“Like human consciousness?”

“That’s what John von Neumann suggested. But what makes humans so special that they can determine the outcome of a quantum system to collapse into a single defined state? What if it’s not a human…what if a ferret is watching? Or what about the cat in the box? You know it has a vested interest in the outcome. So does it have the power to collapse the state of the electron, or trigger, or gun?” Brian said. “The collapse theory was the one the cool kids believed until the 1950s, when Hugh Everett III came up with another reason why we don’t see zombie cats walking the earth. He said that just like the electron and the trigger and the gun and the cat are quantum objects, so is whoever or whatever is observing what’s in that box.” He drew a little stick figure wearing a skirt, waving. “At first, she is standing outside the box, and doesn’t know what she’s going to see when she looks inside. But the minute she lifts the lid…she is split into two distinct copies of herself. In one version she sees a cat with its brains exploded all over the box. In another, she hears a meow. If you asked her what she saw, one version is going to say the cat is dead, and the other will say the cat is alive. The observer only ever sees one outcome, but never both, even though the laws of quantum mechanics tell us that both versions of that poor damn cat exist. And the reason she sees only one outcome is because she’s trapped in one of the timelines and is unable to see the other one.” He grinned at me. “That’s Everett’s whole deal. The reason we don’t see zombie cats or electrons spinning both ways at the same time is because the minute we look at them, we become part of that mathematical equation and we ourselves get split into multiple timelines, where different versions of us see different, concrete outcomes.”

“Like a parallel universe,” I said.

“Exactly. I’ve been using the word timeline but you could easily say universe. And the reason this matters isn’t because there are cats in boxes, but because we’re all made up of molecules, like those electrons. If you zoom in and zoom in and zoom in, everything we do is explained by quantum mechanics.”

“What happens to those two different timelines?”

“They get farther and farther apart. For example, the observer who sees the dead cat might be so bummed out she drops out of grad school and becomes a meth addict and never invents the technology that would help us develop a cure for cancer. Meanwhile, the observer who sees the live cat thinks she is onto something and becomes the dean of physics at Oxford.” He ran a thumb over the stack of papers he had been working on. “That’s what I’m doing. Slowly destroying my career by insisting that the multiverse is constantly branching off, creating a new timeline whenever we make a decision or have an interaction.”

“Why would that ruin your career?”

“Let’s just say the physicists who believe it are outliers. But one day—”

“One day they’ll be calling you a genius.” I hesitated. “Or maybe that’s already happening in some other timeline.”

“Exactly. Everything that can happen does happen—in another life.”

I tilted my head, staring at him. “So in another universe, my mother isn’t dying.”

There was a pause. “No,” he said. “She’s not.”

“And in another universe, we never met.”

Brian shook his head, and a blush rushed over his skin like the tide. “But in this universe,” he said, “I’d really like to take you out to dinner.”

* * *

—

WHEN I COME out of the shower, Brian’s overnight bag is sitting on the bed. I hear the water start again in the bathroom and stare at it. With a groan I turn away and pull on underwear, a pair of shorts, a tank top.

I run a comb through my hair and twist it into a braid and there’s no reason anymore for me to be in the bedroom, except that I can’t leave.

The shower is still running.

I move toward the duffel and tug the zipper open. Brian’s Dopp kit and shoes are on top. I set them aside and pull out a cotton sweater and sniff it. There’s something floral there—is it roses, again? Or am I imagining it?

“Dawn?”

He stands behind me, a towel wrapped around his waist. My hands go numb, body freezes. Caught in the act. I am a thief, a spy. I am Daisy, wallowing in Gatsby’s clothing.

“I thought…we were okay,” Brian says.

“Because we had sex?” I reply. “I’m pretty sure you were the one who told me that doesn’t mean anything.”

“I didn’t have sex with her.” Brian sits on the bed and pulls the sweater out of my arms.

“No. You just thought about it.”

I am being spiteful and nasty and unforgiving. I am licking my wounds with poison. Brian has apologized; I should forgive him. Shouldn’t I?

But he was with her the day of Meret’s birthday. He missed dinner. He came home wrapped in the scent of roses—on his clothes, in his hair, strewn across our marriage.

“Do you like her?” I force myself to ask. The words feel like knives in my throat.

“Well…I mean,” Brian stumbles. “I hired her.”

“Wrong answer,” I snap, and I get off the bed. I am halfway out the door when he grabs my wrist and spins me around.

“I have never loved anyone but you.”

Once, there was an earthquake in Boston. I was driving Meret home from preschool and along the route, a few trees had fallen. It was a tiny earthquake compared to the ones on the San Andreas Fault, but for people who are not used to having the ground shudder beneath their feet, it was shocking.

I went about the day, making mac and cheese for Meret for lunch, taking her to the park to push her on the swings, turning her over to the babysitter so that I could check in on a hospice patient. The woman was wide-eyed, chattering about how the bed had shimmied across the floor with her in it; how her pill bottles had tumbled from the shelf like they had been pushed by the hand of a ghost. Did you feel it? she asked me, but I shook my head. Because I had been in the car, the tires rumbling just as the earth did, I didn’t even know something had happened until she told me. A catastrophe had subtly changed the world, and I hadn’t even noticed.

Brian will not let go of my hand. He traces my knuckles with his thumb. “Please, Dawn. I know I can’t undo it. But it will never happen again.”

I believe him. I just don’t trust him.

“I fucking hate roses,” I say, and I walk out of the bedroom.

* * *

—

HERE’S THE INSANE thing about resuming your old life when it’s nearly ended: it is business as usual. Your heart may be broken, your nerves may be shattered, but the trash needs to be taken out. Groceries must be bought. You have to fill your car with gas. People still depend on you.

On the way to the home of a new potential client, I call my brother. As a neurosurgery resident, he rarely picks up, so it’s startling when I get him instead of voicemail.

“Kieran?”

“Dawn?”

“I didn’t expect you to be there.”

I can hear the amusement in his voice. “Sorry to disappoint you. I just got out of surgery. What’s up? Wait, let me guess. You have a weird rash.”

Granted, I tend to call him when I have a medical question, like if the flu has hit Boston yet, or what to do for plantar fasciitis, or any of a dozen other things that he tells me he can’t answer because they’re not his specialty. “I’m not sick. I just really wanted to hear your voice. I…missed you.”

“Shit, forget the rash, you’re sicker than I thought. Maybe you should come straight to the ER.”

“Shut up,” I reply, but I’m smiling.

“So what’s really going on?” my brother asks.

I hesitate. “I was trying to remember if Mom and Dad ever fought.”

“Can’t help you. On account of I was only a zygote when Dad was still alive.”

“I know,” I say.

“Is this about you and Brian?” Kieran asks. “You never fight.”

“There’s a first time for everything, I guess.”

He waits, expecting me to expound, but I am reluctant to say more.

“Look, Dawn, you have nothing to worry about. You and Brian, you’re like the rule. The standard. You’re the marital equivalent of the sun coming up every morning and the sky being blue when you open your eyes. You’ll be together until the end of time. That’s what you want, right?”

“Yes,” I say. “Of course.”

* * *

—