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Name: Richard
Status: other
Grade: other
Location: NV
Country: N/A
Date: N/A


Question:
Scientists believe that the universe is around 14 billion years old, give or take. We are able to look into the past using telescopes, in which we are able to see, according to the Hubble Ultra Deep Field images, the way the universe looked 13 billion years. But the image shows galaxies that look completely formed, and not in the process or forming. None of these deep space images shows a primordial universe, with structures that should later have formed into galaxies billions of years later. My question is, do these images of well formed galaxies from 13 billion years ago therefore shed doubt on the Big Bang theory, and if not, why not, and why are we unable to view a primordial universe when looking back in time?


Replies:
Howdy Richard,

Indeed, we do look back in time by observing objects father away.

I think most of the objects in the Hubble Deep Field are around 12 billion years in age. This would give them a rather long time to develop after the big-bang. There are images where objects older are observed, for instance in the Hubble Ultra Deep Field (HUDF).

The HUDF images appear to observe galaxies that were already forming within the first billion years after the big bang. Indeed, many of these galaxies do appear to be quite young in character when compared to other, closer galaxies. There are a few surprises, for instance finding galaxies that appear slightly older than anticipated. However, these are most probably a chance for further explanation and refinement of the existing ideas and not direct contradictions.

A discussion of this very topic, a "teenager" galaxy among a group of "toddler" galaxies can be found at :

http://hubblesite.org/newscenter/archive/releases/2005/28/full/

This suggests that our ideas about exactly what was happening with galaxy formation in the early universe need a little refinement, but not a wholesale revision. The article itself mentions that interactions (or even collisions) between new galaxies may well explain the presence of a more developed galaxy amongst younger appearing ones. It's actually a nice example of how science works.

Furthermore, the basic idea and predictions of the big-bang theory are quite sound and robust. In short the big-bang theory predicts a red shift that increases with distance, a cosmic background radiation, and the relative abundance of Hydrogen and Helium in the universe. It does all this with some rather simple ideas.

I suppose the other things to remember in all this, is that the time scales involved are ones which we have difficulty fully appreciating. A million years is a very long time for things to happen. A hundred million years, a billion years, those are really huge lengths of time.

best wishes,

Michael S. Pierce
Materials Science Division
Argonne National Laboratory


The deep field galaxies are small, close together, and irregular. They are not equivalent to the galaxies that exist in the present time. A lot of evolution and merging has occurred since the time of the galaxies imaged in the deep field and ultra deep field pictures.

Some of the galaxies seen in the deep field photo are not so old because they are not so far away. To get an idea of where things are, take a look at the deep field picture posted at

http://nedwww.ipac.caltech.edu/level5/Deep_Fields/mirror/hdfn/.

This image map is rigged so that you can click on a galaxy in the image and learn about its characteristics, including its red shift "z" value, which correlates to its distance and age. (The bigger the z value, the farther away the galaxy, and the sooner after the big bang.)

You will note that all of the galaxies of recognizable classical shape (spirals, ellipticals) are fairly contemporary. The really old stuff (note, for example, a little smudge above one of the stars in the image - a star in the lower left right next to a yellow spiral galaxy oriented upper left-to-lower right - the smudge galaxy is to the right of the yellow spiral galaxy and above the star, and has a z value of 3-4) is fairly undistinguished. These are not the galaxies in our local group.

Richard Barrans
University of Wyoming



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