the rheology of women in science

I'm multitasking, bouncing between reading a classic structural geology article, brainstorming possible speakers to invite to campus next year, and mulling over the implications of Virginia Valian's tutorials about gender schemas and science (mentioned in this month's Association for Women Geoscientists newsletter). And it struck me: the experience of women in science (and, according to Dr. Valian's work, a lot of other fields, as well) feels like strain hardening.

Rocks may seem solid when we stub our toes on them, but rocks actually can change shape in a lot of different ways. There's brittle behavior - breaking rocks. That's fairly familiar - my four-year-old has even been experimenting with brittle behavior by dropping rocks onto one another and watching them smash into little pieces. Brittle behavior is responsible for things like earthquakes. Rocks near the earth's surface are brittle.

And then there's a whole suite of ductile deformation mechanisms -- ways in which rocks change shape without breaking, the way Silly Putty does. There's pressure solution, in which minerals dissolve because they've been pushed against one another too hard. There's Coble creep, which sounds kind of like somebody you would avoid sitting next to at lunch, but which really is just a way in which atoms move through the space between mineral grains. It's like pressure solution without the water. And there's Superplastic Creep, which isn't really capitalized, but really, how could I avoid capitalizing something that sounds like the ultimate geeky superhero? In superplastic creep, small grains both change in shape (maybe by pressure solution or Coble creep) and slide past each other.

All three of those mechanisms ought to let rocks deform more easily when the rock is made of smaller pieces of stuff - they should experience "strain softening," in which deformation gets easier as time goes by.

But there's one deformation mechanism that behaves in the opposite manner, and it's an important one: dislocation glide. Dislocation glide sounds like something that ought to be easy and graceful. And maybe it is, for a little while. Dislocations are lines where crystal lattices are contorted, and they're supposed to actually be easier places to break and reform bonds than is possible in a perfect crystal. And if a crystal had only one dislocation, the dislocation could glide right through from one side to the other, changing the crystal's shape ever so slightly. But crystals have lots of dislocations, and when they try to glide past one another, they get tangled up. (I keep imagining every Olympic ice skating champion for the past 30 years trying to simultaneously do a routine in a small ice rink. Crash. Tangle.) And when dislocations tangle, they get stuck, and it gets more difficult for the crystal to change shape -- the rock undergoes "work hardening."

And it strikes me that women scientists (or women in lots of fields) can experience a kind of work hardening. Valian argues that women constantly face little setbacks as a result of "gender schemas" - expectations about differences between women and men that lead people to overrate men and underrate women. For example, in academia, maybe a woman gets slightly weaker letters of recommendation, and then is hired by a slightly less prestigious institution, and then gets slightly weaker reviews of grant proposals, and gets slightly less funding, and then is less likely to be invited to collaborate on important projects, and then is not invited to participate in an NSF panel or to give invited talks, and then she's a weaker candidate for, say, the Young Scientist Medal at GSA. All those little qualitative things add up to a far weaker CV, and might result in getting delayed promotion, or receiving a lower salary than men, or not getting invited to join the National Academy of Sciences. The molehills become a mountain. But there's more to it than that. Those little things are exhausting, and it's easy to come to believe that, you know, maybe I didn't deserve tenure. Maybe I'm not that great of a teacher. Maybe my research isn't very exciting. They tangle together until the thought occurs: maybe I would make a pretty good stay-at-home mom, even though I'm happiest when I'm out in the field with a student, brainstorming alternate working hypotheses for a rock that doesn't make sense.

Dislocation glide happens under conditions of high differential stress and fairly low temperature. But with higher temperature - with just a little more energy - dislocations can "climb" - they can move out of each other's way and let the deformation continue. The work doesn't get easier with time, but it doesn't get harder, either. It reaches a steady state (which sounds really Zen, doesn't it?) as dislocation creep (which doesn't sound very Zen).

And I wonder. How much energy, exactly, is necessary to achieve the steady state of dislocation creep in the work world? And, well, will somebody figure out how to add water to the system so that pressure solution can take over? Because there are definitely times that I would prefer to dissolve away and precipitate someplace where the stress is lower.