“Do you have any other models? So I can comparison shop?”

The clerk glowers back at Jonas, emits a grunt, and returns to the back room.

The moment he’s gone, Jonas bolts for the door with the demo phone gripped tight in his hand. He spills out onto the street with his heart jackhammering. Nothing in this universe suggests that law enforcement goes easy on thieves. He walks as fast as he can without appearing to hurry. The next corner can’t come fast enough, and he rounds it hastily and buries himself inside the nearest cluster of people.

He visibly startles when a sharp clanging rings out, the rapid chiming of a bell. From its distance and direction, Jonas knows it’s the electronics store’s alarm. It takes enormous effort to resist the urge to turn toward it, but he forces his feet to keep walking, his legs to keep pumping. He wills his eyes to remain forward yet cast slightly down. He adopts the posture of the other citizenry, hands buried in his pockets, back rolled forward. Be small. Be invisible.

But then the cry of a Klaxon punches his gut. A jet-black police car barrels directly toward him, iron crosses on its flanks, flashing red lights on its roof. He feels the blood rush from his face as two storm troopers stride directly toward him. He grips the phone and calculates whether it’s possible to drop it. Better yet, can he slip it into a passerby’s purse or pocket?

The police car careens past, close enough that its siren’s wail hurts his ears. It whips from view, but the storm troopers are on top of him. One collides with Jonas’s shoulder, bodychecking him. “Out of the way,” he grunts as he moves past.

People on the street crane their necks to trace the storm troopers’ path. Jonas can’t decide whether to go along with the crowd, so he settles on a noncommittal head bob. The storm troopers recede from view, and Jonas finally notices he’s been holding his breath.

With each block he clears, those breaths come a little easier. After ten or so, his heart is no longer trying to punch its way out of his chest. But the ill-gotten phone still feels like a weight in his pocket, an albatross. He’s convinced the people he passes can sense it, that it marks him. He assures himself again and again that the fear is just his imagination.

Hours pass. Jonas’s legs burn with the exertion of walking the length of the city. Even when he wants to stop, is desperate to stop, he doesn’t know where it is safe. All of Manhattan—or whatever it’s called here—feels as if it’s under occupation. He staggers, the muscles in his legs no longer cooperating with the madness he’s demanded of them.

The sun hangs low as he meanders into what he knows as Stuyvesant Square park, though a sign reads SCHRECK SQUARE PARK. The greenery is pockmarked with benches, and the desire to sit, if for only a moment, is overwhelming.

Then, a flash of panic. It occurs to Jonas that the store clerk might be able to trace the purloined phone. Jonas berates himself for his failure to consider every possibility. But the concern is reason enough for him finally to chance a look at the stolen phone. If it is being used to track him, he has to make quick use of it and then dispose of it as fast as possible.

He brings the browser back up and searches Henri Thibault’s name. As the phone makes its wireless connections, Jonas risks a glance at the people milling about the park, watching for any sign of anyone watching him.

The search produces a waterfall of results. Jonas reviews them with desperate interest. Thibault is not only alive in this reality, but he’s also a scientist of the same renown. Jonas feels a swell of hope as he reads about Thibault’s receipt of the Nobel Prize in Physics six years ago. He lives in Prague, not Switzerland, but Jonas reminds himself that Europe is where he must go in any case, assuming that this universe has a CERN in Europe.

He is already working out ways he might be able to get across the Atlantic when he reads about the arrest. He scans the article with growing concern. It’s worse than an arrest. Thibault was tried and convicted. And is now serving a life term for “crimes against the state.”

Jonas fights despair. This universe’s Thibault could have arranged for access to a particle collider. It seems that the reward for clearing one hurdle is just another hurdle to clear. No, a series of hurdles, stretching into infinity. But he tells himself to shake off that feeling. One step at a time.

Following that edict, he types another name into the search field. Please. I can’t do it alone. I need someone to help me through this world. Please. He taps Enter.

A hit. A series of hits. Jonas breathes out his relief. He pours over the web page and is rewarded with the stunning discovery that Eva Stamper not only exists in this reality but is living and teaching right here in Manhattan. His body sags with relief.

“You.” The word comes down to him from on high. Jonas looks up to see a storm trooper towering over him. His pulse quickens. The storm trooper’s crotch is at eye level, and one strike to the balls could buy Jonas precious seconds to make a run for it.

“What are you still doing out?” the man demands.

Confusion buffets Jonas. The phone shakes in his hand. He commands his fingers to still and forces himself to speak. “Excuse me?” The words come out in a croak.

The storm trooper shifts on his boot heels. Impatient. He cocks his head in the direction of the rest of the park, which is disquietingly empty. “It’s almost curfew.”

Jonas’s terror quickly transmutes into relief. He can’t help but imagine that he looks like an idiot to the jackboot.

“Get yourself home,” the storm trooper says, agitated. “And do it fast.”

Jonas stands, nodding his compliance. “Yes, sir. Sorry, sir.” He shuffles off as fast as he can.

With no money for a taxi or public transportation, Jonas treks uptown to Columbia University, which in this reality is called Von Braun University. Fortunately, the rest of the city is also racing the curfew, and he’s once again able to cloak himself in the bustle. Less fortunately, the sun outruns him, and he’s forced to continue past curfew.

As darkness drapes the city, Jonas traverses each block, deliberate but cautious. Storm troopers are everywhere. Armored trucks festooned with iron crosses rumble past, their roof-mounted spotlights dancing over sidewalks and skulking up the sides of buildings. Any group of two or more people is accosted, but Jonas doesn’t slow down enough to see if the same is true for loners like himself.

He breathes a sigh of relief when he sees that the university’s open campus hasn’t changed. He doesn’t see any gates or guards or fences, and he’s able to stride onto the quad just as he had back when he was a professor in another universe.

The academic building off West 120th Street, where Eva Stamper has her office, is a redbrick affair fronted by an entrance of tinted glass and black steel. In Jonas’s universe, the building is known as Pupin Hall, after Michael Idvorsky Pupin, inventor of the overload coil that made long-distance telephone calls possible. Here the building is named for Werner Heisenberg, a more apt dedication for a physics building, given that Heisenberg is—at least, in Jonas’s home universe—one of the pioneers of quantum mechanics.

Just as he did back at the Université de Lausanne, Jonas spies a heating vent to sleep on. He curls up, feeling the temperate air, imagining that he’s never felt quite as tired. He doesn’t remember falling asleep, but he dreams, as he always does, of Amanda. Every night, she tells him the same thing, as regular as the tide: I know you’ll find me. You won’t let anything stand in your way. Not even the universe. I know what people tell you, what you sometimes tell yourself, that it’s impossible. But I know—I know—it’s not impossible. Her entire body vibrates with the force of her convictions. It’s not impossible because you’re doing it. You believe in the existence of a multiverse, but I believe in you.

And he sleeps, deeply, nuzzled in the warm embrace of that faith.

FOUR YEARS AGO

In 1939, Enrico Fermi, Leo Szilard, and a group of other physicists began work on inventing a self-sustaining neutron chain reaction. They worked in the basement of Pupin Hall at Columbia University. When the Japanese attack on Pearl Harbor prompted a relocation of this work away from the coast—to the University of Chicago—the endeavor retained the name of its city of origin: the Manhattan Project.

The cradle of nuclear warfare loomed over Amanda’s head. Eleven floors of red brick, topped with the copper dome of the Rutherford Observatory, stretched up to the winter sky, a black sheet with pinpricks of light piercing it.

Amanda paced in front of the building as her breath birthed tiny clouds in the air. She felt her gut begin to give back what little dinner she had been able to get down. She balled her hands into fists to keep them from trembling.

She turned back toward the building, with its neat grid of windows and its copper roofline, and wondered what was happening inside, but the stalwart, storied edifice held no answers.

As worry rose within her, it occurred to her that this was as concerned as she’d ever been for another human being. It didn’t matter that they weren’t married. Her life was now entwined with Jonas’s, and his with hers. Marriage, she understood in that moment, was a bureaucratic distinction, the legal amalgamation of two bank accounts, the public acknowledgment of the more meaningful union that preceded it—the joining of two souls. This was what it meant to share a life, to take on another’s hopes and dreams as your own, and for them to do the same with yours. She felt fear for Jonas and his career, his personal and professional reputations, as viscerally as he did.

The only difference was that he was in the building while she was exiled to the outside, forbidden to enter the place where everything was being decided. She had no voice. She had no means to affect the verdict of the disciplinary hearing that Victor had wielded his influence to convene. She was not invited to give her account of how he’d shown up at Jonas’s apartment—their apartment—abusive and belligerent and paranoid. She couldn’t tell the Columbia faculty and administrators that she believed Victor Kovacevic to be unhinged. No, that wasn’t quite right. Beliefs were subjective. Victor’s rage-filled, borderline violent affect that morning wasn’t a product of her imagination. She’d witnessed it. As dispassionate an observation as recognizing that cobalt was blue. Indeed, her entire career, her life, was centered around what she took in with her own two eyes, and that power had never failed her. She knew in her bones the kind of man Victor was, what he was capable of.

And she was terrified.

She knew Victor had not only the ability to destroy the man she loved but also possessed the means to do so. It was a frightening combination. She had tried consoling herself with platitudes like “the truth always prevails,” but even at thirty-four, she was old enough to know what a fiction that was. The world worked the way men like Victor wanted it to, and they learned how to manipulate it to their own advantage.

After what seemed an eternity, the building’s double doors swung open, and Jonas spilled out. She looked at him and felt her heart plunge. He was a husk, his expression vacant. The brilliance she’d become so accustomed to, had fallen in love with, was gone from his gaze. In its place, she saw only confusion, as if he’d just learned that water wasn’t wet or the sky wasn’t blue. She didn’t ask him what had happened. She didn’t need to. She knew the verdict he had just received was dire.

She watched him stagger to a nearby bench and fall into it. She lowered herself to his side and took his hand in both of hers. She waited until he could find the words, until he was ready to speak. She would wait forever if she had to.

When he finally spoke, it wasn’t what she expected. “They cleared me of the plagiarism,” he breathed. He sounded neither despondent nor triumphant. He didn’t even sound relieved. He sounded spent, beyond the point of exhaustion.

She exhaled without even being aware that she had been holding her breath. But although the news was good, the best that either of them could hope for, she knew better than to celebrate and resisted the urge to embrace him. She just kept his hand clasped and waited to hear the reason he looked so lost.

“But Victor is department chair,” Jonas finally said.

“What does that mean?” she asked, dreading the answer.

“That the board couldn’t stop him from firing me.” He delivered the news with as much dispassion as he would a weather report, but Amanda’s world instantly constricted to that little bench. She felt the same despondency and fear and anger that Jonas must have been feeling in that moment but evidently couldn’t express. She wanted to shoot to her feet and storm off into that building, to find Victor and rage at him. She wanted to thunder at the administrators, the bureaucrats, the petty little people who had been either so stupid as to believe Victor or too spineless to defy his wishes. She wanted to burn the entire building to embers and felt like she could do so merely with the force of the fury she felt.

Jonas leaned forward and rested his arms on his legs. He stared out into nothingness. He spoke, but Amanda couldn’t make out what he was saying.

“What, honey?” she asked, her voice a whisper.

“What if he’s right?” Jonas repeated. “If not for him, I never would have started work on parallel universes. I never would have tried to formulate a proof for their existence.”

“And I never would have taken up painting,” she replied, “if my parents hadn’t taken me to see a David Hockney exhibit when I was six.” She turned Jonas’s face toward hers. “Inspiration isn’t imitation, Jonas. Artists and scientists both build on the work of those who came before them.” He looked away, seeming unconvinced. “If you had really stolen from Victor, stolen anything,” she said, “the board would have said so.”