> Red shift is not caused by dust, and it is not "tired light". Gamma and
> x-rays don't give a whit about dust, yet they are equally red shifted.
> Even the duration of supernovas are red shifted.
> 
> David A. Smith


Well, why wouldn't they be? If x is the displacement from earth to
the galaxy at the time the light is emitted, then x=ct, where c is the
velocity of light.
Since the light is deflected, whether by some average or not, a photon
travels a longer distance than x to get to earth. If we call that
longer distance d, then d=ct where c is the speed of light and t is
the time it takes for the light to get to earth. But since d>x, and
c=c=300,000 km /sec, even though one c is velocity and the other is
speed, then t in the second equation is greater than t in the first
equation.
In other words, relative to the light, a clock on earth is running
faster than a clock on the galaxy, or the light is redshifted.

If we consider light from our sun being observed at the galaxy,
relative to the light, a clock on the galaxy is running faster than a
clock on earth,meaning that the light from the sun would be redshifted
to a person at the galaxy.

Robert B. Winn