John von Neumann stood tight-lipped at the front of the room. He had left all the windows closed because of the blowing dust from the streets. Metal fans clicked on empty desks around the room. The scientist with “The Problem Of The Day” paced just outside the door. Elizabeth couldn’t make out who he was.
Thirty women, most of them younger than she by at least five years, waited at their desks for the morning instructions. They were arranged in five rows of six columns. Each desk sat a precise two feet from its neighboring desk, close enough so that when one woman finished her calculation, she would have no trouble handing her answer to the next woman in the queue.
The simplicity of it all impressed Elizabeth. The whole process reminded her of a computer program—each woman would execute one line of the program, either by adding several numbers or performing some other mathematical operation, then hand off her answer to the next woman in line. The solution zigzagged around the room until the last woman tallied the final result.
Once every woman had been briefed on the precise operation she was expected to perform, von Neumann would start off the process by handing the first woman a number written on a sheet of paper. He would continue to hand numbers to the first person in line, taking up all morning and afternoon.
Most of the times the numbers were different, but often Elizabeth could remember identical numbers coming down the pipe. In his brittle Hungarian accent, von Neumann had explained that this was to double-check the accuracy of their calculations. He strode among the desks, looking down at them with his sad, dark eyes, like a Napoleonic schoolteacher.
Before each morning’s session, one of the working scientists would give a short tutorial on what the women were calculating. Elizabeth looked forward to the lectures, eager to learn more about what paths the Los Alamos scientists were taking to design the Gadget and how far along they had come. At first she thought she would be amused at the relative naiveté of the old methods, but she quickly learned that the sophistication was high. Since no one could rely on supercomputers to check models, the Manhattan Project scientists displayed an uncanny intuitive feel for the pertinent physics.
Once the calculations room quieted down, von Neumann cleared his throat. His voice was rich and exotic, with an accent that made him sound like Bela Lugosi in Dracula. “Today’s problem will be covered by Professor Feynman. Dick?”
Elizabeth slid down in her chair as Feynman entered the room. The young man’s infectious grin put the room at ease. He seemed to be flirting with everyone at once. Most of the women just wanted to get started.
Feynman picked up a piece of chalk. He flipped the chalk as he walked around the front of the room, tossing it up and down and catching it precisely each time, though he seemed to be paying no attention at all. As he spoke, Feynman met the eyes of his audience, roving back and forth along the lines of desks.
“We’re trying to overcome a problem of neutron absorption by some of the nonfissile materials. If you can imagine yourself as a little neutron being spit out of a newly formed nucleus”—he crouched low, then sprang high into the air—“and suddenly being grabbed by the wrong type of atom.” He landed on the floor and put his hands around his neck, gasping and choking. “Well, we’re trying to prevent that.”
He released his hands from his neck and spread them wide. “Today you ladies are going to calculate what we call absorption probabilities. Most of the absorption is defined randomly, and the whole process is called the Monte Carlo method—Monte Carlo because it’s based on that famous casino city located in Morocco.
“Anyway, you can look at this calculation as trying to see how many neutrons can survive being absorbed by the wrong material—like when you ladies first got here and fought off the Army types to keep yourselves available for a decent scientist, who would make a much better husband.”
Some of the ladies laughed weakly. Elizabeth did her best to ignore it. Feynman didn’t even know where Monte Carlo was.
“Now these particular calculations are going to be used in what we’re calling our gun experiment. Basically, we want to shoot two blobs of uranium-235 at each other, and we think if we can do it fast enough, then the one resulting hunk will be at critical mass—and that’s what will make our Gadget work. So, what you ladies are doing is very critical.” Feynman grimaced at his own pun, but Elizabeth didn’t think any of the other women understood it. “If the answers look good, we’ll try a small experiment with depleted uranium to get the mechanics down.”
None of the other people seemed to care or understand what the egghead du jour was talking about. Elizabeth listened to everything.
“All right, ladies,” Feynman continued. “The numbers I’ll be giving you correspond to initial neutron velocities and material temperatures. Get ready, and have fun. I’ll ring the bell every ninety seconds to let you know when to transfer your result—that should give you plenty of time to check your calculations.”
At the bell, Elizabeth knew that she had another ten minutes before the first number would work its way through the chain of calculations to reach her position in the string of workers. She kept her eyes averted from Feynman.
She wondered if anyone else might have been desperate enough to steal into the locked offices and change their particular assignments. She dismissed the thought after looking around the room; the rest of the women—they didn’t mind being called “girls”—stared at their work, oblivious to Feynman’s teasing. To the rest of them, this was just assisting the war effort, as much as assembling bomb casings or sewing infantry uniforms. They had no grasp of the big picture.
Feynman looked directly at her for the first time; he winked to show he had known she was there all along. Elizabeth tried to ignore him, but she felt her face grow red.
At any time he could divulge what she had done, that she had falsified her records, that she didn’t belong here inside the fence. And if anyone thought to question her, she would have no answers to give them….
“Elizabeth! Hey, Liz-here!”
“Uh? Oh, sorry.” Elizabeth grabbed the sheet thrust at her. She had not heard the bell ring and had forgotten where she sat. The metal fans continued to make noise, but the air felt too thick for it to stir. Feynman stood at the front of the room watching a miniature hourglass dripping ninety seconds worth of sand. Von Neumann had vanished, probably to work on his own calculations. Elizabeth glanced down at the paper. Written on it was:
She plugged the values into the lengthy equation written on yet another sheet of paper. If only her college physics work had been so simplistic. Seconds later she ran through the algebra and produced another set of values, which she wrote down on a fresh sheet of paper.
She started to set down her pencil and hand the paper to the woman on her right when a thought struck her. What was to keep her from introducing her own errors? To muck things up a little bit. It would take the scientists a while to unravel the problems, to double-check the work. In the meantime, she could be delaying the development of the atomic bomb.
The thought stunned her. Could she change the future? She needed only to stall the work by a few weeks—when Fat Man and Little Boy had been dropped on Hiroshima and Nagasaki, Germany had already fallen and Japan was trying to surrender. A delay of even a handful of days might make the destruction of all those human beings unnecessary. By changing a minus sign or two, she could save a few million lives!
If the atomic bomb could be demonstrated, during peacetime, as part of an exhibition of the potential horrors of nuclear war, then maybe the superpowers would sign immediate agreements to halt, or at least control, their research. The shock that led to the terrible Cold War paranoia would not be nearly so severe.