MARGIN OF ERROR
by Nancy Kress
Paula came back in a blaze of glory, her Institute uniform with its pseudo-military medals crisp and bright, her spine straight as an engineered diamond-fiber rod. I heard her heels clicking on the sidewalk and I looked up from the bottom porch step, a child on my lap. Paula's face was genemod now, the blemishes gone, the skin fine-pored, the cheekbones chiseled under green eyes. But I would have known that face anywhere. No matter what she did to it.
"Karen?" Her voice held disbelief.
"Paula," I said.
"Karen?" This time I didn't answer. The child, my oldest, twisted in my arms to eye the visitor. The slight movement made the porch step creak.
It was the kind of neighborhood where women sat all morning on porches or stoops, watching children play on the sidewalk. Steps sagged; paint peeled; small front lawns were scraped bare by feet and tricycles and plastic wading pools. Women lived a few doors down from their mothers, both of them growing heavier every year. There were few men. The ones there were, didn't seem to stay long.
I said, "How did you find me?"
"It wasn't hard," Paula said, and I knew she didn't understand my smile. Of course it wasn't hard. I had never intended it should be. This was undoubtedly the first time in nearly five years that Paula had looked.
She lowered her perfect body gingerly onto the porch steps. My little girl, Lollie, gazed at her from my lap. Then Lollie opened her cupped hands and smiled. "See my frog, lady?"
"Very nice," Paula said. She was trying hard to hide her contempt, but I could see it. For the sad imprisoned frog, for Lollie's dirty face, for the worn yard, for the way I looked.
"Karen," Paula said, "I'm here because there's a problem. With the project. More specifically, with the initial formulas, we think. With portion of the nanoassembler code from five years ago, when you were...still with us."
"A problem," I repeated. Inside the house, a baby wailed. "Just a minute."
I set Lollie down and went inside. Lori cried in her crib. Her diaper reeked. I put a pacifier in her mouth and cradled her in my left arm. With the right arm I scooped Timmy from his crib. When he didn't wake, I jostled him a little. I carried both babies back to the porch, deposited Timmy in the portacrib, and sat down next to Paula.
"Lollie, go get me a diaper, honey. And wipes. You can carry your frog inside to get them."
Lollie went; she's a sweet-natured kid. Paula stared incredulously at the twins. I unwrapped Lori's diaper and Paula grimaced and slid farther away.
"Karen--are you listening to me? This is important!"
"I'm listening."
"The nanocomputer instructions are off, somehow. The major results check out, obviously--" Obviously. The media had spent five years exclaiming over the major results.
"--but there are some odd foldings in the proteins of the twelfth-generation nano-assemblers."
Twelfth generation. The nanocomputer attached to each assembler replicates itself every six months. That was one of the project's checks and balances on the margin of error. It had been five and a half years. Twelfth generation was about right.
"Also," Paula continued, and I heard the strain in her voice, "there are some unforeseen macro-level developments. We're not sure yet that they're tied to the nanocomputer protein folds. There might not be any connection. What we're trying to do now is cover all the variables."
