back safely. Promise?”

You nodded. “I promise.” You were surprised your voice worked at all. That you were able to form a coherent, albeit a simplistic, sentence. That you could think at all. The door swung shut and you shifted the car into drive.

The whole way home felt automatic, limbs working separate from your internal instructions. When you returned home, you pulled up beside your mailbox and turned the car off, pulling the keys and letting them rest in your hand. You sat motionless, seatbelt still in place, as you stared, eyes fixated at someone mindless spot on the dashboard. The pearls were cool against your heated skin.

It was dumb. It didn’t mean anything.

It’s all you can think about.

You flip the mixtape over in your hands, reading the slightly-faded yet still legible handwriting. MT-HVC-5. You’d run through the songs already, and Sunghoon had switched to some CD mixes he had brought. Why he didn’t get a car with Bluetooth, something you’d done a while ago, you’d never know. Maybe that was part of his charm.

You’d managed to learn to forget about that kiss, or at least ignore it. But Sunghoon pulling out the mixtape he’d given you that night pulls it back up to the surface. You aren’t even sure how it even got into his possession. The longer you recall the memory, the more you can feel the burn on your cheek from where his warm lips touched your skin. The rest of the flush comes back from how you wish so badly it would happen again.

“What’s up?”

“Huh?” You turn towards his voice, away from the window.

“I asked what’s up,” Sunghoon repeats, looking over at you for a split second before returning to the road. “You seem like we’re on another planet.”

“Just thinking about when we were younger, you know...” Did he? What did you want him to think about? The day you’ve been obsessing over? And then what would he do about it? Pull over and confess? Kiss you, but mean it this time?

Sunghoon laughs, breaking your thoughts. He spares another quick glance in your direction. “Younger like what? Like third grade or two days ago?”

You reach across the center console to smack his shoulder. “Why would it be two days ago?”

“We were younger then. Wild, foolish.” Sunghoon takes one hand off the wheel and places his knuckles on his forehead. “The way we were is actually unimaginable now.”

“I’m done with you.”

Sunghoon scoffs. “Sure you are.” A quick beat, a hum to the music. “Anyway, what were you thinking about?”

You’re quiet for a moment. Then, “Do you think we'll change?”

“We have changed.”

“Really?” He said it so simply, it takes you off guard. You turn to look at him, even though you know he’ll keep his eyes glued safely to the road.

“Yeah,” he shrugs. “We’ve totally changed. We don't like the same kinds of music as the old us used to. We don't eat mac and cheese for every conceivable meal—except for the day after that one chem exam.”

“That final was hard!” You reach across the center console to shove at his shoulder–oh, god, why do you keep finding ways to put your hands on him?–earning a smug grin. “None of it was covered in class and you know it!”

“See what I mean?” Sunghoon asks. “We're different, but like, a good different. We’ve adapted.”

The silence that fills the car after isn’t weighty or overbearing. It’s comfortable and common, safe like a child-loved security blanket. Yet, somehow, your stomach fills with stones of dread, and all you want to do is sleep off any bad feelings.

You keep your eyes trained ahead, the curving mountain road, when you ask, “Do you ever think we'll be bad different?

Sunghoon spares a confused glance at you, brows knit together as he switches focus between you and the road. He shakes his head. “No, not us. Never us.”

“Is that a promise?”

The hand closest to you leaves the steering wheel and drifts over the center console, pinky out. “Always.”

You wrap your pinky around his, and try to ignore the heated flush you feel creeping up your neck and the backs of your ears. You focus, instead, on how real Sunghoon feels. How solid the mixtape is in your hands. How, here out in what feels like the middle of nowhere surrounded by evergreens and roadside snow piles that have started to pop up and tall mountain views, time doesn’t feel like it can get you.

Maybe he’s right.

Maybe, out here, there’s only good different.

Maybe, that’s all you need.

The clouds from the morning have turned darker, more potent. You can smell rain in the air, hear it as the wind rushes through the trees. It’s so cold though, you wonder if it will snow instead. The mountain weather you’d been looking forward to for so long.

Sunghoon knocks his shoulder into yours, cheeks pink from the cold. He swings your duffle bag towards you, letting go of the strap before you’ve gotten a good grip on it. “Your luggage,” he declares, before marching towards the hotel entrance.

You’d both decided, with your combined measly college student incomes, that wherever the last hotel would be, it needed to be the best you could afford. Standing in front of it now, styled like a fancy chateau with white walls and a red roof, you think the two of you made the right choice.

You had forgot what made such a nice place so affordable, until Sunghoon swipes the key, opens the door for you, gesturing for you to walk in first. The room is cute and delicate, with pretty yet aged wainscotting, petite floral wallpaper, a nice view of the surrounding mountains and–

And one bed.

You freeze. You can’t help it. Maybe the you from this morning, before that girl talked to you, could handle this. The you of right now? The lady at the front desk calling you a cute couple, and Sunghoon going along with it and not correcting her, didn’t help. You aren’t sure if you’re strong enough to keep everything the same.

“Rats,” Sunghoon says, and you breathe a sigh of relief. He’s not cool with this either, you think. He turns toward you with a coy smile. “I’m gonna go back downstairs and ask for more pillows. Three simply won’t cut it. Want me to ask for some fancy water?”

You shake your head, voice gone, and you don’t move until you hear the door shut behind Sunghoon.

And that’s when it starts, as you drag your feet in circles trying to think your way through this. Your hands clench and unclench, fists forming so tightly you leave half-moons from your nails in the fleshy part of your palm. Your breath comes ragged and shallow, and you feel like drowning, except from too much instead of not enough. Too many memories reminding you of too many things. Too many emotions leading to too many feelings you neither want to recognize or acknowledge.

But one keeps pushing its way to the forefront, demanding attention and definition. The one that’s been bothering you all day. It makes you dizzy, to the point you feel you need to lay down and clutch at your stomach. Maybe that’s it, you think as you sit on the edge of the one bed. You’re just sick. Breakfast was bad. But you know it’s not. It makes you angry, because how dare you feel this way about him. It makes you flustered, since you shouldn't look at your best friend's face and have your gaze wander to his lips and wonder what they'd feel like against yours.

It makes you happy, so undeniably happy that you feel like crying, because it feels so right. When you allow yourself to think more about it, and imagine what life would be like if you were able to confirm and agree with all the strangers who already think you’re dating. Lovers. It fills you up with breaths of fresh air to the point it's like floating on cotton clouds.

It makes you fearful. Its dark side claws at your heart, threatening to tear at the tender seams and leave you bloody and raw, so intensely damaged you're afraid of doing anything along the same lines. You had asked about a bad different, and Sunghoon said it wasn’t possible. Right now, you feel like you have to disagree–confessing this? Altering the relationship you’ve carefully crafted for so long?

That would be a bad different.

That’s why, when Sunghoon comes back, three more pillows and a bottle of sparkling water, you don’t answer. You roll over on the bed, curling up away from him, hiding with a pillow on your head. You hear Sunghoon say something about it being a long drive, and he gets it, you should rest. You hear him open the closet door, then feel the spare blanket get draped over you.

And, as you lay here, hot silent tears threatening to spill over and run down your cheeks, you let yourself think about it. You're in love with your best friend. Your nail-bitten palms come to swipe at your eyes, you make the mistake of sniffing aloud. Sunghoon calls your name, and you hate how much you savor the worry in his voice.

But, it’s also too much. He can’t know, you decide. Not now, not ever. That is what would be best, you decide, for the two of you. To be able to get through the rest of this trip.

“[Y/N], what is it?” he calls again. Sunghoon’s voice is laced with care, something tender and soft and so distinctly him it pulls at the tears in your eyes. How can he make this so unfair? “What's wrong?”

“You wouldn't understand,” you snap, pulling yourself to sit up, the pillow falling off. You don’t look at him, but instead at your hands, fists in your lap. Sunghoon easily notes your posture, and confusion floods his features. You hate how quickly he can figure out something’s wrong, that something is bothering you.

“Can I try to understand, at least?” You look up at him, lips pursed, tears smarting your eyes. You take him in–turned towards you in the chair, sitting on the edge, like he can jump to your rescue at any time. The confused look in his eyes hurts—you've always been straightforward with one another. But you know you can’t about this. “I can’t try to fix it if you don’t tell me what’s wrong.”

You shake your head, wiping one of your cheeks with your fingers, a half laugh falling from your lips. “No, Hoon it's—”

“No.”

The force of the single word hits you, and it hurts more than the angry look in his eye.

He stands, takes a step toward you, then sits hesitantly on the edge of the bed. He's close, and he's been closer, but it's still too much. The rushing sound is back in your ears and your heart pounds against your ribs, telling you to do something, anything, but you stay still.

“Hoon—”

“I said no, [Y/N].” Sunghoon’s words are ice, colder than the breeze outside and sharper than butcher knives. His eyes, once warm and homey, that romantic shade of brown you love, are now dark and piercing. “You don't get to call me special names when you aren't telling me what's wrong. When you aren't acting like the [Y/N] I've known since third grade.” His hands come up to run through his hair, and it flips slowly back into place. His voice drops, the softer, confused Sunghoon returning. “You've been acting weird this whole trip, and especially since this morning. It's driving me insane that I can't figure it out and fix it. I know you better than this.”

He's so close, so, so close. Much too close. Somehow he’s scooted towards you on the bed. You can smell his cologne—when did he start doing that? Why hadn’t you noticed earlier? His eyes are back to the romantic brown, the warm and homey color, the ones that remind you of so many good memories—his eyes are so pretty. Your gaze follows its past patterns and drops to his lips, redder from being gnawed on with worry. A kiss would—

A shaky breath leaves you, and you're talking before you realize, voice so small it's hard to hear. But Sunghoon is listening. He always does.

You blink. “Do you want to know what's wrong?”

“Of course. I need to know if I can do anything or—”

“It's you.”

You want to be upset, angry. How dare it come to this. But you can’t, you realize. You can’t be angry at him. Whatever energy you had coursing through your veins leaves after your pseudo confession, and you turn away, resting your weight on the headboard, hoping he’ll go away.

This, for certain, was bad different. You can feel it, weighing you down. Here, in a chilly, single bed hotel room, you’d ruined everything. Your brain told you to shut up, to be quiet, to try and save anything you could manage from this shattering relationship. But your mouth—or maybe your heart—kept going, and going, and going.

“It’s you,” you repeat, turning back towards him. He’s still there, frozen in place, face filled with concern. “It’s everything you do. The way you... you tell me bad jokes when I’m upset over a grade or make me mixtapes because you want to share your music with me. It’s–I’m–I’m sick of it. I hate it. I hate you”

Sunghoon recoils, eyes wide. He looks around the room, as if the answers to what to say are hidden around. He stands, backing up without turning away, like you’re something he has to keep his eyes on or he’ll get hurt again.

Again.

Sunghoon’s voice is flat when he speaks, like he’s out of breath. Shaky, like he’s about to cry, too. What have you done? “I’m… I’ll go downstairs and ask about if there’s anything nice around for dinner. I’ll–I’ll wait for you in the lobby. Whenever you’re ready, you know.”

Even now, after the nasty things–after I hate you left your lips–he’s still trying to make peace with you.

What did you do to ever deserve him?

And would he even stay with you once you return home?

The door falling shut is what starts your tears again. You slump down off the bed, between it and the window. You pull your knees up to your chest, put your head in your hands, and you cry.

***

It still isn’t over.

You’re breathing heavy, tears still stinging your eyes, but you aren’t sure if you’ve actually cried yet or not. Your fists are balled at your sides. Years of friendship are stuck in your throat, enough to make you want to scream or cry or vomit from the nauseous feeling it induces. The pouring rain, those clouds finally opening up, doesn’t help.

Dinner had been awful, awkward. The only person either of you talked to had been the waiter. You can’t remember what the food tasted like. You can’t remember what, if any, songs played on the radio on the way back. Sunghoon hadn’t bothered to pick anything out. All you could remember, or hear, or see in your head–I hate you. The look in his eyes. How he has barely looked at you since.

You aren’t sure what you have to do to get away, but you’d be willing to make a deal.

Anything to get away from this moment.

Anything to get away from your best friend.

Sunghoon stares at you like he’s only just now met you, and maybe he has. He’d stopped you halfway between the car and the hotel’s entrance, despite the rain. He’d called your name in such a way you froze. Your angered confession from earlier hangs in the air, untouched or acknowledged. A single parking lot light illuminates you two, dim yellow casting shadows through the rain.

“Do you mean that? What you said?” he asks, daring to step forward. You don’t move, anchored in place. By fear or something else, you aren’t sure. He takes another, then a third. The gap between you has been halved. “I know you don’t mean it. I’ve been thinking about it this whole time. You don’t mean it.”

“What makes you so sure?” you spit, taking a step closer in your upset. You level Sunghoon with a stare you hope is intimidating, bitter. You hope he sees the duress. You have to push him away. “I said what I said. I hate you, Park Sunghoon.”

The boy shakes his head, hair stuck to his forehead from the rain. He seems almost incredulous, and it angers you even more. Why doesn’t he get it? There’s a small smirk at the corners of his lips, but you’ve known him long enough to recognize it as mock confidence. “You didn’t mean what you said.”

“I did!” Another step, and now you’re nose to nose with him, staring into the eyes you’ve had memorized for so long, that romantic brown even in the rain and yellow streetlight. Your gaze betrays you and you drink in the slope of his nose, see how his eyes examine you as well. Note the downturn of his lips, almost unnoticeable. Your voice is weaker when you speak again. “I did mean it, Sunghoon.”

He leans in, closer and closer until he stops–a breath away from your lips. He freezes, closes his eyes, and waits.

And you cave, despite your best interests. You find yourself tilting your head and wishing he’d do something more. This can’t be how your first kiss with Sunghoon goes? When he pulls back, and you nearly stumble forward. You look up at him, and the smile on his face is no longer mock. You know what his question will be before he says it, and you know he’s caught you in your lie. “You hate me so much–why did you kiss me back?”

You want to spit back, I didn’t! You want to argue. But the truth is, ever since you’d remembered that day in high school, you’d been imagining what it would be like to actually kiss him, and again, and again. You wanted to know what kissing Sunghoon would be like, even if it meant redefining the relationship you worked so hard to keep as is. The one you said you hated him to protect.

Sunghoon gently cups the sides of your face, forcing you to look at him, and you see worry and concern etched into the space between his brows, spilt in the color of his eyes. “Tell me,” he whispers, voice almost breaking, “what’s wrong. Let me try to fix it.”

You shake your head, trying to form words to explain everything, but all you do is shiver drastically beneath his touch. You watch as Sunghoon’s eyes grow wide, and he leads you inside, arm over your shoulder. The woman at the front desks awards you a quirked eyebrow, but that’s all you get before she returns to her clipboard.

The room is icy cold when you return, but Sunghoon adjusts the temperature in silence. “You get dry first,” he says, pointing at the bathroom. “Take a shower and get warm.”

“But about you?” You want to point out the subtle shake in his hands, and the way his breath catches. “There’s not enough towels to share.”

“I’ll ask for more at the front desk. I’ll be fine. Go.”

The shower water never feels hot enough, but you do stop shivering. You do your best to towel dry your hair. When you peek the door open to see if he’s back, and if you could get your things, you see that Sunghoon has already done it for you. Everything you could need taken from your bag, folded and placed nicely right outside the door. You have no idea when he did it–you’re thankful he did.

When he comes back with extra towels–which, surely, did not take this long–you’re curled up on the bed, similar to before. You rest your weight on the headboard, looking out the window at how the rain patters against the glass. You wish you could see the stars.

Sunghoon is fast, but who’s to say? You aren’t exactly keeping track of time. You know he’s back because you feel the mattress shift. His voice is almost silent when he speaks. “Can we talk?”

“About what?” you ask, turning towards him. You haven’t seen Sunghoon look this tired in a while. And you know it’s your fault. “How I was mean to you?”

Sunghoon smiles, looking down at his clasped hands. He takes a moment to determine what he actually wants to say. “Let’s start with…what it is about me that made you say that?”

His eyes are pleading in the dark. The room is barely lit, the overhead light off. There’s just a lamp on the desk and the streetlight from outside. The rain sound is almost overwhelming in the silence. “If there’s something I’ve done that hurt you–”

“It’s not that. It’s–” You pause, trying to find the right thing to say. You decide to start with the obvious. “There’s a reason I kissed you outside.”

Sunghoon rolls his eyes. “Yeah, because I’m charming and irresistible.”

“This is serious!” You do what you always do when he makes some kind of quip–you reach out to push his shoulder, scooting closer, but Sunghoon catches you by your wrist.

“I am serious. Do you know how much you hurt me when you said you hated me?” He levels you a stare, one that makes you want to shrink away, but you can’t. “When I left, I didn’t ask the front desk about restaurants. I went to my car and sat down and cried because the person I love just said they hated me.”

“You love me?”

“Not like that,” he corrects, and now you have to know what he means.

“Tell me how then.” You take your free hand and grab his other wrist, a mirror of what he’s done to you. “When you say you love me, what do you mean?”

“It’s not like you think, not like what it has been.” Sunghoon looks down, takes a deep breath, then carries on. “Not like friends, or like siblings, but like–”

“Lovers?” you offer.

Sunghoon swallows, sets his jaw. Then, “Yes. Like that. And I don’t know when it happened. I don’t know if it was overnight or gradual or all at once. I do know that I woke up one morning and I realized that I didn’t want to imagine my future with anyone else. And I didn’t want to see you with anyone else, either.”

“Kinda selfish,” you say.

Sunghoon laughs. “Yeah. I couldn’t help it.”

Somehow, you’ve both moved closer to each other. The knees of your crossed legs knock into each other. You still have a hold on the other’s wrist. Sunghoon levels you another stare. “Will you tell me why?”

“Why I said I hated you?” He nods, and you take a deep sigh. “Do you remember the night we snuck into the pool to get my car keys back?”

He nods again, a small smile on his face. “You mean the first night I got enough courage to kiss you? You looked so pretty, with the pearls and the perfume.”

You blush, hearing Sunghoon talk about you like that. “That night. I’ve been thinking a lot about it. And you know how all these people always say we look like a couple or whatever. And it all just stuck together and made me realize that I haven’t seen you like a friend in a long time. I’ve seen you like–”

“A lover?” Sunghoon offers, copying you from earlier.

You smile. “I said I hated you because I was afraid and overwhelmed, and I need you away from me. I thought that if you hated me, I could get over you and just move on. We could make up, and I wouldn’t have these feelings anymore, and we could go back to being friends.

“But if I’m being honest,” you add, moving even closer. Your shoulders knock into one other. “Even though it wasn’t even that long, those hours over dinner just now were some of the worst things I have ever had to do. I was ugly to you, Sunghoon, and you’re the last person on earth who would ever deserve to be talked to that way. But if you could forgive me, I…”

You try to look down again, but Sunghoon lets go of your wrist to place a finger under your chin, tipping your head up to his gaze. “You what?”

“I love you. I’m in love with you, I’ve been in love with you. I love you, Park Sunghoon.” You take a deep breath, just as lightning strikes somewhere far away and the thunder rumbles through the room.

Sunghoon reaches out for you, his hands reach cupping your face again. It’s the most reverent you’ve ever seen him. His eyes roam over your every feature, as if you’ll break if he breathes too hard. It’s thrilling. “Genuinely?” he asks, voice fragile. “You love me?”

“Yes,” you whisper. It feels wrong to be too loud right now, like someone else could join in this moment between the two of you. “And if you would have me, I’d like to love you for a long time after this.”

Sunghoon pulls you to him, resting your forehead against his. He takes a deep breath. Then, “We’ve both just been really, really stupid about it, haven’t we?”

You laugh, savoring his touch and his warm and his smile. You stare into his eyes, those romantic brown ones you love so much. “I guess so.”

“Can I kiss you?” he asks, and your heart jumps. “I know we did outside, but that’s a terrible story for a first kiss.”

“And the one from so long ago doesn’t count, because you just gave me a kiss then,” you say, not sure why you’re rambling when you have the opportunity to just kiss him already.

So, you shut up, and you do.

This kiss is reverent, unlike any that came before. You probably shouldn’t even bother comparing them. Maybe it’s the intentions behind the kiss—that you both want to be here, doing this, for the sake of just being, not proving. Maybe it’s because it hasn’t followed any dramatic late night outings or arguments. Maybe, it’s how you shiver closer to his frame, hands on his shoulders, and his own find the small of your back. You feel his smile against your lips, and the butterflies against your ribs.

Maybe, you should have said something a while ago. You could have avoided the whole I hate you stint, but then would anything else have been dramatic? Some couples are like puzzle pieces, perfectly fitting together with no stress. And maybe you two are a puzzle, one that fits together with ease, but you both intentionally hid pieces from the other, making it difficult to complete. Maybe airing grievances is the only way to get all the pieces back on the table.

You sigh as Sunghoon’s lips travel from your own down the line of your jaw, tickling in a delightful way. You feel safe in his arms, a safe you’ve always felt, but now it feels like something more, something even greater. Your heart jumps, and you throw your arms around his neck, pulling him close. Sunghoon instinctively holds you tighter, his hands against your shoulder blades.

“What is it?” he asks.

You shake your head, finding any words to be incredibly difficult. “I’m just—I’m glad.”

Sunghoon pulls back gently, quirking his head to one side as he looks at you. He uses the pad of his thumb to gently wipe away a stray tear. “Glad for what?” he asks, still cupping your cheek.

You lean into his touch, feeling dizzy with excitement and relief. “Glad that it’s you,” you say, your voice quiet. You lean in, placing a chaste kiss against his lips and, for once, he’s the one to shiver. “I’m glad you’re the one I love. Glad we’re here now, finally.”

Sunghoon pauses. His eyes dart between yours, your lips, and back. He rests his forehead on yours again, and you can already imagine getting used to this, and craving it when you can’t have it. “I waited so long, and I didn’t even know if...” There’s a catch in his voice, and he sounds like he’s about to cry. When he opens his eyes, there’s an honesty to them, a gaze you’ve only seen in Sunghoon’s eyes a handful of times. He smiles, his eyes going soft once more, like you are the most beautiful thing he has ever beheld. And to him, you are. “I always knew we were meant to be.”

***

The lady behind the desk did, in fact, look at you two like you were crazy. The night before you were acting like you were gonna tear each other to pieces. But now you’re walking out in each other’s arms? His around your shoulder, yours around his waist?

The sun is out, and there’s hardly any evidence of the downpour from last night. Maybe the earth needed to be just as dramatic as the two of you.

With the luggage in back, you two climb into the front seats. Sunghoon leans over the center console to press a kiss to your temple, just like he did when you woke up in each other’s arms and just like he did when he insisted on getting you whatever you wanted for breakfast.

“That’s not something new though?” you laugh, as he brings you small portions of everything the hotel had to offer. “You did this before.”

“Well, it’s obviously different now,” he replies. “I didn’t get to kiss you before.”

Now, Sunghoon taps at the Valentine heart on the dash–your wanderlist. What started this all. “We need a new one,” he says. “It took us a while, but we did everything on here. Should the new one be full of cringey couple things?”

“Only if you’d like to go back to being single.”

Sunghoon fakes shock as he shifts the car into gear. “You wouldn’t.”

This time, you lean over to give him a kiss, and you relish how quickly he blushes. “You’re right, I wouldn’t.” You sit back down, still turned towards him, hand atop his. “Maybe, we make the list up as we go. I mean, we’ve never been here before.”

“Didn’t stop third grade us,” he says. “Honestly, they seemed like they had everything together. We should think more like third grade us.”

“You mean complaining about how much things cost? Because I can think of so many things we could do together that would put major dents in our wallets.”

Sunghoon turns to you, a mischievous twinkle in his eye, and you know you’ve got this right, even if it took a while to get here. He reaches over, poking your cheek, before turning out of the parking lot. “Then let’s go find it, together.”

#kdiarynet #kwritersworld #kflixnet #k-labels #enhypen fluff #enhypen headcanons #enhypen scenarioes #enhypen imagines #sunghoon fluff #sunghoon headcanons #sunghoon scenarioes #sunghoon imagines #enhypen #fluff #angst #college!au #ftl

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crapeaucrapeau · 3 months ago

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G2HGE Part 1 : Canon-Gleaning - Post 6a : How Much Faster Than Light ? (Speed, Acceleration and Inertia, and Speculation Thereof)

Hi ! This post (???? 202X ----ERROR : Insert Date Here) is the sixth post in the Galactic Geography and History of Galactic Exploration series (or G2HGE, announced and explained with excessively verbose details here). In this chain of posts, I air out my thoughts and hypotheses on the geography of the Milky Way in the Mass Effect setting - in particular, in order to determine when the various mass relay-centered clusters were opened and accessible, based on what canon data we have. I tell you what I think, and you tell me what you think of that.

A long time ago, I did a five-part post on the various regions of the Milky Way. It was fun !

Right here, right now : How fast are starships in the Mass Effect universe ? Isaac Newton ? Why are there interludes on acceleration and inertia ? What are the constraints of FTL travel ? Do we have any indication as to the evolution of FTL travel throughout history ? What is that about constant acceleration ? Those questions will eventually lead us to what really interests me : How would all of that impact the development of clusters ?

1 - How fast are starships in the Mass Effect universe ?

You know me ; the questions we'll be asking are : What's the data in canon ? How can we complicate the picture ?

The major indication we get on FTL speeds is from a comment in ME1, when Ashley reacts to Shepard admiring her for making the trip from the Czarnobóg Fleet Depot to Amaterasu : "It was only a dozen light-years. Like a day's cruise. It's not like I was going to Earth or something." The phrasing suggests people expect to travel more than a day if they're travelling.

Moreover, Ashley tells us that Czarnobóg and Amaterasu are in the same cluster, and what being "a dozen L.Y. away" represents to the average person : "Close enough to talk regularly, too far to make it back in an emergency. I couldn't afford a fast packet flight."

(To keep you from wondering : a packet flight would be a starship travelling at regular intervals between two ports ; historically, a packet boat or a steam packet refers to boats that did so to convey mail from one port to another.) (In a cut ambient conversation from ME1, extracted by @lyricsaboutcats,the salarian businessman Rulamin mentioned trying to get "a packet" from Noveria to Ryskos to a friend, then finding that it won't be possible to get "a packet flight" for at least six days.)

(The mention of a "fast packet flight" suggests that you have a range of options among packet flights : presumably, the faster ones are more expensive.)

To provide a sense of perspective, the Tempest, which benefits from using "several once-proprietary technologies" and "[not] being weighed down by heavy armor or a main gun", has an "average speed" (see below) of 13 light-years per day, making it "easily the fastest ship in her class", i.e. a frigate-sized survey ship. Given that lighter starships can accelerate to greater FTL speeds than more massive ships, with the fastest military ships being frigates, as well as the unique conditions that made the Tempest possible, I find it probable that the Tempest is one of the fastest ships ever made by the current Citadel species. It is certainly faster than the heavier Normandy SR-1 or SR-2.

The Reapers "can travel nearly 30 light-years in a 24-hour period". This is "more than twice the speed of Citadel ships", in keeping with what we've outlined above. In addition, this sets a very hard upper limit : at the moment, there is no Citadel ship which can reach a speed virtually or absolutely equal to 15 light-years per day (which would be exactly half the estimated Reaper speed).

2 - Which starships are the fastest in the Mass Effect universe ?

In canon, there are at least two factors which have an impact on a starship's speed : its thruster type (or how much motive power they can have, given that starships "use their sublight thrusters for motive power in FTL") and its mass (or how much eezo and power is required to move the damn thing).

The Codex is fairly clear that a starship's speed depends on its type and what thrusters it has ; there are "several varieties of thruster, varying in performance versus economy" :

"All ships are equipped with arrays of hydrogen-oxygen reaction control thrusters for maneuvering." Note that those are "liquid hydrogen/liquid oxygen reactions", not gas. From my own research, I found that the exhaust velocity of a rocket flame usually is several thousands of meters per second.

"Ion drives electrically accelerate charged particles as a reaction mass. They are extremely efficient, but produce negligible thrust. They are mainly used for automated cargo barges." The noble gas xenon appears to be the propellant of choice, in keeping with real life, as there is evidence that it is harvested specifically for ion drives on the planets Alingon, Uzin (in the Eagle Nebula), and Venture, and logically elsewhere. Per my research, the exhaust of an ion drive would be an order of magnitude faster than a chemical rocket's.

"The primary commercial engine is a "fusion torch", which vents the plasma of a ship's power plant. Fusion torches offer powerful acceleration at the cost of difficult heat management. Torch fuel is fairly cheap: helium-3 skimmed from gas giants and deuterium extracted from seawater or cometary bodies. Propellant is hydrogen, likewise skimmed from gas giants." If I can trust my own research, the exhaust velocity of a torch drive would supposedly be measured in thousands of kilometers per second.

"In combat, military vessels require accelerations beyond the capability of fusion torches. Warship thrusters inject antiprotons into a reaction chamber filled with hydrogen. The matter-antimatter annihilation provides unmatched motive power. The drawback is fuel production; antiprotons must be manufactured one particle at a time. Most antimatter production is done at massive solar arrays orbiting energetic stars, making them high-value targets in wartime."

Finally, in 2185, some cutting-edge technology like the Helios Thruster Module uses "metastable metallic hydrogen" both as a superior alternative to "liquid H2/O2" reactions powering "maneuvering thrusters", as well as a slower but cheaper viable alternative to antiprotons for "forward impulse".

Since the fusion torch is the primary engine type in the setting by the time ME1 rolls, we can conclude that the fusion torch allows the average Citadel spaceship, including military starships when out of combat, to travel at a cruising speed around 12 light-years per day (24 Earth hours) - "cruising speed" being defined as "the maximum speed at which a vehicle is able to travel continuously and comfortably, without using a large amount of fuel or effort". In other words, starships can in all likelihood reach FTL speeds faster than 12 ly/day, but that isn't meant to happen, as they are not designed for that, and doing so would a) make the trip uneconomical, and/or b) start damaging the ship.

The other significant limit is the mass of the starship, as "[the] amount of eezo and power required for a drive increases exponentially to the mass being moved and the degree it is being lightened. Very massive ships or very high speeds are prohibitively expensive." What is in bold suggests that mass relates to the mass effect field in two ways : it appears that the more massive an object, the harder it is to affect it ; and that the lighter one wants to make an object, the more eezo and electricity one will need.

This is apparent in the various weights of large military vessels : a dreadnought needs to be as long and massive as possible to bring the greatest firepower to bear, resulting in ships ranging "from 800 meters to one kilometer long" and weighing "millions of tons" - but this mass results in low maneuverability and the slowest speed. By contrast, frigates are the lightest and smallest large military starships, the only large vessels "able to land on planets" ; as a result, they "achieve high FTL cruise speeds because of their high-performance drives. They also have proportionally larger thrusters and lighter design mass, allowing them greater maneuverability. In combat, speed and maneuverability make frigates immune to long-range fire of larger vessels."

Given that cruisers appear be to the standard for military starships, balanced between frigates (faster, but with far lower offensive and defensive capabilities) and dreadnoughts (far more destructive and tough, but slower), it may be that most commercial vessels are in the same weight and have access to the same FTL speeds, perhaps slightly faster because of their lack of guns and armor. Thus, I posit that most Citadel starships probably fall close to cruisers when it comes to FTL speeds.

As a logical consequence of the above, some of the fastest ships you could find travelling in the Milky Way would be couriers, as the shortest travel time possible would be vital for their job ; this would be in keeping with the analysis presented here over on Atomic Rockets. We know the galaxy at large relies on "high-speed couriers" when comm buoys aren't available, as well as "diplomatic couriers". However, we know that courier ships aren't substantively faster out of FTL than other ships, since the ship of the Rachni Queen's emissary in ME2 - should you spare the rachni on Noveria - had been a courier's ship which was nonetheless ambushed by pirates and forced to land on an uncharted world.

But it's probable that the very fastest are fighters, whose extremely low mass makes them "capable of greater acceleration and sharper maneuvers than starships". Contrary to what I thought for years, fighters are FTL-capable, as what separates spaceplanes (any vessel that can fly both in an atmosphere and in space) from "true deep-space fighters" is that the former "have no FTL drive".

That being said, this probably doesn't amount to much, since fighters won't be travelling through star clusters. Fighters aren't independent ; indeed, they rely on cruisers and carriers to get them anywhere. This is logical : since you want the lightest possible vessel to reach the highest possible speed, there's probably little in the way of life support or other systems that don't anything to do with getting close to some enemy starship as fast as possible without getting shot down. In other words, fighters are irrelevant when considering how FTL speeds impact the development of clusters.

To sum up :

the cruise speed of Citadel starships is around 12 light-years/Earth day. The Tempest, at 13 ly/day, is exceptional.

this speed of 12 light-years/day is presumably the average speed one can reach with a fusion torch ; starships with ion drives are going to be much slower, because their design concern isn't how fast you can get anywhere but how cheaply.

the less massive a ship, the faster it will be in FTL. Out of military ships, dreadnoughts would be the slowest, while frigates would be the fastest. Because the Tempest is extraordinary for its size, that means the FTL speed of frigates (Normandies included) is probably superior or equal to 12 ly/day and certainly strictly inferior to 13 ly/day.

the fastest starships would be even lighter than the Tempest and only be concerned with speed - the Tempest is built for scientific survey and analysis, as well as long-term habitation. Nonetheless, the Tempest is canonically the fastest ship by far for a ship its size (for the reasons outlined above).

the fastest ships of them all are therefore likely to be fighters, but they are not going to have an impact on the economic development of star clusters because they are not independent. I posit that the fastest after them are couriers, but that's a very specific, somewhat uncommon kind of ship.

basically, you're probably going to find vessels going at different FTL speeds depending on their purpose, with very specialized (and therefore rarer) vessels at the extremes of performance ; 12 ly/day is either the average or the median Citadel FTL speed.

tl;dr : 12 light-years per day is the relevant speed for our purposes.

3 - How fast can starships accelerate ?

3.a : The basics of acceleration in canon

There is an additional consideration which is barely touched upon in canon : the rate of acceleration and deceleration.

In the Codex, we are told this : "Any long-duration interstellar flight consists of two phases: acceleration and deceleration. Starships accelerate to the half-way point of their journey, then flip 180 degrees and apply thrust on the opposite vector, decelerating as they finish the trip. The engines are always operating, and peak speed is attained at the middle of the flight."

(The reason the Codex stresses that engines are always operating is to emphasize that a starship is never moving at a constant speed - because if the goal is to remain in motion, then a starship doesn't need engines, it just needs to keep on drifting. Indeed, in the vacuum of space - i.e. a virtually frictionless environment - a starship in motion stays in motion at a constant speed in a straight line until and unless acted upon by an outside force, sir - AND THAT IS WHY SIR ISAAC NEWTON IS THE DEADLIEST SON-OF-A-BITCH IN SPACE!)

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So ! The Codex informs us that a starship is either accelerating or decelerating at any given time, that its engines are always operating, and that its speed therefore constantly varies, with its maximum FTL speed during the journey achieved at the exact middle of the flight.

In the games, this is referenced in an exchange Shepard may have with Marab, the manager of the Saronis Applications store in Zakera Ward, in ME2 (link).

SHEPARD : You know, I use quite a bit of software in my line of work.

MARAB : It's a shame so few understand their own equipment. Besides the most obvious point-and-go nav interfaces anyway.

SHEPARD : You wouldn't believe how often I hear, "Why is the ship turning around ? We're only halfway there !" [MORDIN nods in sympathy.]

MARAB : [He chuckles.] Oh, I would !

In space nerd parlance, this is known as a brachistochrone, while the midpoint flip-over is alternatively called a "skew flip" or a "flip-and-burn" in sci-fi. A brachistochrone is typical of starships with fusion torches, or torchships, which indeed fits with what we've seen, as we've established that fusion torches are the standard thruster type for Mass Effect starships as of 2183. For more information on brachistochrones, let me refer you to the supreme space nerd website, the wonderful and exhaustive Atomic Rockets ; I'll be quoting select excerpts throughout.

tl;dr : Starships are always either accelerating or decelerating, and reach their maximal speed at the exact halfway point of their journey, at which point they turn around and start decelerating. This is known as a brachistochrone.

Corollaries of that piece of information worth stressing include :

if a starship's peak speed is attained at the middle of the flight - e.g. 12 hours in during your 24-hour trip where you'll be travelling 13 light-years - because it takes exactly as much time for a starship to decelerate as to accelerate, then you're also halfway to the destination at the same moment - in our example, 6.5 light-years from your starting point (see also Shepard's exchange with Marab above) ;

however, because that starship is always accelerating (then decelerating), it starts covering very little distance at the beginning of its journey before progressively picking up speed ; this means that at 25% of its travel time, it will not have travelled 25% of the distance. The reverse is also true : at 75% of its travel time, our hypothetical starship will have flown more than 75% of the journey.

Moreover, we know that the initial mass of the starship and its type of drive core (i.e. how much eezo there is in it and how much power they can inject in it) are the hard constraints on how much a ship can accelerate. Again : "Faster-than-light drives use element zero cores to reduce the mass of the ship, allowing higher rates of acceleration. … The amount of eezo and power required for a drive increases exponentially to the mass being moved and the degree it is being lightened. Very massive ships or very high speeds are prohibitively expensive."

Until now, I've talked about starships in terms of which is the fastest ; but really when we are discussing the speed of starships, we are talking about how quickly a starship can change its speed. The size of an eezo drive core relative to the vessel has an impact on the vessel's acceleration : deep-space fighters, for example, "are economically fitted with powerful element zero cores, making them capable of greater acceleration and sharper maneuvers than starships" (Source : Codex : Starships: Fighters). For the other military vessel types, frigates, which can achieve "high FTL cruise speeds", would have the second-fastest acceleration, followed by cruisers, with carriers and dreadnoughts dead last.

tl;dr : Talking about a starship's "average speed" or "cruising speed" doesn't mean much because what really matters is how much it can accelerate. Lighter starships can achieve greater acceleration.

So, uh, I have to address some things about acceleration in physics.

OH BOY HERE COMES THE INTERLUDE

Interlude : A genteel Reminder on Fundamentals of Acceleration

The speed of an object is a measure of how much distance it travels (change in position) over time ; the velocity of an object is its speed alongside the direction in which it moves. Both speed and velocity are usually noted v, and both are measured in meters (for distance) per second (for time), or m/s. You will note that "12 light-years per day" is a measure of speed, since it is expressed by units of distance ("light-years") and time ("day"). In SI base units, that should be (if I can calculate) 1.314e+12 m/s, or 1.31 trillion meters every second ; as the speed of light in vacuum (c) is exactly 299,792,458 m/s, I'll note that the cruise speed of a starship is about 4380 times the speed of light in vacuum, or 4380 c.

Acceleration is any change in the speed or direction (or both) of an object in motion ; from the point of view of physics, deceleration is acceleration. Acceleration is noted a ; since it measures the change of speed and/or direction over time, it is measured with the unit of velocity (m/s) divided by the unit of time (s), or meters per second per second (or (m/s)/s), which mathematically entails that it's the same as meters per second squared, or m/s^2.

Another unit which is going to be very useful soon is g (not to be confused with "G" [the gravitational constant] or "g" [that's grams]). g is another unit of acceleration, measuring the standard acceleration due to Earth's gravity, i.e. how much the gravity of Earth causes an object near the surface of Earth to steadily gain speed (i.e. accelerate) in a vacuum - that is to say, in a context where the only force acting upon that object is Earth's gravity. g is a constant defined as 9.80665 m/s^2 ; in Mass Effect, you probably know it because, on the data description for every single planet, g is used as the unit of gravity, with Earth as the standard at 1 g.

In classical mechanics (i.e. the Newtonian equations that don't involve anything starting to try to get close to the speed of light, since the closer you get to it, the more Einstein starts to mess with your stuff ; by convention, the threshold is 0.14 c), the sacrosanct equation is F = m*a (or a = F/m), where F is the net balance of all forces acting on an object, m is the object's mass, and a is its acceleration (quoth Wikipedia). In plain English, the more acceleration you want, the more force you'll need (and that is Sir Izzy's Second Law of Motion) - something you're likely to have experienced if you have ever ridden a bike, for example : your top speed is limited by how much energy you can pour into your pedaling (and friction, thankfully virtually absent from the deadly vacuum of space, is always slowing you down).

Now, to prepare yourself for what's to come, I'll also note two things :

in the context of spaceflight, acceleration is equal to rocket thrust divided by starship mass (a = F/Mc, where F is the starship's thrust measured in Newtons (N), i.e. in kg*m/s^2 ; and Mc is the starship's mass at a given point in time measured in kg) ; because the mass of a starship decreases during its flight as it expends propellant and fuel, any equation trying to calculate the acceleration of a spacecraft will have to take that variation into account.

also relevant to our talking about mass and acceleration is inertia, i.e. the phenomenon in the deadliest son-of-a-bitch in space's First Law of Motion described above, i.e. how tough it is to change the speed of any object (such as setting an object at rest in motion), i.e. how tough it is to accelerate (or decelerate) anything. SPOILERS : inertia is dependent on mass, because the more massive an object, the harder it is to accelerate it, and the more energy will be required to do so (drop a rock and a sock, try rolling them forward on the floor ; one is significantly easier to move than the other). A consequence of this is that it requires increasingly ludicrous quantities of energy to accelerate any object with mass to a velocity close to the speed of light (c), and it would require an infinite amount of energy to accelerate any object with mass to c ; it's only because light is virtually massless that it can get to c in the first place.

But that's not a problem when you have magical eezo allowing you to travel faster than light without any physics-breaking consequence !

Thus endeth the Interlude.

The Interlude Has Ended - please return to your seats

All of that is important because all starships have an upper limit to how fast they can go, a maximum speed past which they can no longer accelerate (at which point the sensible thing is to turn off the engines), perhaps even the same speed in starships of different weight classes, for all we know ; but crucially, some starships can reach that top speed much faster than others.

So, uh, how much acceleration can the starships in Mass Effect (and the squishy people inside) take ? Well, we know that large ships like cruisers and dreadnoughts actually rely on constant acceleration to simulate gravity : "Mass effect fields create an artificial gravity (a-grav) plane below the decks, preventing muscle atrophy and bone loss in zero-gee. Large vessels arrange their decks perpendicular to their thrust axis. The "highest" decks are at the bow, and the "lowest" at the engines. This allows a-grav to work with the inertial effects of thrust. Ships that can land arrange their decks laterally [i.e. frigates and smaller vessels], so the crew can move about while the vessel is on the ground."

This is achieved because acceleration can effectively simulate gravity, what is known as the equivalence principle : inertia "pulls" you in the direction opposite that of the vehicle's motion (think about how your body is pulled back when the car or public transport you're in starts moving forward, whereas you're thrust forward if the same vehicle brakes suddenly). In effect, if you are in a vehicle accelerating at 9.80665 m/s^2, i.e. 1 g, every object within that vehicle behaves as if they were on Earth, "falling" toward the back of the vehicle.

That is what the larger starships rely upon : presumably to avoid spending power (thus fuel, thus money) on a-grav, Alliance cruisers or dreadnoughts, for example, need to be constantly accelerating at 1 g to simulate Earth's gravity, never changing that acceleration because it would change the pseudo-gravity.

tl;dr : The heavier starships use acceleration to simulate gravity. This means even the heaviest Alliance starships can reach at least 1 g of acceleration. Because lighter starships are capable of greater acceleration, they are also able to accelerate to at least 1 g.

(By the by, this suggests that whereas frigates like the Normandy may have thrusters which can fire in opposite directions to accelerate and decelerate, the larger starships do need to physically "turn around", otherwise "gravity" would shift and stick them to the ceiling ; if such a starship doesn't "park in reverse" when it leaves FTL, as it does in cutscenes (for example when Hackett's ship arrives guns first in ME3), this suggests in turn that its engines are killed, stopping any deceleration, and that the starship then turns around a second time before switching off FTL.)

The problem of course is that starships need to be accelerating much, much faster to achieve the range that has been observed in the OT : at a constant acceleration of 1 g, a starship would cover 9,144,576,000 meters in 12 hours, i.e. 9,144,576 km, i.e. 0.00000000000095 light-years - and twice that over 24 hours if we assume this is a brachistochrone, or 0.0000000000019 light-years - a very far cry from 12 light-years.

Now, there are some things we should keep in mind :

there's all the timey-wimey handwavium stuff related to FTL travel in Mass Effect ; it appears that there is a difference between the speed of the starship as perceived within the envelope by aboard observers (the subjective speed) and the speed of the starship as perceived outside the envelope (the "objective" speed). FTL is a can of worms best left unopened, but suffice to say 1 g will, in all likelihood, allow a starship within an FTL envelope to travel faster and farther than it would under normal circumstances.

there's also the hard limits of engineering : to maintain a continuous acceleration, i.e. to keep going faster and faster, the starship is going to need more and more thrust, thus more energy, which will be harder to provide and start taxing the ship at some point. Now, Atomic Rockets kindly informs me that a torchship is just about the only ship type which can manage constant acceleration, but nonetheless, there's going to be an upper limit at some point. This in fact appears to be a non-issue ; after all, the Codex takes it as a given that a starship never stops accelerating. I'd argue this is likely because of how the Mass Effect franchise enjoys the benefits of the, uh, mass effect : if the starship's mass is decreased as it accelerates, then no additional energy may be needed, and continuous acceleration may just be maintained.

and then of course we need to talk about inertial dampeners.

3.b : Inertial dampeners

Inertial dampeners, also known as inertial dampers, inertial compensators, inertia compensators, internal compensators, acceleration compensators and many, many other things, are a mainstay of science-fiction, as they're the piece of technology which explains why everyone inside a starship isn't crushed to a pulp by their acceleration to truly plaid ludicrous speeds.

Their effect can be inferred in Mass Effect every time we're aboard the Normandy (a ship whose active artificial gravity isn't aligned to its thrust but perpendicular to it) and we don't see the crew thrust toward the engines screaming for their lives whenever the ship is flying. In text or dialogue, the earliest reference I could find was in some of Joker's ambient dialogue in ME2 when you come to the bridge : "Sometimes I get the urge to turn off the internal compensators and pull a Crazy Ivan, you know ?" (i.e. he wants to yaw 180° with full inertia to send people and small objects flying).

But the technology got the spotlight during the Citadel DLC if you spend some time with Steve, where he demonstrates what happens when you turn off the inertial dampeners in the Kodiak shuttle :

CORTEZ : Before mass effect fields, there was no such thing as inertial dampeners.

SHEPARD : Yeah ?

CORTEZ : Here, feel this.

[The Kodiak roars to life and elevates off the landing pad. SHEPARD stumbles and falls into his chair.]

SHEPARD : Whoa.

CORTEZ : That, my friend, is unadulterated momentum. Want to really feel it ?

[If "Go for it" is selected.] SHEPARD : Show me.

[The Kodiak goes up and down and does a barrel roll. CORTEZ and SHEPARD's bodies move with the momentum, through they remain in their seats despite the lack of visible seatbelts. SHEPARD hoots and laughs.]

CORTEZ : See ? Doesn't take much to pull a few [g's].

[If "Keep it steady" is selected.] SHEPARD : You can turn those dampeners back on anytime.

CORTEZ : Okay, okay. Doesn't take much to pull a few [g's], and we don't want to paint the windows with your breakfast, right ?

[End of branching conversation] CORTEZ : Back in the day, pilots would wear G-suits. It squeezes your body so that the blood stays in your head in tight maneuvers. I'd wear a G-suit flying my Trident. In a fighter it's common to transfer power from the inertial dampeners to other systems.

Here is how inertial dampeners are relevant to the conversation about acceleration simulating gravity : presumably, a cruiser or a dreadnought can accelerate at a rate much higher than 1 g and still use its inertial dampeners to compensate that acceleration and simulate 1 g regardless of its actual acceleration, as long as it is in excess of 1 g. This is very nice, because human beings tend to die at some point after 4 g.

In-universe, this is logical and worthwhile as it allows a spaceship to turn off its artificial gravity and use its inertial dampeners less, instead of nullifying 100% of the effects of acceleration and wasting power on a-grav.

tl;dr : Inertial dampeners can be and probably are used to make starships accelerate at rates far superior to 1 g.

(How mass effect fields make inertial dampeners work is entirely speculative and quite beyond the purview of this very long post. Likewise, whether negating inertia has an impact on Newton's First Law of Motion and the object in motion staying in motion is beyond me, though I should note that neither the games nor the Codex show anything that would suggest this law is altered.)

3.c : What factors in a starship's acceleration ?

So let's say I am Joker and that I have a spaceship. When I want to go anywhere, I light up my thrusters to get going, i.e. accelerate ; I use eezo and the mass effect to lower my spaceship's mass to accelerate even more without changing my thrust ; and I use my inertial dampeners to survive enormous acceleration, the type of acceleration which would otherwise purée me and anyone made of pulpy meat.

Is there something else we can surmise about a starship's acceleration ? Yes. Yes, I think we can.

You see, we might expect how much a starship accelerates to depend on the variously varying variables of an individual journey : after all, sometimes you may want to get somewhere as fast as you can, whereas sometimes using as little propellant and fuel as you can and making the journey less expensive are your top priorities. The problem is that muddles what might be plausibly considered everyone's highest acceleration.

Luckily for us - and unfortunately for everyone else - in Mass Effect 3, we know how fast everyone is moving during the Reaper War, when everyone's priority is either a) get somewhere as fast as you can because you are a warship and time is of the essence, or b) get somewhere as fast as you can because eldritch starships from the depths of dark space want to kill you and everyone you love ; either way, everyone wants to get anywhere as fast as technologically possible, i.e. at a speed less than half the speed of the Reapers ; as we've seen, this fits with the idea that a Citadel ship with a torch drive is moving at 12 ly/day, accelerating then decelerating from the midway point.

This means that the range of 12 light-years in a single day is in all likelihood what a Citadel spaceship can achieve when it is moving at the maximum acceleration it can generate, because maximum acceleration is what will allow a starship (or anything) to get anywhere as fast as possible. A corollary of this is that we understand that Citadel spaceships are always moving at maximum acceleration in all circumstances, including in times of peace. Remember this : this will be relevant later.

Complicating matters is that we (ugh) have to get into the specifics of FTL travel. As I've said before, the crux of what we know is in this phrase : "Faster-than-light drives use element zero cores to reduce the mass of the ship, allowing higher rates of acceleration. This effectively raises the speed of light within the mass effect field, allowing high speed travel with negligible relativistic time dilation effects."

The problem is that there can be no causal link between the two sentences above, not with the way they are presented. Logically, we appear to have two discrete effects instead :

if, theoretically, a starship's mass is reduced to 0 kg, i.e. is made mass-less (and we don't know if the technology can do that), then this does allow "higher rates of acceleration" - but only up to the speed of light. You can't go faster than light if you have no mass because light, which has no mass, can't - that's why it's called the speed of light. (Before someone says anything : There's nothing in canon which suggests negative mass is involved, and we don't even know what negative mass would be beyond a number in an equation.) But in any case, the lighter a ship becomes, the less energy it will need to accelerate. That's your bog-standard mass effect, or Effect #1.

then something else happens that "effectively raises the speed of light" within the envelope, which allows for FTL travel relative to the universe outside the envelope, but presumably never going past lightspeed within the envelope. That's Effect #2.

So it appears that "how much a starship can accelerate" and "how far the speed of light is raised" are separate phenomena but which are difficult to distinguish (let alone to see how they relate together) from an outside perspective. There's going to be a difference between the spaceship's perspective on its acceleration from inside the envelope, and everyone else's perspective on the spaceship's acceleration from outside the envelope.

We can actually safely assume that a starship doesn't lower their mass all the way to 0 kg and get to lightspeed at any point of the journey, even subjectively, because if they did that they would just turn off the engines - and we know that a starship never coasts, they just keep on accelerating (this always was very likely because if you reach the speed of light, time effectively stops for you, but there's no way to know if Mass Effect writers know that and take that into account). This probably tells us something about the limits of mass effect fields and the associated technology : it might just take exponential power to get to pure masslessness - perhaps even infinite power.

So, to sum up : a spaceship's maximum speed is dependent on maximum acceleration - because if they're no longer able to accelerate then they just turn off the engines and drift. A spaceship's maximum acceleration, in turn, will be dependent on :

its thrust ;

how much its drive core can lower its mass ;

and how much its inertial dampeners can cancel out its acceleration's effects on the squishy crew.

(Note that if you increase one, you don't have to increase the others. If you lower your mass, you will start accelerating without increasing your thrust or demanding more of the inertial dampeners. The inertial dampeners come into play when you're undergoing accelerations that would be putting your starship on a high-gravity world.)

We've already established that, in any context, the current generation of Citadel starships in the 2180s is always traveling at the maximum acceleration they're capable of, i.e. what gets a starship at FTL to travel 6 light-years in 12 Earth hours from an initial state of rest.

We can also deduce that it takes more than 12 Earth hours for a starship to reach the point where they wouldn't be able to pile more energy to keep accelerating. Otherwise a spaceship would accelerate in as little time as possible to their top speed, then turn off its engines and its inertial dampeners to make huge savings as it drifts at constant speed (there ain't no friction in space after all).

Another corollary is that, at 12 light-years per day, a starship's mass is lowered and a starship's inertia is dampened as much as the starship can without risking its integrity and the lives of everyone aboard - we might speak of "cruising mass-lowering" and "cruising inertia-dampening" to reach "cruising acceleration". In other words, I think it's safe to assume that, since a spaceship would be undergoing cruising acceleration, i.e. the highest acceleration it can provide at all times without damaging itself or endangering its crew, then its inertial dampeners would be handling at all times the maximum acceleration they can safely take.

"Please, crapeaucrapeau," I hear a fictional stand-in for the reader hypothetically whine, "I can't take it anymore, just stop talking about acceleration." Ah, but dear long-suffering reader, the reason I'm doing all this is that, while we've established that starships in Mass Effect are always in continuous acceleration, the fact they appear to be actually always going at their maximum acceleration entails that they are also moving in constant acceleration.

And that's interesting because we can actually get actual numbers from that.

3.d : Constant acceleration

If a starship is always moving at the maximum acceleration it can reach, then it's undergoing constant acceleration, i.e. a rate of acceleration that remains the same throughout the duration of the flight. The longer a starship flies, the faster it gets.

I should point out that Mass Effect, in keeping with its original hard science-fiction ambitions, is once more entirely coherent with the science and science-fiction it pilfers is influenced by : every single article I've read suggests that constant acceleration is indeed what anyone with a starship able to do brachistrochrones would be doing.

Constant acceleration (which we need, even with inertial compensators) leads to a speed which is proportional to that acceleration ; hence why it's assumed by everyone who mentions it in the OT that it always takes exactly as much time to decelerate as to accelerate.

We actually can squeeze what is our average 12-light-years-per-day starship's constant acceleration out of the data, focusing only on a single burst of constant acceleration during the initial half of that journey :

its initial time - t0 - is when it starts moving, i.e. 0 seconds, i.e. 0 hours, i.e. 0 days ;

its initial velocity - v0 - is how fast it is at t0, i.e. 0 ly/day or 0 m/s^2, since it is at rest relative to the frame of reference ;

its final time - t - is at the midpoint of the entire journey, i.e. 12 hours, i.e. 0.5 day, i.e. 43,200 seconds ;

its average velocity is 12 light-years per day, since it has covered 6 light-years in 12 hours ;

therefore, at constant or uniform acceleration for the duration of the flight, its final velocity - v - will be twice its average velocity, or 24 ly/day.

Assuming that this starship's acceleration - a - is constant, then its average acceleration is the same as its acceleration at any point of its journey ; therefore, a starship's acceleration can be calculated first by subtracting the starship's initial velocity from its final velocity, or v - v0 ; then by dividing the result by the starship's final time, i.e. t.

In other words : a = (v - v0)/t ; and therefore v = v0 + a*t

In our example, v - v0 = 24 - 0 = 24 ly/day = v ;

and a = v/t = 24/0.5 = 48 ly/day^2.

(Of course, the constant acceleration for the other half of the journey - the decelerating part - would be -48 ly/day^2.)

Now, if we put those results in SI units : we need to change "days" to "seconds" as the unit of time, and "light-years" to "meters" as the unit of distance. As a reminder, there are exactly 9,461,730,472,580,800 meters in a light-year, or 9.46 quadrillions.

If v = 24 ly/day, then it's equal to 227,064,000,000,000,000 m/day (or 227.1 quadrillion m/day), which is equal to 2,628,055,555,555.56 m/s (or 2.6 trillion m/s).

If a = v/t = 48 ly/day^2, then it's equal to 2.6 trillion m/s divided by 0.5 day, or 2.6 trillion m/s divided by 43,200 seconds, or 60,834,619.3 (m/s)/s (that's 60.8 million (m/s)/s).

To check if we are correct, a*t should equal v ; or 60.8 millions multiplied by 43,200 should equal 2.6 trillions — which is indeed the case.

Note that this is the starship's constant acceleration as measured by a stationary observer outside the envelope : within the envelope, where an observer is not measuring any speed that is superior to the speed of light in a vacuum, the values would be much lower, and the corresponding energy required to generate that acceleration would also be lower.

(Yet another piece of circumstantial evidence in favor of constant acceleration is that the fact the average distance covered by Citadel starships in the OT becomes comparable to the Tempest's average speed in ME:A actually makes sense : with constant acceleration, average speed is equal to range/distance travelled.)

3.e : Putting it all together

So, if we keep in mind a maximum and constant acceleration of 48 ly/day^2, here is what the average velocity/range of a starship for a full brachistochrone would look like depending on time :

One minute : 30 seconds acceleration, 30 seconds deceleration - 30 seconds being 1/2880 of a day, 0.000347 day. If a = v/t, then v = a*t ; 48*0.000347 = 0.016667 ly/day for final velocity ; its average velocity, in a constant acceleration situation is, v/2, or 0.0083335 ly/day. To calculate the final position of the starship at the mid-point of the flight (x), one must multiply average velocity (here, 0.0083335) by t (here, 0.000347) ; the result is 0.00000289 ly. Double it, and you have the full length of the minute-long FTL brachistochrone, or 0.00000578 ly, which is about 0.365526 AU, or 54,681,895.93 km.

Five minutes : 2.5 minutes accel, 2.5 minutes decel ; 2.5 minutes is 0.001736111 days. Now, wonderfully, the way the math works, you can simplify the equations by multiplying v (final velocity) by t (time) to get the final result. v = 48*0.001736111 = 0.083333328 ; 0.083333328*0.001736111 = 0.0002 ly, which is about 9.1495 AU (far greater distance than the distance between the Earth and the Sun, at 1 AU, though still short of the average distance between Earth and Jupiter).

Ten minutes : 5 minutes accel, 5 minutes decel ; 5 minutes is 0.003472222 days. v = 48*0.003472222 = 0.166666656 ; 0.166666656*0.003472222 = 0.0006 ly, which is about 36.5971 AU (an enormous distance, but a bit short of the average distance between Earth and Pluto at 39.5 AU ; keep this in mind, this will be relevant later).

Fifteen minutes : 7.5 minutes accel, 7.5 minutes decel ; 7.5 minutes is 0.005208333 days. v = 48*0.005208333 = 0.249999984 ; 0.249999984*0.005208333 = 0.001 ly, or about 82.3434 AU (greater distance than the average distance between Earth and Jump Zero).

Thirty minutes : 15 minutes accel, 15 minutes decel ; 15 minutes is 0.01041667 days. v = 48*0.01041667 = 0.50000016 ; 0.50000016*0.01041667 = 0.005 ly, or about 329.37 AU.

One hour : 30 minutes accel, 30 minutes decel ; 30 minutes is 0.02083333 days. v = 48*0.02083333 = 0.99999984 ; 0.99999984*0.02083333 = 0.02 ly, or about 1317.49 AU.

Two hours : 1 hour accel, 1 hour decel ; 1 hour is 0.04166667 days. v = 48*0.04166667 = 2.00000016 ; 2.00000016*0.04166667 = 0.08 ly, or about 5269.98 AU.

Three hours : 1.5 hours accel, 1.5 hours decel ; 1.5 hours is 0.0625 days. v = 48*0.0625 = 3 ; 3*0.0625 = 0.19 ly, or about 11,857.45 AU

Six hours : 3 hours accel, 3 hours decel ; 3 hours is 0.125 days. v = 48*0.125 = 6 ; 6*0125 = 0.75 light-years.

Twelve hours : 6 hours accel, 6 hours decel ; 6 hours is 0.25 days. v = 48*0.25 = 12 ; 12*0.25 = 3 light-years.

1 day : 12 light-years (duh) ; v = a*t = 48*0.5 = 24 ; v/2 = 24/2 = 12 = Average velocity ; x = 12*t*2 = 12*0.5*2 = 12

As you can see, the distance travelled increases exponentially to the time spent travelling. Note that the above numbers do not take into account minutiae like any trajectory other than a straight line, or the time when, presumably, the engines are switched off, the starship does a skew flip, and the engines are reignited.

Now, theoretically, assuming that starships can accelerate indefinitely and don't need to stop to get fuel/radiate heat/discharge drive charge/etc…

2 days : 48 ly ; v = a*t = 48*1 = 48 ; v/2 = 48/2 = 24 = Average velocity ; x = 24*1*2 = 24*2 = 48

3 days : 108 ly ; v = 48*1.5 = 72 ; 72/2 = 36 ; x = 36*1.5*2 = 108

4 days : 192 ly ; 48*2 = 96 ; 96/2 = 48 ; x = 48*2*2 = 192

5 days : 300 ly ; 48*2.5 = 120 ; 120/2 = 60 ; x = 60*2.5*2 = 300

But we can pretty much guess that's not the case, or the mass relays would be obsolete.

Going forward, our concerns are :

what are the non-mathematical limits to constant acceleration in FTL ?

And do whatever pieces of information we have about travel time and distance travel in Mass Effect agree with the numbers I've figured out ?

And oh, gosh, I've run out of letters again, I'll have to split this post in twain.

UP NEXT (eventually) : Camala ! Drew Karpyshyn ! Hawking Eta ! Oh, and every data point on speed and travel time in canon. Plus, all those nice numbers I calculated are shown to be… pointless. Fun !

G2HGE Index :

Post 0 : Presentation and Purpose

Post 1 : Methodology and general lamentation over the incoherent state of the lore.

Post 2a : Oldest canon date for activity in every single cluster

Post 2b : Organization and Visualization of the above

Post 3 : The oversized impact of the asari, and a surprising amount of stuff to discover.

Post 4 : The Problem with the Galaxy Maps

Post 5a : The Regions of the Milky Way : Overview and Council Space

Post 5b : The Regions of the Milky Way : The Terminus Systems

Post 5c : The Regions of the Milky Way : The Attican Traverse and Earth Systems Alliance Space

Post 5d : The Regions of the Milky Way : The Nemean Abyss and the Perseus Veil

Post 5e : The Regions of the Milky Way : The Skyllian Verge

Post 6a : You're here !

#mass effect #galactic geography #G2HGE #starships #mass effect 1 #Mass Effect: Revelation #Tempest #deep-space fighters #FTL #faster-than-light travel #mass relays

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