Vera Rubin, “Mother of Dark Matter,” Dies

The holidays brought sad news to astronomers across the world after they learned that Vera Rubin, whose pioneering work led to the confirmation of dark matter, passed away.

Vera Rubin in 1965

Vera Rubin at Lowell Observatory in 1965.

Astronomer Vera Rubin, known for her revolutionary work confirming the existence of dark matter, died on December 25th. She was 88.

Rubin’s love for celestial motions began at a young age. In 1938, when she was just 10 years old, her family moved from Philadelphia to Washington, D.C., where she inherited a north-facing bedroom window. There, she would watch the night sky revolve, entranced by the sense of Earth’s motion. Four years later, she built her own telescope with her father and started attending amateur astronomers’ meetings.

But that isn’t to say this pioneering female scientist walked an easy path. Although her parents were supportive, Rubin received little encouragement from others to pursue her passion in astronomy. Her high school physics teacher told her to stay away from science in college. And a college admissions officer suggested she become an astronomical artist instead.

Determined nonetheless, Rubin followed in the footsteps of Maria Mitchell — the first professional female astronomer — by attending Vassar College in Poughkeepsie, New York. On a summer break she met Bob Rubin, then a graduate student at Cornell. They married after her graduation from Vassar.

Rubin completed her master’s at Cornell (her dream was to attend Princeton, but the university didn’t accept women into its graduate astrophysics program at the time) while her husband finished his PhD. The couple then moved to Maryland for Bob Rubin’s new job at the Applied Physics Lab. Thanks to a chance office arrangement, noted physicist George Gamow learned of Rubin’s master’s work on galaxies and asked to talk with her. It was a stroke of luck that ultimately led her to complete her PhD work at Georgetown University under him. Her 1954 thesis broke new ground on the spatial distribution of galaxies.

She subsequently joined the Georgetown faculty but her work remained uneventful. She focused on raising four children, who would later become scientists themselves. “It took me a long time to believe I was a real astronomer,” she told Science in 2002.

The turning point came when Rubin was invited to collaborate with Margaret and Geoffrey Burbidge at the University of California at San Diego. She and her husband spent a year working with the husband-and-wife team, who encouraged her ideas and ultimately gave her a new sense of professional accomplishment.

She returned to Maryland a changed woman, with an eagerness so strong she walked into Carnegie’s Department of Terrestrial Magnetism and demanded a job. In the following years she took multiple observing trips with collaborator Kent Ford to Kitt Peak in Arizona and Cerro Tololo in Chile. In 1965, she even became the first woman legally permitted to use the Palomar Observatory in southern California.

The new work allowed Rubin to return to her initial curiosity of stellar motions within galaxies. With new advances in technology, she was able to study the rotation of the outer reaches of galaxies much as she used to watch the rotation of the stars outside her bedroom window. Her observations of stars orbiting on the outskirts of galaxies helped spark a remarkable discovery: the vast majority of matter is invisible.

Galaxies Are Overflowing with Dark Matter

In 1933, Swiss astronomer Fritz Zwicky observed the Coma Cluster, a galaxy cluster roughly 50 million light-years across that’s filled with thousands of galaxies. He found that these galaxies move so rapidly through the cluster that it ought to fly apart. There simply wasn’t enough visible matter to hold the galaxy cluster together with its constituents zipping through it that fast. Yet the cluster was stable.

Zwicky decided there must be a hidden ingredient, which he called dunkle Materie, or “dark matter,” that held the cluster together.

The issue remained relatively quiet for the next three decades. It was Rubin, Ford, and their colleagues who gathered further evidence that individual galaxies also did not rotate as expected. Because most galaxies have a luminous central bulge composed of densely packed stars, and faint outskirts composed of far fewer stars, astronomers had largely assumed that most of a galaxy’s mass was concentrated in the center. The natural conclusion then is that galaxies should rotate much as our solar system does, where the inner planets orbit the Sun faster than the outer planets.

rotational velocities show hidden matter

This figure from Rubin's 1978 paper shows rotational velocities for seven of the 10 galaxies the team studied. If visible matter were the only matter present, the curves would dive back down on the far right. Their flatness indicates that, assuming our understanding of gravity is correct, additional unseen matter exists in the galaxies.
Rubin et al. / ApJL 1978

But the team’s work showed that wasn’t the case. In their 1978 Astrophysical Journal letter, the astronomers looked at the galactic rotation curves — graphs showing the orbital speeds of stars versus their distance from the galactic center — of 10 galaxies (seven are shown at right). If the visible matter was the only character in this story, then these curves would dip down at large distances, much like it does for the solar system.

Instead, all the rotation curves are relatively flat. The stars far from the centers of galaxies, in the sparsely populated fringes, rotate just as rapidly as the stars closer in. The team’s calculations showed that galaxies must contain about 10 times as much dark matter as light matter.

Rubin is notorious for having once said: "In a spiral galaxy, the ratio of dark-to-light matter is about a factor of 10. That's probably a good number for the ratio of our ignorance-to-knowledge. We're out of kindergarten, but only in about third grade."

Over the next decade, Rubin continued to study hundreds of galaxies, amassing even more evidence for dark matter. Although the nature of that matter remains a mystery today, it has become one of the biggest buzzwords in astronomy. Observers continue to study it, much in the same way Rubin once did, and theorists are desperate to explain it.

Rubin’s Legacy

Vera Rubin at a NASA-sponsored Women in Astronomy and Space Science Conference in 2009. NASA

Vera Rubin at a NASA-sponsored Women in Astronomy and Space Science Conference in 2009.
NASA

Rubin’s love for science swept over her family: all of her children grew up to become scientists. Judith Young was an astronomer at the University of Massachusetts, Amherst, until her untimely death due to cancer in 2014; David Rubin is a geologist with the U.S. Geological Survey; Karl Rubin is a mathematician at University of California, Irvine; and Allan Rubin is a geologist at Princeton University.

Her husband, a mathematician and physicist, was also one of her greatest supporters; he passed in 2008.

Rubin’s achievements earned her election (as the second female astronomer) to the National Academy of Sciences in 1981. In 1996 she became the first woman to receive the Royal Astronomical Society’s Gold Medal since Caroline Hershel in 1828. She repeatedly called for more women to join the sciences, providing encouragement and fighting problems that persist today. Sadly, she never received the Nobel Prize that many feel she deserved.

While many have praised Rubin for her remarkable discoveries, advancement for women in science, and successful juggling of career and family, she stands tallest as a role model in her unabashed love of astronomy. Her child-like curiosity and wonder present throughout her entire life will encourage many to come.

 

Select References:

American Institute of Physics. Oral History Interview. 1989.

Bartusiak, Marcia. "Dark Matter." Archives of the Universe: A Treasury of Astronomy's Historic Works of Discovery. New York: Pantheon, 2004.

Irion, R. "VERA RUBIN PROFILE: The Bright Face Behind the Dark Sides of Galaxies." Science 295.5557 (2002): 960-61.

Rubin, V. C. et al. “Extended rotation curves of high-luminosity spiral galaxies. IV – Systematic dynamical properties, SA through SC.” Astrophysical Journal Letters. November 1, 1978.

 

 

10 thoughts on “Vera Rubin, “Mother of Dark Matter,” Dies

  1. Barbarina

    You are not being “clever” but disrespectful to my father’s memory, the Father of Dark Matter.
    Rubin incessantly advanced herself as the “Discoverer of Dark Matter” which was corrected by Vassar College, PBS Makers Women, and a front page correction in the Poughkeepsie Journal. I encountered a sonorous chorus of trumpeters on a continuum, who even sought to advance the undeserved credit to seek the Nobel Prize.
    My father can now finally rest assured and in peace that credit for his amazing work and prescient discovery, Dark Matter, will be freed from this endless and disrespectful campaign. I hope that you and other journalists
    will respect my father’s memory and work and follow suit.

    FRITZ ZWICKY – FATHER OF DARK MATTER

    History tells us that prophets are persecuted during their lifetime only to have their prescient

    theorem realized and acknowledged by the prevailing hierarchy decades or centuries later. The surety

    for the powers of intellectual obfuscation are twofold, literary malefic of the prophet or the assignment

    of credit posthumously to a masquerader of their time.

    The assignment of forced credit to Vera Rubin as the authentic discoverer of dark matter is not

    only errantly untrue but lamentable, in light of the hostile established guard advancing this fallacy, that

    was resistant to my father in his time, advancing literary assaults which became as common as grains of

    sand, but were equally unstable, holding no structure thus becoming dissolute with the tide and time. To

    ascribe credit to Vera Rubin as the discoverer of dark matter pollutes the real contribution of her life’s

    work, which is equally lamentable to the assigned forced credit displacing Fritz Zwicky. The

    advancement of bringing the gravitational phenomena of dark matter to light and into the modern

    consciousness of physicists worldwide would have regardless been unsealed from the echoes of my

    father’s original work in 1933.

    Fritz Zwicky: “I consequently engaged in the application of certain simple general principles of

    morphological research, and in particular the method of Directed Intuition that would allow me to

    predict and visualize the existence of as yet unknown cosmic objects and phenomena.”

    Fritz Zwicky’s eidolon was realized from the results of his observations published in “Die

    Rotverschiebung von extragalaktischen Nebeln”, Helv. Phys. Acta 6, 110-127 (1933). English

    translation Johannes Nicolai Meyling – Barbarina Exita Zwicky (2013).

    Fritz Zwicky discovered Dark Matter and coined, dunkle (kalte) Materie (cold dark matter) in

    his 1933 article referenced above. The Mass-Radial Acceleration Discrepancy by measuring the speeds

    of galaxies in the Coma Cluster originated with Fritz Zwicky, not Rubin, as using the more

    challenging methodology of the virial theorem, by relating the total average kinetic energy and the total

    average potential energy of the galaxies of the Coma Cluster. He advanced that the virial for a pair of

    orbiting masses is zero, and used the principle of superposition to craft the argument to a system of

    interacting mass points. Zwicky then used the position and velocity measurements to determine the

    mass of the galaxy cluster.

  2. Wayne H. Warren JrWayne H. Warren Jr

    Ms. Hall has written a nice article about Vera Rubin, but I must dispute what she writes in the first paragraph about “confirmation”. The existence of dark matter has not yet been confirmed because it has neither been directly observed nor identified. The evidence is strong, to be sure, but we are not quite there yet. This in no way detracts from the brilliance of Vera Rubin’s work.

    On a stronger note, I must disagree with what Barbarina stated. In many conversations over the years, I never heard Vera claim that she had “discovered” dark matter. I also heard her, on several occasions, give Fritz Zwicky credit for having first hypothesized the existence of unseen material in clusters of galaxies.

    1. rocksnstarsrocksnstars

      “One could make the argument that the correct formulation of her achievement is that she discovered evidence for the existence of dark matter, and while Rubin likely would have acquiesced to that construction, she would have found it incomplete, perhaps even misleading. She would have said that while she discovered evidence for the existence of dark matter, you shouldn’t infer from that statement that dark matter actually exists.” ~ Richard Panek (in the link below)

      https://blogs.scientificamerican.com/guest-blog/vera-rubin-didnt-discover-dark-matter/

    2. SpenceB

      Barbarina seems to have become sensitized as to the credit for discovery and has lumped together all of the otherwise involved. I suspect she did not read much past the misleading title of a well-written article, except for stating that dark matter has been confirmed to exist. It is for now only a possibility that can fit the observations.

  3. Graham-Wolf

    RIP Vera Rubin.
    The “Dark-Matter Lady”.

    Nearly all my heroes and role models are women.
    Vera Rubin was right up there, with Caroline Herschel and Annie Jump Cannon, for me.
    WOW!

    What an incredible female astro-physicist!!
    The only one of her kind.

    Regards from 46 South, NZ.

    Graham W. Wolf.

  4. Graham-Wolf

    Sad to see such strong comments (and put-downs) about Vera Rubin. Zwicky is the “father” of dark matter, and Vera Rubin is the “mother”. Both sobriquets are mutually compatible, in my opinion, and should have never generated any offence. As a former NZ National Obs staff member and professional astronomer, I admire them both. We often spoke of Rubin and Shoemaker around the Carter National Observatory Morning Tea table, with deep professional respect and admiration.

    We must also appreciate and understand that women have had to fight the “glass ceiling” in astrophysics (and other fields too). Our own Kiwi- raised Beatrice Tinsley (who initially studied at Christchurch) was only one such example…. Vera Rubin is a more recent example. In the 1960’s people like Sandage et al, could metaphorically walk right into Palomar and have the proverbial “run of the place”… women astronomers were totally barred, other than public daytime tourists! Vera broke that mould for sure. Then along came Carolyn Shoemaker… another astro-hero of mine!

    Promotion and University tenure should always be based on ability and competence, not on gender. I have never known Vera Rubin to bad-mouth anyone, let alone Zwicky… she was most humble and very quietly spoken. Yes, she had a dry wit at times… that just seemed to make her even more wonderful. She freely and unconditionally praised other’s. I enjoyed Shannon’s wider-scoping bio on Vera… excepting one small slip (forgiveable). The first professional astronomer was indeed Caroline Herschel… one of my paramount heroes, above Galileo. I acknowledge the awesome Maria Mitchell as the first USA professional astronomer, and Vassar College as an “academic sanctuary” for forthcoming female astro-luminaries… let’s have more! I would have considered it an honour to have studied at Vassar, but I’m not female. The Nobel Prize in physics is hugely competitive… particle physicists tend to get more attention than astro-physicists.. I think Ryle and Hewish are the only 2 successful ones. To be merely nominated as vera was, is a huge honour in itself.

    Vera has joined the astro-ancestors… let us all globally rejoice in her hard work, and contribution to science, and please let her rest in piece. She has secured a proud place in our global scientific history:- most deservedly. Thank you Vera, for your wonderful efforts and raising the bar so high for the rest of us lesser astro-mortals. Say “hi” to Patrick up there, for me. I proudly salute you! Regards from 46 South, NZ. Graham W. Wolf.

  5. Graham-Wolf

    Apologies for my recent typo.
    Caroline Herschel was the first professional FEMALE astronomer.
    Her brother William (discoverer of planet Uranus) was immediately offered a salary stipend by King George of England, and only accepted it in the condition that Caroline was also given one. The king was so impressed with Caroline’s efforts and William’s raving about her, he just couldn’t refuse! If you care to look at William’s Observing logs (I used to have photocopies before they were stolen), you’ll soon see all the data is in Caroline’s own handwriting:- not William’s. She also helped her brother build several of his telescopes, and I understand, she even discovered eight comets. AND in her spare time, she was a world-class opera singer!

    It’s interesting that many female astro-luminaries claim a strong motivational closeness to Caroline (as I also do). I suspect Vera was another example.

    Regards from 46 South, NZ. Graham W. Wolf.

All comments must follow the Sky & Telescope Terms of Use and will be moderated prior to posting. Please be civil in your comments. Sky & Telescope reserves the right to use the comments we receive, in whole or in part, and to use the commenter’s username, in any medium. See also the Terms of Use and Privacy Policy.

COMMENT