The Rubin–Ford effect is, per Ian Ridpath's astronomical dictionary, an apparent rather than actual "

anisotropy Anisotropy () is the property of a material which allows it to change or assume different properties in different directions, as opposed to isotropy. It can be defined as a difference, when measured along different axes, in a material's physic ...

in the expansion of the Universe on a scale of around 100 million ight yearsas revealed by a study of the motions of a sample of spiral galaxies," as initially described by

Vera Rubin Vera Florence Cooper Rubin (; July 23, 1928 – December 25, 2016) was an American astronomer who pioneered work on galaxy rotation rates. She uncovered the discrepancy between the predicted and observed angular motion of galaxies by study ...

, William Kent Ford Jr., and Norbert Thonnard of the

Carnegie Institution of Washington The Carnegie Institution of Washington (the organization's legal name), known also for public purposes as the Carnegie Institution for Science (CIS), is an organization in the United States established to fund and perform scientific research. Th ...

, Morton S. Roberts of the National Radio Astronomy Observatory, and John A. Graham of the

Cerro Tololo Inter-American Observatory The Cerro Tololo Inter-American Observatory (CTIO) is an astronomical observatory located on Cerro Tololo in the Coquimbo Region of northern Chile, with additional facilities located on Cerro Pachón about to the southeast. It is approximately ...

, in

La Serena, Chile La Serena () is a city and commune in northern Chile, capital of the Coquimbo Region. Founded in 1544, it is the country's second oldest city after the national capital, Santiago. As of 2012, it had a communal population of roughly 200,000, an ...

. Specifically, their conclusion was that a sample of galaxies (referred to as ScI) was, on the whole, moving with a velocity of 885 km s⁻¹ toward a specific astronomical position (l = 304°, b = 26°) relative to the microwave background radiation, which, because it is isotropic, provided a frame of reference for the measurement. Also available as
2002 update
and in a

an

all retrieved December 28, 2016. The description by

Rubin Rubin is both a surname and a given name. Rubins is a Latvian-language form of the name. As a Jewish name, it derives from the biblical name Reuben. The choice is also influenced by the word ''rubin'' meaning "ruby" is some languages.

and colleagues, first appearing in 1976, is considered pioneering work, and has been the subject of "intense discussion" since its first report. The effect, however, is now seen as being apparent, and the data from which it was derived "probably only reflect the inhomogeneous distribution of galaxies in the region of the Rubin–Ford sample"—i.e., that "the Universe is not homogeneous on these scales"—and are actually "consistent with isotropic expansion, an unperturbed galaxy velocity field and hence a low density Universe." As indicated by the opening definition, and as described by Bernard J.T. Jones in review in 2002, the data on which the conclusion of an effect was based are:

References

{{DEFAULTSORT:Rubin-Ford effect Observational astronomy Extragalactic astronomy