Rap, Ginger Root and Patina sat together in the main hall eating breakfast. In between licking bits of fried egg, potato and cabbage off their plates, Rap and Ginger listened to Patina read out the schedule of lessons for the next month.
“We should finish geometry this week, then we will move on to studying algebra, the Griffon calendar, old Equine scripts, and long term weather patterns. And our usual classes on chronometry, mechanics, cake baking and needlework.”
“But what do we have today?” asked Rap.
“Nothing. It’s a holiday today as the Fellows are all busy preparing for the feast tonight.”
“Cool. What shall we do?”
“Do you want to keep looking for something on ice dragons?”
“I’m not sure that’s going to work…” Rap’s enthusiasm for hunting dragons had abated since the previous night. “I mean, the ice dragon probably lives a long way from the abbey. So we probably won’t have time to track it down, catch it, and get back home in time for the feast. Let’s leave it for another day.”
“So what shall we do?” said Patina.
“Let’s go and visit the Practical Scholar,” said Ginger Root. “He’s always fun to talk to, and he won’t be busy as the Abbess never trusts anything important to him.”
The three fillies left the dining hall and walked up the staircase which led to the workshops. The Practical Scholar had a room on the second floor. They knocked on the door. There was no reply. On pushing it, it moved a short distance before sticking against a pile of cast iron metric-standard weights, but they were able to squeeze through the opening into the room.
The room was full of all sorts of random articles which the Practical Scholar considered essential for his work. The walls were covered with bookshelves, holding many old volumes, as well as collections of interestingly shaped rocks, shells, birds’ feathers and old horseshoes. A table in the middle was covered with cogs, spindles, hooks, and all sorts of oddly shaped pieces of metal that went in clockworks. Further shelves housed hourglasses, an abacus, astrolabe—
“What’s that?” asked Apple Bloom.
Twilight grinned. “An astrolabe is an instrument which you can use to measure the inclination of a star, or the sun, or another body, then if you know your latitude you can tell the time, or if you know the time, you can find your latitude and longitude. It’s made with a series of metal disks each marked with—”
“Okay, okay. Carry on Doctor.”
—protractors, dioptres, quadrants and sextants, scrolls, half-full bottles of wine. A pegasus skeleton was hanging from the ceiling (a former Librarian who had insisted, on his death, that his bones were to be used for anatomical research—no other member of the Order wanted to share their room with him). One side of the room was divided by a horizontal floor to create a sleeping platform, accessed by a ladder. From this was hung various models of prototype flying machines made from sticks and strips of paper, as well a hammock full of cans of paint, tools and other junk—this had been installed as a space saving idea by the Practical Scholar as an attempt to clear the floor space, but it had only worked temporarily and the floor was now covered with new debris.
The Practical Scholar, Spin Precession, was lying on the floor underneath an elaborate mechanism of interconnected wheels mounted in a metal frame. The three fillies could just see his tail and exposed flank baring his cutie mark—the image of a spinning top tilted at an angle.
“Hello?” said Ginger.
The noise made him drop the screwdriver he held in his mouth. The screw he had been tightening dropped out of space, releasing a spring, which flew out across the room and landed in a tea cup. He climbed up on his hooves. He had an elaborate headpiece strapped to his forehead, to which a large magnifying lens was attached by a spring. This hung down in front of his left eye, allowing him to focus on the tiny screws he needed to fix. His right eye, unobstructed, was able to focus on the fillies in front of him and on seeing Ginger Root, Rap and Patina he smiled broadly.
“Oh. Hi there!”
“What’s this thing?” asked Rap, staring at the mechanical contraption he had been working on. A long central spindle was sticking upwards out of an assembly of gears. To this was attached a series of rods, leading to the familiar face of a clock.
“It’s my latest invention,” he said. “I’m developing a new sort of clock, as an alternative to the hourglasses, and perhaps one day it could replace the Minute. If I can improve the accuracy.”
“How does it work?”
“It’s driven by the energy stored in the spring.” He pointed out a spiral spring tightly wound around an axis. “This makes the main wheel turn. Then the most important component is the escapement—which causes the gear wheel to advance at a regular interval.” He pointed to a metal wheel with triangular teeth pushed forwards by paddles connected to an axis, which pivoted back and forth. “We need something to prod the escapement at a regular rate, like the lever arm of the Minute. The best thing I’ve found so far is to connect two weights at the ends of a horizontal bar connected to the axis. By adjusting their position I can get it so it swings back and forth once a minute.”
To demonstrate this, he held a horizontal metal rod against the vertical axis and secured this with a pin. He then hung a metal weight on either end, and pushed it so it swung around in an arc, causing the paddle to push the escapement. It slowed, came to halt, then swung back in the other direction, but this time, the paddle was deflected by the slope of the teeth so it didn’t push it back. After completing one cycle, it swung back again to advance the mechanism another step. The escapement drove a train of gears, ultimately connected to clock hands which moved around a flat circular dial.
“That’s cool,” said Rap.
“Most of it is the same mechanism as we have in the main tower,” continued the Practical Scholar. “Which connects the Minute to the clock face and rings the bells at the correct time. But it has to be connected to something which moves back and forth in a super regular way. The best thing we have at the moment is the water-driven lever arm of the Minute. I thought this would work, but it doesn’t seem very accurate. But—” he paused a moment with a big smile. “I think I can do better.”
“How?” ask Patina.
“Atomic theory!” he announced gleefully, throwing his hooves in the air and knocking the lever arm of the escapement. The weight at the end fell off, falling against the spring. Knocked out of its holding cylinder, this sprang free and flew across the room, cutting through the cord holding a prototype model heavier-than-air flying machine from the ceiling and sending this crashing down onto a table of chemical glassware.
Ignoring this distraction, he beckoned them over to a table, pushing a pile of books to one side with a hoof. This in turn pushed a box of cogwheels on the far side of the table onto the floor. He picked up a scroll of paper and unrolled it onto the surface. Then, holding a pencil in his mouth, sketched a picture.
“Atomic theory says everything around us is made of tiny particles called atoms,” he said. “In every atom you have a nucleus in the middle, and lots of electrons circling around it. The electrons and the nucleus are spinning around like a spinning top.”
“How does that make a clock?” asked Ginger Root.
“There’s an intrinsic resonant frequency in the atom,” he said, “corresponding to the different ways the electrons dance around. If we can just give the atoms a kick and find a way to measure it. It must be have a super regular beat, jumping back and forth in a way fixed only by the atom, and not messed about by magic, the weather, ponies or dragons.”
“How fast does it jump?” asked Rap.
“A few hundred billion times a minute.”
“How can you keep count of that?” asked Patina.
“And how can that drive a clock?” said Ginger Root.
“I’m working on it.”
He picked up a small metal foal's toy—a spinning top—lying on the table in front of him, the same shape as his cutie mark, then with a skilled flick of a hoof, set it spinning around.”
“Atoms are like spinning tops on a microscopic scale. If we tip over the spin axis.” He gave the toy a tap with a hoof to tilt it to one side. This was not enough to cause it to fall over, but instead the spinning axis started to spiral outwards, swaying around. “The way it points moves around and around,” he explained, tracing out a circle in the air above the gyroscope with his hoof to illustrate the motion. “But the clever thing is that the rate which it does so stays constant.” The top finally slowed down and fell over, rolled across the table and crashed onto the floor. “Well, in this case it's not so stable, but that's because there are too many variables. We can’t make a clock out of a spinning top like this. But if it were an atom, it would keep spinning with a rhythm so stable we could use it as a clock.”
“That’s not quite true,” said Twilight. “Atoms and electrons have an intrinsic angular momentum, but it’s not correct to picture them as spinning solid bodies. This is where classical physics breaks down. You measure it by the interaction of the quantized spin with the magnetic field. The correct quantum mechanical interpretation would be—”
“Twilight—will you keep quiet and let the Doctor tell the story,” said Apple Bloom, Sweetie Belle and Scootaloo in unison.
As the Practical Scholar said this, the magnifying lens attached to his head was jumping up and down in front of his eyes. Rap stared at this with interest.
“So to drive a clock, you need something which bounces up and down in a regular way,” she said.
“That’s it. An isochronous mechanism.”
“Like a spring?”
“Oh I tried that but it doesn’t work very well—a springs only works for a while before it is dampened down. You would have to find a way to keep kicking it. But then that would interfere with the rhythm...”
Rap looked thoughtfully at the lens jumping up and down in front of the Practical Scholar’s face as he continued talking.
“This is the fundamental problem of timekeeping—finding something regular which we can use to count the passage of the minutes… The flow of water, the rate at which a candle burns, the swinging of an escapement. They all work up to a point, but they all have problems…” He shook his head while looking at his escapement mechanism. “There must be a simple way to do it.”
Clack, clack, clack, clack. The metal foliot swung back and forth, each time nudging a tooth of a cog driving a large gear wheel, which in turn pushed another. The interconnected components all jumping forward in a steady beat. Scootaloo, Apple Bloom and Sweetie Belle all stood staring at the mechanism watching the rocking levers and wheels, mesmerized by the movement. Behind them stood Twilight Sparkle and the Doctor. They had come into the East Hall of the abbey which now housed a museum of historical clocks and other instruments.
“So,” said the Doctor, “this is the verge-and-foliot escapement mechanism built by the Practical Scholar Spin Precession all those years ago. An early attempt to replace the Minute water clock. The position of the weights along the horizontal bars determines the period with which it swings back and forth, each time pushing the cog wheel. Unfortunately it didn’t keep very good time. The speed would change as the spring unwound. But they would soon make a major breakthrough.”
Scootaloo turned away from the museum piece to face the Doctor. “Is that how Rap got her cutie mark?”
Later that day, after lunch, the three fillies were sitting on the roof of the library having climbed up the stairs to the top of the tower and out of an attic window. The slates were warmed by the sun providing some comfort against the chill winter air. Rap outlined a new plan to prove her worth.
“So the Practical Scholar was saying you could keep time with a bouncing spring, but you need some way to keep it jumping up and down. So I was thinking, if I was at the end of the spring, I could always keep it going by flapping my wings or waving my legs or something.”
“But then you would have to be part of a clock forever after,” said Patina logically. “That would get very boring. And you would need to sleep and eat sometimes. And you would probably get seasick from all that bouncing up and down.”
Rap dismissed these technical issues with a casual wave of the hoof. “We’ll sort out the details later. The key thing to do now is to demonstrate the idea!”
“How? You would need a big spring.”
Rap grinned. “I thought of that. I had a look in the Steward’s sewing box while he was busy serving lunch. He had a large reel of elastic braid.” She dropped a reel of white elastic lace trim onto the roof tiles. “I just need to weave a rope from this.”
She held one end of the elastic between her teeth and kicked the reel off the roof so it fell six storeys to the ground. She was good at tying knots and braiding, and in a few minutes she secured the end of the elastic rope with a back splice. She then proceeded to tie one end to a protruding horizontal roof beam (the sort which are left sticking out the side of many pony buildings to provide a convenient perch for passing pegasi), and wrapped the other end around her rear hooves.
“Are you sure this is a good idea Rap?” asked Patina.
“Of course. What can go wrong? Here we go!”
She dived off the roof.
“We have got to try that! Cutie Mark Crusader Bungee Jumpers! That will get us our marks for sure. Where can we get some elastic rope?” said Scootaloo.
“Maybe Rarity has some sewing elastic,” said Sweetie Belle.
“Or we could use Pinkie Pie’s extra stretchy bubble gum,” said Apple Bloom.
“Don’t you want to hear the rest of the story?” said Twilight.
“Yes,” said Scootaloo. “Did Rap get her cutie mark in bungee jumping?”
“We will come back to Rap and her friends in a bit,” said the Doctor. “But first let us now return to the Princesses and the Fellows.”
The meeting of the Fellows and the princesses was held in the council room in the library tower. The library was made up of a large number of rooms, joined together by open doorways. Most of these were filled with shelves housing the tens of thousands of books and scrolls which made up the abbey's collection, but others were furnished with desks where the scholars of the Order worked, documenting the history of the world. Artists sat slowly decorating manuscripts with elaborate coloured strips of pictures. Other ponies were busy reading and scribbling notes onto scrolls.
At the centre of the network of rooms was the octagonal council room. In the geometric centre of this was a large stone table decorated with a beautiful mosaic. Around the edge, a series of images depicted scenes from the history of Equestria: the three ponies tribes coming together to found Equestria, Starswirl the Bearded founding the Order of the Time Turners, the building of the abbey, Canonical Hours demonstrating the first hourglass, the construction of the Minute, and Luna and Celestia defeating Discord and restoring order to the world. In the centre of the table was the emblem of the royal pony sisters chasing each-others' tails.
The table had been made by a team of outstanding craftsponies a century ago. It had served as the focal point for important meetings ever since. Thus it was here where the fellowship and the princesses assembled at none [1]. The princesses were rather less playful than the image on the table. Luna sat on the western side, flanked by two advisers. Celestia and her retinue on the other side. The Abbess, Dean and Librarian sat to the north, with the Cellarer, Steward and Practical Scholar facing them.
[1] 15:00—which would be the ninth hour after dawn at the spring and autumn equinoxes.
As was the custom, the Abbess began the meeting by turning a large hourglass in the centre of the table, and banging a gavel to formally mark the start.
“This meeting will last for two hours, after which we shall adjourn to prepare for the sunset ceremony,” she said. “I would like to begin, on behalf of the Order, by expressing our sincere apologies for the temporary lapse in timekeeping which occurred before sunrise this morning. This was a most unprecedented incident, precipitated by the extreme weather conditions. It is to endeavour to understand the cause of these conditions that I have summoned you all here.”
Princess Luna let out a loud audible yawn, staring out of the window. Her sister gave her a venomous stare, then turned to address the Abbess. “We request that the Lunar contingent keeps quiet.”
Luna gave her sister an icy glare. “Take that instruction thyself. We did not rise two hours before the norm to hear thy voice.”
The Abbess decided to ignore them and continue before Celestia could respond to her sister’s provocation. “To begin, the Librarian has examined the records of the abbey to see how the weather has changed over the last few hundred years.”
The zebra removed a large book from her saddle bag, with many pages of paper between dark blue cloth covers, ornamented with gold leaf. She placed this on the table and opened it at a spot marked by an embroidered bookmark.
“In this tome compiled by many an editor,
Is recorded the daily temperature,
We measure the height of a mercury column,
Through winter, spring, summer and autumn,
And over several hundred years,
A clear long term trend appears,
As the abbey has grown older,
The weather just keeps getting colder.”
“Is it steadily getting colder,” asked the Abbess. “Or has it just been unusually bitter for the last few winters?”
“A small change in living memory,
But it adds up over each century,
So that now, to our great unease,
It's not strange to see the Minute freeze.”
“And that is the problem,” said the Abbess.
“We can take measures to stop it freezing again,” said the Dean. “But we need to make sure it doesn't get any colder. If it gets any worse, it might freeze in the rock itself. Then no amount of dragon diplomacy will save us.”
The Abbess nodded. “Which is why it is imperative that we understand the cause of this long term trend.”
“Tis obvious, is it not?” said Luna. “The heat of the world comes from the sun.” She stared across the table at Celestia. “Explain why you cannot keep us warm sister.”
Celestia replied coldly, “The power of the sun does not waver. It is as hot today, as it was the first day I raised it.”
“There have been days when sunrise was late,” said the Cellarer [2], “is that significant?”
[2] The most common reasons for these events were: 1) Celestia oversleeping and not being available to raise the sun; 2) Luna waking up late and not being available to lower the moon; 3) In times past, when the princesses were on better terms, both sisters failing to turn up having been so engrossed in playing a board game that they forgot about the time.
“That could be it,” said Luna, “Celestia's getting lazy. We're all cold as she can't lift the sun on time.”
“I have been as punctual as the lunar guardian in recent times,” said Celestia.
The Librarian place another book on the table.
“We have recorded every date,
When sunrise was a little late,
Fortunately such events are rare,
But once it happened, we are aware,
That the sun was high for three whole days [3],
(As measured of course in other ways),
But over time it averages out,
There's no net effect, I have no doubt.
If sometimes we see too much of the sun,
At others, the night will overrun.”
[3] This incident occurred 274 years before this story. During a game of hide and seek Celestia managed to lock herself in a closet in the castle of the royal pony sisters. Desperate to beat Luna, after losing the previous three rounds, she had first charmed the cupboard to make it invisible. The royal guards and Luna spent over seventy hours searching the castle, during which the sun remained above the horizon.
It was the Practical Scholar's turn to make a suggestion. “Is it something to do with the way the pegasi are running the weather? Have they been making more clouds of late, which are blocking the sun?”
As the only pegasus present, the Dean responded to this by shaking her head. “The number of clouds hasn’t changed. They are valuable real estate for pegasi. If there was any increase in the cloud cover, property prices would fall, and we would hear about it.”
“Or,” continued the scholar. “Have you read about the greenhouse effect? Layers of air can trap the sun’s heat. Some gases can let light through, but trap heat, and could change the climate.”
“But why would the level of such gases change?” said the Dean.
“Well,” said the Scholar. “Hypothesis one: we are burning more wood, charcoal and oil…”
“That would mean more greenhouse gases,” said the Dean, “so it would be getting warmer, not colder.”
“Hypothesis two: As we ponies change our diet, it would change the gas produced in our guts.”
“But we've been eating more and more fine food over the years,” said the Cellarer. “The resulting extra farts would likewise heat the world up—not cool it down.”
“And to judge from our novices, ponies are getting more, not less, smelly over the years,” said the Dean.
As the meeting went on, the theories became wilder and wilder. As the Practical Scholar and Dean argued over the interpretation of the data, the Abbess looked up to the high windows above the table and watched the condensation forming on the cold glass. Through the glass she could make out a rope hanging in front of the window. She wondered how it had got there.
“As the sun is under suspicion,” said Celestia. “We should also look at the moon. How do we know it does not change the weather?” Evidently angered by Luna's accusations about her sun, she went on the attack. “Art thou sure thou art keeping it steady? A slight misalignment could change the tilt of axis of the world, and point it slightly away from the sun. A few degrees would be enough…”
“Ridiculous,” replied Luna. “The moon is what keeps the spin of our world stable!”
“That’s not exactly right,” said Twilight. “It’s true that the tidal forces from the moon will influence the axial precession but—”
“Twilight, will you keep quiet? We want to hear the rest of the story.”
The Abbess addressed both sisters. “Neither the Sun nor the Moon is at fault. Remember that the Order regulates the length of the day, so the solar power shining on Equestria is constant. There may be rare occasions—as today—when the sun remained down longer than it should. But they cannot explain the long term trend. As long as the Order counts the minutes, day is balanced by night. The days are longer in summer, but this is balanced by longer nights in winter. It is all as it has been for seven centuries, since the Order was founded, back in the days following the foundation of Equestria, as told in the tales of Hearth's Warming Eve.”
As she said this, the entire room fell quiet and stared at her.
“Hearth's Warming Eve...” said the Steward, pausing to think over the phrase. “Could it be... windigos?”
There was a long silence during which all the ponies present considered this new proposal. The Abbess turned her head away from the other ponies, and looked upwards in thought. Staring out of the high windows, a vision of a small blue pony suddenly flashed past the window, flying downwards. She blinked.
“Windigos—the winter spirits that feed off fighting and mistrust,” mused the Dean. “As the legend tells, when ponies were not friends, the spirits grew stronger, and the world became colder.”
The flying foal flashed past the window again, this time flying upwards at some speed. What was going on out there?
“But that was an era ago,” said the Practical Scholar. “All ponies are friends now. And it's not like anything has changed.”
The Abbess continued looking out of the window, not looking at the other Fellows. The blue filly flew back down.
“All ponies?” asked the Cellarer.
The Abbess’s attention was all on the window. As the filly did another fly by, this time going up, she tried to see who it was.
“Not wanting to make too fine a point of it,” said the Steward. “But your royal highnesses have not been quite so cordial to one another of late.”
The Fellows were all looking alternately at Celestia and Luna, except the Abbess, who kept staring at the window. What was that kid playing at?
“Now hang on,” said Celestia angrily. “Just because my sister and I have had an altercation, does not mean we’ve summoned a monster.”
“Quite,” said Luna, surprised to find herself agreeing with Celestia.
The Abbess stared out of the window waiting for another sight of the young pegasus, but it seemed the show was over. She noticed a frayed rope hanging down. Realising that she had been distracted, she brought her focus back to the foreground, and noticed the final grain of sand in the hourglass on the table was about to fall. Her instincts kicked in and before anypony could say another word, a sharp cracking sound echoed around the octagonal room as she brought her gravel down and duly brought the meeting to a close.
“We have had an interesting discussion,” she said. “We have heard many theories as to why the climate has become cooler in the last few hundred years. However we must now withdraw for the ceremony and feast. We shall continue this dialogue. Thank you.”
She got to her hooves and walked out of the room before anypony could add their own last word. The other ponies then followed her, aware that while the argument had been abruptly cut short, this was necessary if they were to achieve the higher priority of keeping to schedule.
The Abbess walked down the spiral staircase of the library tower, her black gown trailing on the steps behind her. All manner of ideas were buzzing around inside her head. Could the princesses’ quarrel have summoned a windigo? Was some long term change in the atmosphere cooling the world? Was the movement of the sun and moon as reliable as the sisters said? This was a riddle beyond anything else the Senior Fellow could set her, and her mind was anxious to tackle it. But she had to force herself to focus on the task in hand. She could not allow anything to go wrong with the evening ceremony.
Outside, sitting on the steps of the main doorway, was the young pegasus Rappel, being tended by her friends. Her feathers were all out of place and her coat was covered with fresh scratches. Evidently she had had another fall. But her face showed a bright grin.
“That was awesome! You saw me?” she said to her friends. “I so want to do that again. We just need to get some stronger elastic rope…”
“So did you make a good clock and keep good time?” asked Patina.
“I kinda forgot about that,” said Rap. “But it was great fun!”
The Abbess walked past them, out onto the plaza and took up her position on the podium. Then she forced herself to meditate, staring only at the clock face and the Minute mechanism, taking steady breaths. Around her the ponies of the order, and the two princesses, took up their positions. Then everypony waited in silence as the clock moved from 5:34, to 5:35, then 5:36. On the final point, she struck her tuning fork with her hoof and proceeded as she had the previous day.
Once the sun and moon had been duly rearranged, the ponies of the Order all walked into the hall together. The Fellows were in an ill humour. The day had started badly and not improved. On another occasion, they might have simply raided the kitchen for some snacks and retreated to their chambers with a bottle of wine. But tonight was the important anniversary which must be marked with a great feast. They had to entertain the princesses. And nopony wanted to challenge tradition. Discord was widely regarded as the arch nemesis of the Order, hence the special feast to celebrate the date of his defeat. The ponies of the Order took particular pride in marking the anniversary at the precise time when the reign of chaos had ended.
The novices, Rap among them, took their places at the low benches, all chattering excitedly. The Fellows walked up to the high table. The presence of the princesses complicated matters. They were known to have large appetites, and must be provided with extra helpings. And they were still not talking to one another. The Abbess arranged the cushions at the table such that Luna and Celestia were on the same side of the table, but separated by herself, the Dean and the Steward, such that they could not look one another in the eye.
The Steward, dressed in his finest frock coat and dress shirt, levitated a menu card before him and read out the schedule for the meal.
“Tonight we shall begin with a pea soup, followed by quails eggs and asparagus on a bed of hay; a daisy and fennel sorbet; carrot, squash, lentil and potato casserole; truffle polenta, avocado and glazed chestnuts; kale, root and peas shoot pie; then poached pears and blackberry and apple tart. We shall get through all main courses before 11 o’clock, in time to mark the moment of the defeat of chaos, then we shall finish off with dessert wines, cheese and chocolate.”
The Abbess nodded her head in approval, then rotated the table hourglass and brought her gavel down to mark the start of the feast.
Once the food was brought in, the two royal sisters both stuck their snouts into their dishes with equal enthusiasm, spraying food onto the Fellows from both sides. During the first course, the Practical Scholar described a new design of water clock to the Librarian, illustrating certain principles using his bowl of soup and a set of spoons. After spilling it all over the table they moved onto the next course. The Steward asked Celestia to tell him about the court fashion of the past two centuries, and she described how silly Luna had dressed at parties. The Librarian asked Luna what she knew about the Sphinx, which turned out to be very little, but she did tell a story about how Celestia once dressed up as a cat and spent two days playing with a ball of wool. The Cellarer rolled in extra barrels of cider and distributed this around the hall. After a few more tankards, some of the novices started singing, before being silenced by a cold hard stare from the Dean. After finishing her casserole, Luna announced that she would take a nap and slept through the next two courses, waking up for dessert. The Abbess sat calmly surveying the hall, saying very little.
Finally they reached the dessert course. By now they had run out of stories to tell. But the Practical Scholar tried to start up another conversation.
“I think the way forward has to be the development of an atomic clock.”
“Really?” The Dean answered without looking up from her food.
“Yes, let me show you how it works.” He took out his spinning top and put it on the table in front of him, then, with a skilled flick of a hoof, set it spinning around.
“All atoms are just like spinning tops on a microscopic scale, they are continuously rotating.”
“You don't say.”
“And if we tilt the spin—” He prodded his toy with a hoof. “The spinning axis wobbles around and around at a regular rate, just like atoms in a magnetic field, it’s a stable system…” The top fell over and rolled across the table crashing into a jug of cream.
“Well, in this case it's not so stable, but that's because there are too many other factors. If it were an atom, it would keep spinning at a fixed frequency so stable we could use it as a clock.”
“So how do you set an atom spinning how you want?”
“Not quite sure yet.”
“And how will you know when you've done it?”
“I'm working on that one.”
“And how will you use that to tell the time anyway?”
“It must be possible somehow, we just need to find a way to manipulate matter at the atomic level.”
“Meanwhile, pass the cream.”
Spin Precession pushed the jug of cream across the table. “You know sometimes I feel my talents are not appreciated here. Maybe I should go and found a satellite abbey on the other side of the mountain. A new community which would take atomic research seriously.”
“I would do that,” said the Dean, nodding vigorously.
“What?”
“Definitely,” she said while a smile and further nodding. “If you feel you are not appreciated here, go and found your own abbey. I would leave soon. No time like the present. I can give you a list of some of the novices who would most benefit from going with you.”
The Scholar looked up from his pear-poached-in-mulled-wine, a little taken aback by this enthusiastic endorsement.
“Err... I'll look into it.”
The Abbess had remained silent throughout this conversation. The steward had now brought in three huge blackberry and apple tarts, on plates which stretched across half the table. All the diners were in the process of cutting slices, shifting these onto these plates, then covering with cream poured from porcelain jugs. The cream was thick and fell onto the dessert as an irregular flow of globs. The Abbess watched this, while her mind was half following the Practical Scholars atomics, and half in an unfocused meditative state. Suddenly something clicked within her head.
She turned to face the Steward. “The cream was a fine liquid when you brought it in.”
The Steward nodded.
“But it's now much thicker.”
“It's getting cold,” he explained. “It's nice and runny when we warm it. But it quickly thickens in the cold. Eat it up quickly before it gets thicker. Or shall I warm it up for you?”
But the Abbess was not thinking about her food.
“Does water do the same thing?”
“Oh no. I've never seen water as thick as cream.”
“But could it get slightly thicker. So slight we would not notice?”
“I guess so, but why does that matter?”
“Suppose the water flowing through the Minute were to thicken, too little for us to notice, but enough to slow down the flow a little...”
The Dean was the first to spot what she was thinking.
“Then the Minute would run slow in cold weather.” She paused and then realised the faux-pas she had said. “Sorry—the Minute doesn't run slow because it runs at a minute per minute. But it would appear to run slow relative to an unaffected clock.”
The Practical Scholar smiled. “That would explain what I saw when I timed it against our best hourglasses!”
“And what happens,” continued the Abbess, talking more to herself than anypony in particular, “if we measure the length of the day and night by such a clock?”
“The day and night would be longer in colder weather,” answered the Dean.
“Would that make any difference?” asked the Cellarer. “It must be a very small effect or we would have noticed it. And it would affect both day and night equally.” The other ponies nodded their heads in agreement.
“But,” continued the Abbess, “if the days and nights are both longer than they should be in the cold of winter, that disproportionately affects the night—as it is longer in winter. And if the days and nights are shorter in the warmth of summer, then the long summer days would be not quite so long...”
“So with slightly longer cold winter nights and slightly shorter hot summer days, we would see slightly less of the sun...” said the Dean.
“Which would make the average annual weather slightly colder,” said the Abbess.
“Making the winters slightly longer and the summers slightly shorter,” continued the Dean, “making it colder still...”
“Which augments the effect even more. Colder weather means a slower Minute in winter, which means longer winter nights, which means colder weather, which means a slower Minute...”
The Abbess’s explanation trailed off as it became repetitive. The whole table fell into silence as they realised the full significance of this revelation. Celestia and Luna, who had not been paying much attention to the conversation until now, instead focussed on the food, realised that something was amiss and looked up.
“Positive feedback…” murmured the Practical Scholar.
“How long has this been going on for?” asked the Cellarer.
“Since the start of the Order,” said the Abbess. “Ever since the Minute was first used to set the sun and moon. A tiny effect. Not enough to notice from day to day, or even year by year. But over seven centuries, we have been cooling our world, little by little.”
“Can we be sure of this?”
The Abbess stood up. “We need to do an experiment,” she said.
“What?” exclaimed the Practical Scholar.
The head of the Order turned to the Steward and Cellarer.
“Bring that barrel of cider from over by the fireplace—the one that has not yet been opened and put it on the table. Then fetch a cold one from the cellar—the same size.” She turned to address the Scholar. “Bring a ten-minute-glass—the most precise we have.”
The instructions were given in a clear authoritative tone. The Fellows moved to follow her instructions straight away. In a short time the two casks of cider were positioned at either end of the table. And an ornate hour-glass—carved oak supporting the clear glass bulbs, filled with the finest coloured sand—was positioned in front of the Abbess.
“Okay,” said the Abbess, “we have two liquid vessels, identical, except they are at different temperatures. We shall measure the flow from each over a ten minute period.” She then banged her gavel to silence the chattering novices and addressed the hall. “Everpony bring your tankard and stand in line for a special holiday cider ration. If you like it warm, stand to the left, or if you prefer your cider chilled, take the right hoof line. Everypony is to take exactly one tankard, filled to the brim. Not a drop more or less.”
At the promise of extra cider, the novices jumped to their hooves and formed two lines on either side of the hall, leading up to the two ends of the high table, where the Steward and Cellarer each stood on either side, next to the spigots on the barrels. The first year novices, for whom this was their first experience of such a feast, assumed that this was all part of the ceremony that defined life in the abbey. The older members of the Order were a little puzzled by the novelty, but nopony was going to question the authority of the Abbess. Not when it meant extra cider.
“Ready?” said the Abbess, looking to the left, then the right, and nodding at the Steward and Cellarer, then she simultaneously turned the hour-glass and hammered her gavel. At this the two serving ponies opened the taps on the barrels, and the first novices in line thrust their tankards under the flow.
The Fellows sat without talking, their eyes flicking from one barrel, to the hour-glass, then the other barrel. As soon as each tankard was filled, the pony next in line pushed it away with his or her empty mug to take the place, and the pony ahead walked away with a full tankard and happy smile. As each tankard was filled, the Abbess marked a tally on a sheet of paper, filling two columns, for the warm and cold liquid.
After the ten minutes had passed, and the final grain of sand fell, the Abbess banged her gavel to mark the end of the experiment. The Cellarer and Steward instantly closed the spigot taps, leaving two ponies with incomplete measures somewhat miffed.
“The result,” said the Abbess. “Cold cider: Thirty-five and a quarter measures. Warm cider: thirty-eight and three sixteenths. The warm liquid flows faster. We have an explanation for why the climate is getting colder.
“That’s not really a properly controlled experiment,” said Twilight. “They really should have repeated it several times exchanging the containers used, and the cider could have a different viscosity to water due to the dissolved gas, and—”
“Twilight!”
The Fellows all smiled at this conclusion, but Luna and Celestia still looked a little confused.
“Canst thou explain thy scientific research such that a simple alicorn princess can understand?” asked Luna.
The Dean answered, “We have shown that colder liquid flows slightly slower than when it is warm. As it is the flow of water which sets the minute, this means the minute—and hence the length of a day and night—is longer during the cold of winter. Every year this has made winter slightly longer than it should be, which is making the weather colder, which, in turn, makes the water flow slower, so the effect keeps on.”
Luna and Celestia both paused for a moment to take in this information. Then Luna's face broke into a smile.
“You mean after all that stuff you said about windigos,” she said, dropping the Royal Canterlot Voice, “it turns out the real reason that it's so cold is that you can't keep time?”
The Abbess could have defended the work of the Order in many ways, but this was a time to show humility.
“Yes,” she said.
Celestia started to giggle as well. “So it's nothing to do with the sun. Or the moon. Or anything to do with us. It was your doing.”
The Abbess nodded slightly.
“All those silly ideas about the balance of the sun and moon,” said Luna with a broad smile, “and it turns out it was your balance that was off. The Order of the Time Turners is running a bit late.”
“A little out of order,” said Celestia.
“A temporary glitch no doubt,” said Luna.
“It will be put right in no time at all.”
The two sisters laughed so hard they had to support one another with their hooves. Eventually they calmed down and Luna looked her sister in the eye.
“I’m sorry I said that you weren’t keeping the sun hot,” she said.
Celestia smiled.
“That’s okay. I’m sorry that Philomena burnt your notebook. And I’m sorry about the moonfrogs.”
Once the Abbess was sure they were not looking at her, she permitted herself a small smile of her own, seen only by the Dean. All eyes in the hall were now turned to the two princesses who were looking at one another as reunited friends.
However just as the audience was waiting for the obligatory tearful happy hug, the magical atmosphere was shattered by the ringing of a bell. A porter, who had been assigned to check the time by the Minute, proclaimed the message:
“Three minutes until eleven o’clock!”