Vera Rubin (1928-2016)

by Paul Gilster on December 28, 2016

When Vera Rubin went to Cornell University to earn a master’s degree, she quickly found herself immersed in galaxy dynamics, lured to the topic by Martha Stahr Carpenter. The interest, though, was a natural one; it drew on Rubin’s childhood fascination with the motion of stars across the sky. You could say that motion captivated her from her earliest days. At Cornell, she studied physics from such luminaries as Richard Feynman, Philip Morrison and Hans Bethe. She would complete the degree in 1951 and head on to Georgetown.

Rubin, who died on Christmas day, was possessed of a curiosity that made her ask questions others hadn’t thought of. In Bright Galaxies, Dark Matters (1997), a collection of her papers, the astronomer recalls writing to Milton Humason in 1949, asking him about the redshifts he and his colleagues were compiling. Rubin had heard that many had yet to be published, and she would use those she had to look for systematic motion among the galaxies, motion that would show up if you removed the Hubble expansion from the data.

“I found that many of these galaxies defined a great circle on the sky, or roughly a circle, and that there were large regions of positive and negative values of residual velocity,” Rubin told editor Sally Stephens in a 1992 interview. “What in fact I really found was the supergalactic plane, although I entitled the paper ‘Rotation of the Universe.’”

Rubin tended to dismiss this early work in later life (“I presume none of this work would hold up today”), and her paper was rejected by the Astrophysical Journal as well as the Astronomical Journal, though later presented at a 1950 AAS meeting. Even so, the questions she raised were hugely significant, and at the time under study by Kurt Gödel at Princeton, the school that turned down her graduate application because of her gender. What Rubin was homing in on was the presence of large-scale galactic motion.

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Today, we talk about the Rubin-Ford effect, the observation that describes the motion of our galaxy relative to a sample of galaxies at varying distances and compares this to its motion relative to the cosmic microwave background (the Ford here is Kent Ford, an astronomer whose spectrometer became critical for Rubin’s studies of stellar motion in spiral galaxies). Early work that had been flawed by insufficient data would eventually grow into this result.

I always tend to link Rubin and Fritz Zwicky in my thinking. Way back in 1933, the Swiss astronomer who taught most of his career at Caltech was noting discrepancies between the apparent mass of galaxies in the Coma cluster and the amount of light they produced, leading him to coin the phrase ‘dunkle Materie’ (dark matter) to explain the effect. Both Zwicky and Rubin had an uncanny knack for seeing places where the universe was posing questions. For Rubin, it would become the motion of spiral galaxies that defined her career.

The problem leaped out at astronomers once Rubin put her finger on it. You would expect galaxies to spin in fairly conventional ways, with stars nearer the center moving faster than those on the outskirts, just as in our own Solar System, the inner planets orbit the Sun much faster than the outer worlds. But by 1974 Rubin was able to show that the outer stars in spiral galaxies move much faster than could be explained by the mass of the visible matter in the galaxies. Dark matter again reared its head, and became the subject of intense investigation.

We still haven’t observed dark matter directly, though the current calculation is that about 27 percent of the universe is made up of the stuff, with only 5 percent being the normal matter we had until recently assumed was all there was. By 1998, we had learned, too, of dark energy and the continuing expansion of the universe, yet another mystery demanding an explanation. The dark energy work would produce a Nobel Prize; dark matter has yet to do so. Rubin’s exclusion from the Nobel occupies much of the media commentary on her death. I think Phil Plait’s discussion is on the money.

Rubin would put her painstaking methods to work on over 200 galaxies in her career. Finishing her PhD in 1954 (her thesis advisor at Georgetown was George Gamow, a science popularizer and early advocate of Big Bang theory), Rubin taught at Georgetown for eleven years before joining the Carnegie Institution for Science in 1965, where she began her collaboration with Ford. She would become the second female astronomer elected to the National Academy of Sciences and would receive the National Medal of Science in 1993.

Rubin’s loss resonates through the world of astronomy and is keenly felt by the many she influenced, especially women who were inspired by her example to tackle a career in the physical sciences. We can measure careers by papers published and ideas propagated, but it’s all too easy to miss the more intangible factors like lives touched and careers launched. On all these scores Vera Rubin deserves the thanks of the field she did so much to shape.

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{ 11 comments… read them below or add one }

Daniel Fischer December 28, 2016 at 15:14

The question why Dark Energy has gotten the Nobel Prize already while Dark Matter has not (yet) was actually ANSWERED – by the Nobel Committee itself, at the very event announcing the prize for DE! For the first question asked during the immediately following Q&A was hey, what about DM (and Rubin in particular)? And the answer was that the discovery history of DM was much more convoluted and there were still investigating who the key players were. Guess what, this is true: It was a process stretching over some five decades and involving many important people entering and leaving the field again. Only in Rubin’s time – and thanks in particular to her diligent work – did it become clear that flat galaxy rotation curves are a general phenomenon worthy of a general and possibly dramatic explanation – which DM probably is, but direct proof has remained elusive. That’s a rather typical process in the history of astronomy which the rules of the Nobel Prize – esp. the maximum number of three laureates – just isn’t very suited to honor.

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Ron S December 28, 2016 at 20:00

Every year it gets less “convoluted” as the scientists involved, such as Rubin, die. Nobels are not awarded posthumously. Perhaps when there are only three left.

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Stanley Winford January 8, 2017 at 6:33

That’s fascinating; I never knew the Nobel Committee ever addressed the question. Do you have a link to a transcript of video of the Q&A? I’m curious to see exactly what they said.

I don’t agree that the history is very convoluted, or that the key players are unclear. There was a Nobel prize for the Higgs boson, even though the theory paper that proposed it had 6 authors while the experimental paper that confirmed it had 178 authors. Similarly Penzias and Wilson got the Nobel for discovering the CMB, even though they weren’t looking for it and didn’t know what they found after stumbling across it. People who worked on the Big Bang theory, predicted the CMB, etc. never got the prize.

In the dark matter case, there are only 3 real contenders for the prize: Zwicky, Rubin, Ford. Zwicky is long dead, and his measurements were off by an order of magnitude. Rubin and Ford were the only authors on the galaxy rotation curves paper, and it was Rubin’s work that eventually convinced everyone of the need for dark matter. In comparison to many other Nobel prizes, Rubin + Ford is a relative no-brainer.

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Daniel Fischer January 8, 2017 at 16:03

Show me a scholarly peer-reviewed review paper about the discovery history of the flat galaxy rotation curves that singles out Ford and Rubin. I have looked while writing an obituary – and to my great surprise I found only late 1970s or 1980s reviews that mention other names as the key players. So did Rubin herself in a major paper in 1978, by the way. This is at least a serious warning sign that the the “popular” account is at least incomplete (as is more the rule than an exception in the history of astronomy) – a sign that the Nobel Committee apparently saw. They addressed the question during Q&A after the 2011 announcement of the Dark Energy prize, “what about Rubin?” was the first question asked. Unfortunately from the recording of that press conference on their website the Q&A is missing. Still looking for recordings elsewhere; some TV stations may have carried – and archived – the clean feed.

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ljk December 28, 2016 at 16:06

How Vera Rubin changed science

By Sarah Kaplan

December 27 at 1:17 PM

Vera Rubin didn’t plan to be a pioneering female astronomer. When she was 10, lying awake at her home in Washington, memorizing the paths of the stars outside her window, “I didn’t know a single astronomer, male or female,” she once said in an interview. “I didn’t think that all astronomers were male, because I didn’t know.”

But pioneer she did. Rubin’s work fundamentally changed astronomy by confirming the existence of dark matter, the invisible stuff that makes up 27 percent of the universe.

The way she worked changed astronomy, too. The field may have been all male when she entered it 70 years ago. But by the time she died Sunday, at age 88, that was no longer true. That’s in large part thanks to Rubin: a brilliant mentor and fierce advocate for women in science.

“She made science kinder & the culture of research more human,” tweeted Mika McKinnon, a science writer and geophysicist.

Full article here:

https://www.washingtonpost.com/news/speaking-of-science/wp/2016/12/27/how-vera-rubin-changed-science/?utm_term=.d0c128dd2e38

To quote:

But if the institutions of astronomy would not accommodate her, Rubin was not afraid to change them. In the mid-1960s, she was granted access to San Diego’s prestigious Palomar Observatory, an old boys’ club so infamous astronomers called it “the monastery.” Though she could use the telescope, Rubin was informed that there was nowhere for her to relieve herself — the facility had no women’s restroom.

“She went to her room, she cut up paper into a skirt image, and she stuck it on the little person image on the door of the bathroom,” former colleague Neta Bahcall of Princeton University told Astronomy magazine in the fall. “She said, ‘There you go; now you have a ladies’ room.’ That’s the type of person Vera is.”

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ljk December 28, 2016 at 16:13

Vera Rubin: 1928–2016

She was a vibrant role model for women in astronomy but was not defined by, nor will she be remembered for, her gender but rather by her remarkable contributions as a scientist.

By Lawrence M. Krauss on December 26, 2016

Full article here:

https://blogs.scientificamerican.com/guest-blog/vera-rubin-1928-2016/

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Alex Tolley December 28, 2016 at 18:04

Shouldn’t we be cautious about Dark Matter? It seems to me we are going down ever more exotic paths to define what it is. Perhaps it is time to more seriously reconsider gravity to see if various alternative solutions might account for the effects we attribute to DM.

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Paul Gilster December 28, 2016 at 20:52

You’re reading my mind, Alex…

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Ron S December 29, 2016 at 0:27

There are many alternatives and the better ones are seriously considered. But so far none does better at addressing all the evidence than DM, not just galaxy rotation. For example, gravitational lensing and galaxy formation in the early universe. It’s interesting to watch the work on this topic progress.

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Brett Bellmore December 29, 2016 at 7:44

“You would expect galaxies to spin in fairly conventional ways, with stars nearer the center moving faster than those on the outskirts, just as in our own Solar System,”

Planets near the center of the Solar system move faster than more distant planets, because virtually all of the mass in the Solar system is concentrated in one body, “the Sun”. Mercury and Venus simply don’t mass enough to appreciably increase Earth’s orbital velocity.

This is visibly not the case for most galaxies, where much of the mass is distributed around in the form of stars. So you wouldn’t expect orbital velocities to drop off in the same way for a galaxy; The further you get from the center, the more mass is in that direction pulling you, and so your orbital velocity doesn’t drop off in the same manner.

The ‘dark matter’ thing comes up because, if you try to calculate the mass distribution based on visible stars, you still don’t get the right orbital velocities. So there has to be a lot of mass present you can’t see, and distributed in a different fashion from the mass you can see.

That doesn’t necessarily imply that it’s some exotic particle, of course. But we do know there’s a lot of mass present that we can’t see. OR gravity is behaving differently than we think, of course.

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Alex Tolley January 6, 2017 at 17:49

Vera Rubin Didn’t Discover Dark Matter

Apparently, she was eventually skeptical and considered it might be something to do with gravity.

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