Uniform expanding universe questions.

Pre-amateur astronomer here. Take it easy on me!

I've been told many times that the universe is expanding uniformly
since the beginning; all objects are moving away from each other,
which makes it seem like every point is the center. Now, I'm not
questioning the validity of that statement - though I probably should
- because it seems that everything I read/hear says nearly the same
thing.

With that said, I would like to know (1) how it's possible that
galaxies collide if everything is expanding away from everything else,
or why we would see blue shifting galaxies at all (Andromeda).

(3) If a galaxy 1000 light years from here is moving away from us at
1000 miles per second (for example), and a galaxy 2000 light years
away is moving 2000 miles per second away from us, you would only have
to get 186000 light years away before the objects are moving away from
us as fast as the speed of light, right? That means that on that edge
we might eventually see a flicker of their light, but then we'll start
seeing less and less of the universe from then on, right? Because
that part of the universe is expanding away from us faster than light
can travel to us.

Well, I can hear the forehead slaps now, just take it easy on me.

Thanks,
Pope Darren

Dear PopeDarren:

wrote in message
...
Pre-amateur astronomer here. Take it easy on me!

I've been told many times that the universe is
expanding uniformly since the beginning; all
objects are moving away from each other,
which makes it seem like every point is the
center. Now, I'm not questioning the validity of
that statement - though I probably should
- because it seems that everything I read/hear
says nearly the same thing.

With that said, I would like to know (1) how it's
possible that galaxies collide if everything is
expanding away from everything else, or why
we would see blue shifting galaxies at all
(Andromeda).

Expansion (so far) does not affect "gravitationally bound
systems". This includes, for example, the Virgo supercluster, of
which Andromeda and the Milky Way are members.

Missing (2)

(3) If a galaxy 1000 light years from here is moving
away from us at 1000 miles per second (for example),
and a galaxy 2000 light years away is moving 2000
miles per second away from us, you would only have
to get 186000 light years away before the objects are
moving away from us as fast as the speed of light,
right?

With that example, yes.

That means that on that edge we might eventually
see a flicker of their light, but then we'll start seeing
less and less of the universe from then on, right?

No and yes. Consider that for classical Doppler (sound) the
fastest receding "redshift" of sound is x2. The CMBR is
redshifted by more than x1000. But much of what we are seeing
now, is no longer within our Rindler horizon.

Because that part of the universe is expanding away
from us faster than light can travel to us.

See the old stuff is not moving away from us, as mauch as new
space is being created between us. Like salt water taffy between
your two hands... sagging, generating longer paths along the
taffy between your hands.

Well, I can hear the forehead slaps now, just take
it easy on me.

Why? Just because you are using your brain? That is a good
thing. You might want to start he
http://www.astro.ucla.edu/~wright/cosmo_01.htm
http://www.astro.ucla.edu/~wright/co...y_faq.html#FTL
http://www.astro.ucla.edu/~wright/photons_outrun.html

Good reading!

David A. Smith