"Roland PJ" wrote in message oups.com...
Red-shift of distant objects could be due to two different reasons:

1. Recession speed away from the earth, a special relativistic
effect.
2. Time dilation due to proximity to a concentration of mass, a
general relativistic effect.

It seems that most discussion of red-shift centres around the
assumption that SR recession is the cause (and hence that the universe
is expanding).

Why has GR time dilation been eliminated as a cause?

It has not been eliminated it is a contributing factor.
See:

http://en.wikipedia.org/wiki/Gravitational_redshift
http://physics.ucr.edu/~wudka/Physic...ww/node99.html

--
Martin Hogbin