A wooden door was suddenly swung open as the brown earth pony stallion with a heroic look on his face, long multicolored scarf around his neck, and hourglass on his flank known as Time Turner a.k.a Doctor Whooves a.k.a. the Doctor galloped into his workshop. He was quickly followed by the light blue unicorn mare with a two-colored off-white-and-blue mane and tail, determined look on her face, and golden hourglass on her flank known as Colgate a.k.a. Minuette a.k.a. The Dentist. Finally, the gray pegasus mare with a wall-eyed look on her face, blonde mane and tail and bubble on her flank known as Derpy Hooves a.k.a. Ditzy Doo a.k.a. Muffin a.k.a. a picture of a muffin a.k.a. a picture of her own face a.k.a. Dearest Heart a.k.a. D.H. flew into the door frame, woozily adjusted herself then slowly flew inside.
“I’m glad you could make it, Dentist,” the Doctor said as he galloped up to an upright, rectangular machine with a blinking red light that seemed to great everypony as they entered with a ‘bing!’ “There isn’t a moment to spare! Not a moment at all!”
The Dentist stopped just short of the Doctor. “Well, that’s an alarming turn of phrase for ponies in our line of work. Where or when is the emergency?”
The Doctor threw up a forehoof. “All in good time, my Dentist. All in good time.”
The Dentist narrowed her eyes. “But you just said—”
“If you’ll excuse me a minute” the Doctor interrupted with a coy smile as he stamped his hoof back on the ground. “I’ll be more than happy to explain.”
The Dentist tossed out a sour look as she turned to the gray pegasus who woozily flapped up to join her. “How in the hell do you tolerate being married to...” she motioned out to the Doctor with both forehooves, “… to all that?!”
D.H. gave the Dentist the most serious, focused look she could manage. “He lets me help build machines of incredible quantum complexity, makes me happy, and is also great in the sack,” she answered.
“… Fair enough…” the Dentist replied with a sideways nod of her head.
“Now,” the Doctor began as he began to trot around the machine with the blinking red light which let out another ‘bing!’ “Dearest and I have created a machine that detects the fluctuations in time that echo through the future when somepony goes and disrupts the past!”
The Dentist felt her forehead tighten. “Uh-huuuuh…”
‘Bing!’
“There, you see!” the Doctor said as he motioned to the machine. “It just went ‘bing!’ that means it’s detecting trace amounts of chronitons! Now, chronit—”
“Are created when time is altered,” the Dentist finished in a bored tone. “Yes. Everyone in this room knows that!”
‘Bing!’
D.H. stared at the machine in concern.
“Well then,” the Doctor said, “if the machine is going on like that it means it’s detecting chronitons. Which means something has been introduced to the past to have altered it!”
The Dentist frowned. “The machine just goes ‘bing’”—
‘Bing!’
—“if it detects chronitons? It doesn’t give you any indication of when or where to look for the point of origin for the chronitons?”
D.H. pursed her lips slightly and wrinkled her muzzle as she trotted up to her husband who gave the Dentist is somewhat soiled look. “Well, aren’t we just Little Miss Picky today?”
‘Bing!’
The Dentist rolled her eyes. “What I’m trying to point out is that everypony in this room has traveled to the past multiple times and probably will travel to the past again, or rather, have traveled to the past even more than we are currently aware of from our linear perspective.”
The Doctor suddenly wrinkled his muzzle and pursed her lips to match his wife’s expression.
‘Bing!’
“Oh…” The Doctor uttered. “So you’re saying…”
“The machine will never not go ‘bing!’” The Dentist said. “There is, in fact, no possible scenario in which this machine you’ve just created will not just go—”
‘Bing!’
The Doctor and D.H. looked at each other thoughtfully for a moment.
D.H.’s face suddenly lit up. “What if we adjusted the machine to ‘bing!’ louder and more frequently depending on how many chronitons it’s detecting?”
“Oh! Brilliant! Now that’s the beautiful woman with the equally beautiful mind I married!” he said as he swept D.H. into a forearm.
D.H. giggled and swatted playfully at the Doctor with a foreleg. “Oh, go on… No, really… Go on…”
‘Bing!’
The Dentist rolled her eyes once more. “Except that, if you took the machine anywhere in time it would immediately go crazy because the instant after you appear in a new time, you technically just altered the immediate past and therefore, released a heaping ton of chronitons!”
‘Bing!’
The Doctor and D.H.’s smiles fell.
The Dentist continued, “In fact… unless the machine could track the exact time and place any such chroniton explosion took place, even if you leave it alone and it starts—”
‘Bing!’
“—ing more than usual, that just means the location in time and space is still a giant set of possibilities that are based on the chroniton distribution which depends on the amount of time that has passed and distance the chronitons have drifted, but you have no way of telling the exact ratio of distance to time or what direction the chronitons even came from!”
‘Bing!’
“The only way it could be of any use at all is if you made the change, left it alone, and then it started going off like mad indicating that something had been changed both very recently and close.”
‘Bing!’
“But because all three of us live here and are routinely taking time traveling devices back in and out of time, the chances of it going off for anything other than a harmless return trip are pretty nonexistence. So, you’d still just have created a rather convoluted machine that goes—”
‘Bing!’
For a moment, nopony said anything, instead electing to stand there in awkward silence. Slowly, D.H. extended a foreleg behind the machine that she gently, but forcefully pushed forward causing the machine to topple red blinking light first the ground.
‘CRASH!’
‘BIIIIiiiiinnnnnnggg…’
“Oh, whoopsy!” D.H. said in a tone of faux innocence. “I just don’t know what went wrong!”
The Doctor sighed. “I’m sorry to, if you‘ll excuse the expression, have wasted your time, Dentist.”
“Oh, that’s alright,” the Dentist said as she shook her head. A slightly crazed smile came across her face that was matched by an equally crazed gleam from her ocean blue eyes. “Say, when’s the last time either of you had had your teeth examined?”
The Doctor and D.H. exchanged worried glances as the Dentist advanced on them
“… We’ve made nothing but poor decisions today…” D.H. uttered.
The Doctor let out a long sigh. “Next time we’ll just have to make a machine that detects the absence of chronitons…”