The Wrong Number

Maya was trying to count the ceiling tiles when her aunt said the number.

"Eighty-six billion," Aunt Rosa said. She was not really talking to Maya. She was talking to a folder in her lap, the way tired people talk to things instead of people. "That is how many neurons Grandma has. Had. Still has, mostly. The stroke took a little corner of them."

"A corner," Maya said.

"A small one. She might mix up some words for a while. Names, maybe." Rosa rubbed her eyes. "Eighty-six billion. You lose a few million and it barely shows."

Maya did not find that comforting, and she could tell Rosa did not either.

The waiting room had a fish tank with two fish and a clock that ticked louder than clocks should. Maya watched the second hand and did the thing she always did, which was start turning a number over to see what it was made of.

Eighty-six billion. She tried to picture it. She could not. She could picture the fish, and the tiles, and maybe a stadium full of people, but not billions of anything.

"How many things does each one touch?" she asked.

Rosa looked up. "What?"

"The neurons. Do they just sit there? Or do they touch each other?"

"They connect." Rosa held up a hand and wiggled all her fingers. "Each one reaches out to others. Some reach a few. Some reach up to ten thousand."

"Ten thousand each."

"Give or take."

Maya went quiet. She was not doing the multiplication, exactly. She was standing at the edge of it. Eighty-six billion little things, each one holding hands with up to ten thousand others, and every hand-hold being a choice, on or off, this one or that one.

"That is a lot of ways," she said slowly.

"A lot of ways to what?"

"To be wired. If every neuron can connect to different ones, there must be a huge number of ways the whole thing could be arranged." She frowned. "Like combinations. Like a lock with billions of dials."

Rosa smiled a little, the first time all afternoon. "Bigger than that. Much bigger."

"Bigger than what?"

Rosa put the folder down. "You know the number of stars?"

"A lot."

"The number of atoms in everything we can see? Every star, every planet, all of it, out to the edge of the observable universe?"

Maya nodded, though she did not really know, nobody really knew, that was the whole point of a number like that.

"The number of ways a single human brain could be wired," Rosa said, "is bigger than the number of atoms in the whole observable universe."

The clock ticked. One of the fish turned around.

"That's wrong," Maya said.

"It is not wrong."

"It has to be. The brain is in the universe. It's inside my head, and my head is inside the universe. How can there be more ways to arrange the inside thing than there are pieces in the whole outside thing?"

Rosa opened her mouth, then closed it. "Say that again."

"The universe has however many atoms. That's the count of stuff. But you're saying the brain has more arrangements than that. More than the stuff." Maya was leaning forward now. "Those aren't the same kind of number."

"No," Rosa said carefully. "They are not."

Maya looked at the fish tank. Two fish. She counted the ways they could arrange themselves in the tank. Fish A in front, fish B behind. Fish B in front, fish A behind. Both at the top. One at the top, one in the corner. She kept going. With only two fish, there were already lots of ways. Add a third fish and the ways did not add, they multiplied. Add a fourth and they exploded.

The atoms were the fish. The arrangements were the ways the fish could swim.

"It's not about how many pieces," Maya said. "It's about how many ways the pieces can go together."

Rosa was watching her the way you watch something you were not expecting.

"You could have a tiny box," Maya went on, "with only a few things in it, and if those things can connect a lot of different ways, the number of patterns is enormous. The box stays small. The patterns don't." She pressed her hands flat on her knees. "So the brain is small. It fits in the universe. Easy. But the number of things it could be is too big for the universe to even hold as a list."

"There is no shelf big enough," Rosa said quietly, "to store every version of you."

Maya sat with that.

Every version of her. The girl who was scared right now. The girl she would be tomorrow. The girl she would have been if she had counted ceiling tiles instead of asking the question. All of them different wirings, all of them her, and the list of possible hers longer than every atom in every star anyone would ever see.

And Grandma, down the hall, missing a small corner. A few million connections gone. Rosa had said it barely shows. Maya understood now why. If you take a few million away from a number that big, you have not made a dent. Grandma had more ways left to be Grandma than the universe had atoms to count them with.

"She's still all in there," Maya said. "The corner is gone. But there's so much left. There's more left than there is anything."

Rosa did not answer. She reached over and took Maya's hand, all five fingers, one small connection.

A nurse came to the doorway. "She's asking for you two," the nurse said. "She keeps calling the girl a different name. Rosie, she keeps saying."

"That's my name," Rosa said. "Not hers."

"She'll get it," Maya said. "There's a path back. There's a billion paths back."

She stood up. The fish rearranged themselves behind her, one in front, then the other, then both at the top, finding a new way to be two fish in a small glass box.