After so much pleading, after hands pressed together in mock prayer, after pleasemompleasemomplease, after promises of rooms cleaned and weeds pulled, the Scientist finally relents. She will allow her son, who is eight years old, to walk home alone from school the following afternoon, even though she is unsure, even though she has been brought to tears by news segments, read horror stories on message boards, and really, if she’s honest, she’s not sure why it matters so much to him, because she was eight years old such a long time ago and has lost track of the feelings that bubbled inside a younger version of herself. The Scientist will not be Lame Mom Destroyer of Fun. She will be Inwardly Trepidatious But Careful Not To Pass On Her Own Manias Mom, which is a challenge, demands more of her mental energy than she can really spare given the work she is doing. She cannot escape the What Mom am I? trap. She knows that she will fight against herself forever, and so, yes, for once she relents. She says fine, whatever, who cares, walk home by yourself. Wait, she says, check with your dad. But her son already has, and the Scientist is not surprised to learn that her husband has no opinions vis-à-vis their son walking home from school.

There are decisions, the Scientist understands later, so close in proximity—temporally, spatially, cosmically—to their consequences (here, picture a black hole slurping up light) that the gap between them feels bridgeable, one rung back down the ladder, so much so that the decision-maker might feel as if he or she (she) could move outside of time and remake the choice. But this is just a feeling and has no bearing on the truth of the matter.

The truth is this: the next day the Scientist’s son did not return home from school. He simply never arrived. The details here are irrelevant. We too have seen the headlines, the parted hair, buck-toothed, polo-shirted school photo hanging over the shoulder of a not-sad-enough news anchor who has only forty seconds left for this segment before he or she has to talk about the baby elephant born in the Cincinnati Zoo the night before. We too have watched the news and said, oh my god; those poor people; Christ almighty; I can’t watch this; what time is Jeopardy on; is it before or after Wheel of Fortune; what the hell is keenwah anyway. And then we moved on with our lives and forgot about the sad pictures on the TV screen because, and listen closely because this makes all the difference, it was not our child. Our child was in the basement playing videogames, or at volleyball practice, or asleep in the crib monitored by a Wi-Fi enabled nanny cam to ensure that our names, our child’s face, never appears on the five o’clock news.

Or maybe our child was never been born, or was born early with a peanut-sized heart that refused to pump blood, or our child grew into a smart, capable young adult and then made a decision that wasn’t really a decision, and then a series of decisions that weren’t really decisions, weren’t anything more than the neurons you had gifted them sparkling like fireworks, and ended up overdosing in the bathroom of a KFC. And maybe because of the pain we had felt, continued to feel, we thought we knew or could at least guess at and pantomime how the Scientist felt when her son disappeared.

But no one had ever felt what the Scientist felt. No one would ever feel it again.

Of the details that are relevant, there is this: there was no body.

There was searching, the calling of his name, flashlights dug out of drawers filled with tape and rubber bands, flyers printed and stapled to telephone poles beside advertisements for concerts by bands with names like The Deadbeat Dads and Flesh River, beside other flyers for missing cats and guitar lessons at twenty-five dollars an hour. To save time, please fill in the gaps here with scenes from films and television you have seen: police dogs and yellow tape, frantic phone calls, hands slammed against steering wheels, shower crying, the interrogation by police of a bald man in oversized glasses who lives in a halfway house a few miles from the victim’s school, who also happens to be a sex offender.

Picture this also. Do some of the heavy lifting. Save me the trouble. Imagine a child’s funeral without a child, the burying of an empty grave.

And now this story diverges from those stories.

The Scientist’s grief is a channel; it’s an inter-dimensional gateway into alternate realities. She builds new worlds every hour. Most often, the worlds she builds, the universe she returns to again and again is identical to our own in every way except one, and it is different only in that she said no when her son asked if he could walk home alone from school, and now he’s nine years old and is very in to Boba Fett and Wolverine and YouTube cartoons about how aliens might one day contact Earth. In the universe she has made in her mind, the Scientist’s husband does not go into the basement to scream, he does not come out of the shower with cherry-colored scratches down his arms and chest. In this universe, the Scientist and her son go on long walks through the park in the evening and he asks her questions that have arisen in his mind throughout the day. Some are pointless trivia (when was the first Super Bowl); some are matters of opinion (who would win in a fight between Thanos and Galactus), and some are scientific inquiries (If the earth is spinning, how come we can’t feel it move). She answers when she can, lies only occasionally, and shrugs when he broadens the scope outside of her purview. In this universe, they walk hand-in-hand as the sun sets casting long shadows across the grass and water, and as the light fades, as the lamps begin to flicker awake, she explains to him how the world works.

She creates more universes than this in her mind, but as you can likely imagine, they all share certain commonalities: a decision made differently, a son returned.

It is this mechanism, this unhealthy pursual of unreachable outcomes that, like a match held to crumpled newspaper, sets off a burning inside of her. She was at certain points in her academic career skeptical of those branches of quantum theory that had been co-opted by the science fiction dreams and acid trip hypotheses posited and built upon by well-known and influential physicists. Why focus on Every Possible Reality when, in this reality, we did not understand how our minds worked, when our bodies could turn on us at any moment and begin pumping poison into our blood. But grief is nothing if not a catalyst for change, so the Scientist revises her opinions concerning the nature of reality and sets about building a machine.

She lives in her lab, dreams about her work, sees her son in the faces of boys who are eleven now. She circumvents playgrounds, closes her eyes when passed by a school bus on the street. The Scientist avoids her husband, who has given himself over to God’s will, and found in a community of big-smiling, too-sympathetic, ancient-text-studying strangers, something akin to, but not exactly, hope. She is grateful for these people, in that she does not have time to deal with him, has no comfort she can share, but maybe one day, she thinks, when the machine is finished, she can take away his pain, if only temporarily.

The Scientist too has been building up a faith, but it is of a different type, it is a faith in the world seen from odd angles, in choices rechosen, her life split infinitely, each moment a new her emerging from some quantum cocoon, and for every version of her that exists, hidden somewhere in the folds between space and time, there is an opportunity to have done differently, to have saved her son. If the theorizing was true, if every possible outcome had been, would be realized, only somewhere else, on some separate plane of existence, then it would be logical to assume that at least one of those infinite outcomes included her son returning home that day. And if a world existed where that outcome had been realized, she would find it.

In secret, she builds the machine. In secret, she finds a way to cross boundaries that had been heretofore uncrossable, to move from one rung of the ladder to another. The theories were mostly right. Imagine an infinitely large tree, every branch a decision; what you ate for breakfast, what shirt you chose to wear, your job, who you married, if you decided to have children and so on and so forth. On these branches are more branches, more decisions, each one its own world, its own singular universe, and in each universe is another version of you, this one a tattoo artist with an affinity for robot pin-ups, and here, this one a bank teller forever unable to express to your family who it is you have fallen in love with, and then there is this one, who has helped develop a cutting-edge navigation technology used in rockets made by the government to annihilate huts and caves in sand-covered countries. But this is not a story about you. It’s about her, the Scientist, in all her variations.

She uses the machine to cross into these other branches of reality, and in each one, she locates herself. Of course, there are realities in which she has died, so she corrects for that, adjusts a few dials on the machine so that it skips those worlds, it skips also worlds where she never married, never gave birth. She finds the other versions of herself mostly in her home, or a version of it, in the same city where her son disappeared. They believe, like she does, that he will return one day, a teenager now, with a passion for rap music and black-and-white samurai movies, wearing thrift store t-shirts and women’s jeans. But when she finds herself, as she always does, she finds a woman working in secret to build a machine to find another version of herself who made a different decision than she made and a son who is not bones and dust buried in a shallow grave in some forest two states over.

But these are only some of the Scientists that exist on the infinite tree of cosmic possibilities, so she continues to search, finding versions of herself in Florida, on to marriage number two, skin the color of a football, and still sonless. She finds versions of herself in Alaska and Japan, in Sacramento and Atlanta, versions who have started charities, scholarship funds, and organizations dedicated to aiding bereaved mothers. Not all of the Scientists are scientists, not all have built machines. But our Scientist is one of those who has, so she keeps searching, getting farther and farther out on the thinning branches of existence, imagining her son as an adult, as a college student studying physics or philosophy, dating a capable young woman, someone a lot like the Scientist used to be, falling in love, getting married. She sees in her mind the possibilities of his life, all the ways he could have been, and it is this hope that spurs her on, the hope that in one of these worlds she made the right choice and he is alive. Twenty-seven years old now and a father himself. She will find him, or she will search until she is dead.

This is, in fact, the case. It’s the machine that kills her, sending poison rays into her bones each time she crossed over. She understood the risk, felt the potential reward was worth a slow and painful death in a hospital bed, no longer capable of searching for her son, watched over by her grey-haired husband who prays silently for her death to be peaceful. The Scientist tells no one about the machine, the other worlds she visited, not even her husband. She casts her mind back and feels nothing but pity for the other hers, for herself. She visited a thousand worlds, saw a distinct version of herself as many times, and in every one she made the wrong decision. In all his permutations, her son never returned to her.

Our Scientist dies in her sleep. Many others live on.