Force and Motion

Vera Rubin: A Journey from Self-Doubt to Galactic Discoveries written by Cara Giovanetti Rubin, JNIPER Fellow (2024)

Part 1

Think about a time you really wanted to accomplish a major goal you had. Maybe you wanted to ace a test, or paint something new, or beat an athletic record. Did you worry whether you might be up to the task? Did it even seem like people who accomplished those goals were on another level, and did you ever worry whether you might ever be like them?

Dr. Vera Rubin, a renowned astronomer who shaped our understanding of the universe, often felt that way. “...one of the biggest problems in my life [during] those years was really attempting to answer the question to myself, ‘Will I ever really be an astronomer?’ That was always in my consciousness,” she recounted to an interviewer in 19961. “Those years” she is referring to are the early 1950s, when she had recently earned her master’s degree in astronomy from Cornell University. Even though she was highly educated in astronomy, she still didn’t feel like she was a peer to the astronomers she idolized.

In this kit, you’ll be learning about the physics of how things move, which was crucial for Dr. Rubin and other astronomers to make sense of her groundbreaking results. You’ll learn more about Dr. Rubin’s story along the way, and see how the physics of bodies in motion was important for her work and discoveries.

Part 2

In many ways, Dr. Rubin wasn’t your stereotypical astronomer. She completed her college and graduate education in the 1940’s and ‘50’s, when many schools and programs weren’t accepting women at all. She decided to go to college at Vassar College, a women’s school (which became co-ed in 1969) about a two-hour train ride north of New York City. She was the only student in her class to choose an astronomy major. During her undergraduate, she got a summer job at the U.S. Naval Research Laboratory, where there were no women’s restrooms and instead she was instructed to use the private bathroom of one of the officers there2. Later on, at Georgetown University in Washington, D.C. where she got her Ph.D. in astronomy, she was prevented from meeting with her adviser in his office because women were not allowed in that part of the building3.

Dr. Rubin didn’t even like physics very much in high school. “The physics class was a big macho boys' club”, she recalls4. Her high school physics teacher made comments that undermined discoveries by women in physics and chemistry, and Dr. Rubin made a point of refusing to study physics much in response. When she later told him she had received a scholarship to Vassar College, he told her “‘As long as you stay away from physics, you should do okay5.’”

But Dr. Rubin loved astronomy. Have you ever noticed that the stars in the sky change their positions throughout the night? Dr. Rubin first noticed this as a child sleeping next to a window in her parents’ cramped house, and later learned that the stars in the sky changed with the seasons too, due to the motion of the earth. Later on she even made her own telescope so she could learn more about astronomy outside of school. She remembers this passion as the beginning of her long journey through astronomy: “As soon as I got interested in astronomy”, she says, “I just decided that's what I was going to do for the rest of my life6.”

Part 3

While she was working on her master’s degree at Cornell, Dr. Rubin was interested in the motion of galaxies. At the time, it was known that galaxies like our own were spinning, like enormous frisbees or spinning plates suspended in the universe. Many astronomers were asking the question: is the whole universe spinning too? Dr. Rubin looked for evidence of this spinning universe by searching the skies for clumps of galaxies that were all moving in the same direction, tracing out the contours of the supposed motion of the universe. By the end of her master’s degree, she had written a paper on the subject.

But her paper was never published. Today, we know that she had not actually found evidence for a spinning universe, but she did find evidence for important geometrical features of the universe around us. When she presented this research at a meeting of astronomers, many of the comments made afterwards were negative, trying to tear her work apart.

Throughout her early career, Dr. Rubin found herself in a number of situations like this that had her coming back to that question–“Will I ever really be an astronomer?” She felt out of place at meetings of astronomers, recalling, “I believe that I put these people in a very special class. They were professional astronomers, and I was not7.”

But later in her career, Dr. Rubin made a discovery that would change physics forever.

Part 4

In the 1970s, when she was appointed at the Department of Terrestrial Magnetism at the Carnegie Institution of Washington in Washington, D.C, Dr. Rubin also made measurements of individual galaxies. She wanted to know how fast each individual galaxy was spinning. Previously, physicists had predicted that stars move slower the further away they get from the center of the galaxy (their prediction came from some of the same physics in this PhysicsQuest kit!). Their model looked a little like the result of stirring heavy cream in a mixer–the cream closer to the mixer paddle moves as fast as the paddle itself, but further away the cream spins lazily without the paddle there to push it along.

When Dr. Rubin made her observations of galaxies, she found this wasn’t the case. Instead, the stars at the edge of the galaxy were moving just as fast as stars near the center. This was a huge shock–as you’ll start to see in the next activity, galaxies should fly apart if they were really spinning that fast! But Dr. Rubin made measurement after measurement, and time after time she found the same strange result. After a while, the astronomy community connected Dr. Rubin’s work to other open questions about the movement of objects through space, and found an explanation for all of these strange phenomena.

The physics that said galaxies should spin slowly wasn’t wrong–and the physics in this kit isn’t wrong either. It was just that galaxies were much, much heavier than astronomers had known, with extra gravity holding them together even as they whipped around. The extra mass was coming from dark matter, a new and unusual kind of particle that’s invisible and can pass through solid objects. Physicists still have not directly observed dark matter, and so no one knows very much about it, except that it makes up about 25% of all of the stuff in the universe (ordinary matter–the stuff you and I are made out of–only makes up a measly 5%). But Dr. Rubin’s work is the reason why we even know it exists at all.

Part 5

Dr. Rubin finally started to feel like an astronomer about 10 years after she got her Ph.D. and about 15 years before her big discovery. In 1963 she moved from Washington, D.C. to La Jolla, California for a year to work with two of her friends and colleagues Geoffrey and Margaret Burbidge She recalls,

...the best thing I got out of my time with [Geoffrey and Margaret Burbidge] was really this feeling that I could be a real astronomer. Up till that point I sort of wondered if I would, especially when I was scrubbing the kitchen floor or something. …I would occasionally say to my children, “Do you think Margaret Burbidge is scrubbing her kitchen floor?”

Then one day I called her from Washington [D.C], and I remember her saying, “Can I call you back in ten minutes, because [my daughter]’s here with her friends and I was just starting to scramble some eggs?” or something like that. And I don’t even think I ever told Margaret, but that was such a nice, reassuring sentence coming from her8.

But her story doesn’t quite end with her new sense of identity and her major discovery. She was still treated unequally from her colleagues, before and after her discovery of dark matter. In 1965, when she was working at the Palomar Observatory in California, there were no restrooms for women in the building (this time, she cut out a picture of a skirt and stuck it on one of the restroom doors to designate one herself9). Later, when she was working on telescopes high above the ground, her work hired an insurance company to insure her and her collaborator–but her male collaborator’s life was insured for four times what her life was10. At a meeting of the National Academy of the Sciences, of which she was a member, she was introduced as the mother of her son (who was an accomplished mathematician), rather than as a distinguished astronomer11.

Dr. Rubin passed away in 2016, yet her legacy can be felt throughout physics and astronomy today. A new observatory that’s meant to discover more about dark matter has been named in her honor. Her discovery injected fresh energy into many fields of physics and astronomy, leading to research initiatives all around the world. She’s a role model and a source of inspiration for countless women in physics–a field where men still outnumber women four to one. And she reminds us that self-doubt doesn’t mean you lack capability; instead, it highlights the courage it takes to push boundaries and explore something new.