Mathematics – Logic
Scientific paper
Apr 1997
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997nrao.pres....5.&link_type=abstract
NRAO Press Release, 04/1997
Mathematics
Logic
Scientific paper
A claim that the universe has a preferred direction is not supported by recent observational evidence, according to three astronomers who analyzed data from the Very Large Array (VLA) radio telescope in New Mexico and the W.M. Keck Telescope in Hawaii.
John Wardle of Brandeis University, Rick Perley of the National Radio Astronomy Observatory, and Marshall Cohen of the California Institute of Technology responded to an article in the April 21 issue of Physical Review Letters, in which Borge Nodland of the University of Rochester and John Ralston of the University of Kansas claimed to have found that the universe has a distinct axis that affects electromagnetic radiation (light, radio waves, etc.).
Nodland and Ralston said that their analysis of previous radio observations of 160 galaxies, made in the 1970s and 1980s, showed that radiation coming from objects had its direction of polarization rotated by different amounts, depending on the direction of the galaxies. The amount of polarization rotation, they said, increases with the distance of the galaxies, and depends on direction, indicating that the universe has an axis along which more rotation occurs.
Wardle, Perley and Cohen say that recent, high-quality observations with the VLA and the 10-meter W.M. Keck telescope show "that the radio and optical data directly refute" the contention of Nodland and Ralston. The more-recent data, consisting of polarization images of galaxies and quasars at a variety of distances and in different directions, simply do not show any evidence for Nodland and Ralston's "cosmic corkscrew" effect, the researchers say. Wardle, Perley and Cohen have submitted their results to Physical Review Letters.
Galaxies and quasars, and the "jets" of subatomic particles ejected at great speeds by some of these objects, have definite patterns of polarized emission of light and radio waves. These patterns are well-known and established. If the polarization of their light were rotated by some cosmological effect, the known relationships between the objects and the direction of polarization of their light should be altered, Wardle, Perley and Cohen reasoned. They examined polarization images to seek evidence for such alteration.
For example, the quasar PKS 2209+152, nearly 9 billion light-years distant, should, according to the Nodland and Ralston "corkscrew" hypothesis, have had the polarization of its radio emission rotated by about 90 degrees. Instead, VLA observations showed no rotation at all.
After studying VLA and Keck data on 26 galaxies and quasars, Wardle, Perley and Cohen conclude that "the observational data at both optical and radio wavelengths show that any rotation of the plane of polarizaton over cosmological distances is unmeasurably small and is indistinguishable from zero."
Wardle said, "The best fit to the high resolution optical and radio data shows that any effect is at least a hundred times smaller than that claimed by Nodland and Ralston."
The VLA is an instrument of the National Radio Astronomy Observatory, a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc. The W.M. Keck Observatory is operated as a scientific partnership between the California Institute of Technology, the University of California and NASA; it was made possible by the generous financial support of the W.M. Keck Foundation.
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