Nikkei Science in English
Scientific America April 2022
The dark matter’s identity has been determined through astronomical observations
|By Chanda Prescod-Weinstein
|Jim Prescod Weinstein
|How do you think the dark matter problem is solved? Vera C. Rubin asked me urgently, within minutes of my presentation at the Women in Astronomy 2009 conference. To this day, I can’t remember what I said in response. I was dumbfounded: the famous astronomer who won the National Medal of Science for her work finding the first Definitive proof of the existence of dark matter was asking I, Ph.D. in her twenties. student in my opinion. I’m sure whatever I came up with wasn’t very good because it was a problem I had, up until that point, without really thinking about it. Until Robin asked me for my opinion, it had never occurred to me that I was entitled to an opinion on the question at all.
|Vera C. Rubin asked me, “How do you think we can solve the dark matter problem?” That was just a few minutes after I introduced her at the 2009 Women in Astronomy conference.
I don’t remember how I answered now. I was in awe. A famous astronomer who was awarded the National Medal of Science for discovering definitive evidence of the existence of dark matter asked me, a PhD student in his twenties, for my opinion. I had never seriously thought about the dark matter problem up until that point, so whatever answer I came up with wouldn’t be very good. I didn’t consider myself qualified to have an opinion on such issues in the first place until Robin asked me for one.
|If my answer disappointed her, she didn’t show it. Instead she asked me to sit down to lunch with her and some other female astronomers, including former NASA Administrator Nancy Grace Roman. Rubin then moved on to admire Roman, who is often referred to as the “mother of the Hubble Space Telescope”. It was a wonderful moment for me, to watch an elderly woman who unraveled one of the greatest scientific mysteries of our time and excitedly introduce us to her hero.
|Robin may have been disappointed with my answer, but he didn’t show it. Instead, she invited me to lunch with another astronomer. Among them was Nancy Grace Roman, chief astronomer at NASA. Rubin then showed his side as an ardent fan of Roman, who is often called the “mother of the Hubble Space Telescope.” It was a very memorable moment for me to watch the elderly woman who excitedly revealed one of the greatest mysteries of modern science as she presented her idol.
|Rubin cemented her legacy in the 1960s, when she studied stars within galaxies and found something strange: The stars at the edges of galaxies were moving faster than previously assumed, as if invisible matter was contributing to the gravitational pull. Her work echoed findings from galaxy cluster studies in the early 1930s by Fritz Zwicky, leading him to suggest the existence of dark matter, German for “dark matter”. Throughout the 1970s, Rubin and astronomer Kent Ford published data consistent with this conclusion, and by the early 1980s scientists were widely agreed that physics had a dark matter problem.
|In the 1960s, Rubin made his mark. At the time, Robin was studying the stars in the galaxy and noticed something strange. The stars outside the galaxy were moving faster than previously thought. It was as if there was an invisible substance in the galaxy exerting a gravitational force on the stars.
Rubin’s work builds on Fritz Zwicky’s 1930s work on galaxy clusters. From this work, Zwicky suggested the existence of a “dunkrematelier” (German for “dark matter”). Rubin and astronomer Kent Ford continued to publish data consistent with Zwicky’s theory throughout the 1970s. By the early 1980s, the prevailing view among scientists was that physics had a dark matter problem.
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