He grips Eva’s hand tighter and pulls them both inside. And the moment—the exact second—they spill into the granite and travertine lobby, a marvel of bleeding edge architecture and design, the earthquake ceases. It happens so fast, it’s as if a switch has been thrown.

“This doesn’t make any kind of scientific sense,” Eva says, disbelieving.

“That’s what every scientist says,” Jonas answers her. “Right before it does.”

Eva looks over to the reception desk, where a guard dutifully remains at his post. He barks at them in urgent Japanese.

“I’ll deal with him,” Jonas tells Eva. “Find Kobayashi.”

“You’re assuming he didn’t evacuate with the others,” she cautions.

“More like hoping like hell,” Jonas corrects as he makes for the reception desk.

Minutes later, Jonas and Eva ride an elevator in solitude. The tower’s technology makes the ascent whisper quiet and conveys the feeling that they are ascending to heaven itself. While CERN’s Large Hadron Collider had been constructed horizontally and spanned two countries, the Spire’s Linear Accelerator has been built vertically, running down the core of the massive tower and deep into the earth.

“Lucky the elevator is working,” Eva remarks.

“It’s not luck,” Jonas says. “It’s seventy thousand yen.” Eva stares at him quizzically. “I bribed the guard to turn the elevators back on.”

Eva appears impressed by his forethought. She reaches into her purse, pulls out a small box tied with a red ribbon, and hands it to him.

Jonas studies the box, turning it over in his hands. “What’s this?”

Eva stares at it in mock fascination. “Hmm. It appears to be a gift of some kind.”

The echo of his distant past gnaws at him. He wills himself to ignore it, unties the ribbon, and opens the box. He pulls out a hand-knit patch of some kind. Its stitching, as delicate as air, forms the shape of an infinity symbol formed by a snake eating its own tail. An Ouroboros. Just like—

“Just like your tattoo,” Eva says. “It’s all cotton. Natural fibers. It should . . . make the trip with you.”

Jonas looks up at her, moved beyond words. This woman he loves. This woman he rejected in the hope of another.

“I wanted you to have something that reminds you of me,” Eva explains.

Jonas looks down at the Ouroboros, then back up at her. “I don’t need a reminder,” he says, meaning every word. His eyes tell her what words feel inadequate to express: I’ll never forget you.

Guilt wells within him. Of all the things he’s done to get back to Amanda, he regrets nothing more than the pain he’s caused this woman whose love he doesn’t deem himself worthy of. He opens his mouth to say as much. And that’s when the elevator stops with a jolt.

“The universe?” Eva asks.

“Or just bad luck. The universe might just snap the cable and send us plummeting.”

“That’s not funny.”

Jonas shrugs—it’s a little funny—and reaches for the doors. He hopes he can pry them open with his hands and is rewarded for his wish. They’re stuck between floors, and he can see the outer doors. He sets to work opening those.

“How do you know how to do that?” Eva asks.

“I watched someone do this kind of thing back in Switzerland, several universes ago,” Jonas says, stretching to reach the outer doors, which ultimately give with an echoing shunk. Jonas holds them open and looks to Eva. “Ladies first.”

“I see they also have sexism in your home universe.”

“Yes,” Jonas retorts, “but there they call it ‘chivalry.’”

Eva chuckles and heaves herself up and out of the elevator. Jonas follows her, extricating himself from the moribund elevator car. A sign tells them they’re on the ninety-ninth floor.

“Seventy-five floors to go,” Eva says, pointing to the stairwell. “Guess the universe wants you to get your exercise.”

The stairs recede beneath their feet as they trudge upward. Eva takes the lead, and Jonas watches from behind as her legs piston up and down. They’re barely three floors into their ascent when his lungs start to burn in protest, but Eva’s stride keeps its regular rhythm.

“Have you thought about what happens after you find her?” she asks.

Jonas has to catch his breath. Speaking is harder than he expected. “What . . . do you mean?”

“If the universe really is trying to stop you, what makes you think it will stop once you find Amanda?”

The thought had never occurred to Jonas. It brings a chill. “I told you, I’m still trying to figure out the universe,” he deflects.

“I’m serious.” The ease with which she’s talking as they climb feels like a taunt. “Your reward for making it to Amanda could just be a lifetime of—I don’t know how to put it—universal mischief.”

It’s hard not for Jonas to feel some irritation that Eva is bringing this up now. Is this some final attempt to dissuade him? Does she expect him to abandon his crusade right at the point when he’s so close to its end? “I don’t know, Eva,” he snaps, gasping.

“I’m sorry if I—”

“My hope is,” he explains, forcing softness back into his tone, “that after the waveform collapse that results from my being reunited with Amanda occurs, the universe will return to homeostasis.”

“Are you just throwing science at me now?”

Yes. But he doesn’t say that. Instead, he admits, “The truth is I don’t know what’s going to happen. This whole”—he searches for the right word—“phenomenon was unexpected. But maybe my understanding about universal destiny was too simplistic. Perhaps the universe isn’t always consistent about the results it favors. After all, this is the same universe that compelled me to work on the Many Worlds Proof in the first place.”

“That sounds a bit like rationalization.”

“Because it is,” he concedes. “But if destiny is real, then I have to believe that hope is too.”

THREE YEARS AGO

Jonas’s paper, “The Many Worlds Proof: Mathematical Evidence of the Existence of Parallel Universes,” had been selected for publication in the Journal of Applied & Computational Mathematics. Although regularly listed among the world’s top ten quantum mechanics journals, its editor had been the last to consider Jonas’s work and the only one to commit to publishing it.

Victor’s reach within the academic community was wide, touching every journal of renown, and the shadow he cast was long, dimming any and all prospects for publication. Worse, Victor dangled the threat of bitter and protracted litigation, and few editors had the stomach for the kind of trench warfare they knew he was capable of.

In the end, though, it only required one courageous editor and the power of Jonas’s idea, which proved too compelling to ignore. Proof of the existence of a multiverse had the power to alter humanity’s perception of its own existence, a shift in perspective no less radical than when Nicolaus Copernicus proposed heliocentrism and ousted Earth from the center of the universe.

The ramifications of Jonas’s work were just as seismic, the equivalent of proving the existence of gravity. The practical applications were endless, and the moral dilemmas were boundless. Chief among both was the feasibility of travel to one of these sister universes. It was an axiom as old as humanity that once a destination is discovered, there immediately follows the desire to reach it. Would it be possible to visit these alternate realities? Should it be possible? Jonas knew he had opened Pandora’s box. But he knew with equal conviction that that is what scientists do, trusting that humanity is prepared to weather the aftermath.

In the weeks leading up to publication, Jonas spent hours ensconced in the New York Public Library, copyediting and fact-checking and pressure testing every word, equation, and idea. The hours flew by while Jonas was cocooned in the main reading room, pecking away on his MacBook. He returned home every night to the new apartment, a co-op on the Upper West Side that he and Amanda had bought.

The place had been Jonas’s idea, a gambit to get Amanda’s mind off their setback. “Setback” was the word they’d tacitly agreed to use during the increasingly rare circumstances when they talked about the difficulty Amanda would have getting pregnant. “Difficulty” was another term they agreed upon. The word maintained a patina of hope, the possibility of possibility, better than “unlikelihood” or “inability.” Unfortunately, the apartment felt more like a consolation prize than a home. Worse, and Jonas had only come to grasp this in hindsight, their home had only one bedroom, and the absence of a second served as a sad reminder that they wouldn’t need one.