In article , jacobnavia
writes:

If the sea of galaxies extends to infinity (or to huge distances) the
farther you look, the more galaxies you will observe for a given solid
angle. At great distances you will see a wall of galaxies that fills
completely the view. The (very red-shifted) light from those galaxies is
the CMB.

[MODERATOR:]
Moreover, you're basically invoking Olber's paradox here... but you
only get the every-line-of-sight-intersects-a-galaxy result *if*
(a) the universe has a flat topology (ok, we're probably close to
that), and

OK.

As I noted in another post, this is irrelevant.

(b) there's no redshift to reduce the energy we receive from the
more distant galaxies, and

Mmmm why shouldn't be a red shift?

There is. You essentially said the farther one looks the more one sees.
The moderator noted that this result is changed somewhat if there is a
redshift. He didn't say there is no redshift, quite the opposite. This
is a misunderstanding. He was implying that you claimed that there is
no redshift since that is necessary for the "farther one looks the more
one sees" argument to work.

I do not think that this is a Doppler effect, and I do not know at all
what it is.

Again, read Edward Harrison's textbook. There is a whole chapter on
this. The cosmological redshift is well understood (despite some
confusing things one can find in some of the literature).

Of course there is a red shift, that imposes a limit to the galaxies we
can possibly observe.

Not sure what you mean here. It makes them more difficult to observe,
but there isn't a hard limit.

And the redshift reduces the energy we receive from galaxies much
farther away. That is certain, the light is redder, then it has less
energy. Up to a limit imposed by the structure and mass of the observer,
it becomes undetectable berlow a certain limit.

OK.

Should it have a perfect black body spectrum?

I do not know but apparently it has one.

As Steve Willner mentioned, adding up galaxy spectra does NOT produce a
black-body spectrum. Why do you claim that it does? Or are you
claiming that the CMB does? The CMB does indeed, but it is not composed
of recycled light from galaxies; one argument it that this does not
produce a black-body spectrum. You seem to be saying: recycled galaxy
light makes the CMB; the CMB has a black-body spectrum; I don't know why
it does.

Too many observations point to
that, but WHY it has this shape I surely can't explain.

The standard CMB explanation explains it.

(c) the galaxies are infinitely old (so their light has had time to
get to us) *and* have been producing lots of light for that
infinite time).

How old is the Universe? I do not know. The observable universe is at
least (if the calculations using "z" are right) 13.5 Gy old. Do galaxies
farther away look younger? Maybe, even if we have discovered old
galaxies very very far away, that look bigger than ours even.

The whole point is that we cannot observe galaxies which are older than
the universe. We also cannot observe things beyond the observable
universe, by definition. Check out the chapter on horizons in
Harrison's textbook.

As far as the VLT and Hubble scopes can see, it goes on and on.

No. Even they can't see beyond the horizon. Yes, it could go on and
on, but that is not something which we can directly observe.