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posted by cmn32480 on Friday December 30 2016, @01:11AM   Printer-friendly
from the changing-our-understanding-of-the-universe dept.

Arthur T Knackerbracket has found the following story:

[...] Renowned astrophysicist and National Medal of Science awardee Vera Rubin passed away in Princeton N.J., the evening of December 25, 2016, at the age of 88. Rubin confirmed the existence of dark matter—the invisible material that makes up more than 90% of the mass of the universe. She was a retired staff astronomer at the Carnegie Institution's Department of Terrestrial Magnetism in Washington, D.C.

"Vera Rubin was a national treasure as an accomplished astronomer and a wonderful role model for young scientists," remarked Carnegie president Matthew Scott. "We are very saddened by this loss."

In the 1960s, Rubin's interest in how stars orbit their galactic centers led her and colleague Kent Ford to study the Andromeda galaxy, M31, a nearby spiral. The two scientists wanted to determine the distribution of mass in M31 by looking at the orbital speeds of stars and gas at varying distances from the galactic center. They expected the speeds to conform to Newtonian gravitational theory, whereby an object farther from its central mass orbits slower than those closer in. To their surprise, the scientists found that stars far from the center traveled as fast as those near the center.

After observing dozens more galaxies by the 1970s, Rubin and colleagues found that something other than the visible mass was responsible for the stars' motions. Each spiral galaxy is embedded in a "halo" of dark matter—material that does not emit light and extends beyond the optical galaxy. They found it contains 5 to 10 times as much mass as the luminous galaxy. As a result of Rubin's groundbreaking work, it has become apparent that more than 90% of the universe is composed of this invisible material. The first inkling that dark matter existed came in 1933 when Swiss astrophysicist Fritz Zwicky of Caltech proposed it. But it was not until Rubin's work that dark matter was confirmed.

Besides her remarkable scientific contributions, as noted by colleague Neta Bahcall of Princeton University: "Vera was an amazing scientist and an amazing human being.  A pioneering astronomer, the 'mother' of flat rotation curves and dark-matter, a champion of women in science, a mentor and role model to generations of astronomers."

-- submitted from IRC


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  • (Score: 2) by requerdanos on Friday December 30 2016, @01:53PM

    by requerdanos (5997) Subscriber Badge on Friday December 30 2016, @01:53PM (#447409) Journal

    A large number of scientific theories start out that way, as fudge factors... 19th century astronomers saw the observed ephemeris of Uranus did not conform... sure enough, they later found Neptune.

    With respect, Neptune isn't invisible [space.com].

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  • (Score: 3, Interesting) by maxwell demon on Friday December 30 2016, @02:57PM

    by maxwell demon (1608) on Friday December 30 2016, @02:57PM (#447444) Journal

    It is, with the naked eye, as seen from earth.

    But then, we know there exists matter which fulfils all properties of dark matter, with one exception: There's not enough of it around. Which is neutrinos.

    Interestingly, Neutrinos also started out as something just introduced because the equations didn't add up. In that case, the conservation laws on beta decay. When they were introduced, people thought they would never be detected. Today, there is no doubt that neutrinos exist.

    So strictly speaking, the question should not be whether dark matter exists (it does, in the form of neutrinos), but whether enough of it exists to explain the observations (the neutrinos alone are not sufficient, as their collective mass is too small).

    --
    The Tao of math: The numbers you can count are not the real numbers.