# Alice and Mirror Alice

> Source: <https://forum.effectivealtruism.org/posts/HtcQcQcTGqhpCJoiY/alice-and-mirror-alice>
> Published: 2026-07-07 21:35:18+00:00

It’s a story about mirror biology, with a bit of a magical framing. Despite the magic, the science is as accurate as I can make it. Specifically - I talked to someone who’d worked on a mirror biology related project (anti- don't worry) before I started writing, and since then I have done many rounds of research with Claude, making use especially of the That said, do let me know if you spot something that isn’t quite right! I’d like this to be an accurate cautionary tale, as well as a good (I hope) piece of fiction. It's never too late to edit (though edits may take a while). |

Suppose there is a girl. Let’s call her Alice.

Alice is off school for the summer. She has already spent a week in France with her parents, where she tried and mostly failed to make friends. The tan, from those long bored days in the pool, will fade before the four weeks of summer are over.

Her parents both work, her father from an office and her mother from the room below hers. Alice is used to occupying herself for the long days while her mother clicks and curses away at her laptop downstairs. From her bedroom, Alice can hear this muffled sound along with the hum of her mother laughing with colleagues.

Today, it is noon, and she’s almost finished her book. She’s been reading a lot of books where children are as competent, if not more so, than adults. Books where children uncover conspiracies, build shelters or boats, fake their own deaths.

Sometimes these books inspire an afternoon of fluttering activity. Alice’s mother will become increasingly frustrated as Alice knocks on her door again and again asking for the sewing kit; *Do we have a laminator? Can I fish in the river? Do you work for the CIA?*

Hours later the mother will find on the kitchen table or else in Alice’s room a half-sewn black eye-patch, some Berol-markered membership cards for a secret society, or the first page of a detective novel, abandoned mid-sentence.

By the time Alice’s mother can contemplate joining her, she will be in her room, napping or reading. Without anyone to reflect her ideas back at her, they don’t go anywhere.

It’s at times like this that Alice dreams obsessively of having a twin. She imagines a little girl, no bigger than her, with the same frizzy hair and intelligent eyes. She has conversations with her twin in her head, sometimes for most of the afternoon. Together they egg each other on in their theories and conspiracies. They end up thinking that Alice’s book will be a bestseller and she’ll be paying off her parents’ house. They believe that their secret society will uncover crimes and bring them to the attention of the police.

Other little girls, she has found, don’t tend to be this encouraging. When she tries to explain her plans to the girls in her class, they laugh at her, call her silly, or else, listen too obligingly, letting Alice ramble on. Eventually, they reply in a way that shows they haven’t listened or haven’t understood.

Just once, she found a girl in her class, Daisy, who listened more accurately, even embellishing her stories. After a night of soul-searching she decided to induct her into her secret society: the Black Patch. They had one fun lunch time, Alice putting Daisy through the induction process: climb the tree, spin around a hundred times, say the alphabet backwards. But the next week, Daisy had forgotten the name of Alice’s society. She called it “the Black Path”. Alice stubbornly ignored her overtures of friendship after that.

She’d figured out when she was younger that if she stared into one spot on the wall for long enough she could hallucinate. Out of the strangely flashing frothing lights in her eyes, she could shape the outline of her sister. Other times when she closed her eyes and focused hard, she could almost feel her standing next to her.

Alice’s mother, looking out of her office window, once saw Alice running around the garden in circles talking to herself. It made her think, with impotent regret, of border collies who, locked in a pound cage, will invent flies to chase when there are none around.

On this particular day, Alice, sitting next to the almost finished book on the bean bag in her room, makes a resolution. Today she will wish her sister into the real world. A small part of her mocks this thought, but Alice is a practised fantasist. The rest of her runs upstairs to her parents’ bathroom, where there is a full-length mirror.

She stands in front of it, places both hands on the mirror, and stares into her twin’s eyes. The glass is cold on her hands. Drawing her head closer and twisting at an angle, she can see the small gap between her palm and her twin’s. The gap pains her. She closes her eyes and wishes hard, hard until the blood is pounding in her ears. She pushes forcefully into the mirror, wishing, wishing. She’s almost faint.

Let us say, just this once, that a wish is granted. Alice’s hands pass through the mirror like air. The cold on her hands becomes a clammy warmth. An astonished hand disengages, grabs her wrist, and pulls her through.

*Between three and a half and four billion years ago, Luca, the Last Universal Common Ancestor of every living thing, was alive in our oceans.*

*When Luca was alive, the earth was different. There was likely no free oxygen in the atmosphere. Whatever lived, lived in the seas. The seas were green because of dissolved iron, and might have been hotter than Dubai in the summer, or not, depending on who you ask. Great chunks of the ocean would be vaporised from time to time by heavy asteroid bombardment.*

*It’s likely that Luca lived in the hot, anarchic area around a thermal vent, where matter was churned up and spewed out. These vents got hot enough to melt lead; they spent the day blasting clouds of metal and sulfur into the ocean. It’s also possible, however, that Luca lived near more relaxed alkaline vents, hovering at temperatures a little above the human body. There is much about Luca that we do not know.*

*What we do know is that even at this extremely early stage in the development of life, before the first archaea had swallowed a bacteria to become the first modern cell, life had already chosen a direction. Luca, or at least the parts that made him up, was chiral.*

*The word chirality comes from the Greek word for hand — ‘cheir’. Our hands are symmetrical along a plane, but they aren’t copies of each other. No matter how you rotate your right hand, you can never make it match your left. If you face the thumbs in the same direction, you can’t show both palms at once.*

*In Luca, the proteins, enzymes, the DNA, and possibly the fats that made up the cell walls, were chiral. They’ve arrived at an orientation and they relied on this orientation being universally agreed upon for everything from digestion to the exchange of genetic material to work. Proteins were built from ‘left’ amino acids and enzymes were shaped to break down ‘right’ sugars.*

*Throughout the rest of the development of life on earth, up to and including you me and Alice, these same chiral patterns persisted. Everything worked.*

The girls stand side to side in front of the mirror. They wonder at each other. Mirror Alice reaches out and touches Alice’s face. They look in the mirror at the two identical girls. Even the fantasist parts of them can’t incorporate this. Staring into their reflection, they feel the rush they get when they place their feet where a step should be. Shivers run up two identical spines.

They breathe for a moment and then make identical resolutions. They turn and embrace. They decide to be happy. They have so much to talk about, and nothing at all. It takes them a few minutes to stop saying the same thing at the same time.

This problem is solved when Alice exclaims in astonishment at the bottles of lotion by the sink: all the words are backwards. More than that, the entire room is backwards. The bath is on the wrong side and the window faces a tree that should not be there. Alice begins to feel dizzy. Mirror Alice takes a minute to understand; for her everything is just where it should be.

A creak from the stairs and both girls start: their mother is coming. They don’t need to communicate the plan. “Black path”, both girls whisper, Alice covering her right eye, Mirror Alice her left.

Alice runs into the adjoining room and… into a wall. Smarting, she turns around and slips under the bed.

“Hey Alice,” said their mother, “did I hear you talking to someone?”

*Okay class, so what happens when a molecule meets another, with an orientation that it isn’t expecting?*

*Well, what happens when a key meets a lock it isn’t designed to fit?*

Alice hides with her sister for the rest of the day, whispering. They build a fort out of sheets in Mirror Alice’s strangely backwards room. Mirror Alice sneaks snacks from downstairs and they feast with each other, hatching plans. Both of them are ecstatic with each other’s reality. They both think of those toys that repeat whatever you say. If you place two of them next to each other, a simple sentence becomes a high-pitched scream as it bounces back and forth between the microphones.

They were especially excited imagining the tricks they could get up to with a secret twin. They could take turns going to school! Or, they could both go, and prank their class by leaving a room from one door, and entering it through another an instant later. Maybe they were magic now, since they’d been through a magic mirror. Maybe they had super powers…

In what feels like a very short time, their mother calls Alice for dinner.

The realisation strikes Alice alone. This is her mirror mother. On the other side of the mirror, her real mother must be calling her for dinner too and getting no reply. Panicked, she turns meaningfully to Mirror Alice. They both dash up to their parents’ bathroom. They embrace each other and then Alice, placing her hands on the cold mirror, begins to wish and to push.

We did say “just this once”. This time, we must imagine, the wish fails. Alice continues to push and to wish in a state of increasing anxiety until she is worried she will break the mirror. Mirror Alice, regretfully, walks down to dinner where she sits and fidgets in her chair. Alice, defeated, goes to hide and cry in her twin’s room. She feels much more alone, much more of a stranger than she ever has before.

*That our bodies can sustain us over a long lifespan is incredible. So many keys, in so many locks. Everything where it should be, or at least, enough to keep us going.*

We can imagine some of the plot from here. The Alices grow more distant as Mirror Alice finds our Alice increasingly burdensome. Mirror Alice has dinner with her parents, goes out for day trips with them on the weekends. Our Alice remains in the room. Perhaps they start plotting against, rather than with each other. Perhaps our Alice succumbs to depression.

The inevitable moment of discovery, either accidental, or forcefully enacted by our Alice, inches closer and yet… this is not what will happen.

*From the moment that Alice passes into the mirror world, a different ending was prefiguring itself, multiplying, multiplying, multiplying without end.*

Bacteria from our world, from the gut of our Alice, are growing in Mirror Alice, in Mirror Mother, Mirror Father, and everyone they touch. In Mirror Father’s office mates. In the scores and scores of people he’s stood pressed against on the underground. In the plants in their garden. In the cat next door. None of the hosts have any defences against this growth.

The bacteria, after leaving the gut of young Alice, cannot be recognised by a mirrored immune system. Like her, it cannot digest most of the mirrored sugars of this world, but it finds enough simple molecules to help it grow slowly. It eats, divides, eats, divides. Its victims have almost no symptoms, maybe some fatigue, as the physical mass of bacteria grows slowly in their blood. When it reaches a critical level, they’ll die of sepsis, or mercifully, a heart attack. There would be nothing doctors could do to help them.

Our Alice would, if she lived long enough, suffer from a unique issue. *Her body cannot digest Mirrored food. *Within weeks, she’d start to exhibit symptoms of kwashiorkor — a severe lack of protein*.* At first — edema, swelling. Eventually, a distended stomach, wasted arms. Her body would begin to eat itself, the only source of non-mirrored protein in the mirror world. That’s if the mirror world’s bacteria didn’t kill her first.

If those who are not yet infected want to stay that way, they’ll have to avoid all life. Not just other humans, but other animals, even plants. For billions of years of evolution, every living thing has shared a set of common assumptions. Now that these no longer hold, there are no defences.

It’d take doctors some time to understand their dire situation. Blood tests from our Alice, patient zero, would show complete nonsense. The lab enzymes would have no grip on her molecules.

Imagine that they make a vaccine in time to save some of the population from infection. That alone would be a wicked problem. Soon, the remaining population would be relying on stock-piled food. Crops would be dead, nothing would grow. They’d have to invent mirrored or immune crops from scratch. In any realistic assessment — they wouldn’t make it.

This story, for now, remains hypothetical.
