Thread: Evidence for expansion of the universe?

What direct evidence is there for the expansion of the universe other than the cosmic redshift?
When evaluating alternative theories, what should be considered related facts?
Cosmic redshift - Yes
Time dilation of distant objects (proven ?)
Rotation of galaxies (Dark matter assumed?)
Cosmic background radiation ?

I have my own pet theory that I am trying to test against observations, real evidence for cosmic time dilation or large amounts of dark matter would kill my theory dead.

Originally Posted by PetTastic

What direct evidence is there for the expansion of the universe other than the cosmic redshift?

Direct evidence is difficult to find. One additional fact may be that the number of merging galaxies is larger at larger distances (= younger cosmic age) than in the local universe (=nowadays). This means that galactic encounters must have been more frequent pointing to a denser universe. In a nutshell, galaxies appear to have been closer to each other.

Originally Posted by PetTastic

When evaluating alternative theories, what should be considered related facts?
Cosmic redshift - Yes

The cosmic redshift is probably the most compelling evidence we have. It is not only its pure existence, but its properties that are so striking. It is isotropic regardless of direction. So, this is at least a universal phenomenon and nothing that can be attributed to individual objects and their true proper motion.

Originally Posted by PetTastic

Time dilation of distant objects (proven ?)

Interesting concept. Is the idea that higher relative expansion velocities should introduce a time dilation effect that increases with redshift? I have never thought nor heard about it. I will try to find out more.

Originally Posted by PetTastic

Rotation of galaxies (Dark matter assumed?)

The phenomenon is observed, but the reason for this is not clear. Everybody is talking about Dark Matter, but nobody knows what it may be. Other explanations are investigated, too.

Originally Posted by PetTastic

Cosmic background radiation ?

This is generally interpreted as the redshifted radiation of an optically thick, dense, hot, and ionised early universe. Fundamental considerations would then point to a denser universe at about 380000 years after the hypothesised so called Big Bang.

Another evidence that can be extracted from the analysis of the anisotropy of the CMBR is the power spectrum of emission cells. If you look at the WMAP maps, you see a granularity that has a certain size distribution. A thorough analysis is able to distinguish between different cosmological models. Again, an expanding universe model provides the best fit to the data. The measurement is currently repeated at a better resolution with the PLANCK satellite.

asking for direct evidence on theories? theories all of them that have yet to be proven.... until we advance technologically ( i saw another 10-15 years the way computers are advancing these days they'll be able to solve all these problems themselves. but i made a little dark matter theory myself but who knows right? i still haven't gotten a reply saying i'm stupid or explaining why its not possible. maybe i'll start some astro-physcist out there and he'll be able to make sense and link things together. I could probably read up and study like a rat in a hole for a long time and figure it out.... but does that sound like fun???

Time dilation of distant objects (proven ?)

Originally Posted by Dishmaster

Interesting concept. Is the idea that higher relative expansion velocities should introduce a time dilation effect that increases with redshift? I have never thought nor heard about it. I will try to find out more.

When calculating the distance to galaxies using Cepheid variables or eclipsing binaries is time dilation assumed & therefor corrected for?

Day job permitting, Ive been playing around with galaxy rotation curves to see the effect on dark matter from various ideas I am playing with.
But the distance to the object & therefor its size has a big effect on the maths of spinning objects.

My current favorite theory does not have a time dilation associated with the comic redshift, but I can't simply adjust other peeps figures without knowing what they have assumed. (all gets a bit chicken & egg)

exactly right on with the chicken and egg theory, cuz we have a universe now and what made the universe start and what made that start making the universe..... did it start somewhere or did it just pop up. you know if we can fake documents and such to look old, don't you think that would apply to the universe... hahah that sounds extremely stupid but still; it sort of makes sense if you take a step back, whats stopping the universe from putting on a display for us, are we gonna be able to fly by any stars in our lifetime let alone in the human races lifetime..... go figure....

Originally Posted by PetTastic

What direct evidence is there for the expansion of the universe other than the cosmic redshift?
When evaluating alternative theories, what should be considered related facts?
Cosmic redshift - Yes
Time dilation of distant objects (proven ?)
Rotation of galaxies (Dark matter assumed?)
Cosmic background radiation ?

I have my own pet theory that I am trying to test against observations, real evidence for cosmic time dilation or large amounts of dark matter would kill my theory dead.

I believe I can disprove expansion using circumstantial evidence, which is what expansion is anyway. I have been debating it on the BBC science forum and cannot get an answer as to what space is, that being the cornerstone of expansion. The very lack of an answer is telling in itself.

Redshift can be explained away as can DM. Time dilation at present is in deep trouble over distant quasars because it is not present. CMB I have ideas on.

The only proof of expansion would be to live enough millions of years to see galaxies actually move away from each other all over the universe (except where local gravity holds them together).

The big problem is we have no point of reference outside space or the universe to see what is going on.

I have been playing around with versions of the expansion of the universe that do not assume we are special. (cosmological principal)

The current version assumes object on the human scale are not effected by the metric expansion, therefor there is no need to correct our view of space for the expansion of the universe effecting the viewpoint.

As for what is space?
There seems to be space & matter, but matter is mostly space with bits held in place by an electromagnetic field.

I am currently guessing that the odd rotation of galaxies & cosmic redshift are the bast clues we have to what is going on. If they are linked in someway.