//------------------------------// // Calibration: Time // Story: The Velocity of Blood // by the dobermans //------------------------------// The tall double doors creaked open, permitting the last orange rays of the sun to fall in a broken slant across the star charts and shelves of the library tower. The unlit lamps told Twilight that its new resident was away: living it up with Minuette and the girls, no doubt, the whole gang doing the Tail Whip on the dance floor, sharing the spotlight. All the pieces coming together at last. She kindled the lamps with quick jets of magic. Unlike the last time she’d come, the soaring space showed signs of use and care. The dust and cobwebs had been swept from the lens caps of the telescopes, which, much to her convenience, had been oiled and unshuttered. A hint of sweater overdue for washing was in the air. Twilight would have smiled. When the place had been hers, she had lived, she now understood, in a deep, recurring dream. Not of the wild release of flight—of a spirit soaring over pastoral quiltworks of wheat fields and dark, tangled orchards until the end of time—or of missed exams and shame before a frowning Celestia, but the kind filled with ancient books and artifacts, gems and medallions imbued with magic and the majesty of bygone generations overflowing in the desk drawers and reliquaries. She couldn’t count the number of notes written in antique quill strokes that had slipped from disintegrating pages as she’d opened the reeking volumes that bound them, betraying hours upon hours spent by nameless astronomers in service to ends to be decided long after their time. All forgotten. Every day at the first rising of the sun, she’d climb the stairs trying to remember where she’d left off the night before, ready to add her contribution: both to the timeless library and to its hidden inner index, buried in the margins and yellowed loose leaf. Something moved outside. The sound of little dragon feet on ivory stone. The same as always. Where am I? she wondered. When? “Spike,” she called out into the deep red of the falling summer sun. “Do you need help?” He made it to the top of the stairs, grabbing the still-open door just in time to prop himself up. “Help?” he wheezed. “Sure. Can you … get me a new spine … and maybe a couple kneecaps? Or just a bag of nice. That would be ice.” His inward flop onto the floor slammed the door shut. “Come on,” said Twilight, splashing him in the face with a magical mock-up of a bucket of water. “No rest for the weary.” Spike pulled himself up, shaking shreds of purple magic from his face. “I guess that’s a ‘no’ on the ice.” He threaded an arm through the loops of his bags and dragged them toward the nearest reading table. “Wow,” he sighed, marveling at the shiny surfaces of the flasks and metal tubes that glittered in the dancing light of the lamps, “Moon Dancer sure went to town in here. Wonder how many trash cans she needed just to get rid of the dust bunnies.” “Town is probably where she is right now,” replied Twilight. With a wave of her hoof, a long curtain hanging by the room’s central pillar racked to the side, undraping not a window, but a broad metal cylinder bonded to the granite. “You can set the compass down, right there behind you on the floor. It’s the most stable surface in the room. We’ll have to avoid vibrations as much as possible while you operate it, or else the curvature of the workpiece will be non-uniform. That would be just like denting the Projector tube: a complete disaster!” Spike placed the compass on the clean-swept tile with a reverence due the most delicate crystal statue. “I won’t so much as breathe on it,” he said. “By the way, what’s a ‘workpiece’?” A dull lump of metal rose from Twilight’s bag. Spike held out his paws as it floated towards him, and when it landed in his grip, he gave it a quick heft. “Actually, breathing on it is exactly what I want you to do,” said Twilight, sending two more items his way. “That’s an ingot of iron, and here are a few sheets of sandpaper and a bottle of polishing grit oil. What I want you to do is, place the ingot on the compass’s goniometer …” Spike’s eyes glassed over behind the pile of supplies he was holding. “The turny thing in the middle,” Twilight continued, giving the floor a sharp hoof tap, “and breathe some fire on the top to soften it up. Not too much, or it will start to deform under the gravitational body force, and you won’t be able to mold it properly.” She unwound the twine from her ruler. “While I adjust the height of the markings on the collection cylinder here—” she pointed over her shoulder “—you form the ingot into a ball while it’s still soft, then use the compass, sandpaper and polishing oil to shape it into a perfect sphere.” Spike eyed the ingot, judging the odds. “A sphere, huh? That shouldn’t be too hard.” “We want it to be hard!” snapped Twilight. “I mean, any deformation during the experiment will result in parasitic energy losses. Do I have to spell it out for you? And it’s not … and it’s not …” She fell silent, the ruler floating in the air between them. Spike began picking at the brass knobs of the compass, downtrodden. “It’s not as easy as you think,” Twilight giggled. “Sorry, I misunderstood. No big deal. Just do your best. That’s what Celestia would always tell me when I couldn’t figure out how to cast a spell, or manufacture an ideal mathematical form, or get to the bottom of some philosopher’s centuries-old rabbit hole. ‘Do your best, Twilight.’” She turned away, and sweeping the ruler to her side, buried her head in the tall metal column behind her. Spike watched her for a moment before the sparkling of the iron ingot’s tiny facets captured his attention. He gave it a few wary puffs of flame, and began pressing it with cupped paws. “So,” he ventured, slipping the still-glowing ball onto the protrusion at the center of the compass, “just curious: I get my part, but what are you up to? I don’t remember what was next on the checklist.” The downward arc of Twilight’s tail jounced as she shifted. “We’re calibrating time,” she replied, her voice resonant and metallic inside the cylinder. “Distance and time are the two quantities one needs to measure velocity. We took care of the distance part during our visit with Celestia, remember?” Spike nodded. “Yeah, that makes sense. But how can anypony calibrate time? Celestia’s horn is easy, but nopony can see or touch time.” “You can calibrate time with a clepsydra,” Twilight replied. “A water clock. It’s a classical invention, based on the principle that water at a constant pressure will flow through an orifice at a constant rate.” “Oh yeah, one of those,” Spike grumbled. He jabbed the mechanical claws of the compass into the ingot’s viscous skin and gave the crank at the bottom a turn. The rough-hewn ball rotated a hair’s breadth. “Now Spike,” said Twilight, withdrawing from the tube just far enough so that he could see the side of her face, “that tone! I’ll have you know that anypony with a few thousand bits and access to a millwright and a hundred gallons of distilled water can make one of these. I mean, all this effort we’re devoting to precision and validation is pretty pointless if nopony has the means of performing their own validation.” She tittered into the shadows below her. “An experiment that can’t be reproduced is a meaningless experiment.” Spike counted on his claws. “So we’re talking Flim and Flam, Filthy Rich, Fancy Pants, the Princesses, Rarity maybe … I bet she has a gorgeous clepsydra.” “Anypony with access to sufficient private or public funds, yes,” Twilight spat. “Continuing. I could use the outflow type, but those require that the radius of the container vary with the fourth root of its height to ensure a constant flow rate. By now the problem with that should be obvious. I can’t be sure that the continuously-varying radius was accurately measured. Not to worry, though. This unit is an inflow type. It’s much easier keep the container full of water than fiddle with its geometry. And in case you were wondering, it’s tall enough such that fluctuations in pressure due to surface turbulence that might affect the flow rate should be buffered from the outlet valve at the bottom.” “Rarity’s got private funds for miles,” crooned Spike. He hugged the compass’s rounded support shafts. “Spike!” Twilight shouted, ringing the collection cylinder with her hoof like a gong, “I know this is all very technical, but could you please save your inner fires for the ingot and pretend like you’re paying attention? This part is important.” Spike cringed, and returned to turning the compass’s crank. “OK then,” Twilight proceeded. “Time is Celestiacentric, just as distance is. One day is defined as the length of time between the rising and the setting of the sun. We could just as easily have used the night, but we got here a bit late, and … well … Lunacentric standards are no longer widely accepted.” “Becoming a foal-eating monster and being imprisoned in the moon for a thousand years will do that to your standards, I guess,” Spike murmured. Twilight rolled her eyes. “That first part is undocumented, but yes, Luna’s fall damaged her reputation with the scientific community. Adherence to the lunar annual cycle is all that’s left of her post-classical scholarly work, and frankly I’m surprised they kept that. But that’s beside the point. What I’m going to do, very simply, is block the outlet valve using this impermeable photosensitive film—” she levitated a sliver of white material “—and focus the light coming from that window on it, so that the moment the first rays of the sun break over the horizon, they’ll converge on the film, incinerate it, and open the valve to start the clock. Neat, huh?” Spike scratched his head. “So, is the length of the day different for ponies who live in hilly areas? I mean, you’d have a hard time proving—” “Proving?” said Twilight. She reared, grabbing her sides to keep herself from shaking until the laughter overtook her. Down she went, rolling and blubbering and dripping tears. When she caught her breath, she settled on her back, gave Spike an upside down grin and said, “Science doesn’t aim to prove anything! It confirms or falsifies hypotheses that themselves survived prior confirmation/falsification processes. It takes you down a path, just like other ponies do. And most of those paths are wrong, but that’s how it goes.” She considered the bulging shelves of titles and authors that lined the walls. “Can you imagine, Spike, what it’s like for a pony to cling to a theory they know is wrong, because they’ve devoted every waking hour trying to prove it—built their life around it—only to find halfway through that nature disagrees with them? Can you picture Starswirl’s dismay when he discovered that the years he spent trying to complete the Friendship Spell wouldn’t pay off for him, or maybe for anypony?” She continued laughing, kicking her legs in the air. “I, uh, don’t see what’s so funny, Twi,” said Spike. He gave the rattling handle of his crank a spin. “You’re kinda saying nopony can find out the truth. So if that’s true, what are we doing here? I don’t mean to be rude, but there are a lot of love poems I could be writing to Rarity right now.” He flinched. “I said that out loud, didn’t I?” Twilight flopped onto her belly. “I’ll pretend I didn’t hear that. And you’re right! Science doesn’t tell you what’s true. It tells you what’s convenient and reliable for the ponies who have something to gain from the process. Because if it can accomplish whatever it is you put it in your mind to do, it’s good enough.” She stood up, still chuckling, and smoothed out her feathers. Spike smiled, raising a fist into the air. “And who knows what the best thing to put in our minds is? Twilight does.” Twilight dipped her head back into the collection cylinder, signaling Spike to see to his task. The rumbling of distant carriage wheels and shouted farewells in the city faded with the final moments of the day, receding below the chatter of the night birds that nested in the exposed gaps in the tower’s stonework. Spike sat at his compass, scraping at the ever-shrinking sphere, while Twilight contorted herself to reach the lower levels of the tube and scratch at the skewed level lines. On they worked. A few lamp-lit hours spent, Twilight emerged from the cylinder and set the stop-gap within the valve. Satisfied, she filled the upper tank with water, and began adjusting the focusing lens at the eastern window. When the dawn came, the film vanished in a swirl of smoke. A thin, powerful stream of water erupted from the valve and began pooling at the bottom of the cylinder. With her magic, Twilight opened a valve in a third tank tucked away in the ceiling, causing a cascade of water to fall and keep the source container full. Nodding at her work, she slumped her shoulders and exhaled. With red, bleary eyes she turned to Spike. “So, how’s it going?” “I … think I got it?” Spike estimated. He held out the mirror-smooth ball for Twilight to inspect. She took it, balancing it in her hoof. “Great job! This will be my cavitation sphere. An essential component of the Projector.” Her reflection spoke back at her, its misshapen mouth spreading to the poles where it became one with the rest of the distorted library. “Thanks, Twilight, but no matter how much I polished and re-melted and polished again, I couldn’t get everything to line up. It’s not perfect.” “It’s OK,” she said, brushing his cheek with her wing. “Perfect spheres don’t exist. It’ll do what I need it to do. And hey, right now I need you to tally up the number of markers the water level passes today. I’ll call them out and you mark them down.” “You’re the mare with the plan,” Spike replied. He snatched a quill from the reading table and joined her by the clock. For the rest of the day, they sat side by side, marking every time the water crept to a new measured height, telling jokes, and stories, and nudging each other when they started to nod off. When Spike’s cramped paw started to ache from hours of cranking, Twilight conjured an ice pack and a pair of emeralds for him to munch on. There were times when he caught her watching him, her gaze full of pride, and something more. He nestled under her wing when it was offered. When the light began to fail once more, Twilight lowered one end of another strip of material into the water in the collection cylinder, and fixed the other end to the top. Satisfied that it wouldn’t fall, she flew to the focusing lens and redirected it onto the strip. The part above the water’s surface became a bright red, while the submerged end remained white. As the water level rose, the red retreated upward, until the light disappeared. In the dark, the colors remained fixed. Twilight wiped her brow and extracted the strip. “That’s a wrap, Spike. We did it.” “We did it!” Spike cried, “and none the worse for the wear. Though I gotta say, I won’t be playing the viola anytime soon. And I’m gonna have to cancel my rock climbing trip with Dragon Lord Ember in the Dragon Lands this Saturday. She’ll understand. She’ll understand, won’t she Twilight?” He whipped his sore paw back and forth. “I’m sure she will, Spike. Friends always do.” As she went to the reading table to extinguish its lamp, she noticed a stack of aborted letters in a pile beside the inkwell. She bent to get a closer look. Dear Princess Twilight, I know we had some words at the party you threw for me Hi Twilight, I hope everything is going well. I wanted to thank Twilight, I don’t know how “Spike,” she called. “Yeah?” “Gather the things, please. Quick. We need to get back to … sorry, I’m nickering like a filly. Just remembering your joke about the mustard moustache. We need to catch the late train to Ponyville.” “Sure thing. I’ll have the bags packed in a second.” As Spike occupied himself with the saddlebags, she located Haycart’s Treatise on Ponies and yanked it from the shelf. Lowering it onto the reading table, she grabbed a quill with her magic, scrawled two words on a loose scrap of paper and stuck it and the unfinished letters inside. Without a second glance, she went to the doorway to wait for Spike to finish. The night, like almost every night in Canterlot, was quiet and serene. Down on the path below, a lone mare was trundling at the head of a wagon full of books, levitating a lantern in front of her. Twilight took a step back. “Hey, Spike, you know, we really need to get back to the castle and analyze our data. I’m OK with teleporting this time. You ready?” Spike appeared in the doorway with their supplies. “I was born ready,” he said, placing a paw on Twilight’s shoulder. “Analyze. That means study, right?” “To break apart,” Twilight giggled, wiping a stray tear from her cheek. She tracked Moon Dancer as she climbed the stairs. “To destroy. You can’t truly know something without destroying it. And even then …”