La Dame D'Esprit: A Biography of The Marquise Du Châtelet
by Judith P. Zinsser
Viking, 2006

Out of The Shadows: Contributions of Twentieth-Century Women To Physics
edited by Nina Byers and Gary Williams
Cambridge University Press, 2006

During the past 40 years, study after study has addressed why more women do not become scientists. The question is most apt for physics. Advanced physics degrees awarded to women have always lagged, hitting a nadir at under 5 percent from the 1950s to the 1970s. Progress has been made since; in 2003, 193 women (17.9 percent) received a Ph.D. in physics, according to the National Science Foundation. But physics still trails the other sciences.

The flip side of the question is: Why and how did those few prominent female physicists succeed? Historian Judith P. Zinsser's La Dame d'Esprit and the profiles of women physicists in Out of the Shadows unveil the scintillating lives of women who overcame discrimination and made major contributions that went largely unacknowledged.

Zinsser debunks legends about the life and loves of the vivacious and unorthodox 18th-century French noblewoman Marquise du Châtelet and analyzes her contribution to physics. Du Châtelet (1706-49) gained notoriety as Voltaire's lover. When government censors deemed his literature subversive, she offered him shelter at her château in Cirey. There they collaborated and commented on each other's manuscripts. Du Châtelet transformed a room into a laboratory for experimenting in the "natural sciences," as physics was then called, and built a small theater for Voltaire's plays.

According to Zinsser, du Châtelet's mother recognized her daughter's prodigious curiosity and fostered it by permitting her to question elders even though that was considered impolite. Other biographers report that du Châtelet's father considered her too plain for marriage, so he educated her with the best teachers.

Du Châtelet was in her 20s when she and Voltaire became lovers in 1733, and several biographers have highlighted their affair at the expense of the marquise's accomplishments. To trace her development as a mathematician and physicist, Zinsser plumbed archives all over Europe and the U.S.

Voltaire did introduce du Châtelet to the ideas of Descartes, Leibniz and Newton, which were being debated at the French Academy of Sciences, from which women were barred. When the academy held a competition for best essay on the nature of fire, the interpretations of the lovers differed, and both entered the contest--she under an assumed name. Leonhard Euler won, but the academy considered Euler's, Voltaire's and du Châtelet's essays so outstanding that it published all three. The couple then collaborated on The Elements of the Philosophy of Newton, introducing Newton's theories to readers with no background in higher mathematics.

As Zinsser interprets it, du Châtelet and Voltaire's relationship faltered as her scientific expertise exceeded his, as it did in her next book, Institutions of Physics. Not merely explaining the metaphysical theories of Descartes, Leibniz and Newton, du Châtelet synthesized them, Zinsser says, whereas academy members, including one of her mentors, only spoke of doing so. She explored a broad sweep of concerns, from "how one can know anything, to the origins of the universe and the role of the divine."

Du Châtelet also devoted a chapter to the scientific method, explaining hypotheses as "probable propositions" that could be rejected because of one contradiction. One confirmation, however, was insufficient to prove a hypothesis. Rather "each non-contradictory result would add to the probability of the hypothesis and ultimately ... we would arrive at a point where its 'certitude' and even its 'truth,' was so probable that we could not refuse our assent." If antievolutionists today understood the scientific method as well as this woman of the Enlightenment did, perhaps they wouldn't glibly say, "It's only a theory."