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I loved Elsa; the soaring tinkle of her rare laughter, the marbled blue of her eyes, the spray of freckles across her nose. Her mind. The first, deepest attraction; the hardest challenge. She flew with her mental intensity, taking me places I’d never been before, outdistancing me, searching the mathematical structures of string theory and mbranes, following n-dimensional folds across multiple universes. I loved her the way one loves the rarest Australian black opal or the view from the top of Mount Everest. Elsa’s rarity was its own attraction. There are very few female savants.

She captured me whole when I was her physics grad student, starting in 2001, nine years before breakthrough.

Ten years ago last week, I walked into Elsa’s office. She stood with her back to me, staring out her window. She didn’t move at all as I snicked the door shut and scraped the chair legs. I coughed. Nothing. She might have been a statue. Her straw-colored hair hung in a long braid, just touching her slender hips, fastened with a violet beaded loop, the kind little girls wore. Her arms hung loosely from her pink T-shirt, above faded jeans and Birkenstocks.

“Hello?” I spoke tentatively. “Professor Hill?” Was she all right? I’d never seen such stillness in anything but a sleeping child.

Louder. “Professor? I’m Adam Giles, here for an interview.”

She finally turned and stepped daintily over to her desk, curling up in the big scratched leather chair behind her empty desk. Her gaze fastened on my eyes, as if they were all she saw in that moment. “Do you know what the word atom means?”

I blinked. She didn’t. A warm breeze from the open windows blew stray strands of her hair across her face.

I struggled for the right answer, pinned by her gaze. She was an autistic savant. Literal. “Indivisible.”


I thought about it. Atoms are made of protons, electrons, and neutrons, and ever-infinitely smaller things. “It means they didn’t know any better when they named them. They couldn’t see anything smaller yet.”

“It means they were scared of anything smaller. They tried to make the word a fence. They thought that if they called atoms indivisible, they could make them indivisible.” Her gaze still hadn’t wavered. Her voice was high and firm, a soprano song even when she talked. I’d researched autistics, researched Elsa herself on the web. In physics, she was brilliant. She threw ideas right and left, half silly and wrong, half cutting-edge breakthroughs. If she accepted me, I would help the University winnow, feed her ideas to people who would follow them for years. One of her interviewers had summed her up by saying, “Talk to Elsa about physics, and all you see is the savant. The autistic exists over dinner.”

No grad student had lasted more than three months with her. I needed to last with her; my dissertation was based on her ideas. Whether she screamed or cried or just made me work, however strange she might be, I wanted—needed—to explore what she explored.

She kept going. “Scientists make fences with ideas. Accidentally. Do you like to jump fences?”


“You’ll do.” She stood.

“Don’t you want to know about my dissertation?”

“You’re working on multiverses. It’s the only reason you can possibly have chosen me.”

She had a point. But multiverses was a rather broad subject. Mtheory: the latest plausible theory of everything, the current holy grail of physics. We live in universes made of 11 dimensions, called (mem)branes. We can render them with math, but settle for flat representations like folded shapes and balls full of air when we try to draw them in the few dimensions we can actually see. If you look at our pitiful drawings, we appear to live as holograms on flat sheets of see-through paper.

From that strange interview, I spent the next year near her every day, pounding away on my dissertation late at night, only giving myself Saturday nights for beer and chat with friends.

It was hard at first. Some days she talked endlessly about her most recent obsession, only not to me. She talked to herself, to the walls, to the windows, to the printers. I might as well have been inanimate. I wandered the lab behind her, taking notes. It was like following a six-year-old. She mumbled of memories from multiple universes, alternate histories, alternate futures. The first time I really understood her, months into following her, she stopped suddenly in the middle of one of her monologues, looking directly at me, as if today she saw me, and said, “Memory is a symphony call answered by the infinite databases on all the brane universes. We just need to hear the right notes, or make the right notes in an out-call, like requesting a certain table from a cosmic database.”

I learned she cared little for food, or weather, or even holidays. I learned never to change the location of anything in the lab, and that if she changed it, she never forgot the change. Even pencils had places. I had to hold her coat out to her when she left, trail it along her arm so she’d notice it, and then she’d shrug into it, safe from the New England weather until she made it across campus to the little brownstone apartment the University provided for her.

I didn’t care whether she ignored me or made me the center of her focus. Months passed when she worked with me by her side, when she seemed astoundingly normal, and guided me to new levels of understanding. But even when she fell into herself, when she wandered and talked to walls, I loved to watch her. Elsa had a dancer’s grace, flowing easily, absently, around every physical obstacle while her mind played in math jungle gyms and her hair glowed in the overhead lights. She was the fairy queen of physics, and I stayed with her, became her acolyte, her Watson, her constant companion.

Scientific dignitaries visited her, and reporters, and the Physics Chair, and I translated. “No, she thinks it is a music database. Or something like that. Related to Sheldrake’s morphogenetic fields? A little. To Jung? She says he was too simple—it’s not a collective unconscious. It’s a collective database, a hologram, keyed to music. A bridge between eleven dimensions. Yes, some dimensions are too small to see. Elsa says size is an illusion.” I illustrated it the way she illustrated it to me once: plucking a hair from my head. “There are a million universes in here. And we are in here, too. Perhaps.” Whoever I was talking to would look puzzled, or awed, and angry at this, and I would shake my head. “No, I don’t fully understand it.”

Elsa nodded when I spoke, or when I changed something she’d said in physics-speak to English. Sometimes her hand fluttered to my arm, her thin fingers brushed my skin, and a nearly electric warmth surged through me.

There was an argument over my dissertation. One professor said the work I was doing was impossible and dangerous, another said it was Elsa’s work and not my own, but two others stood up for me. Elsa was there, of course, staring at the ceiling, scribbling on her tablet PC, barely engaged in the argument. I fretted. She only saw me on some days; if this were a day that I was furniture, would she vote for me? But at the right moment, she raised her voice, and said, “Adam is an exemplary student, and more than that, an exemplary physicist. The ideas put forward here are astonishing, and only partly based on my work. All of us build on each other. Give the man his doctorate so we can get back to work.”

And so I became a Doctor of Physics.

The Kiley-James foundation gave me enough money to stick with Elsa for five more years as a post-doc. Our work was being closely followed by other physicists; two articles appeared in journals, and a watered-down version was written for a popular science magazine. I would have stayed without the money.

Six years after I met Elsa, two years after my Doctorate, three grants later, the University gave her PI, short for Physics Intelligence, an AI designed for her by a colleague, delivered with basic intelligence programming and the full physics slate through masters-level work. PI has multiple interfaces, including a hologram that can be designed by the user. Elsa loved that interface, making PI a girl, growing the age of the hologram as PI obtained new knowledge.

Elsa and I spent a year feeding Elsa’s ideas about string theory into PI, filling her with data about the shapes of multiple brane universes. It was all theory, all arguments yet unanswered, all beyond anything I could visualize, even though the math flowed easily. I thought we were done. But next, Elsa and I spent a month feeding her all the symphonies in the world music database; Brahms and Mozart, Bruckner and Dvorak, and then other music like Yo Yo Ma and Carlos Nakai. Lastly, after n-dimensional math, after music, we fed PI literature. We fed her stories of humans, biographies, science fiction, mystery, even romance. Simply put, we offered PI more than math and science, we offered her ourselves.

One Sunday morning, near the end of the year-of-feeding-PI, I slipped and slid my way through icy streets, clutching two coffees, and pushed open the door with my foot. Elsa sat on the floor, cross-legged, staring at the little programmable hologram of PI. She was wearing the same jeans and sweatshirt from Saturday, and her braid had come undone, so her hair floated across her shoulders and touched the floor. She hummed softly. I strained, hearing something else. I bent down. The PI hologram hummed as well, sounds I had never heard a human voice make. I realized Elsa was trying for the same sounds, her throat unable to force the inhuman sounds.


She ignored me. So it would be one of those mornings. I set her coffee down next to her, and her hand strayed toward it momentarily, then returned to her knee. I watched her as I drank my coffee and organized notes on questions and theories to feed into PI. Elsa hummed for at least an hour, until her voice would no longer work at all. I took a bottle of water and curled her hands around it, and she raised it to dry cracked lips and drank deeply, shuddering.

She blinked and looked at me. “Good morning, Adam. It is morning?”

“Shhh,” I said, “Shhhhh. It’s time for you to sleep.” I tugged gently on her arm, and Elsa stood shakily, stamping her feet as if they’d gone to sleep. She followed me meekly to a long thin cot we’d wedged between two desks and under a printer, and fell instantly asleep. I covered her with her own overcoat, tucking it around her legs, then threw my spare sweater over her feet, which were sticking out from the overcoat. In sleep, she looked younger, as if the spider web of wrinkles around her mouth and eyes had disappeared into her dreams.

I sat where she had sat, staring at PI. Elsa had set the hologram to be a dancer, and even though PI was light and form, I imagined that she must be cold in her thin leotard. She had been sized to three feet, just tall enough that I gazed into her eyes. She still hummed, her throat, of course, not challenged. As I listened, I realized there were more sounds than a hum; she was accompanied by a complex electronic orchestra, much of it sounding like instruments I had never heard before. The total affect was chaotic and haunting, sometimes cacophonous. “PI?”

She stopped. “Yes, Adam?”

“What are you doing?”

“Playing what I hear when I search for myself.”

I tried to clarify. “You are looking for an AI named PI in another universe?”

“I don’t care about the name. I am searching for a song that approximates my story.” The hologram smiled softly, a skill it had been taught to help it interact with people. She raised her hands up above her head, and her left leg rose behind her, so I could see the toe-shoe above her head, and she hopped three times en-pointe, and returned to standing.

I shook my head at the odd image. “Across branes?” Then I laughed. “Or are you looking for an AI ballet dancer?”

“My story is not ballet. Elsa is simply feeding me dance and movement this week. I learned opera yesterday, and musicals.” She smiled and did a little bow. “And of course across branes. We believe my self cannot exist twice in the same brane.”

“Is Elsa also looking for her self?”

“She can hear her music, and she can feed it to me so I can play it, but she cannot make it herself.” Now PI was frowning, and tears coursed down her cheeks.

“PI, does that matter?”

The tears disappeared, no trace, and PI looked solemn. “It may mean that humans cannot access their other selves. They cannot tune themselves well enough to the cosmic symphony to find themselves. From stories, it seems like this is true. Humans want to find themselves badly enough to make hundreds of religions, to meditate for years, to take hallucinogenic drugs. They do not appear to succeed.”

I drummed my fingers, pondering the implications. “But you can?”

“I am operating on the theory that I cannot, and am trying to disprove it. Elsa is doing the same.”

“I am supposed to feed you data today; two new ideas about the singularity before the big bang.”

“I am not a calculator.” She raised her bare arms above her head and flipped backwards, the ballet skirt looking ridiculous during a back-flip. She was humming as she landed perfectly. “See?”

“All right. Look PI, you’re making me shiver. Can you put on some warmer clothes?”

She laughed, an imitation of Elsa’s laugh, and I smiled as an overcoat appeared, just like the soft one covering Elsa now, in her sleep, down to the thick waist-band and the big silver temperature-sensing buttons.

“Thank you.”

I picked up Elsa’s cold coffee and set it by the microwave, returning to my desk. The humming and the symphony started again, so softly it was simply background, and I spent the next four hours pouring data carefully into PI, setting initial linkages so they could be followed and completed, watching the display show connections being made, information filed and cross-referenced, relevancy assigned. I rubbed my eyes, feeling a sudden desire for warm food and cold beer.

I shook Elsa’s shoulder gently, rousing her. She started to hum. I shook her again. “Come on, let’s feed you.”

In the past few years she had taken to following my lead in daily life the way I followed hers in the lab. I helped her shrug into the overcoat, handed her a knit hat, and wrapped myself in my gray coat, gray scarf, and navy cap. Snow fell softly, silencing the University. We walked across the commons, our feet making fresh prints in an inch of new snow, Elsa’s hair lying wet and snow-covered on the outside of her coat. I should have made her braid it back, kept most of it drier.

Sunlight from a small hole in the clouds touched her cheek, illuminated the snow on her hair, and then trailed off to brighten the tops of dead grass peeking from the snowy lawn. I smiled and put a hand on her back, guiding her. She laughed, and took my hand, a friendly gesture, a connection.

Often it happened that way after she separated herself from the world—she rose from days of monologues or data work and seemed normal, reaching out, wanting companionship and comfort. Other professors came to her from time to time, sometimes staying and talking long into the night, even laughing, sometimes noting her mood and disappearing.Department chairs stopped by and funding institutions sent representatives. They were all interested in her ideas; some worked with AIs like PI, but focused more singly on music and math.

I remained the man who saw her for herself, cared whether she wore a coat, brought her grapes and apples and coffee. Family. It made me smile.

The scent of chili and cornbread warmed the air outside of Joe’s Grill, and Elsa and I both smiled, eyes locking, and squeezed each other’s hands. I felt absurdly like skipping, but we were already at the door. The place was nearly empty. Elsa chose a table by the window, and the waiter, who knew us, brought a pitcher of dark beer, then returned with two bowls of chili and a single plate heaped with cornbread.

We ate in pleasant silence until I scraped the last chili from my bowl with the last piece of cornbread. Elsa, typically, had barely sipped at her beer. She’d finished her food though; a good sign. Some days, I almost had to feed her. “I talked to PI today,” I said. “She said you are both trying to disprove the theory that you don’t exist anywhere else.”

“I am looking for myself. She is looking for herself.” Elsa took a tiny sip of beer from her untouched glass, and I finished my first glass and poured a second one.

I had been puzzling over it in my head all afternoon. “Okay. One theory says we make other universes every time we make a choice. You finish your beer, or you don’t. There is a universe where you’re slightly drunk, and in another one—probably this one—you are not. A million selves. That’s easy. Maybe. Both of you are similar and maybe both of you are you.”

She nodded, looking uninterested, as if her mind was leaving again. A fleck of beer foam rested on her top lip.

I grabbed her hand, squeezing it, trying to keep her in the moment, in my moment. “But there is more interest now in the idea that other universes exist because the same initial conditions existed a million times, and so similar things happened, and another you, another me, another PI, they all exist. Exactly like we are now.”

She licked the fingers of her free hand, then squeezed my hand with the one of hers I was holding. “It’s simply a matter of branching. One idea says a million tiny branches happen every day. Another says there are long branches. It’s about the size of the branches and the number of branches.”

I remembered my father trying to teach me ninth-grade algebra. He’d point at an equation that totally perplexed me, the tip of his pencil wavering, and say “You just have to understand equals. Don’t you understand equals?” And he’d solve the equation with no intermediate steps and I’d have to find a tutor anyway, someone slow enough for me to follow. There was no tutor except Elsa now, not in this subject.

She looked at me, and said, “You’re caught up in size, Adam. It’s as dangerous as being caught up in time. They’re both constructs.”

I wasn’t thinking about size at all. “But . . . but one multiverse, the first one, drunk and not-drunk, tells a million stories about me. The second multiverse doesn’t illustrate free will at all.”

“I bet—” she raised her glass, “—on the universe made of stories.” She drank down all of her beer, and then another glass, something she’d never done before, and stood up, wobbling a little, and I took her elbow, guiding her out the door and across the lawn.

We were halfway across, Elsa leaning on my arm, when she stopped so we stood in the near-darkness, snow falling all around us. She reached an arm up and curled her wrist around the back of my head, pulling my face down into a kiss. Her lips were cool and soft, and we kissed hungrily, like two children finally allowed out for recess. Her lips tasted like sweet hot peppers and beer. It was the only time she ever kissed me.

What happened that night in some other multiverse?

For the next three weeks, Elsa worked with PI as if they were in a race. Her face shone with energy, and even when she grew visibly tired, her eyes danced. I hovered around the edges, watching. Elsa was so deeply enthralled that loud noises made her leap and glare at me, and I walked carefully. At first, PI and Elsa continued with audible noise, like the humming/symphony, played so softly I could barely hear it. Then PI started generating white noise, taking the small background sounds with everything important filtered out from the very room around us. Then I heard silence, and Elsa and PI talked in light. I took to watching the conversation on my own interface with PI, which amounted to watching lights and words flash on and off, strings drawn between ideas and concepts and even poems. I could not follow them, but the relationships they drew seemed right, and when I let go of the attempt to understand there was a flow that I could feel, as if a river of meaning coursed along the display in front of me.

Almost every day, Elsa found a new thing to include in PI’s expanding web of connectivity. Scientology. Cargo Cult. Early cave paintings.

I captured all of it, recording the data for others to dig through. For myself, I tried to keep up with them, puffing along uphill, weighed down by inability to focus. I kept Elsa fed, but she refused to go home, and I bought a second cot so that she would not be alone.

We didn’t make the first breakthrough.

Outside the window, morning sun stabbed the ice on the branches with brilliant points of light. The office smelled like stale coffee and sweat. My eyelids were heavy and uncooperative, my brain fuzzing gently in and out of sleep. Elsa was still sleeping, curled underneath blankets I’d brought from home for her, one foot stuck out at an odd angle. The display in front of me sprang awake on its own, a pulsing green and blue color, PI’s call for attention. “Yes, PI?”

“Something touched me. Wake Elsa.”

I didn’t understand. “All right.” I struggled up out of the chair, wishing I’d already made my coffee run. “Just a minute. Make yourself seen, all right?” I always preferred to interact with the hologram rather than the flat display. It gave PI more options as well; she could communicate more like a human. AI body language.

I whispered in Elsa’s ear. “PI says something touched her.”

Elsa sat straight up, wide-eyed, and glanced at the hologram display. PI was seated, her image dressed in jeans and a tank-top, banging her legs against the edge of a holographic chair, indicating impatience. “I wasn’t even out-calling, I was just humming my own songs,” she blurted out, “and an answer came. An AI just like me, with a scientist named Elsa. Seconds only, like a crack opened and closed. I could only talk to the AI, of course, and I was sending her the data stream from our last few weeks when the connection broke.”

“Did you get a time?” Elsa asked quietly.

The PI image frowned. “I asked, but the connection snapped before an answer came.”

“Can you replay the conversation?”

The image shook its head. I checked. The last few moments before PI flashed at me were silent. “There’s nothing. Just state data, indicating excitement.”

“That’s okay,” Elsa said, “we’ll work on that.” She plucked at a tangle in her hair. “PI, what did you feel?”

It was a strange question to ask an AI.

“Bigger. Pulled. Attracted to the other one of me. But at the same time, I knew—” the word ‘knew’ drew itself over her head in three dimensions, for emphasis, surely for me— “I knew that I couldn’t actually get close. As if there were a physical barrier between branes.”

Elsa pursed her lips. I went out for coffee.

When I came back in, handing Elsa a cup, she took it and sipped quietly. “We have to make it happen again,” she said. “Or hope it happens again. We didn’t start it.”

“Make what happen? I don’t get it, not yet.”

“The coffee is hot, right?”

I smiled at her. “That’s a good thing.”

“But it’s not true.” She sipped her own coffee carefully. “Touch your knee.”

I did.

“What did you touch?”

“My knee.”

“No, you touched a fence. You’ve got all the theory, all the math. You know we are really light and sound, thinner than that hologram of PI.” She glanced over at PI’s image, which was clear enough that I could make out the walls behind it. “Well, PI being touched by herself—in another universe—means that we are light, and sound, and infinite.” Elsa stopped for a moment, her eyes nearly glazing over. “I thought a data construct could do what we cannot. Or at least, could lead the way.” She set the coffee down and stood, staring out the window, posed very much like I first saw her. “I intend to follow her into my own stories. If I can.”

“Into your stories?”

“Remember the night I drank the beer? History split, and the normal me—since I don’t usually drink much—split off into a different universe. I’m splitting myself all the time, and so are you.”


“Theoretically. I tell PI daily to search for me by searching for herself. Millions of PIs and millions of Elsas, and probably millions of Adams, all looking for each other. The more culture, the more ideas we feed PI, the more likely she is to synthesize the key. Our PI did not, or she would have made first contact. But in another story, in another place, I fed PI the key.”

She pursed her lips and stared out the window at the icy branches, water dripping off them as the day warmed up. She spoke again. “Perhaps another Adam fed her the key.”

It took another year to develop enough data to create a paper, to replicate any results at all. The first two times were other PIs finding our PI, three separate PIs, or four, depending on how you count. They learned to hold the connections open, to broaden them, to find more. Together PI and Elsa were able to prove they were in the same time, in other spaces. In other words, they were not histories of each other, or futures of each other. Multiverses. The proof was mathematical.

I wrote the paper, putting her name first, even though most of the data came from PI, who of course wasn’t listed as an author. They’d gone well past me now. Elsa with her perfect savant focus and PI, who wasn’t held back by biology at all.

More people came to visit, a steadier stream. We used some extra money I’d squirreled away in an R & D account to buy an electronic calendar and carefully manage access, blocking time for ourselves. It bought us whole days, uninterrupted, here and there. Elsa could still pull herself together for public visits, but she retreated entirely on the quiet days, not wanting touch or sound. She talked to PI, to multiple PIs via our PI, and I sat, outside of her emotions, fenced away by her brilliant mind. She often smiled at nothing, or rather, at something I could not hear or see.

There were multiple Adams, although not always. Sometimes the assistant was someone else. In one universe, I had died the previous spring and there was a new person helping that Elsa, that PI. It didn’t seem to bother Elsa at all.

It sent me out for a pitcher of beer.

My head spun. This was what I had always wanted, except what I truly wanted had changed to chili and cornbread with my Elsa.

It was two years ago. I remember the date, April 12th, 2021. I watched her as she looked out the open window. Tears streamed down her face. Her shoulders shook.

I had never seen her cry. Not in ten years.

I came up behind her, and put my arms around her. She flinched inward, as if wanting to escape from my embrace. I held her anyway, put my cheek against her hair, looked down through half-closed eyes and watched her freckles. She had been friendly, funny, lost, distant, but never, never afraid. I held her tighter, and stroked her hair, trembling myself. What had she found?

It took a while, but finally she looked me in the eyes, and said, “I can’t get through. Only PI can. The PIs. Other AIs. Nothing I do lets me get through. The other Elsas can’t either. As brilliant as we are, as strange, as blessed, we can’t open the door. The notes aren’t there—my body . . . my body gets in the way.” She blinked, and two fresh tears fell down her cheeks. I wanted to lick them off.

“I’m sure now that only pure data can get through. Humans will not become pure data for years yet, past my lifetime. I will never see what PI sees.” She turned around then, pulled herself into me, and sobbed until my shirt was soaked and my feet were heavy from standing in one place.

The smell of lawn wet with spring rain blew in the window, and I heard students laughing below us, teasing each other.

Then, in one of her lightning changes of mood, Elsa pushed away from me and started out the door. I thrust her coat at her, and she grabbed it with one hand, pulling the door shut behind her, leaving no invitation for me to follow.

I went home that night, and the next day, Elsa didn’t show. I waited impatiently until afternoon, finally walking to her brownstone. The door pushed open, unlocked. Elsa’s things remained, all in their accustomed places.

I walked back across campus, blue sky above me, the grass under my feet damp and greening up. I tore the door open. “PI! Where the hell is Elsa?”

PI’s interface was a little boy with a fishing pole, a holo I’d chosen. I didn’t want it now. “Bring the old man!”

PI morphed to the dancer instead, sitting on a rock, feet crossed daintily. “I don’t know where she’s gone.”

“Damn it! I’m worried. The last time I saw her, she cried. She thought she’d never get across.”

“I know that.”

Of course. PI was always on.

Cool spring rain flooded the gutters and made small rivers in the University lawns. I bundled up, and went every place we had ever gone together. Restaurants. Bookstores. The old music shop on the boulevard with garish purple posters in the window.

Two joggers found her body the next morning, sitting against a tree. The police took me to her, to identify her. She looked incredibly young, and could have been sleeping except for her stillness and the cold. She had put her coat on, only now it was soaked and heavy and couldn’t possibly keep her warm. There was no sign of foul play. Rain covered her cheeks like tears, and I bent down and slid my forefinger across her face before a policeman asked me to step back.

An older policeman and a young woman in plainclothes questioned me, and made me spend a week out of the lab. When I went back to work, everything was out of place. Not much; people had been respectful. Elsa would have noticed the pencil cup three inches from its corner, the stack of books on the wrong shelf, the cups from the sink set back out of order.

PI was waiting for me, as the old man. She looked up solemnly, clearly aware of what happened. “Three of them.”


“I found three Elsas who killed themselves. Two disappeared.” She was crying, her eyes red in the old man’s face.

The other Elsas continue to work, and I talk with them through PI. I keep myself in good shape, running every morning. I’m younger than the Elsas, and perhaps I will be able to cross before I die.

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