It's based on Borge Nodland's thesis work, which he completed in
1995, but its just now being publicized because it appears in the
21Apr97 Phys Rev Letters.
Nodland describes the effect as the sort of thing produced by magnetic
fields, but dismisses mag field correlations on billion light year
scales as improbable, and so opts for saying the speed of light is
anisotropic. Having just heard a talk here at Caltech on the
mysteriously large strength of most large scale (including galactic)
magnetic fields, I'm inclined to guess that there really are billion ly
scale correlations of magnetic fields.
I think that the next 15-20 years will be a golden era for empirical
and hopefully also theoretical cosmology. There are so many projects
that promise to bring lots more data in soon on 10 billion light year
scales, which should finally give theorists some real concrete clues.
The next 20 years will be the time we finally learn the overall
structure of the universe that we hope to spend the next 10+ billion
years colonizing (assuming no FTL).
Robin D. Hanson hanson@hss.caltech.edu http://hss.caltech.edu/~hanson/