Always a Bridesmaid: Vera Rubin and the Nobel Prize

This year's crop of Nobel Prizes has been awarded, and the deserving winners duly feted for their impressive accomplishments. The 2010 Nobel Prize in Physics went to the University of Manchester's Andre Geim and Konstantin Novoselov for their ingenious method for making graphene, i.e., two-dimensional carbon in the form of a honeycomb latice just one atomc thick. (The secret? Scotch tape! I kid you not.)

The choice surprised several people, not because Geim and Novoselov aren't deserving - they most certainly are - but because graphene is a fairly recent development, and while it holds tremendous potential for applications, few of those are close to being realized. I guess it struck some folks as premature, particularly when there are so many other eminent scientists of advancing years who are waiting for their scientific achievements to be Nobel-y recognized. (The Nobel Prizes are awarded to living individuals, not posthumously.)

Personally, I've been a fan of Geim's lab for years: the place is known for unusually creative and innovative approaches to research, along with a media-friendly sense of play. (Geim's gecko-inspired sticky tape a few years back was tested by suspending a Spiderman action figure from the ceiling.)

But frankly, I was rooting for the prize to go to astronomer Vera Rubin, now 82, whose quiet, unassuming demeanor might seem incongruent with her extraordinary career in science. A former postdoc, David Burstein, once recalled that Rubin often told him, "You don't do astronomy for money or publicity; you do it for your own satisfaction." (The vast majority of scientists would agree.)

Rubin was 10 years old and living in Washington DC when she first fell in love with with the night sky, peering up at the heavens from her bedroom window. It was rare for a woman to study science at the time, but she was a true pioneer. Rubin earned a B.S. in astronomy from Vassar College in 1948 - the only astronomy major that year. She tried to get into grad school at Princeton, but no women were allowed in the astronomy program (that didn't change until 1975). She wound up earning a master's degree from Cornell two years later.

That's where she met her husband, Robert Rubin, who supported her desire to earn a PhD. So much so, that when she attended night classes at Georgetown University, he drove her to classes and ate his dinner in the car until class was finished and he could drive her home. (Her parents babysat their young children.)

The hard work paid off: she got her PhD in 1954, with a thesis on the unusual "clumping" of galaxies in the universe - results that were largely dismissed at the time, but were confirmed some 15 years later.

Years later, having landed a position with the Carnegie Institute, she returned to the topic of her master's thesis with her collaborator, Kent Ford, reaching the same conclusion. The ensuing controversy convinced Rubin to pursue a less hotly contested area of research for awhile, and she started looking into why spiral galaxies vary in their brightness, assuming it had something to do with their rotation. It turned out to be an especially promising avenue to explore.

She and Ford used a spectrograph to break down the spectrum of light emitted by stars in different parts of select spiral galaxies. She expected to see that the stars were orbiting the center of the galaxy more slowly the further they were from the center, much like the larger outer planets in our solar system take longer to complete an orbit around the Sun than the planets closer in. That's because the visible mass of a given galaxy - and hence, its gravitational pull - is concentrated at the center.

Instead, Rubin and Ford found that the outer stars were orbiting just as quickly as those at the center. The visible matter wasn't sufficient to account for this; the spiral galaxy should be flying apart! Clearly, there had to be some kind of hidden "dark" mass adding to the galaxy's gravitational influence.

And that's when Rubin remembered encountering as a grad student a 1933 paper by Fritz Zwicky analyzing the velocities of galaxies in the Coma cluster. Zwicky's paper concluded that the individual galaxies were moving so quickly that they should be able to escape from the cluster if visible mass was the only thing contributing to the cluster's gravitational pull. Since the cluster hadn't flown apart, he proposed the existence of "dark matter" (from the German Dunkle Materie) - about ten times more abundant than the visible matter - to account for the observational data.

Rubin and Ford had made a direct observation of Zwicky's predicted dark matter, which remains the top candidate for explaining such observations, although Rubin herself has admitted to favoring slightly the competing notion of modified gravity (MOND, or Modified Newtonian Dynamics). She finds MOND "more appealing than a universe filled with a new kind of sub-nuclear particle." Alas, nature doesn't take our aesthetic tastes into account; only time - and multiple experiements, now underway - will tell which hypothesis is correct.

If you asked Rubin, she might tell you that her greatest contribution to science is her four children, all of who have scientific careers: two geologists, an astronomer, and a mathematician. But she's also been justly lauded for her research, having analyzed over 200 galaxies since 1978. She has won election to the National Academy of Sciences and snagged the 1993 National Medal of Science in the process. But the Nobel Prize continues to elude her.

There have been so few women scientists honored by the Nobel Committee over the years: only two have won the physics prize, Marie Curie in 1903 and Maria Goeppert-Mayer in 1963. Rubin is eminently deserving of the honor, and frankly, she's not getting any younger.

Here's hoping she gets another shot at the short list next year. If not - well, I'm guessing Rubin would be fine with that. She's already left an impressive legacy. "Fame is fleeting," she told Discover back in October 1990. "My numbers mean more to me than my name. If astronomers are still using my data years from now, that's my greatest compliment."

Image credits: NASA/HST (top), American Institute of Physics (bottom)