Saturday, February 7, 2009

Female Mathematicians during WW II

Check out this 8 minute trailer for an up-coming movie "Top Secret Rosies", where "Math may be the most secret weapon of all". (Hat tip to Sherman Dorn.)

I'd take a bit of an exception to the claim in the intro that this is an untold story, since there wasn't a single thing in it that I didn't already know from histories of the projects those women worked on (or the history taught in conjunction with learning "numerical analysis"), but it is great that it has been assembled into a coherent story with a central focus on the role of mathematicians, mostly female, in winning World War II.

I hope that people who see this movie do not interpret the presence of electromechanical "adding" machines as an indication of mindless labor. That was not the case then, any more than the essential skill of entering the correct numbers into a calculator or computer program is simply clerical labor today. It still takes a person who knows what they are doing to put the right numbers in the machine and verify that the numbers that come out are not wrong.

What people today don't realize is that digital computers with the capability of doing sophisticated engineering (or physics) calculations were too expensive for a small or mid-size company until relatively recently, and you didn't have time (and could not afford the risk) to explain the task to a low-paid clerk. Your engineering license hung on those numbers being right, just as lives depended on whether a 155mm Howitzer shell landed on the enemy rather than your own troops during WW II. This was a job for experts.

One place my dad worked had a "programmable" desktop calculator, where the key sequences could be stored on a magnetic card in much the way that a program is written on a TI-83. This was in the late 1960s, when that device cost thousands of dollars, and it was operated by the engineers. A company he joined in 1969 had an in-house computer for payroll and billing, but only a few engineering tasks were done on it. Everything else was done with an electromechanical calculator like you see in this movie clip, plus lots of log and trig tables. One of the engineers bought one of the first HP-35 calculators (at a price that would be several thousand dollars today), explaining that it saved the cost of the books of log tables that he wore out every year. Highly efficient algorithms for computation were really important when you were doing it essentially by hand.

Even before the war, many women worked as mathematicians or computers who applied mathematics to engineering or physics problems. Many engineers and physicists also did this work. That is what Feynman and Teller and others did at Los Alamos, working side by side with women like the ones in this movie. Although one woman mentioned her background with business calculations on an adding machine, the complexity of the work often required someone who knew what was being done, someone who could spot a computational error because s/he knew the math or physics behind the correct answer.

[Perhaps it was inevitable that histories in the 1950s would put the focus on the men (much in the way Feynman put the focus on himself) and that female mathematicians would be expected to go back to "women's work" after the war. What is disturbing is the degree to which young women still have to fight stereotypes imposed by their fellow students. One great thing at our CC is that we have a number of highly capable women teaching mathematics, and they have served as role models for young women who never realized they could have a technical career.]

The mathematical problem being solved by the women mentioned in this clip was the solution of sophisticated equations for the flight of a bomb or shell, such as the shell fired by a 6" gun or 16" cannon. Models of the many forces acting on an object, most never even mentioned in an intro physics textbook, were used to predict where the object would land if released at some specific angle, velocity, and altitude. The models were verified against experiments done with the actual, specific ballistic projectile, and then used to construct extensive tables that filled in all the gaps between the experimental results they had available. Gunners could reverse the process, looking up the firing angle needed to get a particular shell to land at a particular distance away for given cross winds, etc.

The ENIAC, actually the second electronic computer built rather than the first as stated in the film clip, was built to replace the labor of a room full of people working with calculators. Naturally, the people (women mathematicians) who had organized the work on the hand calculations were tapped to do the same for the new machine. This was not an uncommon occupation. One of the first computer programmers I knew was a woman who wrote code used for accelerator design in the 1950s. She was old enough to have done war work, but I don't know if she did.

But she (like the women featured in this movie) would not be the only person who might have done hugely significant work during WW II without anyone knowing what they did. Until the classification rules were lifted in the mid 1990s, all I knew was that my thesis advisor had "given orders to Admirals" during WW II. It turns out that he worked at Bletchley Park, breaking German codes, and knew John von Neumann, among others. Another person I knew had been in the plane that followed the Enola Gay to Hiroshima, taking pictures of the effects of the bomb. I didn't know that until I read his obituary.

Side note:
The first electronic computer ever built, Colossus, was so secret that its mere existence was classified as part of the "Ultra" code breaking work done at Bletchley Park in the UK. It was only after the classification of that project expired that it became known that the ENIAC was not the first programmable computer.

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