Friend says many of her students look at her and see a lifestyle that they don’t want, which is why she feels it’s important for young women to see that there are other ways to pursue a career in science.

With greater attention to the issues of mentorship, teaching and culture, many professors and students are hopeful that women will eventually reach a critical mass in the natural sciences at Harvard.

Looking at the students and professors at work in the laboratories of Jefferson Hall, home to Harvard’s physics department, Holton sees a positive trend.

He points out a photograph of the current physics faculty that hangs near his office. It shows a department with four tenured female professors among its ranks.

He then shuffles excitedly down the hallway to show off a wall covered with the photographs of all the current undergraduate physics concentrators. About a fifth of the faces on this wall belong to women.

The point, Holton says, is that women—generation by generation—are slowly breaking into physics at Harvard.

“There is this crowd coming on at last,” he says.