Time's Arrow

by Proulxes

"Life is an unfoldment, and the further we travel, the more truth we can comprehend. To understand the things that are at our door is the best preparation for understanding those that lie beyond." Hypatia of Alexandria b. AD350-370

"It matters not what someone is born, but what they grow to be." Albus Percival Wulfric Brian Dumbledore b. AD1881

Prologue

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It was hot and airless in the small alcove of the library. Dust motes danced in the thick beam of sunlight that illuminated the parchments and scrolls on the little desk by the window.

Outside, the noise from the busy marketplace could be heard. Muffled cries from the market sellers mingled with the calls of seagulls and the thin wail of the reeded instruments outside on the temple's steps.

Within the Serapeum itself, a low murmur of voices could be heard from the lower levels, animated discussions from which only the odd word or phrase could be clearly distinguished. Closer to the figure in the bright alcove, other distractions fought for attention: the susurration of parchment and papyrus rolls being withdrawn from and replaced on shelves, the scuff of sandals and boots on the ancient stone steps and passageways, the scritch-scratch of nib on paper, the sighs of the students.

The tall woman, sitting hunched at the littered table in the sunlit alcove, bent over the ancient papyrus scroll, one hand holding a parchment roll open, the other absently twirling a thin, bronze stylus in her fingers, did not appear to notice. All her attention was fixed on the words before her.

Her brow furrowed in fierce concentration as she traced the line of spidery Greek letters with the stylus, ignoring the beating heat of the sun on the back of her hand. Just as the change is always other and other, so the time is too, though the whole time in sum is the same. For the now is the same X, whatever X it may be which makes it what it is; but its being is not the same. It is the now that measures time—

"... Lady? Are you there?"

The woman frowned but said nothing, brushing a strand of her hair behind her ear and stabbing her stylus into the thin wax of her tablet.

—considered as before and after. The now is in a way the same, and in a way not the same: considered as being at different stages, it is different—that is what it is for it to be a now—but whatever it is that makes it a now is the same—*

Quick, anxious steps on the stairs that led up to her quiet space were coming closer.

"Hypatia? Lady?" The voice was louder, breathless, insistent.

She sighed and rubbed her forehead in irritation, her train of thought broken. "I'm here, Orestes."

A young man appeared at the top of the steps, his curly, black hair standing up in crazy waves from a scarred forehead. He was breathing heavily, as if from some exertion, but he halted as soon as his eyes settled on hers, hovering and tentative. "Are you alright?" the young man stuttered. "I heard about the disturbance in the city precinct..."

She made a quick, disparaging snort. "It was nothing. Two Christians arguing with one another over a trick in the market place." When he didn't comment, she shifted the parchments self-consciously about on the table. "It was nothing," she repeated, darting a defensive glance up at him.

He was staring at her, his arms crossed over a small, linen-wrapped package against his chest and a frown drawing his brows close.

She snorted again. "One was trying to pass off walking quickly over hot coals as some sort of divine miracle. As if the divine can be reduced to parlour tricks and such nonsense. Do sit down, Orestes. You are blocking the light."

The youth slowly lowered himself to sit opposite her, the package still cradled in his arms. "I heard that the Prefect was called to break up the fighting," he said stubbornly.

She rolled her eyes. "Fighting? A few stones hurled and a lot of shouting."

"You should take more care, going about the city as you do. It is not safe for a woman to be so..."

She felt a hot flush of anger in her chest, and her chin raised. "'So', what, Orestes? I ride about the city as I always have done. It is my prerogative to do so."

Orestes muttered something under his breath that sounded like, "...arrogance," and she felt her anger softening.

"Perhaps," she murmured quietly. "Enough squabbling, Orestes. I shall do as I always have done, and no doubt you shall continue to scold me for it."

She waved off his half-formed protest, leaning forwards instead and pointing at the linen-wrapped article in his arms. "Is that the new astrolabe?" she asked, changing the subject deliberately, her voice raised in excited anticipation. "I didn't know that Borusius had finished it – show me!"

Orestes smiled at her impatience and placed it carefully onto the table top.

She reached forward eagerly and pulled the linen covering to one side, revealing a brightly polished circular device, some eight inches or so across, composed of a series of interlinked plates, each one decorated with intricately etched designs. Letters, symbols and numbers vied with each other. The plates were formed in different metals. Bronze, steel, copper... and a mixture of other alloys which were not so commonly used.

She couldn't help herself. "It's beautiful," she breathed. Her fingers brushed over the top plate, the intricately carved metal net that formed the outermost layer of the astrolabe, and she felt a familiar and thrilling sense as the metal called to her. She shivered at the sensation, half afraid of her body's reaction. "And Borusius was able to incorporate my design for the mechanism entirely?"

Orestes nodded. "He's some sort of magician. I don't know how he is able to create such intricate perfection."

"How many times do I have to tell you, Orestes? There is no such thing as magic," she snapped, fighting the blush that fought to stain her cheeks with colour. "Only logic, reason and method. Have I taught you nothing?"

Orestes grinned again and bowed his head. "As you say, Lady," he agreed with mock seriousness. "Logic, reason and method."

"And the divine," she added firmly, still not prepared to let him off the hook.

He leaned forward. "However that may be revealed," he whispered and quirked an eyebrow.

"You are incorrigible," she threw back at him, but her fingers, tracing lightly over the finely engraved wheels of the astrolabe, brought her attention back to the mechanism on the table.

"He smelted the bronze as you instructed - the black sand is buried within the central piece." Orestes pulled a humorous grimace. "He said that it nearly killed him to deliberately put something so impure into such a beautiful creation."

Hypatia smiled as she pictured the huge smith, his heavy brow furrowed in concentration as she had explained her designs, her measurements, and the specific materials that she insisted he use. It had taken hours to go through the specifications, and at the end of their meeting, when she had asked if he thought such a thing could be made, the smith had settled back into his chair and pulled his fingers through the great tangled beard he wore, snagging the fingers roughly in the wiry strands.

Hypatia had watched for his answer, her breath caught in her throat, heart thundering beneath her ribs. The artisan blacksmiths of Alexandria were the best in the world, and Borusius was the best of them all. If he could not achieve the level of perfection she was asking for, the delicate precision needed to make the mechanism function as she had designed it, then her ideas would forever remain trapped in mere theoretical discourse. The relief when the giant smith had grunted his assent had sent her head swimming.

She picked the astrolabe up and made to flip it over in her hands, but Orestes caught her fingers in his. "Careful," he admonished. "With all that Numidian sand in there, the metal could snap easily. Borusius was practically weeping at the prospect."

Hypatia nodded and turned the mechanism over gently, taking care to support it as fully as she could in her hands. She smiled as the tiny cogs and wheels of the complicated mechanism came into view through the finely wrought holes in the back of the device.

"The sand is key," she said softly, almost to herself. "Earth in metal, sand in glass."

She turned the astrolabe carefully once more so that it was facing upwards again. The markings were correct. She could see the relationship between the stars, the path of the sun, the division of the skies into measurable units. She squinted past the rete into the heart of the device, her eyes focusing on the intersecting plates behind it. The stereoscopic projection looked perfect, a looping, scaled network of astrological lines mapping the night sky—

"Lady?"

His quiet question startled her. She felt herself flush in embarrassment that she had been caught up in thrall at the beautiful, intricate thing.

Orestes cleared his throat and she saw him tactfully avert his eyes. "Why is this one so... different?" he asked softly. "It is easily twice the thickness of Theon's astrolabe, with so many more plates, and the rete... I've never seen one so detailed. What—?"

She smiled at him, feeling the delight sparkle through her at his question and a thrill of nervousness as she wondered if the machine, despite all her careful calculations would actually work. "Do you remember what Aristotle teaches us about time?"

Orestes tapped his fingers on the parchment covering the table. He's a good student, she thought, intelligent and dogged in his desire to learn, although his emotions all too often overwhelm his reason.

"He speaks about time being in relation to movement," he began tentatively.

"Yes," she agreed. Placing the astrolabe carefully down on the table before her, Hypatia's fingers found the tiny switch at the side of the astrolabe, hidden beneath one of the edges, and carefully touched it. Her heart in her mouth, chest thrumming with sudden nervousness, she flicked it downwards.

Immediately, the device began to emit a whirring and clicking sound, and the plates of the astrolabe began to move. The golden rete moved slowly, and within the body of the device, the plates circled and moved at different rates, shifting and aligning beneath it.

"Oh Lady...," Orestes breathed. "This is magic...!"

She made a sharp, disparaging noise. "I've already told you, Orestes. You are as superstitious as those monks in the precinct. There is no such thing as magic. It's a mechanism. Cogs, gears and wheels, driven by springs of coiled steel."

She crushed the rebellious thought that stole into her mind at the thought of the black sands at the heart of the device.

"If we had magic - we would know everything," she continued. "We'd know the future, what form the universe really takes... We would not be scrabbling around in the dust of our own ignorance, clutching at dreams and visions. We could see the Wanderers' paths in the sky... understand the depths of the oceans... cure all ills... be masters of life itself." "There. Is. No. Magic." She punctuated her words with a stab of her fingers on the table.

She didn't mention the reaction that her body had to the black sands. For how could she explain the desperate calling that she felt when she had first encountered the strange material - a dark, glass like residue from a huge, ancient crater to the west of the city.

Orestes stared at the whirling astrolabe. "It's beautiful," he said eventually. "But I still don't understand. What does Aristotle have to do with it?"

"Aristotle claims that 'time is a number of motion in respect of before and after'," she recited. "I simply calculated the changes that we might see to the night sky if we accept that the stars and planets are in motion as he suggests."

Orestes' eyes widened as the implications of her words hit home. "But... but...," he stuttered. "That means... you have charted the universe, through time," he whispered.

The astrolabe whirred quietly before them.

"Yes," she said, watching him closely, wondering if he could work it all out for himself.

Orestes stared back. "Such knowledge," he breathed. "You... you could predict the future... predict the pathways of the Wanderers... understand the very universe itself..."

Hypatia carefully reached out and flicked the little switch upwards, pausing the mechanism. "Perhaps more than that," she whispered. "It is a first step down a path that Aristotle himself suggested."

Orestes' brow furrowed as he fought to follow her train of thought. She watched him study the device carefully, noting the specific markings that were carefully etched into its surfaces.

"What is that inscription on the rim of the mater?" he asked, running his fingers lightly around the outer circlet of inscribed bronze. He squinted at it, his lips moving slightly as he read the unfamiliar symbols.

She shifted self-consciously on her seat. It had been a moment of vanity, she was certain, but her instincts had insisted on naming the device. "The name of the thing increases the power of the thing," she murmured, thinking of the black sands at the astrolabe's heart, hoping against all sense and reason that she was right about the power that they held.

"El... Tirin..." Orestes stumbled over the words, looking up at her in confusion.

"I have named it for what it is," she said quietly. "Or what it might become... in the language of the Numidians, the symbols say El-Ouak-Tiriner**. Time Turner."

"You cannot mean...?" he suggested, disbelief clearly evident in his voice.

"Yes," she said calmly.

Hypatia carefully picked up the astrolabe in her hands and considered the time it had taken her to conceive and produce the plans for it, to say nothing of Borusius' skill and effort. The diffused sunlight from the window above reflected warmly from its surface.

It was a truly beautiful mechanism, both in terms of its design as well as its function. Even though it was still now, she could still feel its potential in her hands. She frowned at the odd sensation in her hands, sensing the black sands as they curled and twisted, trapped within the carefully smelted metal inside the device. She could sense a restlessness within the machine itself, an echo of that same uncomfortable sensation that had caused her palms to prickle and her skin to itch when she allowed the black sands to run through her fingers.

It pulled her close and terrified her in equal measure.

"But Aristotle tells us that such a thing is not possible!" Orestes protested, drawing her attention. "Travelling through time is inconceivable."

"Is it?" she argued, hunching forwards over the table towards him. "Pliny talks about the cyclical nature of time... the Stoics believed that all things come from and return to the Mind Fire... Parmenides goes further, maintaining that time, motion and change are illusions." She paused, flicking a glance towards the window and the market place beyond. "While the Christians, of course, contend that time is linear, beginning with the act of creation by God and ending with the end of the world. A finite line... like an arrow, shot from a bow. Humans are born, live and die." She moved her hand like a blade along an imaginary line as she spoke, punctuating her explanation with a sharp, chopping motion.

"I believe that this device will allow me to test those theories. Any evidence to the contrary will confound that linear view... and perhaps...," she sat back, regarding him steadily, "perhaps I can make a difference to the madness out there, the madness that sees men fight and kill each other over the existence of one God or another."

A few seconds passed.

"How?" Orestes blurted out.

Hypatia stroked the finely wrought metal of the rete with the tips of her fingers. Of all her experiments, perhaps this would be the most extraordinary.

She took a deep breath.

"We are going to bury it, of course."

Orestes blinked. "Bury it?" he asked weakly. "But the cost alone, Lady...!"

"The cost is irrelevant," she rejoined, exasperated by his lack of understanding. "This is a chance for us to discover the truth!"

"I don't...," he began but she waved him silent.

"Look," she explained. "I set the correct astral measurements for this time, here and now..." Her quick, confident fingers dialled the correct coordinates on the Time Turner. "Then we determine to place the device in a safe place, burying it deliberately, hiding it well, and trusting that, in many years' time, a future philosopher may discover it and know what to do, so they may return to us here, in this place." As if to emphasise her words, Hypatia flicked the switch on the Time Turner once again.

"I still don't—" Orestes began again, but his words were drowned out by the sound of a sharp crack and a sudden, sharp smell of ozone.

A young woman had suddenly appeared out of thin air behind Orestes' shoulder.

The woman's wild, unbraided hair stood out from around her head like a halo, illuminated in the diffused beam of sunlight from the window. She was slim and pale, her features not particularly striking or memorable, with a broad, open face and wide-spaced, hazel eyes. Her clothes, though, did catch the eye. They were outlandish; brightly coloured and patterned, with tight fitting blue breeches and thick boots. Around her neck, a small, golden pendant on a long, golden chain, shone so brightly that it hurt to look at it.

The woman said something, her voice sounding guttural and strange. She shook her head and spoke again. This time, the Greek words spoken "Lupoumai eilikrina – I'm sorry!" were poorly pronounced and she was shaking with a terrible emotion. "I'm s— so, so sorry!" She began again, dragging the back of her hand across her mouth, smearing it over her lips, staring into Hypatia's eyes with a desperate, desolate intensity.

Hypatia stared back, at once terrified and intrigued, shocked into silence by the extraordinary vision.

But then the young woman seemed to still, clenching her other hand tightly into a fist by her side around a narrow, dark rod and slowly lifting it until it was pointing directly at Hypatia herself.

"Please forgive me," the stranger whispered. "Avada K—"

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* quoted from Aristotle's The Physics
** الوقت تيرنر

A/N: I am indebted to the wonderful nagandsev and Clairvoyant for the beta reading and corrections, and to the lovely beaweasley2 for the alpha read. All the characters you recognise are the intellectual property of JK Rowling. I am not making any money from this exercise in fanfiction. Thank you in advice to all who read and review. I hope you enjoy this story. Think action, adventure, angst, romance and tattoos...