Eva brightens. Suddenly, it all makes sense. She understands what’s happening here, and she’s relieved. “Roberta put you up to this, didn’t she? Tell her that her sense of humor still needs adjustment.”

She turns to unlock the door, but the man won’t be deterred. “This equation here,” he says, jabbing at his skin and leaving tiny white circles on the formulae, “this is a Schrödinger equation. What do you know about the Many Worlds Theory?”

Eva doesn’t have time for games. “Only what I learned in Introduction to Quantum Mechanics,” she tosses off.

“You got an A, though.”

Eva looks back at him, utterly flustered. It’s not that he knows her college transcript—anyone could uncover that—it’s that he knows exactly what she was about to say, and the way she was going to say it. She pales. Her stomach performs a barrel roll, and she stares at him with frightened eyes.

“Invite me inside, Dr. Stamper,” the man says. “We have a lot to talk about.”

One of the corollaries of the principle that all universes share certain qualities is that people’s reactions demonstrate a relatively predictable consistency. Although hardened by coming of age in a fascist society, this reality’s Eva retains her inquisitive spark, the same curiosity that drew “his” Eva to Jonas, that opened her mind to the incredible. Jonas can’t help but find the quality alluring.

Eva spends twenty minutes sweeping her modest faculty office for listening devices. After pronouncing the room clean, she explains, “I admit it’s more than a little paranoid, but I’ve heard stories of the State Directorate conducting surveillance on academics. Ideas are the most dangerous things in the world. And I have a feeling your ideas, Mr. Cullen, are among the most hazardous.”

This observation proves to be a profound understatement as Jonas shares his story, beginning with the night in Stockholm, the Nobel, the crash. He tells her about his tether and the quantum energy slowly leaking from his body. He explains that he knows what she’s thinking because of his encounter with her doppelgänger. He leaves out Victor and Amanda’s second death. He omits the other Eva’s demise.

Eva appears to take it all in with the same calm as her twin. “If I understand the Many Worlds Theory properly, there’s a world where you and your wife are both alive, where perhaps the accident never even happened.”

Jonas has to admire the parallel. “Yes. There’s already a world where I’m happy,” he says, remembering the words of her doppelgänger. He watches her startle slightly, knowing that’s what she was going to say next. It’s like a form of telepathy. “But I—this me, myself—I can’t be happy without her. I can’t be anything without her. I might as well be dead.”

He feels her staring, and he lets her. He can only imagine the multitude of thoughts that must be racing through her mind as she works her way from skepticism to acceptance. On some level, he admits that he wants the turn to be quick, to get back to the same easy rapport they had once enjoyed.

From the new vantage offered by this alternate reality, he notices qualities her twin had possessed but which he hadn’t allowed himself to notice. The way the left corner of her mouth curls up ever so slightly in a subtle perpetual smirk as though she sees through you but is amused by what she observes. How the lilt of her voice betrays a reassuring kindness. Despite the omnipresent dread of this universe, she has a vibrancy to her even her counterpart didn’t possess.

For a breath, they share a gaze like a cable pulling taut between them. That this all unfolds instinctively, in a matter of seconds, doesn’t shield the moment from feeling like a betrayal. He watches her move to a state-issued computer and begin typing away.

“What are you doing?” Jonas asks.

“Searching the internet for information about your wife in this reality.”

“I already did. I stole a smartphone, or whatever it is you call it here. She doesn’t exist in this universe.”

“You ran a search on a commercial phone using public internet, the information on which is heavily redacted by government censors.” She types away, eventually stopping with the final stab of a key. “You said your wife—”

“Amanda.”

“You said Amanda died in a car crash?”

“Yes.”

Eva points to her computer monitor. “In this reality, she died in a plane crash.”

Jonas fights to keep the image from his mind. He’d have better luck holding back the tide.

“A car crash,” Eva is saying, “a plane crash. Have you considered the possibility . . .”

“That the universe wants my wife dead?”

“The universe doesn’t ‘want’ anything, and I was going to put it a bit more delicately than that. But generally . . . yes.”

“I’m definitely aware that variations in the multiverse are limited by what we call ‘fate.’” His eyes wander her desk—the top of which is carpeted with an academic’s organized chaos—and sees a framed photograph of a man in military uniform. “Your husband?” he asks.

Eva darkens slightly, the affect of a widow. “Yes. He—”

“Died in action,” Jonas says, completing the thought. “Afghanistan?”

Eva shakes her head. “Israel.” Jonas knows her faraway look well. “I suppose the universe wants Brian dead too.” She looks to Jonas, and her tone is empathetic but firm. “But you don’t see me breaking the laws of the universe to be with him. Why do you get a second chance when the rest of us don’t? What makes you so special?”

Eva’s doppelgänger had asked the same question. So had Victor aboard the airliner. Each time, Jonas evaded answering.

“What makes you so special?” Eva repeats.

“Because I’m the one who can do it,” Jonas says. “Don’t tell me that if you had the means to be with your husband again—”

“Don’t,” Eva warns. Again, Jonas is reminded that they’re not friends in this reality.

“—that you wouldn’t make everything of that opportunity,” Jonas continues. “And if you had that chance and didn’t take it? Wouldn’t that be a kind of murder?”

“That’s offensive.”

“But not wrong. My life’s work has been about seeing the world as it is. Not how we want it to be or wish it to be, but how it really is. The rules that comprise our reality.” Bottom line: “I can’t pretend I don’t have the ability to find her. And with that ability comes a responsibility, don’t you think?”

Eva rubs her forehead as though trying to push an idea into it. Her jaw pulses with gritted teeth. “I thought you didn’t know which universe your wife is in.”

Jonas pulls up his sleeve. Other Jonas’s equations run up his arm. “These calculations were worked up by a doppelgänger of mine, a version of myself from another reality.”

Eva pulls on a pair of wire-rimmed glasses and examines the formulae with a practiced eye. “Don’t take this personally, but from the look of these equations, I think this other you might just be a bit smarter.”

“And a bit crazier. Either way, he had a breakthrough.” Jonas taps the new tattoo with his free hand. “He calculated the correct reality. The one—the only one left—where she is still alive.”

Eva studies the equations. Encountering an Eva who pursued physics instead of branching off into psychiatry is a lucky turn. “If I’m reading this right, you’re going to need energy to untether yourself again and make the jump to the proper reality. A lot of energy.”

“I know. I’ve done it before.”

For the first time, Eva appears incredulous. She scoffs, “Where could you possibly get your hands on that much quantum energy?”

“I broke into CERN.”

Eva blinks. “What’s a CERN?”

Jonas deflates, his spirits dashed by the fecklessness of parallel realities. “There’s no Large Hadron Collider in this reality?”

“I don’t know what that is.” Regret passes over her face.

“It’s a particle accelerator. Without one . . .” He can’t complete the thought. Can’t summon the energy to say the words aloud for fear that doing so would make the hopelessness of his situation real. The thought of chancing another reality-slip, of squandering what little quantum energy his cells contain on another ill-fated attempt, is crushing.