Wren sat in a Modern Physics class when it finally happened to her. She was wearing her favorite green cardigan under a summer sundress. The cardigan was hand-stitched with forest-green wool, and had little ebony buttons down the front. The pockets on each side were deep and lined in felt. It was the last gift he’d given her. She wore it all the time.

Her classmates made small-talk behind her. No one spoke to her. Wren preferred it that way. She arranged and rearranged her pencils. Parallel. Then perpendicular. Parallel again.

The door clanked open and the cool, stale air of the basement classroom rushed toward the door. She and her classmates looked as Dr. Novak entered.

“Hello, everyone,” Dr. Novak said in her thick Czech accent. “Sorry I’m late.” She sashayed into the classroom, arms full of textbooks and papers. She set these down on the desk and turned to the mobile chalkboards, arranging them in a neat line before picking up an eraser and smoothing out the ghostly smudges on the board. Dusty clouds puffed around her. Her long fingers were as white as sticks of chalk.

“Okay,” she said. She smiled as she faced the class. “Now that that’s settled, let’s get started.”         

She turned to the boards and poised herself in front of the one farthest to the left. She wrote in chalk:

Her handwriting was bold and elegant, her letters containing thick swirls and serifs foreign to the print of American professors. She said, “This formula should be familiar to all of you, is it not?”

The girl in the green cardigan nodded, having read the chapter the night before. Time prime is equal to the original time divided by the square root of the quantity one minus velocity squared over the speed of light squared. The equation represented the dilation of time, and how this dilation was dependent on speed—only so long as it travelled at large fractions of the speed of light.

A keen sense of vertigo overwhelmed her: a rushing, fleeting feeling like the vacuum created by Dr. Novak when she’d opened the door to the basement classroom. The girl’s hair fluttered around her face; the orangey-yellow of the overhead lighting was too much, too bright, too warm, too artificial. She squinted, closed her eyes, squinted them harder—

“Wren.”

His voice. Tahir.

Her eyes sprung open. The dingy classroom was gone, replaced by an infinite canvas of white light, clear and consuming.

“Wren.” Tahir repeated it. Her name.

She turned in her chair—the chair had come with her—and saw him, his figure at least, a small crumpled heap on a field stretcher, surrounded by the expanse of the white floor.

He must have been thirty, forty feet from her. Wren stood and suddenly she was there by his side. She knelt to him. Their fingers interlaced, her paleness alternating with his deep maroon. Tahir lay on his back, his bright brown eyes staring up at the white Void above them. This meeting was too soon.

He wore the typical blouse and slacks of his profession. The patterned colors covered him from ankle to wrist to neck. She remembered when she’d first seen him in this uniform. How strong he’d looked with the muscles in his arms and chest stretching the fabric tight. How she cried. How he told her not to. He held one of her hands with both of his. Her left hand. With the silver band on her third finger. A place-holder, he’d called it. For when he came back.

Tahir was much thinner now. Wren noticed the sand under his normally meticulously manicured fingernails. His lips: dry and cracked. His face: smudged with soot and haunted memory.

“Wren, I’m sorry,” he said.

“It’s okay,” she said, keeping her voice soft. She ran her free hand through the quarter-inch fuzz on his scalp. She’d asked to shave off his long black hair when he enlisted. At the time, his hair was longer than hers, wound into tight curls that he’d let roll loose around his face. She’d loved playing with the hair, feeling it’s texture between her fingers, twisting it into braids while they sat in the shade of a massive oak and planned their future together. When she ran the trimmer across his scalp, his hair fell off in bold tufts, exposing his hard brow and long jaw. He’d looked more like a man than teenage boy, and the transition had thrilled and terrified her. When he wasn’t looking, she’d gathered some of his hair and sealed it in a plastic bag. After his departure, on nights when she was particularly lonely, she’d pull the bag of Tahir’s hair from its hiding spot in her drawer and crack it open, breathing the scent of him in, spending the rest of the night lost in the memory of his heated hands trailing over the curve of her breasts, the small of her back, quenching the flame between her legs. Each of these solo sessions left her lonelier than the last; her fingers were no substitute for his, and her desire compounded, unsatiated.

Wren continued to run her fingers through Tahir’s hair. He was dying. That’s why they were here. The Void. It happened to everyone. It was just a matter of time.

Their gazes met. Tahir’s brown eyes were intense, bright and clear against his soiled skin. But there were no blood splatters, no bullet holes, no rips in cloth or flesh. He seemed, to Wren, perfect as ever. She pressed her hand, the one he held so tightly, to his chest. She felt the familiar percussion falter.

“I’m not sure how much time we have,” Tahir said. “So fast. It was so fast.” His baritone voice shook, rattled in his chest. He squeezed her hand.

“Do you still want to try?” she asked. She wanted him so badly she shook.

Tahir nodded. “Wren,” he asked, “what if it doesn’t work?”

She leaned down and kissed him softly. “It will work. It has to.”

He fumbled at his belt.

Her hands stayed his. “Let me,” she said.

He raised an eyebrow.         

She undid the belt clasp and pulled the worked leather through the metal hoop. She untucked the front of his blouse and slipped her cool fingertips between his slacks and his stomach, pleased that his back arched at her touch.        

Her hands worked delicately. What she wanted wasn’t hard to find.

He’d always told her it was not a race, so she moved slowly, deliberately. She took him in his mouth and savored the stretch in her jaw, the salty taste of him, the way he groaned when she moved her tongue just so. She got him going, then straddled him, fanning her dress out around them. Under the dress, Tahir’s hands traced up her thighs found her wet lips. He tugged the elastic edge of her panties out of the way and she mounted him, easing into a steady rhythm. Together, they rode each growing wave of heat until finally hers crested and she emptied her lungs into the Void. He followed closely after, a deep, long, masculine sigh as he pulled her pelvis close.

After, she slumped against the curve of her neck.

“Good?” Wren asked, tracing the edge of his ear.

Tahir reached for her hand, sandwiching it between his palm and his cheek. “You have to ask?”

Wren smiled at him, loving the moment of stillness and satisfaction.

He began coughing sharply, a deep bark from his diaphragm that wouldn’t stop. She sat up so he could breathe. His coughing fit ceased. She pressed her lips into a thin line of worry; asking him if he was okay would be stupid, given the circumstances.

Tahir thumped his chest with his fist and cleared his throat. He blinked a few times, then looked around. The Void was still white and featureless, save for desk chair a few yards off, though it seemed less bright. Wren watched him, memorizing the little bump on the bridge of his nose, the length of his eyelashes, the way his ear lobes made a smooth line to the beginnings of his jaw.

He watched her study him. “What will you do?” Tahir finally asked.

Wren snuggled back into his embrace. “Make do,” she said.

This satisfied him. The soldier’s shoulders relaxed. His eyes flitted closed. His breathing fell into the rhythm of sleep.

The girl lay with him, listening to the faltering beat of his heart. The room lost intensity and the white light started to dim. Wren had heard stories of those lost to the Void: lovers and loved ones in comas, their minds suspended purgatory because they valued the dead more than their obligation to the world of life.

She had to leave.

She kissed Tahir’s closed eyelids and left him sprawled on his stretcher.    

Wren shoved her hands deep into the pockets of her favorite cardigan—this wonderful gift from Tahir that kept her warm while he was away—and walked back to her chair, each step away from him a small agony. In her left pocket she clutched the clinking metal of the tags she’d taken from around his neck. When she sat in her chair, she did not look back at him. She closed her eyes. She clutched the tags in her left hand, pressed the palm of her right against the soft flesh below her belly button. She would bring part of him back. She willed it.

Transient vertigo overwhelmed her.

“Very good, very good,” the professor said. “Time dilation, that is correct.”

Wren blinked as she readjusted to the amber artificial lighting of the room. Back to Modern Physics. The blackboards looked the same as before, holding only the one formula written in white. Dr. Novak faced the class, chalk held high. Wren’s left cardigan pocket was empty; the tags didn’t make the trip back.

“Now what is the other formula that we need to take into consideration for travel at speeds close to c?” Dr. Novak asked. “Remember, the fabric of our universe is dependent on the inherent correlation between time and space.”

The yellow of the basement classroom hurt the girl’s eyes. She kept her hazy gaze on her pencils. One of her classmates coughed behind her.

Wren raised her left hand. Illegible shapes were pressed into her palm.

“Yes, Wren?”

“Length contraction,” the girl said to her pencils. Why the tags didn’t make it.

“Very good.” Dr. Novak smiled. She turned to the board. “Can you give me the formula for that?”

The girl squinted against the yellow light, fighting dizziness. “Length prime is equal to the original length times the square root of the quantity one minus velocity squared over the speed of light squared,” she said.

“Yes, that is correct,” the professor said. Wren let out a long, slow breath. She did not think she’d remembered it properly, but the words were out of her mouth before she could think about it too long.

Next to the time dilation formula, Dr. Novak wrote:

“Now,” Dr. Novak turned back to the class, “what do both of these formulas have in common?”

A student’s chair squeaked when he shifted. Another student sneezed. Wren wished she had picked a seat in the back of the room.

“They both have that square root,” someone called from the back of the classroom.

The dizziness from her trip back from the Void would not subside. Wren tried deep breathing again.

“Very good,” Dr. Novak said. “What is that factor called?”

Wren folded her arms on her desk and nuzzled her forehead into the soft wool. She would not cry in class. She would not cry in class.

Another classmate behind her coughed.

“No one knows the answer?” Dr. Novak asked, her hand on her hip.

Wren spoke without lifting her head from her desk. “The inverse of the radical is called the Lorentz factor,” she said.

Dr. Novak nodded. “Very good,” she said. She moved to write the formula on the board, but stopped and frowned. “Wren, you are not looking well. Are you okay?”

Wren shook her head.

“Go. Come see me later, during office hours.”

“Thank you,” she said. Wren stood, left her notebook and pencils in perpendicular. A refreshing rush of air hit her as she pulled open the classroom door and calmed her nausea.

Wren took the stairs up to the entry level. She faltered as her stomach cramped when she passed by the Foucault pendulum in the lobby. The pain in her abdomen was sharp and to the left, leaving her breathless for a moment. She gripped the railing by the pendulum and watched it sway, syncing her breathing with the steady tilt of the mass.

When the pain subsided, she made her way out of the old brick building, down the concrete steps, and across the lush Florida grass. Wren lay under a giant oak tree by a water molecule fountain. A light autumnal breeze flitted through the trees. The light of the sun filtered through the tree leaves. It left a dappled pattern of light and shadow dancing on her cardigan, not unlike the pattern on Tahir’s uniform.

Wren recounted her trip to the Void, the blankness of the space, the vibrancy of Tahir in the flesh, the curiosity of the desk chair and field stretcher as placeholders. She mourned the loss of the tags, but knew this quantum entanglement required equal exchange. Three-quarters of a teaspoonful with the average volume of ejaculate in men—she’d looked it up. Had she shed enough sweat and tears to balance the equation? For all her love of formulas and physics, Wren hoped for this impractical application that she got the math right.

Leslie Salas is a multimodal writer-poet-cartoonist whose work can be found in The Southeast Review, Rogue Agent, and more. She is the editor of the Other Orlandos Anthology (Burrow Press, 2017) and co-editor of Condoms & Hot Tubs Don’t Mix: An Anthology of Sexcapades (Beating Windward Press, 2018). She serves as the graphic nonfiction / poetry comics editor for Sweet: A Literary Confection and pays the bills by teaching college students about writing, despite having earned a minor in Physics as an undergrad. Follow her (@profplans) on Instagram.