Her findings highlighted how much we don’t know. Astronomers thought they were studying the universe, she once said, “and now we learn that we are just studying the 5% or 10% that is luminous.”
Her breakthrough arose from research—started in the 1960s and conducted with Kent Ford—into how fast stars orbited around galaxies. It was assumed that mass in galaxies was concentrated in their luminous centers. If so, the stars farthest from that center were expected to orbit more slowly because they would be subject to less gravitational pull. Instead, Dr. Rubin found they orbited at about the same speed. The finding suggested there must be some other, unseen masses exerting gravitational force.
Dark matter had been posited by the Swiss astrophysicist Fritz Zwicky in 1933, but now there was powerful evidence for it. Her observations of orbital speeds forced other theorists to rethink their ideas. She considered herself an observer, not a theorist. “The role of observers,” she wrote in 1995, “is to confound the theorists,” spurring them toward better models.
WSJ, James R. Hagerty, 12/31/16
HOW VERA RUBIN CONFIRMED DARK MATTER