In 1975, Stephen Hawking showed that the principles of quantum mechanics would mean that a black hole emits a slow stream of particles and would eventually evaporate.
Everett takes the punch on the jaw. He's old as dirt and can't dodge it, despite knowing for sixty years that it was coming. He falls to the frozen city streets.
The puncher, a teenage girl, screams at him, "It's not fair, you had so much time not knowing!" She crumples and sobs like there's no tomorrow, because for her there isn't. She will die in nine minutes and she knows it. Everett's heart breaks for her, for all of humanity, and he curses Presenton, the physicist who stole the future.
Everett crawls towards the girl over snow that's been trampled by people too desperate to stay home. People like Everett, who chose a punch because it beat being stabbed or shot or any of the infinitely worse possibilities that would have befallen him. Hard to stay safe when criminals can see the future.
"It's an aneurysm," she says like he doesn't already know.
Everett sits beside her. Hard to get surgery when everyone is busy trying not to get killed.
"What are you, like a hundred?"
"Ninety-two," he says.
"Tell me what it was like not knowing. Tell me the story of your life. But don't tell me how it ends." She clutches his arm. "For once I don't wanna know how it ends."
Everett can't tell her how it ends, because he doesn't know how he will die. He knows the when: today. And the where: the Institute of Particle Physics, after he infiltrates the protective field surrounding it. Everett can see nothing past that point; the future is unknown inside the field.
He tells the girl about Luna, his wife. How he would give anything to hold her, to smooth the frown that deepened between her brows every time she worked on her research. It was her team that proposed a hypothetical particle: the presenton. They could potentially collapse wave functions like dominoes, felling them far into the future, converting the future to the present. Someone on her team insisted they not only prove it, but start those dominoes falling. Luna scoffed and dubbed him Presenton, a wannabe superhero determined to free humanity from the chains of the present. But her frown deepened with worry.
"And then one day Luna didn't come home." Everett knew she never would, because he was suddenly able to perceive every moment of his life. Except his death.
"Ten seconds until I die." The girl's eyes bulge with fear.
Everett holds her while the time bomb ticking inside her head explodes, a bomb that would have been defused had society not collapsed. Everett can't finish his story now, can't tell her he had spent the remaining sixty years of his life studying particle physics in order to infiltrate the institute's field and restore the future to an unknown quantity. He tries to find comfort in the fact the girl did not want to hear the ending, but he cries anyway.
Everett drapes his coat over the girl and limps to the institute.
Sixty years is a long time. Everett has advanced the team's research considerably, and linked two apps. Each will drain energy from the institute's field, but for different purposes. One will reverse the domino effect of the presenton all the way into the past, enabling him to change it, and thus, the future. The other will suspend anyone within one metre of his phone forever in a state of superposition. Hopefully, Presenton.
Everett stands before the institute. He taps his phone's projection display and activates the first app. Ice crystals dancing in the field's transparent perimeter morph into the spring blossoms of a mayday tree, chickadees flitting from branch to branch. Everett can't stop staring, suddenly glad Luna never saw birds fall from the sky when faced with a future they could not comprehend.
Everett steps through the field. For the first time in sixty years, he has no idea what's going to happen.
He limps through the revolving doors, to the elevators, to Luna's floor, his phone overriding decades-old security, his heart skipping too many beats.
Luna. He stumbles towards her desk through a maze of semi-transparent office walls, her frown deepening as she watches him approach.
"Where's Presenton?" Everett says.
"Who, Dave? He got fired."
"Dude was unhinged. Have we met? You look familiar."
He manages to spit out, "I'm Everett. Your husband."
Her smile fades. "I'm calling security."
"Please don't. I can prove it." Everett explains her own research to her, and his as well.
Luna pales. "I've been working on that hypothesis for years. And a stranger walks in and proves it?"
Everett is at a loss. If not Presenton, then who—? He sucks in a breath. It hits him at the same moment the pain from his bruised jaw shoots down his arm and blooms in his chest.
Luna. She is Presenton. Because Everett has unwittingly given Luna the key to destroy the world.
He must warn her not to use this newfound knowledge. But the pain crushes his chest and steals his breath. Everett collapses.
Luna drops beside him. "Sir! Are you okay? I'll call for help."
Everett's good arm flails. It connects with hers and he grasps her hand.
Her eyes widen as they take in his wedding ring, the crescent-shaped birthmark on his wrist. "My God. It is you. You came from the future to prove my hypothesis."
He shakes his head, no no no.
Luna wraps her arms around him, her breath in his ear. "Hang on. It's gonna be okay."
It's not going to be okay.
Everett clutches his phone. He knows what he must do. No, please, not that. Tears roll down his face. Nobody said this was going to be easy.
His eyes open wide. He sees a future where a teenage girl doesn't die. Where birds still fly. Where he is forever holding Luna.
As Everett activates the second app, he finally knows how his story ends.