I have a question that has been bothering me for years. I find it so
confusing that it is difficult to formulate the question.  But I
finally have come up with a "stage-setter", followed by the fairly
short question that must be followed by other secondary questions that
help clarify exactly what the primary the question is, and what my
confusion is.  They are all the same question to me.

I have a Master's in Chemical Engineering, read Scientific American,
and am familiar with modern cosmoslogy on the level of that magazine,
and don't mind seeing the mathematics behind the answer, even though I
am very stale in that.
My favorite course in graduate school was "Transport Phenomenon",
which used math that would have some relation to that used in
cosmology, I would think.

Every so often astronomers announce that they have discovered a new
set of galaxies on "the edge of the universe" that may be, say, 12
billion light years away.

The short question is: Why is the light from those galaxies just getting to us now?

Secondary questions:  Isn't the universe expanding?  Doesn't that mean
that those galaxies were much closer to the cosmological coordinates
that represent "us" 12 billion years ago when the light first left on
its journey?  Why didn't it "arrive" billions of years ago?  Shouldn't
we be seeing "newer" light? Or, is the universe expanding faster than
the speed of light?  Is the galaxy "12 billion light years away" based
on "now" or based on "then"?

It is my guess that my confusion has something to do with the fact
that it is SPACE itself that is expanding.

If this question can't be answered outright, can you at least give me
references that address this?

Pardon the pun, but I think I can shed some light on the situation...

>> Why is the light from those galaxies just getting to us now?
   It's not so much that light is just now arriving here at Earth, but
that our detectors (and techniques) are improving. The light from
distant objects has been reaching earth for some time- it's not as
though an astronomer was peeping at the sky through his telescope and
saw a new galaxy 'appear' when its light finally got here.
   In 1995, the Hubble Space Telescope (HST)  made a 'deep field'
survey with a 10-day 'exposure' time. This long exposure, with the
then-updraded optics of the HST, showed galaxies from billions of
years ago. The light from these objects has been reaching us for some
time, but it was so faint (inverse square law) that a *long* exposure
was necessary to see them.

>> It is my guess that my confusion has something to do with the fact
that it is SPACE itself that is expanding.
   Space *is* expanding; the rate of this expansion is known as the
Hubble Constant, and is one of the reasons why the space telescope was
called 'Hubble'- astronomers needed a tool to help them determine the
magnitude of the Hubble constant.
   The rate of expansion depends on the distance involved. Current
measurements put this rate (the Hubble constant) somewhere around 55
km/s per 3 million lightyears. (Other rates have been suggested.)
Thus, an object 12 billion light years away appears to be moving away
from us at 220,000 km/s! Obviously, there are some serious issues
involved with this; anything older than about 16.3 billion years may
not be visible to us because of this expansion rate. However, the age
of the universe is currently estimated to be around 13.7 billion years
old.

>> is the universe expanding faster than the speed of light? 
There is nothing in physics, as now understood, which would prevent
space from expanding faster than the speed of light. If the universe
was expanding faster than the speed of light, the light from these
objects might not ever reach us.

>> Is the galaxy "12 billion light years away" based on "now" or based on "then"?
The answer is "yes". Some assumptions have been made- that the speed
of light, for example, has been constant over all that time. It took
12 billion years for the light from that distant object to reach
Earth.

Resources:
Google for 'hubble deep field','hubble deep field south','hubble constant'
Inflation: http://www.biols.susx.ac.uk/home/John_Gribbin/cosmo.htm
Age of the universe: http://www.astro.ucla.edu/~wright/age.html

The answer is very simple but very difficult to grasp. According to
current postulation, the present size of the universe is in the region
of 156 billion light years across yet the age is only 13.7 billion
years. So I sympathise with your problem. Point is though, that the
universe must not be visualised as an expanding ball because there is
nothing into which it is expanding. The universe is *everything* and
it is *that* which is expanding. Light travelling in the expanding
medium of the universe is likewise expanded so even though light is
received from objects far further than 13.7 billion light years away,
it still hasn?t travelled faster than the speed of light. You?re dead
right when you say it?s something to do with space expanding.

The initial bang expanded the universe at very nearly the speed of
light so light had a tough time making progress from one object to
another even though they were in simple terms very close. Little green
men on far distant objects look towards earth and see merely the
nebula from which earth etc will evolve -- which is the image we have
of them. Also of course, they see *us* as being on the edge of the
universe. Tricky, but the link below does a fuller explanation.

http://www.space.com/scienceastronomy/mystery_monday_040524.html

Join the confused club :-)

Best

another interesting thing is wether or not the travel of light is
affected but the expansion of the universe.

eg. a star 3 million light years away emits a flash of light. during
the time it takes for us to see it, if the star which emitted it moved
another 30 million light years away and, theoretically, the position
of sol and our solar system does not greatly change its position from
when the light was first emitted, does it only the first 30 million
light years or does it travel a further distance?

Hi,

>> The short question is: Why is the light from those galaxies just
getting to us now?

Short answer: because it took 12 billion years for photons to travel to us.

>> Secondary questions:  Isn't the universe expanding? 
>> Doesn't that mean that those galaxies were much closer to the
cosmological >> coordinates that represent "us" 12 billion years ago
when the light first >> left on its journey?

Probably, or only pieces of galaxies, or even, at the time of big
bang, a homogeneous entity.

>> Why didn't it "arrive" billions of years ago?  Shouldn't
>> we be seeing "newer" light? Or, is the universe expanding faster than
>> the speed of light?  Is the galaxy "12 billion light years away" based
>> on "now" or based on "then"?

Something being 12 billion light years away means actually that we are
able to see NOW reflection of light that reflected 12 billions AGO
from a certain object which was on a certain location and looked like
that 12 billion years ago. We are actually seeing a very old picture
of them. However, the light is constant, if not interrupted by some
other object along the viewing path. We can continue watching that
galaxy in Earth-real-time, but unless it comes closer to us (or our
galaxy to it), the difference between what we see and what is
immediatelly going on will remain constantly these 12 billion years.
So, you can actually never see what is going on NOW with these
galaxies. For that fact, you could never see what is going on really
"now" on even solar system planets. If you further look at this matter
from the micro-view, everyting your eye can see is more "old picture"
the further the object you are looking at is.

Following all this, if we adopt the calculations saying universe is
only about 14 billion years old and that, in the begining everything
was coloser to each other, we did always "recieved information" (such
as images, sounds, etc) of everything that exist - it was just a
question where and what we were looking at and with which sensors
(eyes as basic ones, telescopeas as most advanced). As time passed,
and galaxies went/were formed further one from another, a slowdown of
information flow occured.

If universe was expanding faster than light can travel, you simply
wouldn't be able to see anything. Also, atomic structure of materials
which are able to reflect light (like soil, gas, etc) prohibits such
materials to travel faster than light.

However, if we presume this 12 billion light years away galaxy and our
galaxy were first neighbours in the beginning, that would mean that,
in average, the two galaxieas in question (ours and the one you've
mentioned) traveled away fom each other at speed a bit lower than half
of light speed, if they travelled as result of universe expansion in
exactly opposite direction (at 180 degree angle). On the other hand,
if we also count in the assumption that whole universe is 156 billion
light years wide (meaning - counting in only one dimension!), that
would mean that "something" travelled at light speed from each other,
under the same 180 deg. angle, about 78 billion years, which is.. um,
a bit longer than 13.7. This is explained through Hubbles law, but in
basic - if you are measuring a distance from one point to another, as
we do with light in this case, and starting point moves away, because
of this expansion, it results that light actually travelled further
distance than it could only by it's speed. This is halfway to claim
that traveling faster than light is possible, but it's not - starting
point A in referential system X (a galaxy) did not change, same as
ending point B in referential system Y (another galaxy), but as the
Universe itself, as the ultimate referential system for measurement,
expands - these figures are the only helpers to describe relative
positions and distances in units and by maths we know and understand.

At least, that's the theory.