I look around the lecture hall. Since this is an extension class, it’s not just college-age kids. There are elderly couples, women in yoga pants, professionals whose schedules allow them to take a long lunch break. “According to quantum mechanics,” Brian says, “you may well be immortal.” He reminds me of a tiger as he paces in front of an audience that knows he is toying with them. “A very controversial proposal was put forth by Max Tegmark—from that physics department down the street.” He means MIT, and that makes some of the audience laugh. “It’s called ‘quantum suicide.’?” He clicks a remote in his hand and a slide appears: a ket bracket with pictures of an electron, a gun, and a kitten inside. “You remember the quantum state of the electron that spins both ways at the same time? The one that both killed and didn’t kill Schr?dinger’s cat? Let’s take that a step farther. Let’s say that in this ket, we have that spinning electron, and a trigger, and a gun…but now, you take the place of the cat. If the electron spins clockwise, the trigger goes off, the gun fires, and you’re dead. If the electron spins counterclockwise, the trigger doesn’t go off, the gun never fires, and you live. We’re playing Russian roulette with an electron.”

A new slide appears on the screen. “We know that the laws of quantum mechanics say that as a result of this experiment, you’ll be split into two versions: one who gets killed, and one who does not. In one universe, you leave your physics lab and go pick your kid up from summer camp and have a beer on the back porch and watch an episode of Fleabag on Amazon Prime. In the other universe, everyone’s coming to your funeral.”

He spreads his hands. “Here’s where it gets really interesting. The dead version of you has no experience of where you are and what’s happening. Because, face it, you’re dead. On the other hand, the live, conscious version of you bears witness to the fact that you’ve survived the experiment. So the only outcome you will ever perceive, if you run the quantum suicide experiment, is the one where you live. You can literally run it a thousand times, and every single time—a statistical near impossibility—you will survive…because that is the only version of you that can experience anything.”

He raises a brow. “Ironically, for those of you who are still doubting the concept of a multiverse, this experiment might actually prove to you that parallel universes exist. If there actually is only a single universe, you should expect to die half the time you run the experiment. But…if there truly are multiple universes, and you perform the quantum suicide experiment a few dozen times and always come out alive, you can’t help but admit that multiple worlds or timelines must exist.”

I sink back into the wooden chair, wondering if another version of myself is in a world where her husband catches her eye just then and smiles to see her there.

If it fixes everything between them.

When Meret was ten we took her to Disney World. I was most excited about Space Mountain—a roller coaster in the dark. But in the middle of our ride, our little car screeched to a stop. A voice came over a loudspeaker, asking us to remain seated, while a technical difficulty was addressed. And then the lights came on.

If it had been exciting in the dark, it was terrifying well lit. I could suddenly see how tight the curves were, how little space existed between the tops of our heads and the tracks. It was absolutely shocking, in its transformation. What I thought I’d been looking at was something else entirely.

Now, staring at Brian, I have the same sensation. As if the home we have created, the marriage we’ve settled into, the life we have, has had the lights turned on, and now I can see the grinding gears and steep drops and near misses that constitute it.

“You can take it one step further,” Brian says. “If we assume that cancer, and heart attacks, and Alzheimer’s, and anything else that might kill you is the compilation of a ton of cellular—and therefore subatomic—events, that spinning electron may or may not launch a gene that causes a reaction that will lead to your death. Die-hard quantum immortality buffs will say that we are all, in some universe, the oldest living person on the planet—having dodged all these genetic and literal bullets.

“So,” he continues, “should you go and commit quantum suicide? I wouldn’t advise it, for the same reason I personally have issues with Tegmark’s hypothesis. Every time you run the experiment and survive, there are people who will see you survive, and who will think you’re the luckiest bastard on the planet. But every time you run the experiment and die—there are people who will see that, too, who will grieve and bury you and come visit your grave. From their point of view, in the vast majority of universes, you’re guaranteed to die. Here’s the problem with quantum immortality: it’s subjective, not objective. Even if you can prove it exists, you’d only be able to prove it to yourself—not to anyone else. To them, you’d just be a really stupid dead person.”

He turns off the projector and faces the students again. “Questions?”

A young woman raises her hand. “How do I get to the universe where Hillary Clinton is president?”

Brian grins. “Unfortunately, you can’t. You’re stuck here now. The door is closed.”

You’re stuck here now.

If that’s the case, if Brian is right, then I have to make my peace with the spot that Brian and I have occupied for fifteen years. There has to be value in comfort. When you reach into your closet, do you grab the new, stiff, unwashed jeans, or the pair that feels like pajamas?

“There’s a philosophical component to that question,” Brian continues, and I startle, thinking he has heard my thoughts out loud. “We don’t get to choose the universe we’re in, so no matter what kind of positive thinking or voodoo you do, you don’t get to land in the timeline of your choice. The laws of physics say you just plod along and then there’s a branch point, and you get funneled into one universe or the other. In other words, it’s not free will. It’s chance, based on however that electron happens to be spinning.”

Suddenly Brian looks right at me. Until this moment, I thought that he hadn’t seen me slip into the rear of the lecture hall. As it turns out, he’s known I was here all along. He gives me a half smile, rueful and self-deprecating, as if I have caught him in the act of something embarrassing, rather than his livelihood. “Keep in mind: physics says that if something terrible happened to you, there would still be another version of you somewhere else. A version that realizes how lucky you are to have a second chance. So, we could become devotees of quantum immortality,” he says. “Or we can live every day like it’s our last.”

Brian dismisses the class to a smattering of applause, but I hardly hear it. I swim upstream against the students who are dispersing. He is gathering his notes, and all the while, he keeps glancing up at me. He steps away from the lectern, to meet me halfway.

This is how it happens, I tell myself. This is how we start over.

I can take this first step.

Finally, I am standing in front of Brian. Silence bunches between us.

“Hi,” he says finally, softly.

I open my mouth, but before I can answer I see a movement from the corner of my eye. A young woman with a dark braid, thick as a fist, hovers at the edge of our conversation. She is holding Brian’s battered leather briefcase like it’s the Holy Grail. “If you’re late to the department meeting again, I’m not going to take the fall for you,” she says to him. It is as if I’m invisible.

All I can smell is roses.

* * *

—

BRIAN’S GRANDMOTHER LEARNED English by watching Gone with the Wind over and over at a movie theater. I tried to imagine what it felt like to wind up in a country where you could not speak the language. After being in Egypt for the season, immersed in my doctoral research, coming back to Boston to watch my mother die wasn’t all that different.

On our first date, Brian told me that his grandmother had survived the Nazi occupation of Poland, a work camp called Pionki, a sorting line at Auschwitz, and typhus in Bergen-Belsen. I watched him tear a sourdough roll into quarters and sipped from my second glass of wine as he told me stories about her. “At Pionki, there weren’t supposed to be children. It was a labor camp, and children weren’t strong enough to do the work. But there was one couple from her village who had a little five-year-old, Tobie. They couldn’t stand the thought of being separated from her, so they smuggled her in. My grandmother knew that if Tobie was found, she and her parents would be punished, and probably killed. And she wouldn’t let that happen.”

“Jesus,” I breathed. I tried to reconcile the tiny, birdlike skeleton in the hospice bed with this flesh-and-blood younger version being painted for me by Brian.

“My grandmother spoke fluent German, and because of that, she got to do office work instead of physical labor. This meant she could see the Nazi supervisors coming and going. So she made Tobie play a game—if my grandmother hung a white scarf outside the office, Tobie had to promise to hide herself so well her own parents couldn’t even find her. She couldn’t come out until the white scarf—and the Nazis—was gone.”

I leaned forward. “What happened?”

Brian shrugged. The flame of a candle danced between us. “She got moved to Auschwitz and lost track of Tobie and her parents.”

“That’s a terrible ending,” I told him.

“Who said I was finished?” Brian said. “Fast forward to 1974. The war’s long over, and my grandmother’s visiting my mother in New York City, who’s pregnant with me—”

“Aww.” I settled my chin on my fist and looked at him. I was a little drunk, which was the loveliest alternative to how I’d felt for the past two weeks at my mother’s deathbed.