Why Are There So Few Women in Physics?

I don't know, but I am seeing many attempts to answer it. The first was a study about women who were postdocs in the D-Zero collaboration which runs the D-Zero experiment at Fermilab. This study was interesting. It used a database of internal notes, conference presentations, and where postdocs went after leaving D-Zero. The conclusion was that women received fewer opportunities to present D-Zero results at conferences than equally qualified men and this hurt their ability to get faculty positions.

I read the actual study and it struck me a serious piece of work that cannot be lightly dismissed. If I understood the paper correctly, it claims that by the metric used in the study the women in the cohort were more productive than the men but were only offered faculty positions at the same rate. There was one element that struck me as odd. It limited the study to men and women who went on to faculty positions at universities. Staff scientist positions at laboratories are very comparable to faculty positions. I know of quite a number of women who are staff scientists at Fermilab. I am curious what would have happened if lab staff scientists were also studied. Do women prefer lab positions over university ones?

The second study I saw was written up in the Boston Globe. It covered science and engineering more broadly than the first one. It argues that women self select against the hard sciences and engineering.
Now two new studies by economists and social scientists have reached a perhaps startling conclusion: An important part of the explanation for the gender gap, they are finding, are the preferences of women themselves. When it comes to certain math- and science-related jobs, substantial numbers of women - highly qualified for the work - stay out of those careers because they would simply rather do something else.

One study of information-technology workers found that women's own preferences are the single most important factor in that field's dramatic gender imbalance. Another study followed 5,000 mathematically gifted students and found that qualified women are significantly more likely to avoid physics and the other "hard" sciences in favor of work in medicine and biosciences.
The third article was in the Fashion & Style section of the New York Times, an odd positioning for this topic. On the day that I read it there was large swimsuit ad next to it.

This article cites a study to be published in the Harvard Business Review and claims that scientific workplaces are pretty bad places for women to work.
“It’s almost a time warp,” said Sylvia Ann Hewlett, the founder of the Center for Work-Life Policy, a nonprofit organization that studies women and work. “All the predatory and demeaning and discriminatory stuff that went on in workplaces 20, 30 years ago is alive and well in these professions.”
I can't say that I recognize this as describing anyplace I have worked. If there has been discrimination going on, it has been much more subtle like that described in the first study I mentioned.