Do galaxies appear to be closer together the further we look out in space?

Can we tell the density of space from the number of supernova we see near the end of the visilbe universe compared to stuff closer to us?

It would seem that the universe as we are currently seeing it should be MUCH more dense near the edge of the visible universe as it is around us.

This is a question i have considered about myself.
Reading through some of the theory about the visible edge of the universe it seems that the accelerating expansion rate is so fast that the space is expanding faster than light beyond this point so we seem to have a cosmic event horizon at approx 16 billion light years away from us. Could one conclude from this that the density of matter/energy to space ratio reduces at these regions?

The density should increase ... as we are looking back in time to a point when the universe was much more dense.

Yep, density does increase with redshift, and continues to decrease as time passes.

I see your point, but is that not perception rather than physical reality? the further distance you look the further back in time you see, a time when the universe was much closer and much more dense. In reality wouldn't the expansion of space reduce the density ratio of the most distant universe?

hmmm ... but you should be able to factor that out mathmatically based on the redshift.

Interesting...BUT. Completely wrong.

What we observe as the visible edge of the universe is not,. Mater according to you should be denser at or near this edge area, but the 13.7 billion years of expansion has thrown mater a awful long way from its apparent position or denser start point. Understanding that no such start point might be found... all a little confusing for such a simple mind, mine.

As I understand this accelerating expansion suggests density is dropping as time and distance is covered. We might find detectable remnants of the microwave background radiation from the earliest expansion using very sensitive radio telescopes, or arrays of them... I would not expect higher areas of density at the outer regions of the universe.

To find this increase in density we would need to get back there to when and where this was a much smaller universe. Its not looking like that is a possible conclusion now. But then my confidence could be destroyed by a good argument... bring it on
Mark.

When you look at the galaxies in the "Hubble deep field", you see galaxies that are generally closer together than galaxies are now. If you look even farther, there is not much to see but quasars, and I don't know what can be said about the density of them because there is also the important effect of how they "turn on" as they form and "turn off" as they age. Eventually you can see the cosmic background radiation formed at the epoch of "recombination", almost 400,000 years after the beginning. The density then was indeed much higher than it is today. You cannot see any farther back than that, so you can't see the higher densities at even earlier times. Dark energy and acceleration doesn't do much to these observations-- you are seeing a time when such acceleration was not occuring because the effect of dark energy was comparatively weak then. You do see the acceleration we have undergone in recent years, but that shows up as an increase in the redshift we see, and does not affect the densities we infer when we have independent distance or density indicators.

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If we understood everything going on in the head of a pin... we still wouldn't know not to step on the pointy end.

People think the problem with models is that they are limited by our minds, but the greater problem is that our minds are limited by our models.

So just that I get you ...
As we look a little back in time we see galaxies closer together but after a point we cant see anything really so we cant tell if things are closer together.

It's more correct to say that the galaxy clusters are closer together, moreso than the galaxies themselves, as you don't see the expansion on scales inside a galaxy cluster. But yes, that's more or less correct. After a point we must rely on indirect inferences that we get from running the laws of physics backward and seeing if what we find makes sense with how it could have gotten that way. That becomes harder and harder to do the farther back you go, and impossible if you take it all the way to a "singularity".

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If we understood everything going on in the head of a pin... we still wouldn't know not to step on the pointy end.

People think the problem with models is that they are limited by our minds, but the greater problem is that our minds are limited by our models.

The most distant quasar I know of now is SDSS J114816.64+525150.3 at redshift 6.42 (Fan, et al., 2003). At that redshift the universe is 903,000,000 years old, about 1/15 of its current age of 13,700,000,000 years, in the context of the current concordance cosmology (using Ned Wright's cosmology calculator). Certainly there is no object with an observed redshift greater then 7, which corresponds to a universe that is 778,000,000 years old. Ken G makes the point that it's the distance between galaxy clusters rather than individual galaxies that is important here. The highest galaxy cluster reshifts are rather smaller. Overzier, et al., 2008 reports a protocluster at redshift 4.1, which is the highest cluster redshift I know of, corresponding to a universe aged 1,526,000,000 years. That's still about 1/9 of the current age of the universe, and so still quite a way back in time. So those are the hard limits on how far back we can see, albeit the higher the redshift, the fewer the number of objects we can see.

We can easily measure the angular distance between the objects we see, that's a direct observation. but translating those angular measurements into linear measurements requires a cosmological model that describes the geometry of the universe, and specifies the distance as a function of redshift. So it is potentially misleading to say that we see things closer together in the past. In fact we only "see" this after we apply a cosmological model to the observations. Radically change the cosmology, and you radically change the implied history of the universe. So when we say that things are closer together in the past, we are combining our cosmological model with the comoving volume calculated from general relativity, and thus deriving appropriate volumes (and consequent density) from the data.

Ned Wright discusses comoving coordinates in part 2 of his cosmology tutorial.

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Don't try this at home - We're what you call "professionals" - MythBusters.

We're already seeing all the way back to within 380,000 years of the origin of the Universe when we detect the cosmic microwave background radiation (CMBR), created when protons and electrons were first moving slowly enough to be able to combine to form hydrogen atoms. Before that, the particles comprising the hot primordial plasma were moving so fast that they could only collide and bounce off each other. The CMBR is currently coming to us from 13.7 light years away. As time goes on, we'll continue to receive it from ever increasing distances, but we'll never see it from earlier times.

There is a distance beyond which the expansion rate of the Universe relative to us exceeds the speed of light. That does not mean that anything beyond that distance is actually moving faster than light. It means only that the distances between objects at that distance and us are increasing faster than the speed of light because of expansion of the Universe. The special theory of relativity does not prohibit that.

The above perspective should answer most of the questions raised in this thread. A few questions remain.

Supernovas offer no clues to the density of the Universe at various epochs in the history of the Universe because the frequency of their occurrence in given volumes of space at various times is not known with useful precision.

Acceleration of the expansion of the Universe adds only a secondary perturbation to the history of the expansion. This evidently will not remain true in the future.

Other than because theory says so, how do we know that the CMBR is coming to us from 13.7 light years away ?

We don't. The cosmological interpretation of the CMB is entirely dependent on cosmological models. However, one should not take this too lightly, as in "it's just a model", or fall for the notion that because it is model dependent, then it is "just a guess".

Every observation that we make about anything is subject to interpretation in the context of one model, or a few, or even many, models. We always ask, what are the alternatives? The observational fact that the CMB is strictly thermal is a strong constraint on physical causes for the CMB. I can't think of any local mechanism that can do it.

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Don't try this at home - We're what you call "professionals" - MythBusters.

Thanks, Tim Thompson, you gave a more comprehensive response to tommac than I was going to.

Yes the weight of scientific opinion, is the weight of scientific opinion. Most of us at some time have questioned this... and excepted it.
A very large number of very well read people have questioned this truth...
For the time being this would seem to be the ' The meaning of life the universe and everything' and until some other equally probable idea presents itself I will except it. A suggestion you do the same would save you a lot of wasted time.