tended to linger on her consonants and she had a particular and lovely way of saying the letter s, with almost a sh sound. When she and Yoon talked, Yoon often looked at her and let out a slow yessss, eyes meeting hers, a word that felt full of thought and empathy.
In their first physics conversation, Paul talked to Fan about observation. They were driving, dating. Paul wheeled this way and that to avoid bicyclists, she pretended the white line was a food the car was eating.
“It’s weird,” Paul said, “but it seems like until quantum things are observed they’re in every possible state at once. Outside of any physical place or physical time.” He told her one of the proofs of this came from an experiment known as the double-slit. In it, quantum bits like photons get shot through parallel slits. The photons remain in superposition until they hit a detector. Then the wave-function collapses and they become particles only. They’re not in any definite state until they’re measured.
“It makes no sense,” Paul said, “but there it is. The results have been replicated thousands of times with all kinds of projectiles and quantum particles. Grad students can do the double slit. It’s that clear.”
“What’s happening, then, when we’re not measuring?”
“We’ll never know. Physicists say it’s like looking in the refrigerator to see if the light is on when the door’s closed.”
“But we kind of do know what the fridge light’s doing.”
“There’s that.”
Fan looked over at Paul, neutral as usual, jittering the wheel with one hand on top of it, one in his lap. “Why are you all there, then,” she asked, “stable like that in your body? Why am I? I want to be a wave. I want to hit at things in a big messy way and be everywhere.”
“Your body is complicated. And warm. Quantum effects are stronger at low temperatures.” Paul’s spare hand stroked his chin, as if confirming its warmth.
“You wouldn’t think so.”
“But within you your quanta must be all kinds of coherent.”
Fan loved the language of physics: how objects in a definite state were said to be decoherent, rather than the opposite. Coherent meant in superposition, everywhere and in multiple states at once. And to be a thing like herself was to be a classical object. Classical objects were complex and mostly decoherent structures. But inside them, as Paul said, the little bits could pop around all over the place.
Paul said, “There are physicists like Andrei Linde who think we humans were made to detect things and keep this happening. Decohering and cohering. We participate in making the universe.”
“Why would that have to happen though.” Fan tapped her foot on the dashboard for a minute. She was a squirrely passenger. “Why can’t what made us to watch do the watching? That sounds awfully theological.”
“Linde doesn’t believe in God. It’s like the universe’s need. Just part of the needs of existence, I guess. The rules.”
“The needs of existence.” Both Fan and Paul had been raised Catholic and rejected it. “Existence should have no needs.”
Paul added, “Maybe the answer is we’re always observed, so we’re always in a definite state.”
And Fan thought of Cate Crawley, a woman she watched on TV. It seemed quite true that if Fan or someone did not watch Cate, Cate wouldn’t exist.
“Observation,” said Paul. “It’s a thing, in physics.”
“Observation as reality, huh,” she responded, and answered him, as she often did, with Shakespeare. “There needs no ghost, my lord, come from the grave to tell us this.”
Fan thought of Instagram, Snapchat, many apps her students mentioned that she’d never heard of, like Tea and GibGab and Yakking: didn’t they believe to be seen is to be real? Though the average person wouldn’t know about the double slit, Fan thought, that did not mean their instincts had no merit. Popular culture offered its own intuitive cosmology.
Fan felt about Cate’s show, Crawleys Coming On, the way she felt about physics. There seemed to be something fundamental in the world that the Crawleys, especially Cate, had figured out. As Fan watched the show, she started imagining herself in the scenes, giving Cate advice, asking her questions. In her head she talked like Cate: Paul, you’re being ridick! she thought. Or to Cate: I need your thoughts on this, Cate, she would think, although she’d also interject her own ideas into the show. You can’t live your life for your mother, Cate.
They became one another’s voices of reason.
Paul and Fan invented drinks for one another. Their drinks became little guessing games, and in Korea, the drinks came to represent physicists. One invented; the other had to guess. One would mention drinks in the morning, and it generally suggested an evening in which they’d have sex. One night, Fan came home from the jjimjilbang and met Paul, as she’d promised, at six in the kitchen. He handed her a highball glass, empty.
“It’s the Heisenberg,” he told her.
“And I presume my drink is uncertainty-principled elsewhere.”
“Exactly.” And Paul produced a bottle of Brunello, a wine she loved.
When it was Fan’s turn to create a drink, she handed Paul a martini, running a spoon fast around the glass, so the gin and vermouth mixture in his hand still stirred around the olive. It quaked a little.
“The Einstein,” she told him.
Paul looked at the glass for a minute. “Ah. Mass and energy. I get it.”
Then Paul glanced admiration at her, which she took to mean she’d shown more imagination than he thought she had.
The week after this, after a late Korean class, Fan came home to find in the kitchen a line of plastic cups coiling around the table, each with a sip, maybe a teaspoon, of pastel liquid glazing the bottom.
“Drink,” said Paul, “and guess.”
She walked around the table, dripping the liquid on her tongue. It was vodka, a little sweetened, with a vaguely floral note. Ten cups’ worth barely left a flavor. All the cups had a slightly different color, shading from pale violet to a series of yellows. Paul began to drink too, starting at the other end, drinking towards her.
“This would be the Hugh Everett,” she said finally. Hugh Everett believed in infinite universes—the multiverse theory—and that we constantly pop out new versions of ourselves. Any multiverse theory holds that any possible reality must be, somewhere, true.
“It would be.”
“You know Bryce DeWitt once told Everett, ‘I like your math, but I have the gut feeling I’m not constantly splitting into parallel versions of myself.’ And Everett said, ‘Do you feel like you’re orbiting the Sun at thirty kilometers per second?’”
“Touché.”
There were days when Paul said, “I love you,” and Fan spun him by the shoulder and said, “But are you splitting into parallel versions of yourself?” trying to sound jokey, and he looked at her sadly. What
