  Surface brightness data can distinguish between a Friedman-Robertson-Walker
expanding universe and a non-expanding universe. For surface brightness
measured in AB magnitudes per angular area, all FRW models, regardless of
cosmological parameters, predict that surface brightness declines with redshift
as (z+1)^-3, while any non-expanding model predicts that surface brightness is
constant with distance and thus with z. High-z UV surface brightness data for
galaxies from the Hubble Ultra Deep Field and low-z data from GALEX are used to
test the predictions of these two models up to z=6. A preliminary analysis
presented here of samples observed at the same at-galaxy wavelengths in the UV
shows that surface brightness is constant, mu=kz^0.026+-0.15, consistent with
the non-expanding model. This relationship holds if distance is linearly
proportional to z at all redshifts, but seems insensitive to the particular
choice of d-z relationship. Attempts to reconcile the data with FRW predictions
by assuming that high-z galaxies have intrinsically higher surface brightness
than low-z galaxies appear to face insurmountable problems. The intrinsic FUV
surface brightness required by the FRW models for high-z galaxies exceeds the
maximum FUV surface brightness of any low-z galaxy by as much as a factor of
40. Dust absorption appears to make such extremely high intrinsic FUV surface
brightness physically impossible. If confirmed by further analysis, the
impossibility of such high-surface-brightness galaxies would rule out all FRW
expanding universe (big bang) models.
