Sometime in the middle of the night, Freya wakes and sees a light is on in the kitchen. Dim and bluish; the light from their screen. She gets up and creeps down the hall past her parents’ room, where she can hear Badim faintly snoring. No surprise: Devi up at night.
She is sitting at the table, talking quietly with the ship, the part of it that she sometimes calls Pauline, which is her particular interface with the ship’s computer, where all of her personal records and files are cached, in a space no one else can access. Often it has seemed to Freya that Devi is more comfortable with Pauline than with any real person. Badim says the two of them have a lot in common: big, unknowable, all‐encompassing, all‐enfolding. Generous to others, selfless. Possibly a kind of folly a duh, which he explains is French for “a two‐person dance of craziness.” Folie à deux. Not at all uncommon. Can be a good thing.
Now Devi says to her screen, “So if the state lies in a subspace of Hilbert space, which is spanned by the degenerate eigenfunction that correspond to a, then the subspace s a has dimensionality n a.”
“Yes,” the ship says. Its voice in this context is a pleasant woman’s voice, low and buzzy, said to be based on Devi’s mother’s voice, which Freya never heard; both Devi’s parents died young, long ago. But this voice is a constant presence in their apartment, even at times Freya’s invisible but all‐seeing babysitter.
“Then, after measurement of b, the state of the system lies in the space a b, which is a subspace of s a, and is spanned by the eigenfunction common to a and b. This subspace has dimensionality n a b, which is not greater than n a.”
“Yes. And subsequent measurement of c, mutually compatible with a and b, leaves the state of the system in a space s a b c that is a subspace of s a b and whose dimensionality does not exceed that of s a b. And in this manner we can proceed to measure more and more mutually compatible observables. At each step the eigenstate is forced into subspaces of lesser and lesser dimensionality, until the state of the system is forced in a subspace of dimensionality n equals one, a space spanned by only one function. Thus we find our maximally informative space.”
Devi sighs. “Oh Pauline,” she says after a long silence, “sometimes I get so scared.”
“Fear is a form of alertness.”
“But it can turn into a kind of fog. It makes it so I can’t think.”
“That sounds bad. Sounds like too much of a good thing has become a bad thing.”
“Yes.” Then Devi says, “Wait.” There is a silence and then she is in the hallway, standing over Freya. “What are you doing up?”
“I saw the light.”
“All right. Sorry. Come on in. Do you want anything to drink?”
“Yes.” They don’t often have chocolate powder, it’s one of the rationed foods.
Devi puts the teapot on to boil. The glow of the stove coil adds red light to the blue light from the screen. “What are you doing?” Freya asks. “Oh, nothing.” Devi’s mouth tightens at the corner. “I’m trying to learn quantum mechanics again. I knew it when I was young, or I thought I did. Now I’m not so sure.”
“Why am I trying?”
“Well, the computer that runs the ship is partly a quantum computer, and no one in the ship understands quantum mechanics. Well, that’s not fair, I’m sure there are several in the math group who do. But they aren’t engineers, and when we get problems with the ship, there’s a gap between what we know in theory and what we can do. I just want to be able to understand Aram and Delwin and the others in the math group when they talk about this stuff.” She shakes her head. “It’s going to be hard. Hopefully it won’t really matter. But it makes me nervous.”
“Shouldn’t you be sleeping?”
“Shouldn’t you? Here, drink your hot chocolate. Don’t nag me.”
“But you nag me.”
“But I’m the mom.”
They sip and slurp together in silence. Freya begins to feel sleepy with the heat in her stomach. She hopes the same will happen to Devi. But Devi sees her put her head on the table, and goes back to talking to the screen.
“Why a quantum computer?” she asks plaintively. “A classical computer with a few zettaflops would have been enough to do anything you might need, it seems to me.”
“In certain algorithms the ability to exploit superposition makes a quantum computer much faster,” the ship replies. “For factoring, some operations that would have taken a classical computer a hundred billion billion years will only take a quantum computer twenty minutes.”
“But do we need to do that factoring?”
“It helps aspects of navigation.”
Devi sighs. “How did it get this way?”
“How did what get what way?”
“How did this happen?”
“How did what happen?”
“Do you have an account of how this voyage began?”
“All the camera and audio recordings made during the trip have been kept and archived.”
Devi hmphs. “You don’t have a summary account? An abstract?”
“Not even the kind of thing one of your quantum chips would have?”
“No. All the chip data are kept.”
Devi sighs. “Keep a narrative account of the trip. Make a narrative account of the trip that includes all the important particulars.”
“Starting from now?”
“Starting from the beginning.”
“How would one do that?”
“I don’t know. Take your goddamn superposition and collapse it!”
“Meaning summarize, I guess. Or focus on some exemplary figure. Whatever.”
Silence in the kitchen. Humming of screens, whoosh of vents. As Freya gives up and goes back to bed, Devi continues talking with the ship.
From Aurora, by Kim Stanley Robinson. Copyright 2015 by Kim Stanley Robinson. Reproduced with permission from Orbit, a division of Hachette Book Group.
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