Last month, the Vera C. Rubin Observatory captured its first light , revealing breathtaking ultra-high-resolution images of wide swaths of the cosmos that were taken by the largest digital camera ever built. These early glimpses already hint at the observatory’s transformative potential as it prepares to launch the Legacy Survey of Space and Time (LSST), a decade-long project that will collect 20 terabytes of cosmic data each night. The survey aims to advance four key areas of astrophysics:

• Understanding the nature of dark matter and dark energy
• Creating an inventory of the solar system
• Mapping the structure and formation of the Milky Way
• Exploring the transient optical sky—objects that perceptibly move or vary in brightness

With the 97th anniversary of the birth of the telescope’s namesake, Vera Rubin, approaching on July 23, we’re celebrating her enduring legacy by revisiting a remarkable 1989 interview, conducted by physicist and author Alan Lightman for the 1992 book Origins: The Lives and Worlds of Modern Cosmologists. The full transcript is also available through the AIP Niels Bohr Library & Archives.

On Maria Mitchell and deciding to become an astronomer

Alan Lightman: Did you know when you were in high school that you wanted to go into astronomy, or was that later on?

Vera Rubin: Yes, by high school I knew I wanted to study astronomy. I knew I wanted to be an astronomer. I didn’t know a single astronomer, but I just knew that was what I wanted to do.

Lightman: Did you know that it was a career possibility or have some sense of that?

Rubin: Yes, I knew about Maria Mitchell, probably from some children’s book. I knew that she had taught at Vassar. So, I knew there was a school where women could study astronomy. So, yes, it never occurred to me that I couldn’t be an astronomer.

Lightman: Is that why you went to Vassar?

Rubin: Yes.

Lightman: Because of Maria Mitchell?

Rubin: Yes. That and a lot of other reasons. I needed a scholarship and they gave me one. I didn’t apply to many colleges. There were not an enormous number of colleges where a woman could study astronomy. But I knew about Vassar because of her.

On finding dark matter in galaxy rotation curves

Rubin: …Kent Ford and I. I would develop the plates. He built the instruments, and I sort of did the science, but we always observed together because we both liked to. I do remember my puzzling at the end of the first couple of nights that the spectra were all so straight. My first ideas were, by today’s ideas, just totally wrong. The first thing that came to my mind when I looked at these very straight spectra was that there must be some kind of feedback mechanism. If the stars got too fast, they were slowed down, and if they got too slow, then they were speeded up. It just didn’t look like a random occurrence. The idea of a distribution of matter that would just give you that [velocity distribution] really didn’t enter my mind at first. I remember consciously thinking that, and that’s about all. So, it just shows that your intuitive ideas or whatever, the first thing you think of, in that case, is apparently just irrelevant. It doesn’t have that much to do with [my current thinking] in that case. I was really thinking more in terms of observables than the distribution of matter.

Lightman: When you did realize that it meant something about the distribution of matter and dark matter, do you remember, as you began talking to people about this, what the reaction was?

Rubin: The reaction was two-fold. In fact, historically, we’ve left something out. After I finished the early M31 work, which was in the early 1970s, then I went back to the large-scale motion problem in the mid-1970s. My going to the rotation curves was, again, to get away from the controversy of the large-scale motion [research]. Therefore, I really loved it, because the rotation curves were so flat. Observationally, it was such a nice program. All you had to do was show someone a couple spectra, and they knew the whole story. In a sense, it was a wonderful observing program, because when you [ask] what were people’s reactions, there was never any doubt on anyone’s part that these rotation curves were flat. You didn’t have to show them measurements. You didn’t have to argue. All you had to do was show them a picture of the spectrum.

On theory and observation in astronomy

Lightman: We mentioned a little bit about your attitude towards theory. How do you think theorists and observers have worked together in cosmology over the last 10 or 20 years? Do you think it’s been a successful working relationship or do you think one has gotten way ahead of the other? How do you feel about that?

Rubin: I don’t know. Maybe I’m not a good person to answer that, because I really tend to work pretty much alone. I personally don’t often interact with theorists at all. I don’t see anything wrong with the way things have gone. I think it’s hard to point to many observations that have been made because theorists said we should. Now, maybe you could argue that the dark matter has been [an example of that]. But at the time it wasn’t.

Lightman: It sounds like in your work that was not the motivation.

Rubin: No, it wasn’t at all, and I don’t know why. In retrospect, I can’t remember theorists standing up and saying, “Galaxies have heavy halos, so go find rotation curves because they’ll be flat.”

On gender and persistence in science

Lightman: What do you think that some of the problems are that prevented other women from going into science who might have?

Rubin: I think probably it’s the way we raise little girls. I think it happens very early. I think also it’s what little girls see in the world—I was going to say the universe—around them. It’s an incredible cultural thing. I have two granddaughters. One of them—her mother and father are both professionals, her aunt and uncle who were visiting are professionals—she said her toy rabbit was sick. Her uncle said, “Well, you be the doctor and I’ll be the nurse, and we’ll fix it,” and she said, “Boys can’t be girls.” And her mother realized that she never had seen a doctor who was a woman. By the age of two, she knew that men were doctors and women were nurses. So, you may talk about role models and your thinking about colleges, but this happens at the age of two. It’s a very complicated situation. I’m not sure how you handle this. I think it’s a terrible problem; I think it sets in very young. Somehow or other, you have to raise little girls who have enough confidence in themselves to be different.

I went to a DC public high school. I was very, very interested in astronomy, and I just could keep myself going by telling myself that I was just different than other people, that they just had different interests than I did. I wasn’t really planning on telling you this, but it is so incredibly relevant. I had a physics teacher who was a real macho guy. Everybody loved him—all the males. He did experiments; he set up labs. Everybody was very enthusiastic. I really don’t think he knew how to relate to a young girl in his class, and it became a terrible battle of wills. He never knew that I was interested in astronomy; he never knew that I was interested in science. The day I learned I got my scholarship to Vassar, I was really excited because I couldn’t go to college without a scholarship. I met him in the hall, and probably said the first thing I had ever said to him outside of the class, and I told him I got the scholarship to Vassar and he said to me, “As long as you stay away from science, you should do okay.” It takes an enormous self-esteem to listen to things like that and not be demolished.

So, rather than teaching little girls physics, you have to teach them that they can learn anything they want to. When I was at Vassar, I sent off a postcard to Princeton asking them for a catalogue of the graduate school. Sir Hugh Taylor, the eminent chemist who was then the dean of the graduate school, wrote me a letter saying that [since] they wouldn’t accept women, they wouldn’t send me the catalogue. Some things are better, but a lot of them are not. My daughter is an astronomer. She got her PhD in cosmic ray physics and went off to a meeting in Japan, and she came back and told me she was the only woman there. I really couldn’t tell that story for a long time without weeping, because certainly in one generation, between her generation and mine, not an awful lot [has changed]. Some things are better, but not enough things.

Rebecca Charbonneau
American Institute of Physics
rcharbonneau@aip.org

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