The quantum computer hummed its electric lullaby at 2:47 AM, the same pitch as the fluorescent lights that Marcus Okonkwo pushed his mop beneath, the same frequency as his wife's breathing machine back in their one-bedroom apartment in East Palo Alto. He'd been cleaning this particular floor of QuantumLeap Technologies for three years now, long enough to know that machines sang different songs when no one was listening.
Tonight, though, the song was wrong.
The massive black cube in Lab Seven—what the young engineers called "Schrödinger's Box" during their ping-pong breaks—was supposed to be powered down. Marcus knew the schedule. Tuesday nights were maintenance nights. But cyan light leaked from beneath the door like water from another world, and when he touched his keycard to the reader, the door sighed open to reveal something that made his bucket clatter to the floor.
The air inside shimmered. Not with heat, but with possibility.
The quantum computer's display panels, which usually showed incomprehensible equations that might as well have been ancient runes, now flickered with images. Moving images. Living images. And in them, Marcus saw himself.
But not himself.
In one panel, a Marcus in a white lab coat stood before a classroom of students at MIT, his hands dancing as he explained something beautiful about the nature of reality. In another, a Marcus who'd never left Lagos sat in a garden with a woman who wasn't Amara, three children playing at his feet. In a third—
His heart stopped.
In the third panel, Adaeze was blowing out candles on a birthday cake. His daughter. His daughter who'd been dead for five years, killed by a drunk driver on Highway 101 while walking home from her job at the grocery store. She was older in this image, maybe twenty-three now, wearing a graduation cap that sat crooked on her head the way she'd always worn her hats.
"Beautiful, isn't it?"
Marcus spun around, his hand clutching his chest. Dr. Yuki Chen stood in the doorway, her usually severe face softened by the machine's blue glow. She wasn't supposed to be here. No one was supposed to be here.
"I'm sorry, Dr. Chen, I was just—the light was—"
"You're Marcus, aren't you?" She stepped into the room, her sneakers silent on the polished floor. "Third floor, Tuesdays and Thursdays. You always arrange my desk items in a perfect grid. I appreciate that."
She moved past him to the console, her fingers hovering over keys he'd only ever cleaned around. "Do you know what this machine does, Marcus?"
"It..." He thought of the fragments of conversations he'd overhead, the excitement in young voices discussing qubits and superposition. "It computes things. Quantum things."
"It computes everything." She pressed a key, and the images shifted, multiplied, cascaded like a waterfall of worlds. "Every choice you've ever made, every path you didn't take, every quantum possibility—they're all equally real, Marcus. The machine doesn't create them. It just... looks."
In the panels, he saw himself dying in a thousand ways, living in a thousand more. He saw himself as a child choosing to study science instead of literature, saw himself saying yes to MIT's scholarship instead of following Amara to California, saw himself grabbing Adaeze's keys that night, insisting on driving her home himself.
"Why are you showing me this?"
Dr. Chen turned to him, and in the machine's light, he could see she'd been crying. "Because I've been watching it for months. My own paths. The children I didn't have. The mother I didn't visit before her stroke. The papers I didn't publish because I published other papers instead." She laughed, but it was brittle as old glass. "We're not supposed to use it for personal viewing. But at 3 AM, who's watching the watchers?"
Marcus moved closer to the panel where Adaeze was now opening presents, her smile exactly as he remembered it, down to the way it made her left eye squint slightly. "Can we... can we go there? To these other places?"
"That's the question, isn't it?" Dr. Chen's fingers danced across the keyboard. "The math says yes. The machine creates quantum entanglement between observer and observed. With enough power, enough focus, consciousness could theoretically slide sideways, slip into a parallel track like changing lanes on a highway."
"But?"
"But you can't come back. And more importantly..." She gestured at the thousands of panels, each showing a different Marcus living a different life. "How do you choose? And what happens to the Marcus already living in that reality? Do you merge? Does he disappear? Do you simply... trade places?"
Marcus watched himself in another panel, this one showing him at Adaeze's wedding, walking her down an aisle in a church he didn't recognize. His hand trembled as he reached toward the screen.
"Don't." Dr. Chen's warning was sharp. "Touch it, and the entanglement begins. I've run the simulations. Once you start the process, it accelerates. You'll see more and more possibilities, each one more real than the last, until you can't remember which reality you started from."
But it was too late. His fingertips had already grazed the panel's surface, and the world exploded into infinite fragments.
Suddenly, Marcus was everywhere.
He was accepting his PhD from Cambridge while simultaneously dying in a Lagos hospital. He was holding Amara's hand at their wedding and attending her funeral on the same day. He was a billionaire tech founder and a homeless man sleeping under the Bay Bridge. Each reality pressed against his consciousness with equal weight, equal truth.
"Marcus!" Dr. Chen's voice seemed to come from very far away, or perhaps from very close—it was impossible to tell when distance had become negotiable.
He saw Adaeze in a thousand permutations: alive, dead, never born, born as twins, born as a son named Adaobi. She was a doctor, a dancer, a drug addict, a diplomat. In one reality, she was Dr. Chen's research partner. In another, she was the one cleaning these floors while he lay buried in a cemetery in Lagos.
The realities began to bleed together. He was in his apartment with Amara, but the walls were both blue and green, both crumbling and newly painted. Amara was both sick and healthy, both young and old, both loving him and having never met him.
"Focus!" Dr. Chen had grabbed his shoulders, was shaking him. Or was she? In another reality bleeding through, she was calling security. In yet another, she was kissing him. "You need to choose ONE reality and hold onto it!"
"How?" His voice fractured into harmonics, each one speaking from a different world.
"Remember something specific! Something that could only happen in one timeline! An anchor!"
Marcus tried to think, but thoughts belonged to specific realities, and he was spread across all of them. He was everywhere and nowhere, everyone and no one. The machine's hum had become a roar, or perhaps that was the sound of infinite possibilities collapsing into—
Amara's breathing machine.
That specific wheeze-click-hum that had kept him awake for six months until he learned to love it because it meant she was alive. That sound existed in only one reality—the one where she'd gotten sick but hadn't died, where American healthcare had bankrupted them but not killed them, where he worked three jobs to pay for her treatment, where he mopped these floors while dreaming of equations he'd never solve.
The reality where Adaeze was dead, but where he'd held her hand as she died, been there for her last words: "Tell Mom I love her."
The panels began to fade, all except one. In it, he saw himself as he truly was: a middle-aged man in a janitor's uniform, tears streaming down his face, standing in a lab he'd never understand, in a country that barely acknowledged him, living a life that had broken his heart but not his spirit.
He pulled his hand back from the screen.
The room snapped back to singular focus. One room, one Marcus, one Dr. Chen looking at him with a mixture of awe and terror.
"You came back," she whispered. "The simulations suggested... but you actually came back."
Marcus sank to his knees, his body shaking. "I saw her. I saw all the worlds where she lived."
"And you chose this one. Why?"
He thought of Amara, waiting at home, probably awake despite the late hour, probably worried because he always texted when he started his shift and tonight he'd forgotten. He thought of her hand in his, real and warm and present, not a possibility but a certainty.
"Because in all those other worlds, I hadn't made her that promise. To tell her mother she loved her. And a promise to the dead..." He stood up slowly, his knees protesting. "That's not something you can walk away from, even for all the worlds where they're still alive."
Dr. Chen nodded slowly, then moved to the console. "I'm going to wipe tonight's logs. And I'm going to recommend this lab be relocated to the day shift only. Some doors shouldn't be opened at 3 AM."
"What about you?" Marcus asked, picking up his mop. "Don't you want to see your other lives?"
She was quiet for a long moment, staring at the now-dark panels. "I've seen them. Every night for six months, I've seen them. The life where I chose love over science. The one where I had children. The one where I wasn't alone in this lab at 3 AM talking to a janitor about quantum possibilities."
"And?"
"And I made my choices. We all did. The question isn't whether they were the right choices—there's no such thing, as the machine proves. Every choice is right in some world, wrong in others." She turned off the machine, and the room fell into darkness except for the emergency exit signs. "The question is whether we can live with the choices we made."
Marcus nodded and pushed his bucket toward the door. But before he left, he turned back. "Dr. Chen? In one of those realities, I saw you and Adaeze working together. You were happy. Both of you."
She smiled, and for a moment, in the half-light, she looked younger, like the woman she might have been in any number of other worlds. "Thank you, Marcus. That's... that's good to know."
He finished his shift as the sun began to paint the Silicon Valley sky in shades of possibility. The building hummed with early arrivals, eager young minds ready to change the world, unaware that in the basement, a janitor had held infinity in his hand and chosen the broken, beautiful singular reality of his own life.
When he got home, Amara was awake, as he knew she would be.
"You didn't text," she said, her voice soft with concern and medication.
"I'm sorry. I was... distracted."
She patted the bed beside her, and he sat, taking her hand. It was thin, the veins visible through paper skin, but it was warm and real and here.
"What distracted my brilliant husband?" she asked, using the Nigerian endearment she'd learned for him decades ago.
"I was thinking about choices," he said. "And about Adaeze."
Amara's face softened. She pulled him down beside her, and he curled against her careful not to disturb her IV line. "Tell me."
So he did. Not about the machine or the infinite worlds—that was too large, too impossible for a Tuesday morning in a one-bedroom apartment. Instead, he told her about the dream he'd had while cleaning, about seeing their daughter graduate, get married, have children of her own. He told her about the life Adaeze might have lived, could have lived, had lived in another place beyond reaching.
"She would have been twenty-three now," Amara said.
"Twenty-three and four months."
They lay in silence, listening to the breathing machine's wheeze-click-hum, to the traffic beginning on 101, to the world waking up to its own singular possibilities.
"Marcus?"
"Yes?"
"Do you regret coming here? To America? If we'd stayed in Lagos..."
He thought about the Marcus who'd stayed, the one he'd seen in the panels with his three children and different wife, the one who'd never known loss like this but also never known love like this.
"Every choice costs us the other choices," he said carefully. "But no, I don't regret it. We came here together. We lost her together. We're surviving together. That's not nothing."
"It's everything," Amara corrected.
Later, after she'd fallen asleep, Marcus stood at their small window, looking out at the city that had promised them so much and delivered so little. Somewhere out there, the quantum computer was sleeping, its infinite visions locked away. Somewhere, Dr. Chen was probably starting her day shift, surrounded by colleagues but essentially alone. Somewhere, in a reality he could no longer reach, Adaeze was waking up to her own Tuesday morning, full of her own possibilities.
But here, in this reality, in this moment, Marcus Okonkwo was exactly where he needed to be: holding his wife's hand while she slept, carrying his daughter's last words in his heart, living the life he'd chosen one decision at a time.
The sun climbed higher, burning away the morning fog, revealing the world as it was: broken and beautiful, finite and precious, the only reality that mattered because it was the one where love, even lost love, even grieving love, was real.
That night, when he returned to QuantumLeap Technologies, Lab Seven was locked, a new sign on the door reading "Authorized Day Personnel Only." Marcus cleaned around it, humming his own tune now, one that matched neither the fluorescent lights nor Amara's breathing machine, but something entirely his own—the song of a man who had touched infinity and chosen the finite, who had seen all possibilities and chosen the actual, who had been offered every world and chosen this one.
As he worked, he thought about the thousands of other Marcuses in their thousands of other worlds, each one cleaning or not cleaning, grieving or not grieving, living their own singular truths. He wished them well, these quantum brothers of his, these shadows and echoes of choices unmade. But he did not envy them.
For in this world, he had made a promise to a dying daughter, and kept it. In this world, he held Amara's hand each morning as the sun rose. In this world, he was Marcus Okonkwo, janitor, husband, bereaved father, keeper of small promises and large griefs.
It was enough. More than enough.
It was everything.