The image above (mouse over to watch the animation) visualizes what is mathematically indeed simple: a small shift in the foreground but in the distance the disappearance of dozens of galaxies beyond the particle horizon. (The "speed of moving away" is obviously much higher in the distance – it all mounts up infinitely over distance.)
The "speed of moving away" rises with distance. For very large distances the increase is always 'faster than light' (no discovery is needed to have that math).
Ok, that was the status quo of astrophysics and cosmology for 80 years now, known since 1927.
But what was discovered then at the beginning of the 21st century (awarded with Nobel Prize in Physics 2011) was the ability to draw spectacular conclusions from much more precise measurements than ever before.
There are huge databases now of galaxie's redshift and of brightness from type Ia supernovae. There are unbelievable clever engineered satellites and telescopes. – But do we see really progress? - Collecting data is not enough for advances in science knowledge.
I have to ask again: What is the discovery awarded with Nobel Prize, what are the cosmological conclusions? [alt link]
They measured a mismatch of redshift and brightness of standard supernovae. That's all.
And the conclusions miss the point. They are not capable to see this:
The galaxies' "speed of moving away" is in the distance a billion times faster than light!
So, what are these "physicists" talking about ? .. "Accelerating universe".. – Well. We are all a bit slow in thinking. They need it faster.
[a slightly confused passage of my draft:] Sadly, in the matter scale of space there is the rise of the (in the end pointless) issue 'accelerating universe'. The scaling of space will be better understood one day. But what nowadays unfortunately happens is mainly to try to measure "space-decelerating matter" (mainly dark matter) and "matter-accelerating space" (dark energy).
Both are wrong approaches. ( More precisely: it's idiotic nonsense, see   )
There can't be a recollapse of spacetime when it is not implied by the nature of spacetime itself, whether or not matter could form 'universewide gravity' (If you give it some thought).
The center of 'Everything' is everywhere 
SNAP - Supernovae Acceleration Probe: "Most astronomers assumed [the expansion of the universe] would be slowing down because the gravity of all the combined objects in the universe would be hitting the cosmic brakes." [alt link]
That is a wrong assumption, not only hold by SNAP and "most astronomers" for at least ten years.
Gravity is a vector heading toward the center of matter concentration (in fact it's a warp in spacetime). Cosmic-scale there is for gravity no center to head toward. That means: Gravity can fundamentally not act contrary to space scaling as a whole (decelerate it). (see  )
Space scaling (as opposed to gravity) is not a vector, it has no direction and no center. The big bang is not an explosion with a locatable point of origin and the universe is not a sphere. It has no center.
( To use a SNAP quotation ironically: "This was perhaps the biggest scientific shock of the late 20th Century.")
Momentum of expansion? – Apples to oranges? 
Acceleration by gravity is a relativistic effect in space. Scaling space itself is non-relativistic. Matter does warp the grid of spacetime but it can't pull back the grid itself that was once casted.
Again: Gravity can fundamentally not act contrary to space scaling as a whole. Matter can not influence the alleged recollapse of spacetime. Simplified: it can not retract light once emitted.
When "most astronomers assumed [ .. ] cosmic brakes." (see  ) I would say: majorities really can be scary!
To brake billions of galaxies from a speed billion times faster than light is not a matter of (imaginary quite big) kinetic energy. Space scaling is not Newton's physics. So it could easily happen – if it were in the nature of spacetime itself.
I read a hundred times the wrong sentence (written by professors and Nobel Prize winners): the universe got it's momentum (of expansion) by the big bang and will slow down by gravity. – To say it again clearly: the big bang is not an explosion (so there is no "momentum") and there is no center of mass (for gravity to "brake").
The fun part of the question is: How much Dark Energy is needed to accelerate the galaxies to the measured speed (to drive the universe apart)? You can watch water-level reports by esa, mpi or lbl (just updated from 72.8% to 68.3%). -- It's fun but they all know it's a "zero" question, it's a trick (to catch the public money monthly). (see  )
Distance—age confusion 
There are very few publications that give informations whether or not there are maximum values for the distance of galaxies. Prominent are samples where the values for distance and age of a galaxy are close to the alleged maximum of 13.8bn.
The distance between far galaxies is caused by the (non-relativistic) scaling of space while it is measured by (relativistic) redshift. There is nothing wrong with that interlacing of principles. But the measurement says nothing about how 'large' the universe is. (see  ) There are galaxies in a distance of 100bn light-years as well. The difference is: the light from there didn't arrive here yet resp. can't arrive ever.
The scaling of space – 'the cosmological shift of galaxies to infinity and beyond' – is not bound to the speed of light.
The correlation distance / redshift is reasonable. A correlation distance / 'age of the universe' is not.
Space is a sponge 
Scale of space means to scale the appearance of objects (the length of the edge of a table), atom sizes, wave lengths of electromagnetic waves etc. (Except the speed of light – scaling everything would be identical to scaling nothing.)
That is scaling of space. – In principle, not in real.
In real scaling space of the universe is like scaling a sponge without scaling the holes. (We are in a hole.) Everything that is a cluster of matter is not scaled. Even the diameter of a galaxy is not scaled. Only space where in 10 million light-years is not a grain of dust is scaled.
Otherwise (when scaling everything together) the early stage of the universe wouldn't be more dense than it is today.
Spacetime and it's scaling are universewide. Matter, it's warp of spacetime and the absence of space scaling there are in each cluster locally bounded. (Clusters of galaxies are holes of local influence in the universe where space scaling magically not happens but instead warp of spacetime.)
I would say the term 'scale of space' is not well-chosen for that (from the human-centered point of view).
It's more like unpacking of nothingness.
Energy that is not an energy 
'Dark energy', another term in the same issue, is not well-chosen as well.
It doesn't affect matter, acceleration or speed in space (like energy would do). It's (when I would accept the term) about this: where, when and at what rate takes space scaling place – and where not ( "Where are the holes in the sponge" ).
Dark energy has (when I connect what could be true about it) a correlation to concentration of matter but doesn't interact with matter.
Too stupid to calculate 
The more practical question is: how to calculate intergalactic (space-scaled) distances?
1bn light-years is the distance light travels in 1bn years?
Right, but this information is quite outdated. Actually it is more than 1 bn years old. The distance of a galaxy with that measurement is much larger. It's
1bn light-years + increase of that distance in 1bn years time by space scaling.
Scientists work with algorithms and relativistic dimensions I've never heared of. So, it is very likely I am the one who is too stupid to calculate. But I'm not sure.
Flyspeck thinking 
At the time of my youth the term universe was equivalent to immeasurable and limitless.
Later some mathematicians (who do not know the abstraction of a graph from reality) said to us something like this: the origin of the universe is pea-sized, it's history is condom-shaped and it's weight is 200 bn galaxies.
Well, in this case you can't calculate what the truth is. You only can conceive what the nature of something is. -- What is the nature of the universe when you go from Planck length to DNA code, from octopuses in the ocean to giant black holes and clusters of galaxies?
It's obscene immoderateness and not limitation.
And now let's name the one who believes this: Just at a distance where the particle horizon sets in the existence of galaxies stops. The universe is not obscene limitless but 200 bn galaxies big.
Isn't it the idiot, still today pre-Copernican?
The universe is how we think of the universe. – The universe is just what terms we think in.
Flyspeck or immoderateness.
I don't understand Einstein's attitude 
A. Friedmann und G. Lemaître adapted the Einstein field equations to the universe (in the 1920's). – And I can't understand why. (The difficulty to understand tensors in detail is not the point.) Today most physicists think the Einstein field equations were formulated to describe the universe. But they were not. -- Why didn't at least Einstein say: It would be compelling for becoming famous but it's nonsense. A planet can't orbit the universe (because there is no outside). And so the universe can't act in spacetime as an object in itself. The universe can't force gravity on itself as a whole. It has no shape, no center of mass (no direction for gravity). And there is no value for mass/energy – it's nonsense.
The field equations describe gravity as geometry. There can't be "gravity of the universe" because the universe as a whole has no geometry.
The incessantly circulating 70% dark energy derived from field equations are simply ridiculous.
But I will be lost with this argument. I shall not oppose Einstein. ( B. S. )
" I all the while went beyond.."
A quarter of a year after I published this blogpost some topics of my footnotes already sliped into Wikipedia articles. For example "Expansion of the universe" is renamed "Expansion of space" now and proper calculation of intergalactic distances is mentioned more often.
I guess after a while the whole "dark energy" issue will silently change into what some insurgents silently introduced into science with their blogposts. (Surely I'm not the only one who fights the pseudoscience of the Einstein Mafia.) When Wikipedia articles will have changed, it will become unclear why I had such a critical view on astrophysicists.
What will dinosaur 'astrophysicists' say later? : " I and dark.. what? – I all the while went beyond this silly 'dark energy'." .. .. For sure. Assholes!
I wrote more on the topic here:
Web links - the universe